Note: Descriptions are shown in the official language in which they were submitted.
'7~3
Case 3664 CIP-l
VACUUM PACXED CANNED PRODUCT AND
2 METHOD USING FOIL MEMBRANE END CLO~URE
4 TECHNICAL FIELD
This invention relates to a vacuum packed canned
6 product, especially for foods, having an easy opening
foil membrane closure, and a method of forming such a
8 package.
10 BA~KGRO~ND OF_THE INVENTION
A number of products, and particularly food
12 products in granular form, are packaged in cylindrical
cans wherein one of the can ends is readily opened by
14 peeling back a thin foil membrane which is adhered to
that end. Such membranes comprise a flesible
16 foil/plastic composite structure adapted to define a
closure member which is heat sealed to a tin plated
18 steel or an aluminum can end. Such a closure is
described in two publications. Firæt,
20 Aluminum-Walzwerke Singen Gmbh, Alusingen-Platz 1,
D-7700 Singen/Hohentwiel, Federal Republic of Çermany,
22 in their April 4, 1987 edition entitled A~UFIX
-Laminate Stock for Easy Opening Can Ends. Second, a
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1 February 6, 1988 article entitled "Specialty Stamps Out
Sharp Edges with its New End".
3 Such laminated foil membranes are capable of
numerous combinations in end constructions employiny
Surlyn or heat-sealing lacquers used as he~t-seallng
coatings. Polyamides used as heat-sealing coatings are
7 similarly employable for retortable products, as set
forth in the above-noted Alusingen publication. Such
9 closures have come to be known as Rychiger type
closures.
11 Membrane end closures are also described in the
Hardt U.S. Patent No. 4,328,905, issued May 11, 1982,
13 and the Markert U.S. Patent No. 4,098,404, issued July
4, 1978.
However, while such easy opening foil membrane end
closures have been known heretofore, the
17 state-of-the-art until now has not provided a solution
for successfully and reliably vacuum packaging a dry,
19 granular product su~h as coffee. Cof~ee, esperially
roasted and ground co~fee, is necessarily packaged
21 under a substantially ~ull vacuum o approximately 29
inches of Hg, and more generally speaking, at least 20
23 inches o~ Hg. Only an extremely tight closure can
withstand such rigorous conditions. The need for such
a tight closure is compounded by the fact that products
of this type, especially canned cof~ee, are subjected
27 to abusive physical conditions in the final stages of
the manu~acturing process, after th~ can has been
29 completely closed, in shipping and handling in
commerce, and over a relatively long storage time
31 (o~ten up to a year) until the can is u timately opened
by the consumer. Notwithstanding these rigorous
33 conditions, and especially in view of the long shelf
life o~ such a product, even a small, essentially
unperceivable microscopic leak will in tlme destroy the
vacuum and render the product u~ele~s. And ye~, in
37 order to be commercially ~ucces~ul, the reliability of
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1 such a seal would have to be so great that the
percentage of leaking cans would be extremely low,
probably far below 1/2 of 1 percent of all cans
produced and sold.
In contrast to these extremely rigorous conditions,
the entire concept of an easy opening container is to
7 provide a closure which can be easily opened under
simple manual force by a consumer of average strength.
9 Thus, the entire concept associated with an easy
opening, peelable foil membr~ne closure is essentially
11 at cross purposes with the rlgorous requ rements for
the vaouum packaging of a dry, granular product such as
13 cof~ee or the like.
The vacuum packaging of coffee in a can presents
additional problems. A can containing roasted and
ground coffee must necessarily have a relatively wide
17 openinq. Consequently, a full vacuum will necessarily
pull the foil membrane into a downward concave shape.
19 The larger ~he opening, the farther down the ~oil
membrane will be pulled. To assure the airtight
21 integrity of the seal, the upper boundary of the
product cannot be `so high that it would prevent the
23 foil membrane from deforming downwardly into the can.
However, i~ the product is routinely filled to a lower
level which appears to be too ~ar beneath the top of
the can, the avera~e consumer might well be
27 dissatisfied because the can will appear to be less
than full. This problem is not resolved by making the
29 openi~g smaller. The average consumer demands that the
opening be larger than a minimum size, ~enerally
31 sufficient for the consumer to plac~ h or her hand
down into the can.
