Note: Descriptions are shown in the official language in which they were submitted.
12~;54~8
SPECIFICATION
-
This invention relates generally to containers and,
more particularly, to containers formed of Elexible sheet
materials.
Flexible containers formed of sheet materials have
been used for several years and are now gaining ever wider
acceptance for holding various air-perishable products, e.g.,
foodstu~fs, etc. Prior art flexible, air-tight containers are
rommonly constructed of some plastic film, metal foil, or
1~ combinations thereof, in one or more plies and sealed along
one or more seamsO Such containers are usually vacuumized
a~ter illing but prior to sealing so that the contents of the
container are not exposed to the degradation effects of air.
~ccordingly, products held in such containers can have a shelf
li~e comparable to rigid containers, such as jars with
3crew-on lids or metal cansO
The advantages of flexible containers over rigid
cantainers are many. For example, flexible containers can be
manuactured at substantially lower cost and can be stored
~lat, thereby resulting in enormous space savings over rigid
containers. ~oreover, flexible containers are substantially
lighter in weight, thereby resulting in reduced transportation
costs for unfilled containers. Further still, flexible
containers are generally of an overall parallelopiped shape
when filled so that such containers take up considerably less
shelf or storage space. Needless to say, this feature is of
considerable importance insofar as transportation, storage,
and display are concerned.
3~ - 2
~2~iS~
While prior art air-tight, Elexible containers
exhibit the aforementioned advantages over rigid containers,
they still have not proved a completely acceptable alternative
to hard containers for the air-tight storage of materials,
particularly when it is desired to be able to open and reclose
the container after its initial opening. In this regard, the
seams of prior art flexible containers are usually permanent
in the interest o air tightness and structural integrity and
are c~nmonly formed by conventional heat sealing or welding
techni~ues. Thus, the prior art flexible container is opened
by cutting or tearin~ one or more of its seamsO Owing to the
permanent nature of the sealed seams, the tearing of any seam
to gain a~cess to the contents of the container not only
de~troys the seal but frequently results in the tearing of the
material of the container contiguous with the seam. This is
an obviously undesirable result since it may render the
container useless for reclosure and continued holding of the
contents of the container. If the container is opened by
~utting off its top below the heat seal line, while the wall
2~ portions forming the container are not torn (thus permitting
reclosure), the container is nevertheless shorter and thus of
lower volumetric capacity.
Various flexible packaging structures have been
disclosed in the prior art utilizing tear strips and/or tear
lines to facilitate opening of the container. Examples of
such patents are United States Patent Nos. 3,186,628 (Rohde),
3,535,4Q9 (Rohde), and 3,939,972 (Mayworm).
In the United States Patent Re 30,726 (Otten et al.),
there is disclosed a pouch composed of an extruded polymer
film formed by a blend of polyethylene resin and an ionomer.
~2~S~
The pouch is ~ormed by extruding the polyethylene/
ionomer blend into a continuous tubular film which exhibits a
linear tear property in the machine direction. By linear tear
property, it is meant that the material has the inherent
propert~ to tear readily by hand along the substantially
str.~ight line by a normal shearing or parting motion without
the ne~d for gui~ing the tear. The tubular film is then slit
longitudinally, cut into transverse sections, and heat sealed
adjacent the transverse cuts to form a bag or pouch having an
1~
open top end. After the pouch is filled, the open top end is
heat sealed to close the pouch. By virtue of the orientation
o~ tha film, the resulting pouch exhibits a linear tear
~roperty across its top end. To facilitate the opening of -the
pouch across its top, one edge of the pouch adjacent the top
is slit or nicked ~o provide a starter tear. Thus, opening of
the pouch is accomplished by tearing the top off of the pouch.
While such action may be effective to provide ready
~ccess to the interior of the pouch, the tearing away of the
top portion of the pouch limits the pouch's utility eor being
~a
reused and reclosed at its top end.
OBJECTS OF THE INVENTION
AGcordingly, it is the general object of the instant
invention to provide a flexible material container and a
method of producing the same which overcomes the disadvantages
of the prior art.
It is a further object of the invention to provide a
flexible container having an air-tight sealed mouth but which
can be readily peeled open without resulting in the
destruction of any portion of the container; thereby enablng
the container to be reclosed.
