Note: Descriptions are shown in the official language in which they were submitted.
CA 02349067 2001-05-29
CANADA
APPLICANT: LAFOND, Luc Marcel
TITLE: REMOVABLE SLIT COVER FOR FLEXIBLE PLASTIC CONTAINER BAG
CA 02349067 2001-05-29
Field of the Invention
The invention relates to flexible containers, including plastic bags made from
flexible plastic film to package beverages, food products, or other fluids,
granular
solids and other materials.
s Background of the Invention
Flexible containers, including plastic bags, are used as containers for
various
materials, including by way of example, milk, juices, and other beverages,
snack
foods, and many consumer and industrial products, including granular
fertilizers,
lawn applications, seed products and pelletized materials. Many of the bags
are
to made of polyethylene film, polypropylene film, plastic foil or other
suitable flexible
films containing plastic materials.
Flexible plastic bags offer many advantages for packaging a wide variety of
materials, including foods and beverages. Flexible plastic bags provide
protection against premature spoilage, exposure to moisture or other sources
of
is contamination. Flexible plastic bags also offer many other advantages. They
add little weight to the packaged product and in most instances are a low cost
alternative to other conventional container materials and products made from
rigid materials, such as coated cardboard and glass.
One of the disadvantages of conventional flexible plastic bags is that they
are
20 often difficult to open. Furthermore, consumers are often faced with
particular
difficulties or inconvenience associated with finding a specialized cutting
tool to
create a suitable opening to dispense the packaged commodity. By way of
example, prepackaged milk is available in flexible plastic bags that are often
difficult to open without a specialized cutting tool, scissors or a blade.
2s Consumers must locate a clean cutting tool, position it along an edge of
the milk
bag, and choose a cutting path. While holding the bag or a bag holder with the
bag in it, the consumer must thE;n operate the cutting tool 'free hand' to
provide a
satisfactory opening to dispense the contained milk, preferably without any
significant spillage. Unfortunately, conventional plastic milk bags are often
3o slippery and difficult to handle. It may be difficult to locate a suitable
cutting tool
CA 02349067 2001-05-29
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that may have been misplaced earlier by a child or other member of the
household. Once located, it may be particularly difficult to position the
cutting
tool to cut an opening of optimal size and configuration.
In other instances, flexible plastic bags may be inherently difficult to open.
For
s example, plastic foil bags are commonly used for snack foods, including
roasted
nuts. Plastic foil bags offer superior strength and barriers against food
spoilage
and contamination. However, consumers are often faced with problems in
opening the flexible bags because the materials are inherently strong and tear
resistant. In some instances, where the contents are particularly fragile (by
way
io of example, potato chips, crispy snack foods, cookies and the like) a
consumer
may incidentally damage some of the contents while struggling to open the
flexible plastic bag.
By way of another example, granular fertilizers are often sold in relatively
large
flexible plastic bags containing '10 pounds, 25 pounds or more of granular
is materials. Typically, the plastic bags are made of a generally cushion-
shaped,
elongated tubular construction with welded seals along 3 major edges, namely
one longitudinal weld along the length of the bag, and two transverse welds,
with
one weld at each end of the baq. The size and weight requirements for these
bags often dictate that the plastic film used to make the bag must be of a
2o relatively thicker construction (compared to the previous examples for
packaged
foods or beverages) or other reinforced construction. The generally thicker
plastic film used to manufacture the larger bags often leads to pronounced
difficulties in opening the bags, particularly when the consumer is unable to
locate a cutting blade or suitablE~ tool. It is often particularly difficult
for an
2s individual to muster sufficient strength to tear through the plastic film
to create a
suitable opening in the bag. E=ven if the individual manages to tear the film
without the aid of a cutting tool, the opening is often of an irregular shape
and
inappropriate size.
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The illustrated difficulties are even more pronounced for those individuals
who
may have physical disabilities, muscular or other debilitating conditions
limiting
their ability to open these flexible bag products.
