Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
S P E C I F I C A T I O N
T I T L E
"TAMPER-EVIDENT ZIPPER CLOSED PACK~GE"
BACKGROUND OF THE INVENTION
The present invention relates to improvements in
plastic bags and fasteners therefor, particularly to a
reclosable plastic film bag which is hermetically or
non-hermetically sealed and has tamper-evident features to
show whether the bag has been previously opened.
More particularly, the invention relates to
improvements in reclosable plastic bags which have
reclosable rib and groove profile elements which permit the
bag to be opened and reclosed. Where the bags are used for
containing products such as Poodstuffs, flaps above the rib
and groove elements have been joined to hermetically seal
the bag until such time when it is purchased and opened for
use. To facilitate opening, tear perfora~ions have been
placed at the top above the rib and groove elements so that
a strip can be torn from the top to free the flaps and
permit opening the bag by pulling the rib and groove
elements apart. The addition of perforations ~llowi~g the
tearing of a strip off the top has been known in U.S.
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patents 6uch as 3,9172,443, 3,226,787, 3,473,589, 4,589,145
and 4,846,585.
Such perforations destroy the hermetic 6eal of the
bag and pe~mit the passage of air. While the rib and groove
elements below the perforations may be joined to close and
seal the bag, these elements may inadvertently become
separated during handling, ~torage and merchandising ~o that
air can enter the bag via the perforation holes. Further,
the rib and groove elements per se may not be sufficiently
airtight. The need for airtight integrity is especially
present where the contents of the bag must be protected
against air, ~uch as where the bag contains foodstuffs, and
laminated films have been used for this purpose. The
addition of such perforations creates a problem because the
rib and groove elements below the perforations may not be
sufficiently airtight, although they present the best method
of tearing off the top of the bag for access to the rib and
groove elements without having to use shearing instruments
for cutting off the top. Such perforations can be added by
simple perforation equipment which operates rapidly and
satisfactorily. Other forms of weakened lines of tear
resistance may be employed but perforations provide the
easiest tearing means particularly in plastic film bags.
Another feature of bags formed by thin plastic
film of the type which have been previously available is
that the film has been made as thin as possible for cost
saving and often the film lacks sufficient body to
adeguately provide an easily graspable flange arrangement at
the top for opening the bag. Also, if the film is too
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light, insufficient support for the rib and groove elements
is provided.
_EATURES OF THE INVENTION
An object of the invention i6 to provide an
improved bag structure and method of making utilizing thin
plastic ~ilm wherein the bag has the features of being
her~etically sealed until first used and yet is reclosable
. by having pressure interlocking rib and groove elements,
wherein disadvantages of prior art baqs are avoided.
A further object of the present invention is to
provide an improved hermetically sealed plastic film bag
having a reclosable zipper at the top utilizing an improved
cap seal arrangement for sealing tear perforations at the
bag top.
A further object of the invention is to provide
for improvements in plastic film bag structures wherein thè
bags can be rapidly made in duplicate arrangement and
wherein the pressure reclosable rib and groove elements are
carried on a separate strip which contributes even further
to the functionality of the bag.
In providing a container of plastic film, in
accordance with the invention, opposed film walls are
attached at their edges and are attached in a fin seal at
the top. A doubled zipper strip is placed immediately
adjacent the fin seal with the zipper strip having pressure
reclosable rib and groove elements at its lower edge.
Perforations extend through the outer walls of the bag as
well as through the doubled zipper strip within the top. A
cap seal is sandwiched between the zipper strip and the
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outer layers and ths zipper strip and each outer layer are
heat laminated to each other.
When the top is torn off the bag, the cap ~trip
tears along the perforations having provided an air and
moisture seal at the perforations until the strip is
removed. The sides of the zipper ætrip remain laminated to
the bag top providing stiffness and providing very good pull
flanges for pulling apart the zipper profiles. The
structure provided may taXe the form of different variations
using the principles of the invention. The combination of
the features of the structure adapt themselves to rapid
manufacture of double bags and to remedying defects and
providing advantages not present in baqs heretofore
available.