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~2~
It is still a further object of this invention to
provide a flexible container having a mouth which is sealed by
a peelable interface between abutting wall portions of the
container and which interface can be readily peeled open
without destroying any portion of the container.
It is still a further object of this invention to
provide a flexible container which is resistant to tearing or
opening at all portions thereof but which includes a mouth
having an air-tight interfacial seal which can be readily
1~ paeled open.
It is yet a further object of this invention to
provide a method for producing a flexible container having an
air-tight sealed mouth which can be readily peeled open
without resulting in the destruction of any portion of the
container.
It is still a further object of this invention to
~rovide a simple and economically viable method of producing a
flexible container which is sealed by a peelable interface
between abutting wall portions of the container and which
~a interface can be readily opened without destroying any portion
of the container.
SUMMARY OF TEIE INVENTION
,
These and other objects of the instant invention are
achieved by providing a container and a method for making the
container. The container comprises a flexible sheet material
capable of being sealed for closing off the intarior of the
container from the ambient atmosphere. The sheet material is
resistant to tearing and includes an inner surface and an
outer surface. The container comprises a mouth portion incl-
3n
-- 5 --
~6~
uding peel strip means fixedly secured to the inner surface ofthe material and extending substantially the entire length of
the mouth portion. Adjacent portions of the peel strip means
are in releaseable engagement with each other to form an
air^tigllt interfacial seal at the mouth. The interfacial seal
is readily openable by peeling the engaging portions of the
peel strip means from each other to provide ready access to
the interior o the container without tearing the sheet
material forming the container.
1~ DESCRIPTION OF THE DRAWING
Other objects and many of the attendant advantages of
tl~is invention will be readily appreciated as the same becomes
better understood by reference to the following detailed
description when considered in connection with the
accompanying drawings wherein:
Fig. 1 is a perspective view of an exemplary
embodiment of a container con~structed in accordance with the
t~achings of the subject invention;
Fig~ 2 is an enlarged sectional view of a filled,
~2~ sealed container, like that shown in Fig. 1, and taken along
line 2-2 of Fig l;
Fig. 3 is a sectional view taken along line 3-3 of
Fig. 2;
Fig. 4 is an enlarged sectional view of a portion of
the container shown within the encircled area in Fig, 2;
Fig. 5 is a perspective view, greatly simpl~fied, of
a system for forming the container shown in Fig. l;
Fig. 6 is a sectional view, like that of Fig. 2, but
showing an alternative embodiment of a container constructed
in accordance with the teachings of the subject invention;
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~2~
Fig. 7 is a perspective view of apparatus for forming
the containers of this invention;
Fig. 8 is an exploded persyective view, partially in
section showing a pair of heat sealing jaws oE the apparatus
shown in Fig. 7;
Fig. 9 is a cross-sectional view of the jaws of the
apparatus shown in Fig. 7 immediately prior to sealing the
mouth of the container shown in Fig. 6; and
Fig. 10 is a view similar to Fig. 9 during the
1~ se~ling operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in greater detail to the various
igures o the drawing where like reerence characters refer
to like parts, there is shown generally at 20 in Fig. 1 the
container formed of a flexible sheet material constructed in
accordance with the instan~ invention.
The container 20 is formed oE a sheet of flexible
material, to be described later, and basically comprises a
front wall 22, a rear wall 24, a first gussetted sidewall 26,
20 a second gussetted sidewall 28, a bottom end 30, and a top end
3~. The ront wall 22, rear wall 24 and gussetted sidewalls
~6 and 28 are all integral portions of a single sheet of
1exible material which has been folded and seamed as will be
described later.
In accordance with the subject invention, the
1exible material can be formed of any commercially available
flexible material heretofore used for forming flexible
packaging. Examples of such materials are polyethylene,
polyester, polypropylene, metal foil, and ccmbinations thereof
in single or multiple plies.
~L~65~5~
In the embodiment of the invention disclosed herein,
the sheet material forming the front wall 22, back wall 24,
and gussetted sidewalls 26 and 28 of the container 20 are
formed of cellophane-polyethylene. It must be pointed o~t at
this juncture that such material is merely exemplary and hence
other materials can be used depending upon the desired
characteristics ~or the con~ainer.
