Note: Descriptions are shown in the official language in which they were submitted.
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CONTAINERS WITH OPTIONAL VENTING
FIELD OF INVENTION
The present invention relates generally to the packaging industry. More
particularly, the present invention relates to polymeric foam containers with
optional
venting.
BACKGROUND OF THE INVENTION
The use of inexpensive polymeric foam containers, such as foamed alkenyl
aromatic polymeric containers, has become popular, especially for preparing
and
serving various food products. These containers generally have been used for
heating
and storing the food product(s) disposed therein. These containers typically
comprise
a cover or lid and a base.
One disadvantage of existing containers is the lack of flexibility on venting
given to the end users of these containers. Some food needs to be vented in a
closed
container, while other foods do not need venting in a closed container. For
example,
some fried foods tend to get soggy if the generated steam cannot exit the
container,
while other foods will lose heat quickly if the container has vents.
The lack of flexibility in existing containers often results in store owners
purchasing both vented and non-vented polymeric foam containers.
Alternatively, the
store owners may be forced to vent the container by ripping or puncturing it.
Such
ripping or puncturing often will result in a container that is not
aesthetically pleasing
to the end user.
A need therefore exists for a polymeric foam container to have more
flexibility
and versatility in venting for the end user.
SUIVIMARY OF THE INVENTION
According to one aspect of the invention there is provided an optional venting
container comprising a base and a lid being releasably latched to the base,
the lid
comprising at least one ventable area formed therein, the at least one
ventable area
having a perimeter defined by a cut consisting of a discontinuity between
opposing ends
of the cut, the opposing ends defining a hinge portion therebetween, the
discontinuity
spaced substantially from the hinge to define a single frangible portion, the
ventable area
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being adapted to form a vent by applying pressure within the perimeter to
rupture the
single frangible portion.
According to a further aspect of the invention there is provided an optional
venting container comprising a base and a lid being releasably latched to the
base, the lid
comprising at least one ventable area formed therein, the at least one
ventable area
having a perimeter defined by a cut consisting of a discontinuity between
opposing ends
of the cut, the opposing ends defining a hinge portion therebetween, the
discontinuity
spaced substantially from the hinge to define a single frangible portion, the
ventable area
being adapted to form a vent by applying pressure within the perimeter to
rupture the
single frangible portion, and wherein the lid is made from polymeric foam.
According to another aspect of the invention there is provided an optional
venting
polymeric foam container comprising a base and a lid and a first hinge, the
lid being
releaseably latched to the base, the lid comprising at least one ventable area
formed
therein, the at least one ventable area having a perimeter defined by a cut
consisting of a
discontinuity between opposing ends of the cut, the opposing ends defining a
second
hinge portion therebetween, the discontinuity spaced substantially from the
second hinge
to define a single frangible portion, the ventable area being adapted to form
a vent by
applying pressure within the perimeter to rupture the single frangible
portion, the first
hinge connecting the base to the lid and allowing the lid to pivot with
respect to the base,
and wherein the base and lid are made from the same polymeric foam.
According to yet another aspect of the invention, there is provided a method
of
forming a polymeric foam container comprising:
providing a foamable resin in an extruder;
melting the foamable resin in the extruder;
extruding the foamable resin from the extruder to form an extruded material;
thermoforming the extruded material into a container including a base and a
lid
releasably latched to the base, the lid including at least one ventable area
formed therein,
the at least one ventable area having a perimeter defined by a discontinuous
cut
consisting of a discontinuity between opposing ends of the discontinuous cut,
the
opposing ends defining a hinge portion therebetween and the discontinuity
spaced
substantially from the hinge portion to form a single frangible portion.
According to still another aspect of the invention there is provided a
polymeric
foam lid adapted to be releasably latched to a base, the lid comprising at
least one
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ventable area formed therein, the at least one ventable area having a
perimeter defined by
a cut consisting of a discontinuity between opposing ends of the cut, the
opposing ends
defining a hinge portion therebetween, the discontinuity spaced substantially
from the
hinge to define a single frangible portion, the ventable area being adapted to
form a vent
by applying pressure within the perimeter to rupture the single frangible
portion, and
wherein the lid is made from polymeric foam.