In other instances, children may require close adult supervision or
intervention to
s open conventional flexible plastic bags.
Summary of the Invention
The present invention provides a method and product for use in the manufacture
of flexible containers, including plastic bags. It will be understood by those
persons who are skilled in the art that flexible plastic bags include, but are
not
io limited to bags made from flexible polyetl-~ylene film, plastic foil, and
other
suitable plastic films.
In one embodiment, the invention provides a product, which includes a flexible
plastic film cover laminated over a predetermined opening in a flexible
plastic
bag. The plastic cover is made from a flexible plastic film. The cover is not
is necessarily made from the same film, which may be used, for the main body
of
the flexible plastic bag.
The plastic cover comprises first and second zones and a tear zone. A first
zone
of the cover is secured to the main body of the plastic bag, near the
periphery of
the predetermined opening, to provide a secure seal for the opening. In a
2o preferred embodiment, the first zone is secured by lamination to the body
of the
bag. In a most preferred embodiment, the first zone of the cover is securely
welded to the body of the flexible plastic bag, adjacent to the periphery of
the
opening.
The second zone of the cover comprises a tear zone adjacent the first zone of
2s the cover. The second zone of the cover is removable from the bag by
pulling
the cover so that the cover is preferentially torn along the tear zone. The
cover
may be designed so that the entirety of the second zone is removable from the
bag, or in other embodiments" ii: may be desirable to provide a retainer to
inhibit
complete removal of the second zone from the bag. A portion of the cover
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remains securely fixed to the body of the bag. By way of example, the first
zone
remains securely attached to the bag, near the perimeter of the opening in the
bag.
In a preferred embodiment, the cover is secured to the bag, adjacent to a
s predetermined edge or corner of the bag. For example, in a milk bag of
generally
rectangular shape, it is preferred to secure an embodiment of the plastic
cover in
a selected corner of the flexible plastic milk bag. The selected corner is
provided
with a preformed opening in thE: bag. The preferred cover is secured to the
bag,
adjacent the perimeter of the opening.
to In a preferred embodiment of the improved milk bag, the flexible plastic
cover is
laminated to the body of the bay by welding. A suitable heated production
press
clamps and welds the cover to lrhe bag in a continuous production line
facility. In
particular, the first zone of the cover is secured to the body of the bag,
adjacent
the perimeter of the opening. The first zone is a sheet of flexible plastic
film,
is which is positioned over a sheet of another flexible film, which forms a
wall of the
plastic bag. The cover is positioned over the opening of the bag so that the
two
sheets overlap. The first sheet of film, defining the first zone, is welded to
the
other sheet of film, which forms part of the body of the flexible plastic bag.
The
cover is welded to the body of tlhe bag so that the opening is completely
sealed.
2o The cover defines a tear zone. The tear zone provides a preferred location
for
separation of the second zone of the cover from the first zone wherein the
latter
zone is secured to the body of the milk bag.
In this embodiment, the laminated sheets of the first zone of the cover and
the
other sheet of film, defining the body of the plastic bag, define a collar of
2s reinforced plastic film which ha:~ a nominal thickness greater than either
of the
individual sheets of plastic film. When the second zone of the cover is torn
away
from the bag, exposing the opening, the milk may be poured out of the
preformed
opening. The collar may be formed to provide a spout of predetermined size,
shape and orientation. The collar may also be made to open when the bag is
3o tipped to pour milk from the bag~~. However, the collar may be biased to
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subsequently return to a closed) position when the bag is returned to its
upright
position. This tendency to self seal may be provided by incorporating a memory
into the plastic film during the lamination process.
In another embodiment, the flexible bag comprises a gripping surface to
provide
s a better location for a user to clasp the removable second portion of the
cover.
The user may clasp the gripping surface between a thumb and at least one other
finger, to pull the removable second portion from the flexible plastic bag.