The exemplary embodiment of the sheet material
fonning the bag 20 is shown in considerable detail in the
sectional view of Fig. 4. As can be seen therein, the sheet
material consists o~ two plies, namely, a cellophane ply 34
and a polyethylene ply 36. The cellophane ply is coated on
both sides with polyvinylidene chloride~ Thus, the outer
surface of cellophane ply 34 includes a polyvinylidene
ehloride coating 38, ~hile the inner surface includes a
polyvinylidene chloride coating 40. The coated cellophane ply
34 is secured to the polyethylene ply 36 via an interposed
adhesive layer 42.
As can be seen in Fig. 1, the back wall 24 of the bag
20 includes a longitudinally ~xtending (vertical) seam 44.
The seam 44 is formed by the marginal edges 46 and 48 of a
section of a web o the material forming the bag and which
edges are brought into engagement with one another. The edges
46 and 48 are permanently secured to one another via any
conventional sealing technique, such as heat sealing, welding,
etc. The bottom end 30 of the bag is also sealed closed along
a permanent seam line 50. The seam line S0 is also formed
using conventional sealing techniques, like that used for the
seam 44-
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The resulting construction thus consists of a bag orpouch-like container having an open top end or mouth 52. It
is through the open top end or mouth that the container is
filled.
In accordance with the subject invention, the
container 20 includes peel strip means 54, to be described in
eonsiderable detail later, disposed adjacent the mouth for
sealing the mouth of the container to enclose the contents
therain and protect the contents from the ambient atmosphere.
1~ The peel strip means serves as a mechanism which can be
readily peeled open without destroying the container to
provide ready access to the interior of the container. Thus,
the container 20 of the subject invention can be reclosed
a~ter its initial opening.
The containers 20 of the instant invention are
produced by one of two methods, namely, the manufacture,
~illing, and sealing of the container in one operation by
mechanized equipment, or the manufacture of an empty and
unsealed container which is then provided to the end user for
~illing and subsequent sealing. Both of said methods are a
part of the subject invention and will be described in detail
later.
As can be seen in Fig. 1-4, the peel strip means 54
basically comprises a strip of material which is permanently
secured to the inside surface of the sheet material forming
the front ~all, sidewalls, and back wall of the container 20.
The strip 54 is located adjacent the open mouth 52 and thus
~xtends about the entire inner periphery of the container
~wit~ the exception of the marginal edges forming seam 44) and
3~ is permanently secured thereto.
_ g _
59~58
The strip means 54 is formed of any material which
can be secured to itself via hea-t sealing or welding to
provide an air-tight interface, but which can be readily
peeled apart at its interface without destroying the material
thereof. It has been found that a suitable plastic film for
the strip 54 consists of a blend of polyethylene and an
ionomer like that sold by E. I. DuPont DeNemours & Company
under the Trademark "SURLYN 1601" such as described in Reissue
Patent No. 30,726 identified heretofore. Other ionomers
disclosed in said patent or other plastic materials having
similar characteristics to those disclosed therein may
also be used.
In a preferred embodiment of the subject invention,
the peel strip means 54 consists of a coextrusion (i.e., a
two-layer constructiGn), one layer being a polyethylene-Surlyn
blend and the other layer being polyethylene. Thus, as can
be seen in Fig. 4, the peel strip means 54 consists of
inner ply 56 formed of polyethylene and outer ply 58 formed
of a blend of polyethylene-Surlyn. The strip 54 completely
encircles the inner surface of the sheet material forming
the container adjacent the container's mouth 52 but does
not extend into the seam 44 in the interest of maintaining
the integrity of the seam when the container is later
opened. The peel strip 54 is secured in place on the inner
surface of the container adjacent its mouth 52 via a pair
of longitudinally extending peripheral heat seals or welds
60. Each heat seal or weld is located parallel and closely
adjacent the~respective edge of the strip 54 and produced
in a conventional manner by means to be described later.