3~ To my knowledge, b~ore the present invention there
have been no succes~ful comm~rcial applications o~
easily peelable foil membrane closures ~ )r a vacuum
packed food product such as co~fea or ~ ~l like. ~he
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1 Markert U.S. Patent No. 4,098,404 relates to a vacuum
package, and casually mentions co~ee as one of the
3 products that can be packaged by the invention
disclosed therein. However, this reference does not
disclose the specific parameters which I believe are
necessary for the successful packaging of a dry,
7 granular product under vacuum conditions.
y SUMMARY OF THE INVENTION
Thus, the purpose of the present invention is to
11 provide a vacuum packaged dry, granular product having
a reliable, easy opening, peelable foil membrane
13 closure.
This purpose is achieved, in accordance with the
present invention, by providing a canned product and a
method of packaging same, wherein the cortainer,
17 generally a metallic can, has an upper end having t~e
peelable foil membrane attached thereto such that the
19 holding force between the foil membrane and the end of
the can is su~ficient to reliably maintain vacuum
21 during abusive handling conditions, including
packaging, shipping and long ~torage of the cans,
23 while concurrently being removable with a peel force
acce~able to a consumer o~ average strength.
In accordance with one asp~ct of the present
invention, these desirable characteristic~ are
27 achieved by providing the prop~r combination of the
foil thickness, the adhexence characteristics of the
29 adhe~ive and the width o~ the annular band at which
the ~oil membrane is adhered to the top o~ the can.
31 It would appear that the band width must be at a
minimum of approximately 2.5 mm, but preferably over
3~ approximately 3.0 mm, and ~ven more preferably
approximately 3.4 mm. In contra~t thereto prior ~`oil
membranes, which were used on small di eter,
non-vacuum cans, had a band width o~ r~ nore than 1.9
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1 mm. In combination therewith, the ~oil membran~
should preferably be relatively thic~, preferably
3 approximately loo microns, but generally in the range
of 80-100 microns, or possibly up to 120 microns.
This compares to prior membranes of approximately 60
microns, used in prior non-vacuum applications. In
7 combination therewith, the adhesive is preferably a
hot melt PVC.
9 Foil membranes of the present type are generally
provided with some type of embossing Heretofore, the
11 purpose of such embossing has been primarily to
enhance the appearance of the ~oil membrane. However,
1~ when using foil membranes of this type in the context
of the present invention, the embossing has the added
advantage of forming undulations which resist the
return of the foil membrane to its original shape,
17 after being pulled concavely downwardly by the vacuum
in the can, as the negative pressure in the can is
lY gradually, slightly reduced over the shelf life of the
product.
21 Notwithstanding the rigorous demands upon the
airtight seal between the foil membrane and the end of
23 the can, the foil membrane should be openable by a
peel ~orce acceptable to the average consumer.
Generally, this would be between 4 and 10 pounds.
- Roasted and ground coffee, like many products, is
27 sold in dif~erent size containers. For example, a
so-called on~-pound can of coffee is generally sold in
29 a 401 size can (having a diameter of 4 1/16 inches), a
; so-called two-pound can of coffee is generally sold in
31 a 502 size can (5 2/16 inches in diameter~ and a
so-called three-pound can of co~ee is generally sold
33 in a 603 size can (6 3/16 inches in diameter).
Although the diam~ters o~ these can sizes differ, it
would be undesirable to provld~ larger ixe openings
for the larger size cans ~incc larger openings would
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1 cause the ~oil membrane to ~lex too far concavely
downwardly into the can. ~owever, i~ the size of the
openings on the larger cans is kept the same size as
on the smaller cans, these openings must still include
at least one point relatively close to the edge of the
can so that when the consumer pours the dry, granular
7 product out of the can, there would be at least one
point where the product could pour easily, unhindered
9 by a large flange between the opening and the edye of
the can. Accordingly, in accordance with another
ll feature of the present inventionl when the foil
membrane is applied for use on the larger cans, for
13 example, the 603 size cans, the opening, being much
smaller than the outer diameter o~ the can, is made
eccentric relative to the axis of the can such that at
least one point thereof is relatively close to the
17 edge of ths can, i.e., preferably spaced therefrom by
a distance substantially equal to the said band width.
