U.S. patent number 3,861,433 [Application Number 05/398,212] was granted by the patent office on 1975-01-21 for air tight food container.
This patent grant is currently assigned to Plastofilm Industries, Inc.. Invention is credited to Robert W. Graves, Jacques Schier.
United States Patent |
3,861,433 |
Schier , et al. |
January 21, 1975 |
AIR TIGHT FOOD CONTAINER
Abstract
A two-piece container of self-supporting sheet-like plastic
including a dish and cover therefor. The dish and surmounting cover
are formed and dimensioned to establish in their assembled
configuration a substantially air-tight frictional seal precluding
invasion of atmosphere-carried contaminants into the container,
thereby ensuring enhanced shelf life of comestibles packaged in the
container.
Inventors: |
Schier; Jacques (Deerfield,
IL), Graves; Robert W. (Park Forest, IL) |
Assignee: |
Plastofilm Industries, Inc.
(Wheaton, IL)
|
Family
ID: |
23574459 |
Appl.
No.: |
05/398,212 |
Filed: |
September 17, 1973 |
Current U.S.
Class: |
220/782; D7/610;
220/793 |
Current CPC
Class: |
B65D
43/0222 (20130101); B65D 2543/00842 (20130101); B65D
2543/00351 (20130101); B65D 2543/00092 (20130101); B65D
2543/00157 (20130101); B65D 2543/00296 (20130101); B65D
2543/00537 (20130101); B65D 2543/00527 (20130101) |
Current International
Class: |
B65D
43/02 (20060101); B65d 011/02 (); B65d
011/10 () |
Field of
Search: |
;150/.5
;220/42A,42C,70 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Norton; Donald F.
Attorney, Agent or Firm: Berkman; Michael G.
Claims
What is claimed is:
1. A container for the shipment and storage of comestible products
to retain said products sealed from the ambient atmosphere thereby
to preclude contamination from organisms and other deleterious
agents present in the atmosphere and to provide extended shelf life
for products contained and held in said package,
said container comprising, in combination, a dish-like base, and a
cover for support on and sleeved over said base in hermetically
sealing frictional securement therewith,
said base constituting
a molded dish of thin, self-supporting material and including
a floor,
wall means including an inner principal product-retention wall
extending generally upwardly of said floor and integrally formed
therewith to provide a unitary one-piece structure,
said wall means being reversely curved upon itself at an upper
extremity thereof to define a circumambient ridge,
a skirt-like auxiliary wall constituting a container sealing wall
depending downwardly from said ridge and spaced radially outwardly
from said product retention wall and extending therearound,
said container sealing wall terminating on a circumferential line
along a locus intermediate the vertical expanse of said
product-retention wall in an integrally formed peripheral ledge
continouus with said container sealing wall and projecting
outwardly therefrom in a generally horizontal plane;
said cover constituting an upwardly vaulted closure element of
thin, self-supporting plastic material, said cover being
dimensioned for attachment to said base in contiguous frictional
engagement therewith, said cover including
a top wall,
a side wall integrally formed with said top wall and depending
downwardly therefrom around the periphery thereof,
a lower marginal portion of said side wall constituting a
smooth-surfaced upstanding substantially vertical endless band for
frictional securement to said container sealing wall of said base
in overlying contiguous abutment thereagainst and encircling the
periphery thereof to define an air-tight seal between said cover
and said dish, and
a flange integral with and extending horizontally outwardly from
and substantially normally to said band around the entire perimeter
of said cover,
said flange of said cover seating flatly on said ledge of said base
when said cover is in place on said base to close said container,
and
finger-grip tabs integrally formed with and extending laterally
outwardly from each said ledge of said base and said flange of said
cover,
said tabs being circumferentially offset from one another to
facilitate the grasping thereof to pull said base and said cover
apart.
2. The structure as set forth in claim 1 wherein said band at the
lower marginal portion of the side wall of said cover is offset
outwardly with respect to the side wall projecting upwardly
therefrom to provide shoulder means extending perimetrically about
said cover.
3. The structure as set forth in claim 1 wherein said flange of
said cover and said ledge of said base are in substantially
air-tight abutment to establish a second zone of sealing contact
between said cover and said base.
4. The structure as set forth in claim 1 wherein said side wall of
said cover is deformed to provide perimetrically spaced generally
parallel external rib means extending upwardly from said band
toward said top wall to stiffen said side wall and to strengthen
said package.
5. The structure as set forth in claim 1 wherein said container
sealing wall of said base and said band of said cover of said
package are sleeved in radially stressed engagement to provide a
tensioned seal between said base and said cover.