:
1 0
~%6~
As should thus be appreciated, the completed
container as shown in Fig. L includes an i~nwardly directed
layer of a peelable polyethylene-Surlyn blend 58 adjacent its
~outh. The contiguous surface portlons of the peelable layer
58 are disposed opposi~e each other Eor engagement with each
other to seal the mouth of the container 20. Accordingly,
a~ter the container i5 filled with the desired contents 62 and
then vacuumized to remove any air from the interior thereof,
the opposed peel strip surface portions 58 are brought into
1~ engagement with each other (as shown in Figs. 3 and 4) and
heat sealed. This action causes the opposed strip portions 58
to become releaseably secured to one another at an air-tight
yet weakened interfacial seal 64 ~Fig. 4). This interfacial
seal, while air-tightr can be readily peeled open without
~amaging the strips 58 or the material forming the container's
walls 22, 24, 26, and 28~ Thusr all that is required to open
the container is to apply a force at the top end 32 tending to
s~parate the front wall 22 from the rear wall 24. This action
~uses the abutting peelable surfaces 58 to readily peel away
2a ~rom each other along the interface 64 in a clean opening and
without in any way damaging the walls of the container.
Accordingly, one can readily gain access to the interior
contents 62 of the container 20. Moreover, inasmuch as the
container is intact, albeit open, one can readily reclose the
bag (although not with an air-tight seal), by merely bringing
the mouth's wall surfaces 22, 24, 261 and 28 into engagement
with one another, folding the top edge of those surfaces over
and holding the folded edges in place with mechanical means,
e,g~, a tin tie (not shown) which can be incorporated into the
3~ container's walls adjacent the mouth.
-- 11 --
~2~s~
In acco~dance with the preferred embodiment of the
in~ention, the peelable strip means 54 is located a
substantial distance below the top of the container to provide
the fold or mechanical securement area for reclosure of the
contain~r ater the peel strip 54 has been opened.
As will be appreciated by those skilled in the art,
tha sealing operation can be accomplished through the use of
~n oppo~ed pair of ~eated jaws. Moreover, where the container
to be sealed is of the gussetted type (in which there are more
overlapped layers at the sides than at the middle of the
container-as shown in Fig. 3) the use of one resilient jaw and
one non-resilient jaw is preferred to ensure even pressure
across the container during the sealing operation.
The perameters (e.g., pressure, temperature and dwell
time) of the heat sealing operation to result in the peelable
seal using the peel strip means 54 as disclosed herein are
readily detenminable by those skilled in the art and the
ollowing table sets forth the range of such perameters found
e~ective to produce a one-eighth inch (3.2 mm) width seal:
SURFACE TEMPERATURE
Resilient Jaw Non-Resilient Jaw
150C - 185C 130C 145C
PRESSURE
420 - 450 P.S.I.
DWELL TIME
3 - 6.5 seconds
If two resilient jaws are utilized, the temperature
range is 134 - 136C with a dwell time of approximately three
seconds and a pressure range of 420 - 450 P.S.I.
3a
- 12 -
~2~5~L~8
In Fig. 5 there is shown, in schematic form,
apparatus for producing containers constructed in accordance
with the instant invention. Accordingly, the container-making
system comprises a roll 100 of the sheet material forming the
containers' walls. The material is reeled off the roll in a
web 102, which ~eb ls carried longitudinally in the direc-tion
of arrow 104 past a peel strip application station 106. The
pael strip application station 106 forms only one portion of
the entira container-forming system (not shown) and is
1~ arranged to apply a plurality of peel strips 54 (like that
disclosed heretofore) at equidistantly spaced locations along
the web 102 passing thereby. As can be seen in Fig. 5, each
strip 54 extends for substantially the entire width of the web
102 except for a marginal edge portion 108 on each side of the
strip. The marginal edge portion form the edge portions 46
and 48 of the container's vertical seam 44 (as described
heretofore).