The
gripping surface may take the form of an embossed tab along one edge of the
cover. The embossed tab may be notched at a predetermined location, adjacent
io the collar, to allow the user to initiate tearing of the cover in a
preferred location
and direction within the desired tear zone.
In yet another embodiment of the present invention, the cover is used to
convey
information. By way of examplE:, the information may take the form of a
freshness date, product code, promotional material, redeemable coupons, or
is other suitable information. Complimentary information may appear on the
removable portion of the cover .and on the portion which remains secured to
the
plastic bag after the removable portion of the cover is detached. The cover
may
also be used to support advertising or promotional materials for other
products or
services.
2o In one embodiment of the method of the invention, a flexible plastic bag is
made
from a continuous elongated wE:b of plastic film. The film is fed from a
source
toward a filling station. The film is advanced and then cut or otherwise
shaped to
pre-form a predetermined openung at a location of predetermined distance from
a
similar, adjacent preformed opening. The preformed opening is preferably
2s located so that once the bag is completed, filled, sealed and cut, the
covered
opening will be positioned in a corner of a generally rectangular shaped bag.
A
pre-shaped cover is laminated to the advancing feed stock by welding the cover
over and adjacent the opening. The cover may carry consumer or other
information for display with the saleable product. The advancing feed stock is
3o welded into a sleeve which aciv<~nces to a filling station. The advancing
sleeve is
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closed at one end, further advanced, filled with milk and then sealed at the
other
end.
The cover is shaped to provide a tear zone within a pre-selected area. In
addition, the laminated cover and bag may be provided with an embossed
s gripping surface, one or more notches as a starting point for opening the
filled
bag, and a reinforced collar adjacent the predetermined opening which has been
sealed by the cover.
There are other embodiments of the invention which will become apparent upon
review of the appended drawings and detailed description.
io In the Drawings
Several embodiments of the prEaent invention are represented in the following
drawings.
Fig. 1 is a representation of an .embodiment of an improved flexible plastic
bag of
the present invention, such as a milk bag filled with milk.
is Fig. 2 is an enlarged representation, in plan view, of a preferred
embodiment,
showing a cover secured about and over a preformed opening in a corner of the
milk bag shown in Fig.1.
Fig. 3 is a partial plan view of a section of flexible plastic film, in which
a partial
opening is formed. The film is an intermediate product before a cover is
secured
2o to a milk bag, to make the product shown in Fig. 2.
Fig. 4 is an enlarged representation, in plan view, of another embodiment of
the
invention, in which another cover is secured over a corner of another milk
bag.
Fig. 5 is a partial plan view of a section of flexible plastic film, in which
a partial
opening is formed. The film is an intermediate product before a cover is
secured
2s to a milk bag, to make the product shown in Fig. 4.
Fig. 6 is an enlarged representation, in plan view, of yet another embodiment
of
the invention, in which another cover is secured over a corner of yet another
milk
bag.
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Fig. ? is a partial plan view of a section of flexible plastic film, in which
a partial
opening is formed. The film is an intermediate product before a cover is
secured
to a milk bag, to make the praduct shown in Fig. 6.
Fig. 8 is a partial plan view of another embodiment of the invention, showing
s another embodiment of a cover secured about and over a preformed opening in
a milk bag.
Fig. 9 is a partial plan view of a section of flexible plastic film, in which
an
opening is formed. The film is an intermediate product before a cover is
secured
to a milk bag, to make the praduct shown in Fig. 8.
to Fig. 10 is a schematic representation of a continuous feed of flexible
plastic film,
in a process used to make one embodiment of an improved plastic bag of this
invention, filling and closure of the bag, with an improved cover secured over
a
preformed opening.