6. The structure as set forth in claim 1 and further comprising
gutter means extending peripherally around said floor of said dish
and defining a floor-encircling moat integrally formed with and
separating said floor from said wall means; whereby said floor is
disposed in a horizontal plane displaced upwardly from a lower
limit of said wall means.
7. The structure as set forth in claim 1 wherein the transverse
inside dimensions of said cover are no more than outside dimensions
of said base at corresponding overlapping peripheral positions
thereof, whereby upon forced placement of said cover onto said base
to close said container tensioned contact is established between
said band of said cover and said sealing wall of said base to
enhance the seal therebetween.
8. The structure as set forth in claim 1 wherein inside dimensions
of said cover as measured thereacross at a line defined by an
intersection with said band of a horizontal plane passing
therethrough is less than the outside dimensions of said container
sealing wall as measured at corresponding positions,
whereby stretching of said cover at said band occurs when said
cover is placed in position on said dish to establish between said
cover and said dish a tensioned overlapping engagement.
9. The structure as set forth in claim 8 wherein, prior to
stretching, said cover, as measured transversely thereacross at
said band, has an overall outer dimension about 0.015 inch less
than the transverse dimension of said dish as measured at
corresponding opposed perimetric positions.
10. The structure as set forth in claim 1 wherein said band of said
cover flares upwardly and outwardly from its lower extremity and
wherein the cross sectional dimension of said band at its free end
is less than a maximum horizontal dimension of said base as
measured at said ridge, whereby application of force is necessary
in positioning said cover in place over said ridge and onto said
base.
11. A container for the shipment and storage of comestible products
to retain said products sealed from the ambient atmosphere thereby
to preclude contamination from organisms and other deleterious
agents present in the atmosphere and to provide extended shelf life
for products contained and held in said package,
said container comprising, in combination, a dish-like base, and a
cover for support on and sleeved over said base in hermetically
sealing frictional securement therewith,
said base constituting
a molded dish of thin, self-supporting material and including
a floor,
wall means including an inner principal product-retention wall
extending generally upwardly of said floor and integrally formed
therewith to provide a unitary one-piece structure,
said wall means being reversely curved upon itself at an upper
extremity thereof to define a circumambient ridge,
a skirt-like auxiliary wall constituting a container sealing wall
depending downwardly from said ridge and spaced radially outwardly
from said product retention wall and extending therearound,
said container sealing wall terminating on a circumferential line
along a locus intermediate the vertical expanse of said
product-retention wall in an integrally formed peripheral ledge
continuous with said container sealing wall and projecting
outwardly therefrom in a generally horizontal plane;
said cover constituting an upwardly vaulted closure element of
thin, self-supporting plastic material, said cover being
dimensioned for attachment to said base in contiguous frictional
engagement therewith, said cover including
a top wall,
a side wall integrally formed with said top wall and depending
downwardly therefrom around the periphery thereof,
a lower marginal portion of said side wall constituting a
smooth-surfaced upstanding substantially vertical endless band for
frictional securement to said container sealing wall of said base
in overlying contiguous abutment thereagainst and encircling the
periphery thereof to define an air-tight seal between said cover
and said dish, and
a flange integral with and extending horizontally outwardly from
and substantially normally to said band around the entire perimeter
of said cover,
said flange of said cover seating flatly on said ledge of said base
when said cover is in place on said base to close said container,
and
said band of said cover being flared upwardly and outwardly from
its lower extremity and the cross sectional dimension of said band
at its free end being less than a maximum horizontal dimension of
said base as measured at said ridge, whereby application of force
is necessary in positioning said cover in place over said ridge and
onto said base.
12. The structure as set forth in claim 11 wherein said band at the
lower marginal portion of the side wall of said cover is offset
outwardly with respect to the side wall projecting upwardly
therefrom to provide shoulder means extending perimetrically about
said cover.
13. The structure as set forth in claim 12 wherein said shoulder
means of said cover bears upon said ridge of said dish.
14. The structure as set forth in claim 13 wherein said ridge of
said dish constitutes a radius blend formed upon reversely curving
said wall means of said base upon itself, and wherein said shoulder
means of said cover is in substantial abutment with a cooperating
upper peripheral edge of said ridge.
15. The structure as set forth in claim 11 wherein said flange of
said cover and said ledge of said base are in substantially
air-tight abutment to establish a second zone of sealing contact
between said cover and said base.