19 Th~ foil membrane itsel~ is generally much thinner
and much more ~lexible than the can end to which the
21 foil membrane is attached. The foil membrane will
genPrally include a portion which exten~s beyond the
23 band and is ~olded back against the top of the foil
membrane. This will provide a tab which can be easily
grasped by the consumer and pulled back to peel back
the foil membrane from the end of ~he can, ~hus
27 exposing the opening therein~
2Y BRIEF DESCRIPTION OF THE DRAWINGS
There follows a detailed description of pre~erred
31 embodiments o~ the present inventions, to be read
together with the accompanying drawin~s wherein:
33 Fiyure 1 is a perspective view of a vacuum packed
canned product incorporating the present invention.
~igure 2 is a partial cro~s-~ectie~l view, taken
in the vertical plane through line 2-2 o~ Figure 1.
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1 Figure 3 is a plan view of Figure 1.
Figure 4 is a partial enlarged cross sectional
3 view, taken along line 4-4 of Figure 3.
Figure 5 is a xerographic view o~ the upper end of
a can of the present invention be~ore vacuum is
applied thereto.
7 Figure 6 illustrates a portion of Figure 5.
Figures 7 and 8 are enlaxged partial schematic
9 cross-sectional views illustrating the embossed
structuxe of the foil membrane before and a~ter the
11 application o~ vacuum thereto, respectively.
Figure 9 is a schematic plan view corresponding
13 generally to Figure 3, but illustrating another
embodiment of the present invention.
Figure 10 is a partial cross sectional view taken
along line 10-10 of Fi~ure 9.
17 Figure 11 is a highly schematic view illustrating
the packaging method of the present invention.
19
DETAILED DESCRIPTION OF_T~E PR~FERRED EMBODIMENTS
21 Referring now to the drawings, like elements are
represented by like numerals throughout the separate
23 views.
Figure 1 illustrates a pre~erred embodiment of the
vacuum packed canned product of the present invention,
namely a can of the type generally used for the vacuum
27 pac~ing of roa~ted and ground co~fee~ Such a
container has a metallic, cylindrical wall portion 13,
29 a bottom or lower end 11 and a top or upper end 12.
In the illustrated embodiment, the botto~ ll is of
31 conventional construction and forms no portion of the
present invention. The top 12 is closed by a foil
33 membrane 14 having a tab 15, made in accordance with
the present invention as described more fully below.
The c'an is compl~ted with a snap-on, plastic
attachable and removable cover which i~ shown in
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1 dotted lines in Figure 2 at 18, which would be used by
the consumer to pro~ect the p~oduct after removal of
3 the foil membrane.
Coffee cans are generally o~ three sizes,
including the so-called one-pound can, :sfe~red to as
the 401 size and having a diameter of a~roximately 4
7 1/16 inches, the so-called two-pound can referred to
as the 502 size and having a diameter of approximately
9 5 2/16 inches, and the so-called three-pound can,
referred to as the 603 size, having a diameter of
11 approximately 6 3/16 inches. For reasons to be
discussed in greater detail below, the foil membrane
1~ 14 will generally be concentric with the axis of the
can for the 401 and 502 size cans, as i:'.''ustrated in
Figure 1, but will be eccentric relative to the axis
of the can for larger sizes such as the 603 size can,
17 as shown in Figures 9 and 10.