According to a further aspect of the invention there is provided a method of
forming a polymeric foam lid, the lid being adapted to be releaseably latched
to a base,
the method comprising:
providing a foamable resin in an extruder;
melting the foamable resin in the extruder;
extruding the foamable resin from the extruder to form an extruded material;
thermoforming the extruded material into a lid, the lid including at least one
ventable
area formed therein, the at least ventable area having a perimeter defined by
a
discontinuous cut consisting of a discontinuity between opposing ends of the
discontinuous cut, the opposing ends defining a hinge portion therebetween and
the
discontinuity spaced substantially from the hinge portion to form a single
frangible
portion.
According to one embodiment, an optional venting container comprises a base
and a lid. The lid is releasably latched to the base. The lid comprises at
least one
ventable area formed therein. The at least one ventable area is adapted to
form a vent
only upon a user asserting pressure thereon. The lid is made from a polymeric
foam.
According to another embodiment, an optional venting container comprises a
base and a lid. The lid is releasably latched to the base. The lid comprises
at least one
ventable area formed therein. The at least one ventable area is adapted to
form a vent
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only upon a user assertino pressure thereon. The at least one ventable area is
formed
by a perforation cut. The lid is made from a polymeric foam.
According to a further embodiment, an optional venting polymeric foam
container comprises a base, a lid, and a hinge. The lid is releasably latched
to the
base. The lid comprises at least one ventable area formed therein. The at
least one
ventable area is adapted to form a vent only upon a user asserting pressure
thereon.
The at least one ventable area is formed by a perforation cut. The hinge
connects the
base and the lid and allows the lid to pivot with respect to the base. The
base and the
lid are made from the same polymeric foam.
According to one method, a polymeric foam container is formed by providing
a foamable resin in an extruder. The foamable resin is melted in the.extruder
and then
is extruded from the extruder to form an extruded material. The extruded
material is
thermoformed into a container comprising a base and a lid. The lid is
releasably
latched to the base. The lid comprises at least one ventable area formed
therein. The
at least one ventable area is adapted to form a vent only upon a user
asserting pressure
thereon.
Accordino to yet another embodiment, a polymeric foam lid, which is adapted
to be releasably latched to a base, comprises at least one ventable area
formed therein.
The at least one ventable area is adapted to form a vent only upon a user
asserting
pressure thereon. The lid is made from a polymeric foam.
According to another method, a polymeric foam lid, which is adapted to be
releasably latched to a base, is formed by providing a foamable resin in an
extruder.
The foamable resin is melted in the extruder. The foamable resin is extruded
from the
extruder to form an extruded material. The extruded material is thermoformed
into a
lid. The lid comprises at least one ventable area formed therein. The at least
one
ventable area is adapted to form a vent only upon a user asserting pressure
thereon.
According to an aspect of the present invention there is provided an optional
venting container comprising a base and a lid being releasably latched to the
base, the
lid comprising at least one ventable area formed therein, the at least one
ventable area
having a perimeter defined by a cut consisting of a discontinuity between
opposing
ends of the cut, the opposing ends defining a hinge portion therebetween, the
discontinuity spaced substantially from the hinge to define a single frangible
portion,
the at least one ventable area being adapted to form a vent by applying
pressure within
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the perimeter to rupture the single frangible portion and wherein the lid
further includes
a sidewall and a top wall, the sidewall encompassing and extending generally
downward from the top wall, the top wall having an angled surface located near
intersection of the top wall and the sidewall, the at least one ventable area
being formed
on the angled surface so as to improve venting when containers are stacked
upon each
other.
According to another aspect of the present invention there is provided an
optional venting container comprising a base and a lid being releasably
latched to the
base, the lid comprising at least one ventable area formed therein, the at
least one
ventable area having a perimeter defined by a cut consisting of a
discontinuity between
opposing ends of the cut, the opposing ends defining a hinge portion
therebetween, the
discontinuity spaced substantially from the hinge to define a single frangible
portion,
the at least one ventable area being adapted to form a vent by applying
pressure within
the perimeter to rupture the single frangible portion, and wherein the lid is
made from
polymeric foam and wherein the lid further includes a sidewall and a top wall,
the
sidewall encompassing and extending generally downward from the top wall, the
top
wall having an angled surface located near intersection of the top wall and
the sidewall,
the at least one ventable area being formed on the angled surface so as to
improve
venting when containers are stacked upon each other.