16. The structure as set forth in claim 11 and further comprising
finger-grip tabs integrally formed with and extending laterally
outwardly from each said ledge of said base and said flange of said
cover,
said tabs being circumferentially offset from one another to
facilitate the grasping thereof to pull said base and said cover
apart.
17. The structure as set forth in claim 11 wherein said side wall
of said cover is deformed to provide perimetrically spaced
generally parallel external rib means extending upwardly from said
band toward said top wall to stiffen said side wall and to
strengthen said package.
18. The structure as set forth in claim 11 wherein said container
sealing wall of said base and said band of said cover of said
package are sleeved in radially stressed engagement to provide a
tensioned seal between said base and said cover.
19. The structure as set forth in claim 11 and further comprising
gutter means extending peripherally around said floor of said dish
and defining a floor-encircling moat integrally formed with and
separating said floor from said wall means; whereby said floor is
disposed in a horizontal plane displaced upwardly from a lower
limit of said wall means.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to improvements in plastic
containers of the single use throw-away type for food or other
materials or products. The invention has particular utility as a
container for products or materials which are advantageously kept
substantially air-tight, as for example sandwiches, hamburgers, pie
servings and the like which are stored in and dispensed from
vending machines, including refrigerated machines. Accordingly, for
the sake of simplicity and clarity, the invention will be described
with reference to this particular field of use.
The prior art is replete with plastic containers which have been
used in the packaging of comestibles of the type stored in and
distributed from vending machines. It will be appreciated that
effectiveness and the economics of a successful vending machine
operation depend upon packaging under such conditions as will
ensure a reasonable shelf life for the products offered to the
public. Utilizing the containers of the prior art, it has not been
possible to achieve a shelf life for refrigerated type comestibles
of more than about three days. At the end of this relatively short
period it has been necessary to reclaim or recall those products
which have not been vended and to discard them, a procedure which
is not only inefficient but costly. The prior art packaging of
comestibles for distribution through vending machines has utilized
packages which are, for the most part, poorly sealed against
atmospheric contamination. It is believed that this shortcoming of
the containers is a primary cause of the very limited shelf life of
the food products packaged.
While heat sealing of containers to establish a hermetically sealed
package is an effective protective technique, the procedure is
costly and time consuming and poses certain obvious problems in the
opening of the package preparatory to consumption of the food item
contained therein. Accordingly, it is the aim of the present
invention to obviate the shortcomings of prior art packages and to
provide a simple yet highly effective container which is
hermetically sealable without the application of plastic-fusing
heat, but relies solely on improved frictional engagement between
the component parts.
It is a principal object of the invention to provide a
self-supporting container of sheet-like plastic and which includes
a dish and a surmounting cover, the two being so formed and
dimensioned as to establish therebetween a hermetic seal upon
closure of the container.
Another object of the invention is to provide an improved package
for comestibles to ensure an enhanced shelf life of products stored
for dispensing from a vending machine.
Yet another object of the invention is to provide an improved
plastic container for the shipment and storage of comestibles,
which container is readily closed and opened, manually, without any
need to fracture the container or sever parts thereof.
Still another object of the invention is to provide a two-piece
container for comestibles and including a relatively shallow opaque
base or dish and a surmounting vaulted transparent cover, the
latter frictionally engaging with the former to provide an
essentially hermetic seal therebetween.
A further object of the invention is to provide, in a container of
the type including a dish-like base and a surmounting cover, finger
gripping tabs by means of which the cover may be easily and quickly
removed from the base, merely by pulling the two components
apart.
Still another object of the invention is to provide an inexpensive,
single use, throw-away type container which may be readily
manufactured by conventional vacuum forming and other thermal
forming techniques.
Still another object of the invention is to provide a food
container for vending machine use, which is easy to manufacture and
which may be readily packed to provide a final package which has an
attractive appearance and good sales appeal.
Other objects, features, and advantages of the invention will in
part be ovious and will become evident upon a consideration of the
following specification considered in conjunction with the
drawing.
SUMMARY OF THE INVENTION
In accordance with the present invention, the aims and objects are
accomplished by providing in a container for comestible products a
two-piece structure of sheet plastic material including a dish-like
base and a surmounting cover in which the dish and the cooperating
cover are dimensioned and formed to establish, in their assembled
configuration, a substantially air-tight frictional seal
therebetween to preclude invasion of atmosphere-carried
contaminants into the package. It is an important feature of the
invention that the configuration adopted ensures enhanced
shelf-life of comestibles packaged and stored in the container.