Referring to Figures 2 through 4 as well as Figure
19 1, the can will contain a product 16, generally a dr--,
granular ~ood product, and especially roasted and
21 ground co~fee. The top comprises a stiff, metal
portion comprising a cir~umferential rim 20 and a
23 shel~ portion 21 which curls inwardly and downwardly
to form the opening 22 in the top of the can for
removal of the product 16. The foil membrane 14 is
adhered to the shelf portion 21 throughout the width
27 of band B by a sealant 25 (see Figure 4), the
preferred thickness of this band of sealant extending
29 for substantially completely about the circumference
of the shelf portion 21, although its thickn~ss is
31 slightly reduced at tha outer periphery in the area
where the pull tab lS is bent bacl~. As is evident in
33 Figure 2, because o~ the pull of ~he v-~ uum within the
can, the ~oil membrane 14 i~ flexed cc :avely
downwardly into the opening 22 to a maximum depth at
26. The can is fille~ wlth co~ee 16 up to a level
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1 which will allow the foil membrane 14 to de~orm
downwardly when the can reenters the atmosphere. If
3 the can is grossly over~illed to a higher level which
would hinder the downward deformation o~ the foll
membrane, this would cause an unsightly de~orming of
the foil membrane and hinder proper sealing of the top
7 12 onto the top edge of the can at the circumferential
rim 20.
9 As will be described in greater detail below, the
` material of the foil membrane 14 overlying the opening
ll 22 preferably has an undulated shape which, a~ter
downward ~lexing of the foil membrane 14, is generally
13 smooth, usually retaining only the small protrusions
31. While these protrusions would exist over the
entire area which overlies the opening 22, only a
portion thereof (only one quadrant thereof) is
17 illustrated (See Figure 3). When the vacuum is drawn
on the filled can, the embossments are stretched
19 downwardly and smoothened to varying d~grees. Close~
to the edge portions o~ the foil membrane downward
~1 flexing will generally be less than in the central
area of the foil membrane.
23 Figures 5 through 7 illustrate the nature of the
top 12 before the vacuum is applied, which vacuum
forces the foil membrane 14 into its downwardly
concave shape. Before being applied to the can 13,
27 the top 12 is in the form of a lid with the foil
membrane already attached to the shelf portion of the
2~ piece which forms the shelf 21 and the circumferential
rim 20. In a preferred arrangement, before the vacuum
31 is applied, the undulation~ are in the form of :~
depressions in the form ~ parallelogramj, preferably
33 squares, as illustrated in Figure 6 and at 32 in
Figure 7. Within each parall~logram is a raised
frustroconical portion 31. As noted above, upon the
: application of vacuum, the depressions 32 are
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1 stretched out to varying degrees. In the central area
where the stretching is greatest, only the upper
3 portions o~ the frustroconical portions 31 remain, as
illustrated in Figure 8. These portions 31 are also
illustrated in Figure 3.
An essential feature of the present invention is
7 that the foil membrane 14 be adhered to the top 12,
and in particular, to the shelf portion 21, with a
9 sufficient force that the seal will maintain its
airtight integrity, notwithstanding the extremely
11 abusive conditions to which a product o~ this nature
is subjected, while concurrently being removable with
13 a peel force acceptable to a consumer of average
strength. It is an important feature of the present
invention to provide parameters which satisfy these
conflicting purposes. These abusive conditions
17 include, firstly, the application of a substantially
full vacuum, on the order of 29 inches of Hg, a'though
19 the vacuum may be in the range of 20 - 29 inches of
Hg. In addition, the package is subject to both hot
21 and cold conditions and is continually under stress.
After the packaging process, the cans are ~urther
23 abused in shipment in co~merce, to the ultimate
customer's shelf. Additionally, a product of this
nature should have a long ~hel~ life, preferably more
than 5iX months, so that the airtight integrity of the
27 seal must remain over that long shelf life. Fo-- a
commercîal product, an extremely high level of
29 reliability, for example over 99.5%, should be
achieved.
31 If a leak does occur, the re~ults are far more
serious than the simple discarding of the can. Leaks
33 would tend to be of microscopic size, not visually
observable. If th~ leak occurs after the product has
been on ~he consumar's ~hel~, the consumer would not
nece~sariIy notice the same. However, i~ the can
1 happened to be upside down, the loss o~ vacuum plus
the weight of the coffee against the foil membrane
would distort the foil membrane, giving it a
relatively ugly appearance, as the inward ~lexing
returned to some extent, wrinkling the ~oil membrane.
But most importantly, whether the can was rightside up
7 or upside down, the loss of vacuum woul~ cause the
product itself to become stale.