Detailed Description of Several Embodiments of the Invention
is With reference to Figs. 1, 2 and 3, a preferred embodiment of a flexible
container
1 is shown after it has been filled and sealed. Bag 1 is of a general tubular
configuration, with lateral seals 3, 4 at opposing ends. A longitudinal seal
(not
shown) extends along the length of the bag, along the back wall of the bag 1
and
is not visible in this frontal view. The bag may be used to package many
different
2o materials. The bag is made of flexible material suitable for the particular
uses at
hand. By way of example, the bag may be of generally plastic construction,
laminated plastic materials incluiding plastic foil or other suitable flexible
materials. Polypropylene and polyethylene are only two examples of the many
flexible plastics commonly used for packaging. However, other materials may
2s also be selected based on material performance, cost, availability and
other
factors.
The plastic bag of the preferred embodiment is provided with a cover 2 secured
about a preformed opening 1 f3 c;ut in the wall of the bag 1. In this example,
the
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_$_
bag is made of a thermoplastic material. The cover 2 is a generally
rectangular
flap that has been secured to the front and back walls of the bag.
During the manufacturing process, (as shown in the schematic representation of
Fig. 10) the bag 1 is made from a web 100 fed continuously from a web source
s 101. The web is cut to form an opening slit 102. A rectangular cover 106 is
laminated over an underlying opening slit of corresponding size and shape,
further along the web. A similar cover 108 has been welded over and about yet
another corresponding opening slit, further along the advancing web. It will
be
understood that at this point, thc: covers 106, 108 are welded to the web such
io that there are no more than two laminated sheets (namely the web and the
film)
in any one location, and in some locations beneath the covers, as will be
explained further below, the covers are not laminated or welded to the web
(bag
wall) in certain locations immediately adjacent the corresponding opening
slits
102.
is In other embodiments, which are not shown, it may be desirable to provide
openings of different shapes. For example, although the described embodiment
features an opening slit, other openings may take the form of slots and cut
outs
of various shapes. Similarly, the described embodiment refers to a rectangular
shaped cover. However, the shape and relative size of the cover may also be
2o varied, according to the requirements for a particular container design.
Each cover is provided for a separate bag that will be filled, sealed and cut
from
the web, further along in the process. The web is formed into a generally
tubular
configuration, with a longitudinal weld forming a longitudinal seam 104. The
longitudinal seam 104 corresponds to the juncture where the sides of the web
2s have been welded together to form a seal along the length of the tubular
sleeve.
The tubular sleeve is advanced to a filling station (not shown) where the bag
117
(open at its top lateral edge, bui: sealed at its bottom lateral edge during
the
sealing and cutting of a previous bag) is filled with the material to be
packaged.
The bag 115 is shown after it has been filled with the packaged contents and
is
3o being sealed along edge 112 in a sealing and cutting press 111. During the
CA 02349067 2001-05-29
sealing process, the cover of bag 115 (positioned with the press and
consequently not shown) is further heat pressed to weld the cover and walls of
the bag to complete the sealing process about and over the underlying opening
slit. This process will be further described with reference, again, to the
examples
s of Figs. 2 and 3.
In Fig 3, when the web 30 is advanced through the process, an arcuate opening
slit 33 is cut into the flexible web, generally centered about a longitudinal
axis 32
of the web. Axis 32 also corresponds to a fold line, along which the tab 7
will be
secured to the bag during the manufacturing process. The fold line will also
to represent the center line for the overlaid cover so that half of the cover
will be
secured to a front wall of the bag and the other half of the cover will be
secured
to the opposing back wall of the bag. The slit 33 terminates at ends 37, 37'
leaving uncut widths or bands 36, 34 of flexible web between the terminal ends
37, 37' and the lateral line 31. Line 31 represents the expected location of
the
is lateral edge and seam of the bag after it has been filled, sealed and cut.
In Fig. 2, cover 2 is welded to bag 1 such that a tab 7 is provided. The tab 7
may
be embossed to enhance a user's ability to grip and tear open the closed bag.