The container of the invention is characterized in that it provides
an improved band or zone of sealing engagement between the cover
and the cooperating dish, the seal established being essentiallly
hermetic in nature. In a preferred embodiment of the invention the
cover is sized, with respect to the dish portion, so that actual
stretching of the plastic occurs when the cover is superimposed in
sleeve engagement on the supporting base. It is believed that this
"stretching" of the plastic establishes a tensioned gas-tight seal
which accounts for the markedly improved shelf life of products
packaged in the container of the invention. The shelf life of food
packaged in the containers of the invention is 10 days or more as
contrasted with the 3 day maximum heretofore achievable.
In a preferred embodiment of the invention the sealing between the
cover and the dish is established not only along an upstanding
annular band or zone, but in a second area defined by horizontal
flange of the cover which abuts and bears upon a cooperating
horizontal ledge integrally formed with the dish of the container.
Thus, in the specific embodiment described above, there are two
distinct and independent yet cooperating sealing areas, each
contributing to the overall effectiveness of the container in
precluding the admission of ambiant atmosphere and its contained
contaminants.
While the internal diameter or cross sectional dimension of the
cover of the container of the invention is essentially equal to but
not greater than the corresponding cross sectional dimension of the
base, in a preferred embodiment of the invention the cover is
actually slightly smaller so that some stretching of the plastic
actually occurs in positioning the cover in place on the supporting
base or dish. This structural configuration establishes a tensioned
engagement between the cooperating parts so that a live or
resilient seal is produced precluding atmospheric contamination of
the contents of the package.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more specifically and more fully described in
connection with the accompanying drawings in which:
FIG. 1 is a perspective view of one form of the container of the
invention with the cover in place on the supporting dish;
FIG. 2 is a front elevational view of the container of FIG. 1,
FIGS. 3 and 4 are cross sectional views taken respectively on the
lines 3--3 and 4--4 of FIG. 2;
FIG. 5 is a perspective view of a second embodiment of the
container of the invention, the container being in a closed
position;
FIG. 6 is a top plan view of the container of FIG. 5; and
FIGS. 7 and 8 are cross sectional views taken respectively on the
lines 7--7 and 8--8 of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and particularly to FIGS. 1, 2, 3
and 4, there is shown, for the purpose of illustrative disclosure,
a preferred embodiment of one form of the container of the
invention. The embodiment of the invention illustrated includes a
container 20 consisting of a base or dish 24 and a cover 28. As
seen in FIGS. 3 and 4, the cover is sleeved over and supported on
the dish, the peripheral configurations of the base and of the
cover being the same and the dimensional relationship being such as
to establish a hermetic seal therebetween.
The dish 24 includes a floor 30 and an upstanding wall 34
continuous with the floor 30 and integrally formed therewith. At
its upper extremity the wall 34 of the dish 24 is reversely curved
upon itself to define a circumambiant ridge 40. As an integral
continuation of the dish there is formedd a skirt-like wall 44
which depends downwardly from the ridge so that the wall 44 is
spaced radially outwardly from the product retention wall 34. The
skirt-like wall 44 serves as a principal container sealing wall, as
is more fully described and explained herebelow.
The container sealing wall 44 terminates at its lower extremity at
a position intermediate the ridge 40 and the floor 30 to form an
integrally connected outwardly extending peripheral ledge 48
projecting from the wall 44 in a generally horizontal plane. It
will be recognized that in the preferred embodiment of the
invention shown in FIGS. 3 and 4, the skirt-like wall 44 is flared
upwardly and outwardly to a slight degree. This particular
structural arrangement is important in establishing the improved
sealing effected in accordance with the present invention, as is
more fully explained hereinafter.
The cover 28 of the container 20 is upwardly vaulted or domed and
includes a top wall 52 integrally formed with a dependeing side
wall 54 and joined to the latter through an annular interconnecting
web 60, the particular configuration imparting structural stability
to the relatively thin plastic material. A series of perimetrically
spaced generally parallel external ribs 64 which are formed in and
extend vertically in the side wall 54 of the cover 28 impart
additional physical strength to the structure.
A lower marginal extremity of the side wall 54 defines a
smooth-surfaced upstanding substantial vertical endless band 70
which cooperates with the sealing wall 44 of the dish 24 to
establish a hermetically tight seal. In the preferred embodiment of
the container shown in FIGS. 1 through 4, the band 70 is offset
radially outwardly from the principal wall 52 of the cover through
an annular shoulder 74 extending perimetrically about the cover 28.
In the particular form of the invention shown, the shoulder 74 of
the cover bears upon the ridge 40 of the dish 24 therebelow.