According to a further aspect of the invention there is provided an optional
venting polymeric foam container comprising a base and a lid and a first
hinge, the lid
being releaseably latched to the base, the lid comprising at least one
ventable area
formed therein, the at least one ventable area having a perimeter defined by a
cut
consisting of a discontinuity between opposing ends of the cut, the opposing
ends
defining a second hinge therebetween, the discontinuity spaced substantially
from the
second hinge to define a single frangible portion, the at least one ventable
area being
adapted to form a vent by applying pressure within the perimeter to rupture
the single
frangible portion, the first hinge connecting the base to the lid and allowing
the lid to
pivot with respect to the base, and wherein the base and lid are made from the
same
polymeric foam and wherein the lid further includes a sidewall and a top wall,
the
sidewall encompassing and extending generally downward from the top wall, the
top
wall having an angled surface located near intersection of the top wall and
the sidewall,
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the at least one ventable area being formed on the angled surface so as to
improve
venting when containers are stacked upon each other.
According to a further aspect of the present invention there is provided a
method of forming a polymeric foam container, the method comprising:
providing a foamable resin in an extruder;
melting the foamable resin in the extruder;
extruding the foamable resin from the extruder to form an extruded material;
thermoforming the extruded material into a container including a base and a
lid
releasably latched to the base, the lid including at least one ventable area
formed
therein, the at least one ventable area having a perimeter defined by a
discontinuous cut
consisting of a discontinuity between opposing ends of the discontinuous cut,
the
opposing ends defining a hinge portion therebetween and the discontinuity
spaced
substantially from the hinge portion to form a single frangible portion
wherein the lid
further includes a sidewall and a top wall, the sidewall encompassing and
extending
generally downward from the top wall, the top wall having an angled surface
located
near intersection of the top wall and the sidewall, the at least one ventable
area being
formed on the angled surface so as to improve venting when containers are
stacked
upon each other.
According to a further aspect of the invention there is provided a polymeric
foam lid adapted to be releasably latched to a base, the lid comprising at
least one
ventable area formed therein, the at least one ventable area having a
perimeter defined
by a cut consisting of a discontinuity between opposing ends of the cut, the
opposing
ends defining a hinge portion therebetween, the discontinuity spaced
substantially from
the hinge to define a single frangible portion, the at least one ventable area
being
adapted to form a vent by applying pressure within the perimeter to rupture
the single
frangible portion, and wherein the lid is made from polymeric foam and wherein
the lid
further includes a sidewall and a top wall, the sidewall encompassing and
extending
generally downward from the top wall, the top wall having an angled surface
located
near intersection of the top wall and the sidewall, the at least one ventable
area being
formed on the angled surface so as to improve venting when containers are
stacked
upon each other.
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According to a further aspect of the invention there is provided a method of
forming a polymeric foam lid, the lid being adapted to be releaseably latched
to a base,
the method comprising:
providing a foamable resin in an extruder;
melting the foamable resin in the extruder;
extruding the foamable resin from the extruder to form an extruded material;
and
thermoforming the extruded material into a lid, the lid including at least one
ventable
area formed therein, the at least ventable area having a perimeter defined by
a
discontinuous cut consisting of a discontinuity between opposing ends of the
discontinuous cut, the opposing ends defining a hinge portion therebetween and
the
discontinuity spaced substantially from the hinge portion to form a single
frangible
portion, wherein the lid further includes a sidewall and a top wall, the
sidewall
encompassing and extending generally downward from the top wall, the top wall
having an angled surface located near intersection of the top wall and the
sidewall, the
at least one ventable area being formed on the angled surface so as to improve
venting
when containers are stacked upon each other.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the invention will become apparent on reading the
following detailed description and on reference to the drawings.
FIG. I is a perspective view of a container according to one embodiment of the
present invention;
FIG. 2 is a top view of the container of FIG. 1;
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FIG. 3 is a cross-sectional view taken generally along the line 3-3 of FIG. 2
in
a closed position; and
FIG. 4 is a cross-sectional view taken generally along the line 3-3 of FIG. 2
in
a vented position.
While the invention is susceptible to various modifications and alternative
forms, a specific embodiment thereof has been shown by way of example in the
drawing and will herein be described in detail. It should be understood,
however, that
it is not intended to limit the invention to the particular form disclosed
but, on the
contrary, the intention is to cover all modifications, equivalents, and
alternatives
falling within the spirit and scope of the invention as defmed by the appended
claims.
DESCRIPTION OF ILL,USTRATIVE EMBODIMENTS
Referring to FIGs. 1-4, a container 10 according to one embodiment of the
present invention is depicted. The height and shape of the container may vary
from
that shown without departing from the scope of the invention. For example, the
container 10 is shown as being generally rectangular or square, but it is
contemplated
that shapes like oval, circular, and other polygonal and non-polygonal shapes
may be
used.