Other objects, advantages and features will become
more apparent with the teaching of the principles of the
invention in connection with the disclosure of the preferred
embodiments thereof in the specification, claims and
drawings, in which:
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view taken edge-wise of
an assembled plastic film arrangement prior to being formed
into a bag, constructed in accordance with the principles of
the present invention;
FIG. 2 illustrates in section the top end of a bag
after being assembled from a film structure similar to that
of Fig. 1, although the film structure differs in certain
aspects;
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FIG. 3 is an enlarged plan view illustrating an
improved perforation arrangement which may be employed for
accommodating the removal of a tear strip from the top of a
bag;
FIG. 4 is a sectional view taken through a double
zipper having one structure formed in accordance with the
present invention;
FIG. 5 is a view similar t~ Fig. 4 but 6howing a
modified form of double bag structure;
FIG. 6 is an elevational view taken end-wise of a
film structure arrangement for forming into a bag;
FIG. 7 is a sectional view taken through the top
of a bag formed from a structure such as that of Fig. 6;
FIG. 8 is an end elevational view of a zipper
strip arrangement;
FIG. 9 is a sectional view of the top end of a bag
formed utilizing the zipper strip arrangement of Fig. 8;
FIG. 10 is an end elevational view of a zipper
strip of modified structure;
FIG. 11 is an end elevational view of the zipper
strip of Fig. 10 illustrating the flattening of the ribs
when pressure is applied;
FIG. 12 is a sectional view of layers of film at
the top of a bag; and
FIG. 13 is a plan view of the arrangement of Fig.
12.
DESCRIPTION OF IHE PREFERRED Et~BODIMENTS
Fig. 2 illustrates the top of a bag formed ~f an
upper thin film bag layer 10 and a lower thin fil~ ~ag layer
11. These layers are joined at the top 12 in a fin ~eal.
Below the fin seal and between the bag layers is a
zipper strip 13. The zipper strip may be formed of ~eparate
strips but is ~hown as formed of a doubled strip being
folded at 14 with mating pressure interlocking profiles 15
such as rib and groove elements between the lower edges of
the doubled zipper strip 13.
The zipper strip is shown as multilayered having
an inner layer 13a which carries the zipper profiles 15 and
a outer layer 13b.
The film bag layers have perforation lines 15 and
16 in the upper and lower layer for first tearing off the
top of the bag when the bag is to be used. Corresponding
lines of perforations in similar oriented locations are
formed at 17 and 18 in the zipper strip essentially in
alignment with th~ lines of perforations on the bag ~o that
the doubled edge 14 of the zipper strip is torn off at the
top of the bag when the bag is first used.
To block the perforations and prevent the entry of
air or moisture prior to the bag being used, there is a cap
strip provided between the layers of the bag and the layers
of the zipper strip with a cap strip shown at l9 between the
zipper strip and the upper bag layer 10 and a cap strip 20
positioned between the lower bag layer 11 and the zipper
strip. This cap layer is of thin material which will
automatically tear when the top is torn off of the bag but
impervious to air and moisture so that it blocks the
perforations.
In the formation of this bag, the layers of the
bag film will be surface ~ealed to the zipper ~trip 13 thus
making a multilayered lamination.
Therefore, when th~ top is torn off of th~ bag,
there will be flanges above the profiles 15 which will have
substantial bulk. These flanges will provide readily
available and stiff pull flanges for pulling the zipper
profiles apart when the bag is to be opened and the bag will
again be reclosed.
Fig. 1 illustrates the assembly of the zipper
strip as it may be prepared. The layers 13a and 13b of the
zipper strip can be laminated to each other and the cap
strips 19 and 20 laminated over the rows of perforations 18
and 19. The zipper strip is then folded to be doubled at
14, Fig. 2 and placed between the bag layers before the fin
seal 12 is made. Actually, the fin seal is made by the
application of heat and the zipper strip can be bonded in
place at the top of the bag by application of heat to the
outer surface of the upper and lower film layers 10 and 11.
For facilitating this bonding and to prevent any
distortion or damage to the profiles 15, it is desirable
that only sufficient heat be applied to cause a lamination
of the outer layers of the zipper strip to the layers of the
bag. A preferred arrangement to permitting high speed
manufacturing operation without concern as to damaging the
profiles is to manufacture the inner layer of the zipper
strip of a higher melt temperature plastic than the outer
layer. For example, the outer layer 13b may be of the same
or similar melt temperature ~s the outer layers 10 and 11 of
the bag. The inner layer 13a of the zipper ~trip may have a
higher melt temperature so that it does not distort or tend
to melt with the application of heat which bonds the zipper
strip to the bag film. Also, the profiles 15 may be formed
of the higher melt temperature plastic ~o that they resi6t
any distortion due to being heated.