Tab 7 comprises two thicknessE;s of the flexible film from which the cover was
initially made. In this example, the thickness of film used to make the cover
is
2o equivalent to the thickness of the web used to make the bag. Consequently,
the
tab 7 will be approximately twicE: the nominal thickness of one wall of the
plastic
bag. A notch 8 is provided to direct the user's tearing motion toward an
unsealed
zone 14, representing a relatively weakened zone, based on shear strength,
relative to the immediately surrounding areas on the sealed cover 2. Unsealed
2s zone 14 extends from the tab 7, from a first end 21 to opposite end 22.
Although
this example features a notch, other techniques or elements may be used. For
example, the weakened zone may be provided by an embossed surface groove
rather than a cut or notch.
The hatched area 9 represented on the sealed cover corresponds to a reinforced
3o area in which 4 thicknesses of film have been welded together in a
laminated
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array. The reinforced area 9 is bounded along one side by an arcuate edge 24
which is positioned adjacent the precut opening 16 in the bag. The reinforced
area 9 is bounded by upper edge 31. The reinforced area 9 extends from the tab
7, through the reinforced band 34 to the right terminal edge 6 of the cover 2.
s Reinforced band 34 is approximately the width of upper seam 10 of the bag.
It
will be understood that the uppf:r seam 10 is comprised of two thicknesses of
the
web used to make the bag, welded together.
The cover 2 is also reinforced in lower zone 11, an area corresponding to 4
thicknesses of film welded together in a laminated arrangement. The reinforced
io zone 11 is added to inhibit the formation of a capillary along the vertical
intersection line between the talb ~7 and the laminated area 5 of the cover.
Laminated area 5 corresponds 'to two thicknesses of film, a first thickness of
the
bag (one wall), overlaid by the cover and welded together. An additional zone
12
is provided to further inhibit formation of a capillary, by laminating two
is thicknesses of film, namely two walls of the bag together to add
reinforcement
along this sector. The laminated area 5 of the cover is bounded by an arc 18
running adjacent to unsealed zone 14, a lower edge 13, reinforced zone 11, and
the right terminal edge 6 of the .cover. Since approximately half of the cover
also
extends to the back wall of the bag, which is not shown, corresponding areas
are
2o also provided on the back wall.
In this preferred embodiment, the reinforced areas 9, 11 and additional zone
12
are formed during the sealing si:ep, after the bag is filled, during formation
of the
upper closing seal 10.
A consumer may take the filled bag and tear open the bag 1 by applying force
to
2s the tab 7, adjacent the notch $, tearing the tab 7 toward and along the
weaker
(unlaminated) area 14 until a portion of the cover is torn away, leaving
reinforced
band 34 and upper seal 10 in tact. It will be understood that a reinforced
collar is
provided by the remaining reinforced band 34, laminated area 5 and reinforced
area 12 that remain after the other portion of the cover is torn away along
the
3o weaker, unlaminated tear zone 14.
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A second embodiment of a flexible bag is illustrated in Figs. 4 and 5. An
intermediate web 50 is shown in Fig. 4. The web 50 of film is ultimately used
to
make the flexible bag with improved cover 2 shown in Fig. 4. Web 50 is cut to
remove a cutout portion 56' and provide two arcuate slits defined by sections
53',
s 53 extending between terminal ends 57, 55 and 55', 57'. To avoid fouling the
contents of the finished bag, cutout 56' may be removed by a vacuum stream or
in another suitable manner. The opening slits 53', 53 are cut centered about
longitudinal axis 52 leaving uncut bands 56, 54 in place. The slits 53', 53
will
later define the preformed opening of the bag once it is filled, sealed and
cut.
io After the cover 5 is welded to the bag and completely sealed, as shown in
Fig. 4,
longitudinal axis 52 will run along the vertical center line of the secured
cover.