The container of the present invention is typically used to hold food. The
container may be used for serving, storing, preparing and/or re-heating the
food such
as pre-packed meals. The container of the present invention desirably has
insulating
properties to assist in maintaining the temperature of any food contained
therein. One
example of such a container is an alkenyl aromatic polymeric foam container.
The container 10 of FIGs. 1-4 includes a base 12, a lid 14 and a hinge 16. The
hinge 16 connects the base 12 and the lid 14 and enables the lid to rotate
relative to
the base so as to open and close the container 10. The lid 14 is adapted to
releasably
engage the base 12. According to another embodiment, the base and the lid may
be
formed from separate pieces without using a hinge. In this embodiment, the lid
is also
adapted to releasably engage the base.
The base 12 comprises a bottom 18 and a sidewall 20 that encompasses and
projects upwardly and outwardly from the bottom 18. It is contemplated that
the
sidewall may project only upwardly from the bottom. The bottom and/or sidewall
may include ribs for additional carrying strength. It is contemplated that the
base may
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be a generally flat surface that is adapted to releasably engage the lid. In
such an
embodiment, the base would not include a sidewall extending upwardly
therefrom.
The base 12 may further include an optional rim (e.g., continuous rim 22 in
FIGs. 3 and 4) that encompasses and projects laterally outwardly from the
sidewall 20.
The optional rim may be discontinuous, although, if used, it is preferred to
be
continuous. The rim is advantageous for a number of reasons including
providing
supporting strength when the container is being placed in the closed position.
Additionally, the process of making the container, such as by thermoforming,
is made
easier by using a rim. Alternatively, the container may be formed without a
rim.
The lid 14 comprises a top wall 24 and a sidewall 26 that encompasses and
projects downwardly and outwardly from the top wall 24_ The top wall 24 is
desirably
elevated with respect to the cooperating base 12 to accommodate the food
products
therein. The top wall 24 may include a central portion that is recessed
relative to a
remainder of the top wall to cooperate with the base (like base 12) of another
is container stacked atop the container 10. It is contemplated that the
sidewall may
project only downwardly from the top wall. The lid 1.4 further includes an
optional
rim 28 (see FIGs. 3 and 4) encompassing and extending upwardly and outwardly
from
the sidewall 26. It is contemplated that the optional rim may only project
outwardly
from the sidewall. If an optional rim is formed on the lid, it is desirable
that it
corresponds with aii optional rim formed on the base.
The lid 14 further comprises a plurality of ventable areas 30 formed therein.
The plurality of ventable areas 30 is shown in FIGs. 1 and 2 as being located
in the
generally corner of the lid 14 on a top wall 24 thereof. The plurality of
ventable areas
enables a user, if desired, to vent steam, pressure and/or heat caused by food
32
25 located in the container 10 as shown in FIGs. 3 and 4. The plurality of
ventable areas
30 stays closed, keeping in steam, pressure and heat until the user decides
that the
ventable areas should be opened to vent any steam, pressure and/or heat
contained
therein. Additionally, the plurality of ventable areas, when closed, functions
as a
protective barrier or wall to prevent or inhibit dust or other particles from
entering the
30 container 10.
The plurality of ventable areas 30 does not open automatically once the
internal pressure reaches a certain point associated with the heating of
foods. Thus,
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whether the contents of the container are vented is determined solely by the
user. It is
contemplated that the container may have at least one ventable area, which is
formed
in the lid. Thus, it is contemplated that the lid may form exactly one
ventable area.
According to one embodiment, the plurality of ventable areas 30 of FIG. 2 has
5 three sides 30a-c that are not continuous connected. The three sides 30a-c
may be
formed by a knife blade or sharpened section of tool steel that includes at
least one
score therein to assist in keeping the ventable area in a closed position.
This is
referred to herein as a perforated area. Because the at least one score is
formed in one
or more of the sides 30a-c, for example, the three sides 30a-c are not
continuously
connected. This is shown with score 30g in FIGs. 2 and 3. It is contemplated
that
each side 30a-c may have a plurality of scores formed therein.
The perforated areas may be moved to an open position by, for example, a
hinge or crease upon a user asserting pressure thereon. For example, the user
may
push downwardly on the ventable area to assert pressure to move the ventable
area to
is an open position. Alternatively, the user may grasp the ventable area and
assert
pressure to move the ventable area to an open position.