Each strip 54 is secured to the web 102 by heat
sealing it along the parallel heat seal line 60 at station
106. The web is then severed across` its full width at a cut
lina 110. The cut line 110 serves to divide the web 102 into
plural sections 112, each of which is thereafter formed
(folded) into the container 20. Thus, the cut line 110 forms
the top edge 32 of~the section 112 forming one container and a
bottom edge 30 of the section 112 forming the next succeeding
container. Each cut section 1~2 of the web is thereafter
supplied to apparatus (not shown) ~hich forms the section into
a tuba and brings the marginal edge 108 of each section into
engagement with each other to form and heat seal or weld the
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1~65~
seam 44. The resultir.g tubular construction is thereafter
heat sealed or welded along seam 5U adjacent its bottom edye
30 ~y means (not shown) to complete an open container like
that shown in Fig. lo
~ t this point, the container 20 may be removed from
the system and packaged for supply to a processor for
subsequent filling and sealing the containers. Alternatively,
the system forming the container may fill it and seal it in
one operation. Thus, with the latter system, the container
20, after being formed into the construction shown in Fig. 1,
is filled with its contents 62 and vacuumized. The peel strip
means 54 is then closed and hermetically sealed, as described
heretofore, to isolate the contents 62 within the interior
rom the ambient atmosphere. The top edge 32 is then folded
down or left upright, as desired.
It must be pointed out at this juncture that while in
the preferred embodiment of the invention shown in Fig. 1
har~in the peelable closure 54 comprises a strip which is
~ixedly secured to the inner surface of the container adjacent
~a its mouth by a pair of seals, this invention is not limited to
that construction. Hence, the closure strip can be secured in
place by any means.
Moreover, the strip need not even be separate from
the sheet material forming the container and can thus be
applied as a layer (such as described later) or coating strip
on the inner surface of the sheet material before it is formed
into the container. Further still, the strip need not consist
of two plies or layers and thus may be in the form of a single
ply or layer or multi-plies or layers of the same or different
3~ type materials.
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In Fig. 6 tnere is shown an alternative container 200
constructed in accordance with this invention. The container
2~0 is similar to container 20 in most respects and thus its
com~on features are given the same reference numerals as those
o~ c~ntainer 20. However, the major difference between
container 200 and container 20 is that the peelable sealed
interface 64 at the mouth of the container 200 is formed by
~butting portions of a layer 200 covering the entire inner
surface of the walls of the container The layer 200 is
1~ formed of the same peelable strip material as the strip means
54 described heretofore with reference to container 20. The
remaining seams of the container 200, that is, the vertical
raar wall seam ~not shown) and the horizontal bot-tom wall seam
50, are permanent, that is, are not peelable, notwithstanding
the fact that such seams are made at container portions having
the same material layer 200 as at the mouth of the container.
The permanent seams are formed by the application of more heat
to the seams during the fabrication of the container than
~pliad to make the peelable seal at the mouth and as
described heretofore. In this connection, it has been found
that temperatures in slight excess of the ranges set forth
heretofore will result in a permanent seal for the embodiment
disclosed herein.
One apparatus for forming the peelable mouth seals as
well as the permanent seam seals of the containers of this
invention is shown in Fig. 7 and denoted by the reference
numeral 300. Apparatus 300 is a generally conventional vacuum
packing machine, such as that sold by Goglio Luigi --Milano--
S.P.A. of Milan, Italy and designated as Model GL9, which has
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~L26S~
been modi~ied through the use of different heat sealing jaws
and use of an auxiliary control panel (both to be described
later) to effectuate the efficient and economical sealing of
containers formed in accordance with the subject invention.
Thus, as can be seen, the vacuum packaging machine 300
basically comprises a base-table 302 on the front wall of
which a control panel 304 is mounted~ Disposed above the
table is a sealing head in which a pair of heat sealing jaws
308 and 310 (Fig. 8) are disposed. The jaws, which will be
dascribed in detail later, are arranged to be brought into
engagement with the opposite sides of the container at the
mouth thereof to form the peelable seal mouth as described
heretoEore. Moreover, the jaws 308 and 310 are also used to
form the permanent seals (seams) of the container by disposing
th~ portion of the container forming those seals between the
jaws.
The apparatus 300 also includes plural vacuum
chambers 312. ~hese vacuum chambers are each hollow memb~rs
arranged to support therein containers constructed in
a~cordance with the subject invention and filled with a
material to be sealed therein, e.g., cofee. The chambers are
arranged to cooperate with the head 30~ to form a vacuum
chamber so as to evacuate air from the containers being sealed
prior to sealing thereof. The sealing occurs under vacuum.