In the sealed bag 40 shown in F=ig. 4, the cover 2 is defined by upper edge
51,
lower edge 13', left edge 52 and opposing right edge 6'. Reinforced zones 9
and
11 are provided, each zone representing a total of four laminated thicknesses,
is welded together for added strength in their respective areas. The bag 40 is
shown with its upper lateral seal 10 extending from reinforced zone 9 and
along
the upper edge of the bag 40.. In this embodiment, reinforced zone 9 is
bounded
by upper edge 51, left side 52, edge 41 (which corresponds to the upper edge
of
zone 42 described below), arcuate edge 24 and the upper most portion of right
2o edge 6'. Reinforced zone 9 includes reinforced band 54, the latter being of
the
same width as upper seal 10 of the bag.
In this embodiment, a zone 42 is provided in which only two overlying
thicknesses of the cover have been welded together since the cutout 56' was
removed during the bag manufacturing process. That is, the two thicknesses of
2s film representing the cover are welded together in a two-ply arrangement
within
this zone, to provide a relatively weaker zone (based on shear strength)
compared to the immediately surrounding reinforced, four-ply zones 9 and 11.
To inhibit the formation of a capillary near the lower edge of zone 11, the
front
and back walls of the bag are welded together to provide laminated zone 12. A
3o notch 43 is provided, partially e;~ctending into the two-ply zone 42. The
notch 43
is relatively short and extends less than about half way into zone 42. There
is a
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relatively weaker, unlaminated zone extending between the right edge of zone
42, between opposing arcuate ;>ections 24 and 18, and extending up to and
terminating at reinforced band 54. Preformed slit 16 remains in the bag so
that
an opening or spout will be provided when a portion of the cover is later torn
s away from the bag. By way of Example, a consumer wishing to open the bag 40
would grasp the bag in the vicinity of zone 11, and the reinforced area 9 in
the
vicinity of edge 41 and then tear most of the upper reinforced portion 9,
along the
unlaminated zone, and away from the bag 40 and the remaining laminated
portion 5 of the cover. After the bag is opened, slit 16 will define the
opening or
to spout of the bag, to allow the contents to be poured out. The resulting
spout will
have a reinforced collar defined by the portion of the cover that remains
secured
to the bag, about the periphery ~of the spout.
In this embodiment, as well as in other embodiments of the present invention,
portions of the cover may be used to convey information to consumers or others
is concerning the product, packaging or other matters. By way of example, the
tear
away portion of the cover may heave proof of purchase information or coupon -
like matter printed or embossed onto that portion. It may be useful to imprint
important product information on the remaining collar portion of the cover.
For
example, product batch number' information, product code information, and
'best
2o before date' information may be useful in case of product recalls, or to
facilitate
tracing of particular product batches. The use of the cover portion to convey
this
information is particularly useful in association with milk packaged in clear
plastic
bags. For esthetic and other reasons, conventional milk bags are transparent
so
that all of the contents of the bag will be readily visible. Since the cover
of the
2s invention may be adapted to be of a relatively small size compared to a
filled milk
bag, the cover and related information may be secured to the bag without
obscuring the contents of a transparent milk bag.
Figs. 6 and 7 illustrate yet another embodiment of a milk bag made in
accordance with the invention. During the manufacturing process, two arcuate
3o slits represented by segments 77, 75 and 75', 77' are cut into the web 70.
An
uncut segment 76 of the web separates the two arcuate slits. The arcuate slits
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are centered about center line i'2. Once the bag is filled, sealed and cut,
this
center line will correspond to lest edge 72 of the half-portion of cover 2
illustrated
in Fig. 6. (It is to be understoodl that the other portion of cover 2, of
similar size
and configuration, is secured on the back wall of the bag and is not visible
in this
s frontal view.)