The application of a foil m~mbrane to a container
for roasted and ground cof~ee presents the significant
11 additional complication of the relatively large size
of the opening. The con~umer will generally demand a
13 large size opening for a coffee can so that the
consumer can reach down into the can and otherwise
conveniently remove the product. Also, the edge of
opening must be relatively close to the rim so that
17 the consumer can easily pour product out of the can
without an unacceptahly large volume of the food
19 product being caught beneath the shelf.
However, the larger the opening, the more
21 dif~icult it becomes to provide an acceptable ~oil
membrane closure for a container of this type. As
23 illustrated in Figure 2, the pressure differential
across the ~oil membrane 14 forces it downwardly
beneath the level of opening 22~ The larger this
opening, ~he farther the foil membrane 14 will move
27 downwardly. If it is permitted to move down too far,
this could simply rupture the foil. Even i~ the ~oil
29 membrane i not ruptured, it could be pulled
downwardly so far that the product will hinder its
31 full downward flexing as di~cuæsed above, this would
give the foil membrane an unsightly appearance, and
33 hinder complete sealing of the can at circumferential
rim 20. Since this would be unacceptabla, the
~5 packager would have to redesign the container so that
a greater space would be provided b~tween the upper
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1 boundary of the product and the plane of shelf
portion. However, if this occurred, the consumer,
upon originally opening the product, would be
dissatisfied because the larger space would give the
impression that the container was not adequately
filled.
7 Figures 9 and lO illustrate another embodiment of
the present invention which illustrates its
g application to a relatively large diameter can. As
shown therein, the relatively large diameter can 40
11 includes a lid which comprises a circum~erential rim
41 similar to the circumferential rim 20 of Figures 1
13 through 4 and an inner portion 42 which forms a shelf
portion having an eccentrically located circular
opening 43 covered by the foil membrane 14 which is
attached to ths shelf portion of lid. As noted above,
17 for larger size cans, it becomes unacceptable to make
the opening as large as the diameter of the can
19 itself. Assuming that the embodiment of Figures 9 and
lO is such a relatively large can, the opening 43 will
21 be somewhat smaller than the diameter of the can 40,
but in this embodiment, more than the radius of the
23 can 40. However, for reasons discussed above, it is
also necessary that at least a portio~ of the opening
be relatively close to the edge of the can to
facilitate pouring product out of the can without an
27 unacceptably large volume o~ the product being caught
beneath the shelf. It is for this reason that the
29 opening ~3 and its covering foil membrane 14 are
positioned eccentrically on the can 40 relative to its
31 vertical axis.
In the embodiment of Figures 1 through 4, it was
noted that the foil membrane and the piece forming the
shelf portion 21 and circum~erential rim 20 are
initially formed together a~ a single unit, as
illustrated in Figure 5. The same principle would be
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1 applicable in the embodiment of Figures g and lo
except that in that embodiment the pEeformed piece
3 having the foil membrane and the shelf and rim portion
would be provided with the foil membrane 14
eccentrically located, i.e., essentially as shown in
Figure 9, but with the same embossing 30 spread
7 uniformly across the membrane 14 as shown in Figures 5
through 7, and subsequently stretched after the
9 application of the vacuum as al50 discussed above. In
all other respects, the embodiment of Fi~ures 9 and lo
11 is similar to the embodiment oX Figures 1 through 4.
The provision of a reliable, airtight seal for the
13 foil membrane 14 is further complicated by the need to
permit its easy removal, i.e., removal by a force
15 which is not too great for the average consumer.
Using a Chatillon peel tester, the peeling strength
17 could be in the range of from 4 to 10 pounds.
Although the smaller the better for the consumer, and
19 pr~ferably between 5 and 8 pounds, it has be~n found
to date that given the need for the high integrity
21 seal, a peel stre~gth can be achieved generally in the
range of 5 to 10 pounds.
23 Achieving a reliable, high integrity, airtight
seal for a vacuum p^1-ked container of the present
.ype, and considering the limi~ations and demands of
the size of the opening, the need for peel strength,
27 etc., has been achieved by combining ceriain
para~eters.