Control of the sealing operation is effected via the control
panel 304. Apparatus 300 also includes an additional or
auxiliary control panel 314. The auxiliary control panel 314
is connected via a cable 316 to the apparatus 300 and is
arranged to provide means for individually adjusting the
3~
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~s'~
temperature of the two sealing jaws 308 and 310. The
auxiliary control 31~ thus provides dual temperature contr~l
for the apparatu~. Adjustment of the temperature for the two
jaws is established by the settiny of respective digital
temperature dial switches 320 and 322 of control 314. Display
means in the form of analog temperature indicators 324 and 326
are disposed on the front panel of the control 314 to display
the ~emperature of the associated jaws. Additional indicators
328 and 33U, in the form of indicator lamps, are also provided
in control 314. The electrical connections and components as
wall as the hydraulic components of the system are located
within the table-base 302.
A vacuum gauge 332 is located on the head 306 to
display e~isting vacuum within the chambers 312.
Referring to Fig. 8, the details of the jaws 308 and
310 will now be discussed. As can be seen, each jaw basically
comprises an elongated metal bar through which an elongated
electrical cartridge heater 334 extends. The cartridge heater
is in thermal engagement with the body of the bar so that
2~ there is a good thermal transfer therebetween, whereupon the
tamperature of the bar can be precisely controlled. The
temperature of each bar is established by the setting of the
associated temperature switches 320 and 322 on control panel
314. As can be seen, bar 308 includes a tapered inner surface
terminating in a planar working face 336. In a similar
manner, the bar 310 includes a tapered front face terminating
in a working face 338. As can be seen, the working face 338
is substantially narrower than working face 336 inasmuch as
working face 338 is non-resilient while working face 336 is
- 17 -
~2~S~
resilient To that end, the working face 336 includes a
rubber strip 3~0 extending down a channel 342 along the full
length of the jaw 308. A covering of Teflon-coated glass
fabric 344 is disposed over the face 336 of jaw 308 and is
held in place via securement means 346. The non-resilient jaw
310 includes a slight notch extending down the length of the
j~w at its front face 338. The jaw 310 is also covered ~y a
Teflon-coated glass fabric 344 which is held in place by
~steners 346 in the same manner as described with reference
l~ to jaw 308. The narrow front face 338, jaw 310, includes a
~-shaped notch 348 extending down the length thereof.
Operation of the jaws to seal the mouth of the
container 200 to form the peelable interface 64 is shown in
Figs. g and 10. As can be seen therein, the portion of the
~ontainer 200 adjacent the mouth is disposed between the jaws
308 and 310 as shown in Fig. 9~ The jaws are then brought
together to squeeze the opposing portions of the container
into engagement with each other as shown in Fig. 10. This
action causes the resilient jaw to "give" slightly opposite
n the non-resilient jaw to ensure that even pressure is applied
thereacross. Moreover, as will be appreciated by those
skilled in the art, the use of the resilient jaw ensures that
a proper seal is effected across the entire bag, notwith-
standing the presence of the additional folds caused by the
gussetts at the sides of the bag (not shown in Figs. 9 and
10) .
As should be appreciated from the oregoing, the
containers of the subject invention provide a viable
alternative to the use of rigid containers for the air-tight
- 18 -
1~5~
s~orage of materials and without the disadvantages of prior
art flexible containers, namely, either the inability to be
readily reclosed due to structural damage to the container due
to the tearing oE its walls or, if the container is cut open
at its seal, the reduction in storage capacity due to the
removal of the top of the container. The advantages of the
subject invention over the prior art are accomplished in a
simple and expeditious manner through the use of a peelable
closure at the mouth of the container which crsates an
1~ air-tight weakened seal that can be peeled open without
damaging the container itself.
Moreover, the method(s) of the subject invention
provides a viable and commercially feasible means for readily
and inexpensively producing flexible containers having
air-tight peelable mouths with other seamed portions being
permanent seams.
Without further elaboration, the foregoing will so
fully illustrate my invention that others may, by applying
current or future knowledge, readily adapt the same for use
~ under various conditions of service.
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