As described in association with Fig. 10, the cover is initially secured to
the web
so that the two sheets (corresponding to the cover and the bag wall) are
welded
together in a two-ply arrangement, except for predetermined areas surrounding
one or more preformed openingis in the bag. In the embodiment of Fig. 6, there
io is a laminated portion 5 (comprising a corresponding portion of the cover)
which
is shown generally to the right and below an unlaminated arcuate zone
surrounding underlying slit 16. Portion 5 is an area in which the
corresponding
part of the cover film is welded 1:a an underlying sheet of film of the bag
wall,
forming a two-ply construction. Portion 5 is bounded by arcuate edge 18 which
is
is set back from slit 16 to avoid accidental sealing of the opening during the
manufacturing process. The two-ply portion 5 is also bounded by lower leg 11
of
reinforced area 9, and an upper leg of area 9 which extends in line with upper
seam 10, parallel to the upper edge 71 of the bag 60.
The unlaminated arcuate zone is bounded by an arcuate edge 24 of the
2o reinforced zone 9, and complimentary arcuate edge 18, extending from
terminal
ends 22 to the interior edge of reinforced leg 11. Moderately reinforced zone
12
is also provided by laminating the front and back walls of the bag,
immediately
below the lower edge 13" of the cover.
In this embodiment, a notch 63 is provided adjacent one end of the unlaminated
2s zone surrounding the preformed opening. The cover 2 may be embossed or
otherwise treated to improve thE: gripping surface for tearing open the
covered
portion of the bag 60. Most of reinforced area 9 is torn away, from the notch,
along a line within, or adjacent to, the unlaminated zone, and up through to
the
upper edge 71 of the bag 60. The remaining portion of the cover defines a
3o reinforced collar extending about the resulting spout.
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A further embodiment of a milk bag is shown in Figs. 8 and 9. In Fig. 9, a web
90
is cut to provide an inverted triangular opening 94, centered along a fold
line 92
corresponding to edge 92' in thf~ sealed bag 80 shown in Fig. 8. Cutout
portion
94 from the web is removed and discarded to avoid subsequent fouling of the
s packaged contents.
In Fig. 8, cover 2"' is a substantially triangular flexible plastic film that
has been
welded to the body of the bag 80. Bag 80 has an upper edge 91 running along a
welded closing seam 85. Half of the cover 2"' is shown in this frontal view.
The
other half of the cover 2"' is secured in a like manner to the back wall of
the bag
io 80. The cover is welded to the 'bag 80 along a reinforced band 81. The band
81
is of a two-ply construction. The band 81 is made by laminating one thickness
of
film (used to make the cover) over another thickness of film (from the single
sheet of web used to make one wall of the bag). At opposing ends of the band
81, there are two further reinforced zones 11 "' and 89 which are formed by
is laminating four thicknesses of film in overlapping arrangement. In each
case, the
four thicknesses are made up of two thicknesses of film used to make the cover
and two thicknesses of film used to make the bag, for a total of four
overlapping,
welded thicknesses in these areas. Below reinforced zone 11 "', zone 12"' is
provided to strengthen the edge of bag 80 along its edge 92'.
2o Tab 7' is formed along two sides of the cover 2"' by folding two
overlapping
thicknesses of the film and welding those two thicknesses together along a
selected area. Tab 7' is provided with indentations 83, 83' as preferential
tear
points. Tab 7' may be embossed or treated to improve the gripping surface for
tearing open the closed bag. The cover also has an unlaminated tear zone 82
2s wherein the two overlapping thicknesses of film of the cover have not been
welded together.
The closed and sealed bag 80 rnay thereafter be opened by tearing away a
portion of the cover from the body of the bag 80, starting from either of
notches
83, 83' and tearing toward the other notch. The portion of the cover will tear
3o away along a line within the unlaminated zone 82 and the tearing step may
be
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continued until the portion of them cover is separated from the bag 80. (The
tear
line will not necessarily follow edge 84.) Once the indicated portion of the
cover
is torn away, an opening or spout is created in the bag to permit emptying of
the
packaged contents of the bag. The portion of the cover that remains secured to
s the bag, including portions within areas 11 "', 81 and 89, forms a
reinforced collar
about the perimeter of the spout. The collar is of relatively thicker
construction
having at least two thicknesses of overlapping laminated film, compared to the
adjoining single sheet of film f'or'ming the wall of the bag 80.