~9 A~ important parameter is the width of the band
B. At a minimum, this band width should be more than
31 2.5 mm, but preferably over 3.0 mm. In a preferred
embodiment, this band has a wid~h of 3.4 mm. This
33 band width cannot be increased indiscriminately
because a~ its width increases, so too must one
~5 incr~ase the width o~ the shel~ portior
Specifically, in the embodim~nt of Fic :s 1 through
~ 14 -
1 4, the entire shelf portion 21 would have to be
enlarged, while in the embodiment of Figures 9 and 10,
3 one would have to enlarge the shelf portion at least
at the point where the foil membrane 14 is closest to
the edge. Otherwise, as noted above, if this shelf
portion becomes too wide, the consumer will find it
7 inconvenient to pour product out of the container
because too much product would hang up behind the
g shelf portion at the point of pouring.
Another important ~actor is a provision of a
11 suitable sealant. It is necessary to use a sealant
which firmly holds the foil membrane to the metal
13 top. The preferred sealant which satisfies these
conditions would comprise a polyvinyl chloride (PVC)
lS heat sealable coating base, pre~erably applied as a
layer to the underside of the foil mPmbrane 14.
17 Preferably the ~oil membrane would be an aluminum foil
with a composition of approximately 98.3~ aluminum,
19 the sealant would be Alusuisse #410 at 12+2.4
gms/square meter.
21 Another significant parameter of the present
invention is the thickness of the foil membrane. This
2~ membrane must be thick enough to withstand the abusive
conditions referred to above, and also to retain its
downwardly ~lexed shape even as the level of vacuum
within the container is reduced over the shel~ life of
27 the product. For example, over a one-year shelf life
the vacuum could be reduced, owing to carbon dioxide
2Y buildup, from its original level of between 20 and 29
inches of Hg to a lesser level of between 5 and 10
31 inches of Hg. I~ the foil membrane were not of
suf~iclent strength, this reductio~ in the internal
33 vacuum could push the ~oil membrane upwardly. Since
the foil membrane could not possibly return to its
original embossed, undulated sha~?, a~ ~iscussed
earlier with re~erence to Figures 5 a 6, the result
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1 would be a rather ugly wrinkling of the foil membrane
14, unacceptable to the consumer. I~ will be noted
3 that the embossed, undulated shape and, in particular,
the remnants thereo~, including the remaining
frustoconical portions 31, will also assist in
preventing the ~oil membrane 14 Prom moving upwardly
7 from its downwardly flexed shape upon reduction of
vacuum in the can. However, the thickness o~ the foil
g membrane 14 nonetheless i~ a significant factor in
reducing such upward movement of the foil membrane.
11 The preferred thickness of the foil membrane, when
made of the preferred material, 98.3% aluminum, is
13 approximately 100 microns, although it is believed
that the invention would be operable with a somewhat
smaller thickness, pussibly as l~w as 80 microns. At
the upper limit, it is believed that the thickness
17 could approach 120 microns.
However, increasing the foil thickne~s presents an
19 additional problem in that it increases the difficulty
of forming the seal between the foil membrane 14 and
21 the shelf portion. To form such a seal, it is
necessary to use dies which press against the exposed
23 opposed surfaces o~ foil membrane 14 and the shelf
portion and urge them together, driving heat through
them to the sealant at the interface between them.
The thicker the foil membrane, the more difficult it
27 is to drive this heat there~hrough, and hence the more
difficult it will be to properly melt the sealant to
29 form a reliable seal.
As will be apparent from the preceding discussion,
31 the diameter of the foil membrane 14 should be fairly
large, relative to the diameter o~ the can to which it
3~ is applied. Generally, at least ~or all but the
- largsr cans, the ~oil membrane 14 should generally
approach the diameter o~ the can ~nd b concentric
therewith. However, even ~or the larg cans, as
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1 illustrated in Figures g and lo, the diameter of foil
membrane 14 should be greater than the radius of the
3 can.
The tab 15, when gripped and pulled, will transfer
the tearing stresses from the tab to a ~scused region
of points, whereby a more reliable and effective
7 action is afforded, so that the ~oil membrane 14 will
separate from its sealed relationship to the shelf
g portion.