The sealing band 70 of the cover 28 terminates at its lower
extremity in a flange 78 integrally formed with the band 70 and
extending horizontally outwardly from and substantially normally to
the band around the entire perimeter of the cover 28. The flange 78
seats flatly on and in air-tight sealing engagement against the
ledge 48 of the dish 24 when the cover is in place on the ledge to
close the container.
It is an important feature of the invention that the sealing band
70 and the flange 78 of the cover 28 and the cooperating sealing
wall 44 and ledge 48 of the dish are of substantial heights and
widths to provide a maximum of contact area between cooperating and
engaging parts so as further to ensure an effective air-tight
seal.
Referring further to important structural features which contribute
to effective sealing between the cover 28 and the base or dish 24
of the container of the invention, it will be seen in FIGS. 3 and 4
that the sealing band 70 of the cover 28 is contoured to flare
upwardly and outwardly so that in placing the cover 28 on the dish
24 it is necessary to stretch the cover or expand it somewhat
radially at its open end in forcing the band 70 of the cover over
the outer edge or extremity of the ridge 40 of the dish 24. In the
closed position of the container shown, the band 70 bears
resiliently against the sealing wall 44 and tends to force the
latter to conform in resilient and tensioned cooperation and
engagement. It will be appreciated that when the container base is
separated from or apart from the cover, the sealing wall or skirt
44 of the dish 24 extends essentially normally to the floor 30 of
the dish, the perceptible deformation evident in FIGS. 3 and 4
being the result of the tensioned constrictive engagement of the
band 70 of the cover against dish wall 44. In the structure
described there is thus provided not only an effective tensioned
air-tight frictional seal but also a mechanical interlock between
the dish 24 and the sleeved encircling cover 28. In effect, the
sealing wall 44 of the dish 24 is biased radially outwardly and the
superimposition of the sealing band 70 of the cover over the
sealing wall 44 of the dish is effective to overcome the bias and
establish a tensioned sealing engagement.
As seen most clearly in FIG. 1, for ease of separating the cover 28
from the dish or base 24 of the container, there are provided a
pair of finger grip tabs 80 and 82, integrally formed respectively
as lateral extensions of the flange 78 of the cover 28 and the
ledge 48 of the dish 24. The tabs are preferably offset with
respect to one another to facilitate gripping.
A second preferred embodiment of the container of the invention, as
illustrated in FIGS. 5 through 8, differs from first embodiment
primarily in the configuration of the base and in the overall
contour of the container. Whereas the first embodiment is round in
contour, the second is generally triangular. However, the
particular overall shape or configuration of the container
constitutes no part of the invention, the latter being adaptable to
containers of substantially any cross section. The container 100 of
FIGS. 5 through 8 includes a base or dish 104 and a cover 106, the
latter being sized and contoured for frictional engagement with the
former in sleeved arrangement, all as described with reference to
the first embodiment. Accordingly no detailed repetition of this
structure is deemed necessary. However, the dish 104 includes a
floor 108 which is displaced somewhat upwardly with respect to an
annular support ring 110 upon which the container 100 stands.
Internally, the dish 104 is formed with a floor-encircling
gutter-like moat 112 the arrangement described not only imparting
additional structural stability to the dish but providing a
safeguard against any adverse effects associated with the presence
of small quantities of liquid within the package. Any such fluid
would collect in the moat to obviate contact with the packaged
product.
The various other structural elements of the second embodiment have
been identified in the drawing by means of numerals which in each
case "parallel" the numerals assigned to the structural elements of
the first embodiment, but differing by 100, so that the correlation
of parts may be readily evident.
The above description and the drawings are provided for purposes of
illustration only and not in any limiting sense.
Any prefereed fabrication technique and any preferred structural
plastic materials may be used in producing the container of the
invention. A preferred composition is polystyrene and the preferred
manufacturing technique is thermal forming. The starting sheet
material is relatively thin before drawing, thicknesses below 5
mils the product ordinarily lack sufficient mechanical strength,
whereas the use of materials of thicknesses exceeding 50 mils
greatly increases the cost and poses technical problems. A
preferred sheet thickness is 15 mils. In the preferred particular
embodiments of the invention described, the transverse dimension of
the cover as measured at the sealing band is about 0.015 inch less
than the transverse dimension of the dish as measured at a
corresponding position. This arrangement ensures a resiliently
tensioned engagement between the component band and sealing wall
elements of the container.
While the embodiments of the invention herein disclosed are
considered to be preferred, the invention is intended to cover all
changes and modifications which fall within the spirit and scope of
the invention as hereinafter claimed.
* * * * *