Another arrangement which may be employed to
protect the profiles is to make the lower edge of the zipper
strips of a higher temperature plastic. For example, as
6hown at 13c and 13d, the plastic of the zipper strip below
those lines 13c and 13d may be made in its entirety of a
higher melt temperature plastic. The zipper strip plastic
above lines 13c and 13d will be of the lower melt
temperature plastic so that they will bond readily to the
film layers 10 and 11 of the bag and will effectively
sandwich the cap strips 19 and 20 therebetween. The cap
strips may be formed also of a thin plastic of the same melt
temperature as the bag film and the zipper strip or the cap
strips may of a higher or lower melt temperature inasmuch as
they are effectively sandwiched between the layers to
provide a barrier preventing the entry of air and moisture
through the perforati~n openings.
~ he perforation openings such as shown at 15 and
17 in the facing layers of the bag and the zipper strip are
in alignment for ease of tearing. Similarly, the
perforations at the other side of the bag, that is, at 16
and 18 are also in alignment. ~owever, in rapid
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manufacturing operation, sometimes the perforations are not
exactly oriented. For this purpose, an arra~gement 6uch as
Fig. 3 is employed which insures ease of tearing. The
illustration of Fig. 3 shows juxtaposed layers such as that
of the outer film layer of the bag and the next adjacent
layer of the zipper strip. The zipper strip, for example,
will have perforations 24 and the bag will have perforations
25, with the assembled layers ~hown generally at 23. The
perforations in one of the layers, such as the perforations
24, will comprise lines extending straight along the
perforation line. The perforation lines 25 and the other
layer will extend d;agonally so that with any misalignment,
there will still be an overlap of the perforation. The cap
strip will be sufficiently broad to block any passage of air
through these perforations so that this arrangement of Fig.
3 will not impair the functionality of the structure.
Figs. 4 and 5 illustrate a method and structure
for simultaneously making multiple bags.
In Fig. 4 dual zippers are shown being made
utilizing an upper layer of film 26 and placing it over the
top of a lower layer of film 27. Between these layers of
film are doubled layers of zipper strip with the upper strip
layer shown at 29 and the lower zipper strip layer at 30.
At a center line 28, the layers are joined to each
other so that they will form a fin seal at the top of the
bag.
The zipper strips contain double profiles which
are spaced outwardly of the center line 28 of the joined
assembly with the interlocking profiles at one side for one
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of the bags ~hown at 31 and the interlocking profiles at the
other side for the other of the bags shown at 32.
Perforations extend through the layers and as
shown at 33, the aligned perforations will extend through
both layers 26 and 29. In alignment with these perforations
in the lower layers will be a line of perforations 34 which
extend through layers 30 and 27.
At the other side of the center line 28, will be
rows ~f aligned perforations. Perforations at 35 will
extend through layers 26 and 29. In the lower layers,
perforation lines 36 will extend through layers 30 and 27.
Cap strips 37 and 39 will be placed over the upper
layers to block the rows of perforations 33 and 35.
Lower cap strips 38 and 40 will be placed over the
lower rows of the perforations 34 and 36 to block and seal
these perforations.
The upper layer 26 will be laminated or
co-extruded with the layer 29 of the zipper strip.
Similarly, the lower film layer 27 will be laminated to or
co-extruded with lower zipper layer 30.
In the structure of Fig. 5, an upper bag film
layer is shown at 41 and a lower bag film layer is shown at
42. Sandwiched between these layer~ is the upper layer 43
of the zipper film and a lower layer 44 of the zipper film.
The layers of zipper film have profiles 44a and 44b
therebetween spaced outwardly from a center line 49. At the
center line, adeguate heat is applied to form a fin seal and
join all of the layers in a laminated fashion. By the
application of heat over the entire upper surface of ~he bag
film 41 and over the entire lower surface of the bag film
42, the outer layers of the zipper film are laminated
thereto. That is, the outer portion of the upper zipper
film is shown at 43a being of a lower melt temperature than
the inner layer 43b. Similarly, with the lower layer, the
layer 45a which faces the bag film layer 42 is of a lower
melt temperature than the inner layer 45b. When the
lamination has been completed, the bag assembly is ~evered
along the center line 49 to form two separate bags.