In manufacturing the bag, it is possible to provide the collar with a memory
so
to that it will be slightly biased toward maintaining a closed position. When
the bag
is tipped to empty a portion of the contents through the opening, the collar
will
tend to open thereby forming a spout. When the bag is returned to its upright
position, and the collar is no longer under load from the contents of the bag,
the
collar will tend to return to its preferred, closed position. Although the
closed
is position will not provide an airtictht or fluid tight seal, in most
instances the
closure will be sufficient to prevent contamination from dust, particles,
flying
insects and other undesirable matter. It will be particularly desirable to
provide a
closure of this type for flexible packaging used for picnics, boxed lunches
and the
like. This closing feature may also be provided in flexible packaging used for
non
2o food products.
In some embodiments, it may be desirable to make the cover from a film known
to have a particular grain or linearly oriented properties such as tear
resistance.
For example, a film known to have enhanced tearing properties along a certain
axis or grain may be selected to take advantage of those properties. For
2s example, if the film is known to have a certain direction, grain or pattern
of
alignment, the film may be positioned and secured to the bag such that the
resulting tear zone will follow that inherent direction. This pre-determined
orientation will enhance easier separation within the tear zone of the second
zone from the first zone of the cover.
CA 02349067 2001-05-29
-16-
Although the above examples have described embodiments in which the same or
comparable materials have been used to make the cover and bag, other
embodiments will include a cover made from a film with a thickness differing
from
the thickness of web film welded to the cover. The film of the web and the
film of
s the cover may vary in terms of relative strength rating so that the second
portion
of the cover will be easier to tear relative to the nearby portions of the
body of the
bag. The film of the cover may also differ from the web film in other aspects,
including quality, color, and composition.
Furthermore, the preferred embodiments refer to securing the cover to the web
io by welding. However, persons skilled in the art will understand that it
will be
possible, and in some instances desirable, to secure the cover to the web
material by using suitable adhesives or other features or processes.
It will also be apparent to persons skilled in the art that the specific
examples of
openings described above haven been formed by cuts that have pierced through
is the entire thickness of the web. However, it will be appreciated that it is
not
necessary to completely pierce a web or film to provide a preformed opening.
For example, a deeply embossf:d groove or segmented cuts may be provided
along a desired path.
In other embodiments, it may be desirable to provide a preformed opening on
the
2o cover rather than on the web u~;ed to make the bag. For example, it may be
preferable to provide a cover having a preformed opening overlaid above a
fully
sealed container such as a bag. For example, in plastic foil bags used for
peanuts or other snack foods, it may be impractical to cut a slit or opening
in the
bag itself, because of additional undesirable tearing, or other problems which
2s may occur while handling a precut plastic foil web. Accordingly, a plastic
film of a
suitable composition may be used to make the cover with a preformed opening
on the cover itself. In that case, the web (or wall) of the bag will itself
act as a
seal for the opening formed on 'the cover.
It is also noted that the specific embodiments described above have featured
3o covers that have been positioned on the outsides of the respective bags.
CA 02349067 2001-05-29
-17-
However, it will be apparent that the position of the cover may be altered
with
relative ease during the manufacturing process. It may, in some instances, be
particularly desirable to do so. For example, where the contents of the
container
will be packaged under pressure, the cover may be secured on the inside of the
s container to reduce the tendency for delamination of the secured films. In
these
cases, certain features will be provided on the outer wall of the container
(by way
of example, the gripping surfacf:) since the cover piece will be located on
the
inside of the container.
The embodiments described in this specification are merely illustrative and
are
to not intended to be limited to the specific features, elements or steps as
described
herein. Further and other modifications and variations will be apparent to
those
skilled in the art, thus making it possible to practice the other embodiments
of
methods and products, all of which are within the spirit and scope of the
present
invention.