It is contemplated that the plurality of ventable areas may be formed with a
knife cut. The knife cut may cut completely through the surface of the lid. In
this
embodiment, the plurality of ventable areas remains generally closed until the
user
asserts pressure thereon. Thus, in a closed position, the ventable areas
retain a
substantial amoiuit, if not virtually all, of the steain, pressure and/or heat
contained
therein and, thus, does not vent until the user moves the ventable area to an
open
position by asserting pressure thereon. For exainple, the user may push
downwardly
on the ventable area to assert pressure to move the ventable area to ail open
position.
Alternatively, the user may grasp the ventable area and assert pressure to
move the
ventable area to an open position.
It is contemplated that the kraife cut may not extend completely through the
surface of the lid. For example, the knife cut may extend at least 50% into
the surface
so as to allow a user to move the ventable area to an open position by
asserting
pressure thereon. The knife cut typically extends at least 75% or even 90% or
95%
into the surface of the lid so as to allow a user to move the ventable area to
an open
position by asserting pressure thereon.
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The area between ends 30d and 30e of respective sides 30a, 30c may form a
hinge. The hinged area allows a respective one of the plurality of ventable
areas 30 to
pivot in a manner that allows the steam, pressure and/or heat to escape from
the
container 10. Alternatively, the area between ends 30d and 30e of respective
sides
30a, 30c may form a crease. The crease assists in moving a respective one of
the
ventable areas to a vented position. It is contemplated that the plurality of
ventable
areas may be moved to an open position without using a hinge or crease. A
crease,
however, may form after opening the ventable area.
To vent the container according to one method, a user presses downwardly on
the ventable area 30 as shown in FIG. 3, resulting in the ventable area 30
opening and
venting steam, heat and/or pressure from the container 10 as shown in FIG. 4.
Alternatively, a user may grasp the ventable area and assert pressure thereon
to move
the ventable area to an open position. The ventable area 20 after being moved
to a
vented position desirably remains with the remainder of the lid. It is
contemplated
1s that the ventable areas may be detached from the remainder of the lid
during
movement to the vented position.
The plurality of ventable areas may be located in different areas on the lid
than
depicted in FIGs. 1 and 2, including the sidewalls 26 of the lid 14 and other
locations
of the top wall 24 of the lid 14. It is desirable to locate the phirality of
ventable areas
near or in the top wall so as to assist in preventing or inhibiting any liquid
juices of the
food product from escaping the container 10. The liquid juices, if present,
should
remain in the container 10 as long as the container 10 is not substantially
tilted
towards any of the plurality of ventable areas 30. It is also contemplated
that if a
compartmented container is used, then at least one ventable area may be
located over
certain foods. Thus, if a certain food in one of the compartments is the only
one to be
vented, then the ventable area located nearest to this compartment is opened,
while the
remaining ones of the ventable areas remain closed.
At least one ventable area may be located on a relative flat surface such as
top
wall 24 to assist in preventing or inhibiting a scraping action similar to a
shear key.
This assists in forming a ventable area that will open on pressure from the
user. This
also assists in making the cut without having to push the material out of the
way. At
least one ventable area may also be formed on a slight angle (such as shown in
FIG. 1)
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to allow improved venting when the contai.ilers are stacked upon each other.
For
example, this angle may be from 0 to about 45 and, more specifically, from
about 100
to about 20 relative to a parallel plane of the top of the container.
The base and the lid may be formed with one of a variety of latching or
closure
mechanisms known to those skilled in the art. For exainple, the base and lid
may be
releasably latched by a latching mechanism described in U.S. Patent No.
5,758,791.
Releasably latched is defined herein as including snap engagements, firmly-
held
engagements and substantially leak-resistant engagements. It is contemplated
that the
container 10 of the present invention may be releasably latched by other known
latching mechanisms, such as that described in U.S. Patent No. 5,607,709. It
is also
contemplated that the base and the lid may be releasably latched by using
undercuts.
To assist a user in disengaging the lid 14 and the base 12, the lid and the
base may
include one or more tabs.
The plurality of ventable areas 30 of container a 0 is shown as being
generally
fmger shaped or U-shaped. It is contemplated that the at least one ventable
area may
be other shapes, such as a triangular shape, rectangular shape, other
polygonal shapes
or non-polygonal shapes. The ventable areas are desirably formed to be
aesthetically
pleasing to the user in both the open and closed positions.