There has been described a specific preferred
11 embodiment of the foil membrane including a certain
composition, in which case the foil membrane would
13 generally be of the thicknesses described, i.e., 80 to
lO0 microns and preferably 100 microns. ~owever, it
lS is conceivable that the foil membrane can b~ varied in
composition or shape in ways which would alter its
17 stiffness such that the preferred thickness might be
different than the range described above. For
lY example, for a foil having a harder alloy, the
thickness might be somewhat reduced. Also~ for
21 different shapes of the undulations 30 shown in
Figures 5 and 6, the strength of the foil membrane
23 might be changed, thus permitting ~ corresponding
increase or decrease in the thickness of the foil
membrane. The exterior of the foil membrane 14 will
preferably be colored differently from the underside
27 thereof, for example, gold-colored with a lacquer to
thereby provide a contrast with the tab 15 which will
29 be silver in appearance since the visible portion
thereof will be an extension o~ the underside of the
31 foil, bent back over ~he top ~hereof.
In a typical coffee container 10, the top of the
33 can itself, i.e., the material which forms the shelf
portion, thP rim and the c~rled back opening, has a
~5 thickness of 0.00~3 inche~ (i.e., 75 pounds pe ~ase
box of tin-coated steel), the wall portion 13 being
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1 approximately 0.0083 inches. Hence, the foil membrane
14 will have a thickness which is substantially
3 smaller (less than 1/2) o~ the said material forming
the top. Additionally, the foil memhran~ 14 will, of
course, be much more flexible than the mat~rial of the
shelf portion so that when the vacuum is applied, it
7 will flex downwardly far more than the shelf portion,
i~ the latter flexes downwardly at all, as best
illustrated in Figure 2.
The top 12, including ele-ments 20, 21 and 22, or
11 40, 41, and 42, will preferably be composed of steel
electroplated with tin and provided in the form of a
13 metal ring, the rim portion 20 or 40 of which will be
double-seamed to the end of cylindrical portion 13. A
1~ solvent-based compound, Viz, Midland Dexter, No. 2140
for double-seaming the end of can wall 13 may be used,
17 although a water-ba~ed compound, e~g~, Dewey and Almy,
No. 480-T, may also be us~d.
19 The method of vacuum packaging the dried granular
food product in accordance with the present invention
21 will be described with reference to Figure 11.
Initially, as shown as step A, a container 13 or 40 is
23 supplied having a conventional bottom 11 The
container is filled with product, e.g., roasted and
ground coffee at step B. Then, at step C, a lid as
shown in Figure 5 or a corresponding lid ~or the
27 embodiment of Figures 9 and lO is applied loosely to
the container, now ~illed with product. At step D the
29 lid is crimpe~ onto the upper edge of the can at the
circumferential rim. Crimping is the firs~ stage of
~1 forming the double-seam seal, wherein the lid is bent
down onto both the outer side and the inner side of
3~ the upper edge of the can, but only loosely, not yet
airtight, Thls loose, non-air~igh~ crimp will assure
that the lid stay~ in place on the can in the vacuum
chamber, while still allowing air to pass therethrough
.
, ~ ,
.. .
: ~ .
.
- 18 -
1 so a vacuum can be drawn within ~he can. The
container then enters the vacuum chambe:~ a~ E. In the
3 vacuum chamber the vacuum is drawn to evacuate air
from the can. Then, while the can is still in the
vacuum chamber, the airtight double-seam seal of the
lid to the upper edge of the can is completed as both
7 the inner and outer sides of the circumferential rim
are sealed tightly against the upper edge o~ the
g cylindrical portion of the can, completing the
hermetic, airtight, double seam seal The product
11 then passes out of the vacuum chamber at step F
wherein the atmospheric pressure acting downwardly on
13 the foil membrane 14, having the Yacuum therebeneath,
is moved concavely downwardly. Finally, as shown in
step G, a conventional attachable and removable
snap-on plastic cover 18 is applied to the can, this
17 cover to be used by the consumer after the eOi
membrane 14 has been removed.
19 Although the invention has been described in
considerable detail with respect to preferred
21 embodiments, it ~ill b~ apparent that the invention is
capable of numerous modifications and variations,
23 apparent to those skilled in the art, without
departing from the skill and scope of the invention.
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