Figs. 6 and 7 illustrate structures which are used
to form a bag top wherein instead of providing a separate
cap strip, a multiple layered zippered strip is employed and
the outer layer of the zipper strip functions as a cap strip
to provide a barrier seal for the perforations.
Fig~ 7 illustrates the top end of the bag with an
upper film layer 58 and a lower film layer 59. Sandwiched
between the layers at the upper end of the bag is a doubled
zipper strip 56. This zipper strip is shown in its
assembled fashion in Fig. 6 having an inner layer 56a with
rows of separations 57 therealong. The outer layer 54 of
the zipper strip is imperforate. The zipper strip has
interlocking profiles 55 at its edges.
When the zipper strip is doubled as shown in Fig.
7, it is laminated in place between the layers 58 and 59 of
the bag. These layers have rows of perforations 5~a and 59a
which are blocked by the layer 54 of the zipper strip~ The
inner layer of the zipper strip has rows of separations
which are aligned with the rows of perforations in the film.
In the arrangement shown in Figs. 8 and 9, only
outer layer~ of the bag film are perforated and the zipper
strip forms the cap ~trip function of blocking air passage
through the rows of perforaticns.
In Fig. 9 an upper bag film layer 63 is laid over
a lower bag film layer 64 and the two layers are joined at a
fin ~eal 65. The upper layer has a row of perforations 66
and the l~wer layer has a row of perforations 67. Between
the bag layers i6 a doubled zipper strip shown in detail in
Fig. 8~ This zipper strip 60 has interlocking profiles 61
at its edge and rows of ribs 62 extend parallel to the
strip. When the zipper strip is folded and placed within
the top of the bag as shown in Fig. 9, the parallel rows of
ribs provide a tear guide means to insure that when the top
is torn off the bag, that the tear will be even and parallel
to the bag top. Furthermore, the ribs provide bulk and
stability for pull flanges when the bag is to be used after
the top tear strip is removed.
One further arrangement of providing bulk and
stiffness to the top of the pull flanges is in the
arrangement shown in Figs. 10 and 11. In Fig. 10 a zipper
strip 68 is provided with interlocking rib and groove
profiles 69 at the edges. Extending along the surface of
the zipper strip are rows of ribs 70 which are in the form
of small hollow tubes. These hollow tubes, as shown in Fig.
11, flatten when pressure is applied to the outer surface of
the strip such as when the bag side seals are formed but the
ribs provide improved gripping surfaces and bulk for pull
flanges when the zipper strip i5 laminated within the top of
a bag.
A still further way of providing for stiffness to
the pull flanges and for ~he top of the bag is illustrated
in Fig. 12. In Fig. 12 the top of a bag is ~hown formed
between an upper film layer 71 and a lower film layer 72.
The upper film layer has a row of perforations at 76 and the
lower film layer has a row of perforations at 77.
Laminated to the inner surface of the upper layer
at the bag top is a cap strip 73. This cap strip has a
thickened portion along at least one side. A thinner
portion 73c is placed over the row of perforations 76 and
functions adequately to block the row against air
penetration. Yet, at the edges of the cap strip, ar~
thickened portions 73a and 73b which provide rigidity for
the bag top. For the lower layer, a zipper strip 75 is
provided having a thinner portion 75c at the center with
thicker portions 75a and 75b at the edges. While these
strips are referred to as zipper strips, they can be
employed with profiles or used and constructed without
profiles as illustrated performing their functions as cap
strips and stiffeners for the bag. The thickened portions
are offset to match thinner portions in location. The
perforations are thus offset and in some constructions, it
may be desirable to align the perforations and the thinner
portions.
Fig. 13 illustrates the upper film layer of the
bag 71 in plan view with perforations at 76 and the lower
film layer 75 below it with its line of perforations 77.
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The cap strips are sandwiched between the film layers and
provide stiffness and rigidity for the film.
~ hus, it will be ~een that we have provided an
improved bag top structure and method of making plastic film
bags which meets the objectives and advantages above set
forth and accomplishes ~lexibility of purpose and attains
achievements not heretofore possible.
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