According to one embodiment, the lid 14 of the container 10 is made from an
alkenyl aromatic polymeric foam. The term "alkenyl aromatic polymer" as used
herein includes polymers of aromatic hydrocarbon molecules that contain an
aryl
group joined to an olefinic group with only double bonds in the linear
structure, such
as styrene, a-methylstyrene, o-methylstyrene, m-metlrylstyrene, p-
methylstyrene, a-
ethylstyrene, a-vinylxylene, a-chlorostyrene, a-brornostyrene, and vinyl
toluene.
Alkenyl aromatic polymers also include homopolymers of styrene (commonly
referred
to as polystyrene), copolymers of styrene and butadiene, and rubber-toughened
polystyrene (commonly referred to as high impact polystyrene or HIPS). The
alkenyl
aromatic polyiner may be an oriented polystyrene (OPS). The lid may be made
from
more than one alkenyl aromatic polymer.
The lid of the container may also be formed from foams comprising
polyolefins such as polypropylene, polyesters such as polyethylene
terephthalate
(PET), and combinations thereof. The polyineric foam lid may be made from a
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g
mineral-filled polymeric material such as, for example, talc or calcium
carbonate-
filled polyolefin.
The base 12 of the container 10 may be made of the same materials described
above in forming the lid 14. Specifically, the base 12 may be formed of
alkenyl
aromatic polymeric foams, polyolefins foams such as polypropylene, polyesters
foams
such as polyethylene terephthalate (PET), and combinations thereof. The base
may be
made from a mineral-filled polymeric material such as, for example, talc or
calcium
carbonate-filled polyolefin. It is also contemplated that the base may be
formed of
other non-foamed materials such as, for example, aluminum, paper and non-
foamed
io polymeric materials, such as polyolefms and polyesters.
The containers of the present invention are typically disposable, but it is
contemplated that they may be reused at a future time. It is contemplated that
the
containers may be formed of multiple compartments. Such containers are
desirable
for placing food items in different compartments to prevent or inhibit
commingling of
items. Undesirable mixing of food items can corrupt the flavor and the
consistency of
the food items. The thickness of the container generally ranges from about 30
to
about 150 mils, but is typically from about 70 to about 100 mils.
A method of using such a container includes placing the food therein, venting
the container by opening at least one ventable area such as shown in FIGs. 3
and 4.
The container may then be placed in a heating apparatus, such as a microwave,
to heat
the food. The container may contain solid food products. The container may be
used
for storage in the refrigerator and/or the freezer.
The polymeric foam container may be formed using conventional
thermoforming (e.g., by pressure, vacuum or the combination thereof).
According to
one method of thermoforming, polymeric pellets such as an alkenyl aromatic
polymer
resin and additives, if any, are added into an extruder. The pellets of the
alkenyl
aroinatic polymeric resin and additives, if any, are melted to form a blend.
The blend
is extruded through a die to form an extruded foamed sheet. The extruded
foamed
sheet is thermoformed to a desired shape of a container.
According to this method, the container is made in a thermoforming mold.
The mold includes a knife blade or sharpened section of tool material that is
located to
form the at least one ventable area. The knife blade may be serrated. The
knife blade
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9
or sharpened section of tool material may be made of material such as steel.
It is
contemplated that other materials inay be used in forming the knife blade or
sharpened
section of tool material. The at least one ventable area may be formed in a
trirnming
step of the process.
s The knife blade or sharpened section of tool material is positioned to form
the
desired shape of the ventable areas. To assist in allowing the ventable areas
to remain
closed until opened by the user, there may be at least one score in the knife
or
sharpened section of tool material to form a perforated cut. To maintain the
sharpness
of the knife or sharpened section of tool material, the contact area below it
may have
io some cushion while still ensuring reliable contact. This contact area may
be a striker
plate that assists in aligning the knife blade or sharpened section of tool
material to
assist in properly locating the at least one ventable area. To assist in
replacing of
worn or spent tooling, the striker plate and the knife blade or sharpened
section of tool
material are often made of materials with different hardness. For example, the
striker
is plate may be made of a harder material than the knife blade or sharpened
section of
tool material such that the knife blade or sharpened section of tool material
will be
replaced more often than the striker plate.
While the present invention has been described with reference to one or more
particular embodiments, those skilled in the art will recognize that many
changes may
20 be made thereto without departing from the spirit and scope of the present
invention.
Each of these embodiments and obvious variations thereof is contemplated as
falling
within the spirit and scope of the claimed invention, which is set forth in
the following
claims.
