Note: Descriptions are shown in the official language in which they were submitted.
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EASY OPENING, RE-CLOSEABLE BAG
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. ~ 119(e) to U.S. Provisional
Application Serial No. 60!307,353, filed July 23, 2001 (Attorney Docket No.
8644P).
FIELD OF THE INVENTION
This invention relates to bags for use in storing products such as but not
limited
to powdered or granular detergent, pet food, coffee, cereal etc., wherein the
bag has a
line of weakness, which provides for easy opening of the bag. More
particularly the
bags further comprise an adjustable means for re-closing.
BACKGROUND OF THE INVENTION
Flexible bags are used today to package a wide variety of consumer products
including granular detergents. In order to be useful as a package these bags
must be
resistant to opening during shipping and handling at the store. Currently
marketed
detergent bags have several disadvantages. First, current. bags are difficult
to open
without the aid of scissors, a knife or other utensil. Often times the
consumer attempts to
rip open the bag, with the end result being that the contents are spilled out.
Additionally,
the bag and any text printed on the bag, can become distorted by the pulling
and
stretching of the opening action.
Second, once opened, current detergent bags offer no efficient and effective
means of re-closing the bag. The ability to re-close the bag is desired by
many
consumers. This is especially true for bulk size packages. Until now methods
for re-
closing such bags have been unsatisfactory. These methods include zippers and
adhesive
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tapes as well as simple folding mechanisms. The main drawback of the
aforementioned
methods is that contamination of the re-closing means with the contents of the
bag
prevents the means from forming a reliable, re-usable seal. Additionally,
simple folding
mechanisms provide no protection from product leakage.
Third, as the contents of the bag are gradually depleted it is desirable to be
able to
adjust the closing means such that the bag is more thoroughly sealed. Current
flexible
detergent bags do not offer means to adjust for a tight reliable closure.
Accordingly the need remains for a flexible bag for packaging consumer
products
that is easy to open i.e. without the aid of a knife, scissors or other
utensil. There remains
an additional need for a mechanism by which the bag can be securely re-closed
after
opening by the consumer. The re-closing mechanism should be unaffected by any
contamination. The need also remains for a re-closing means that is adjustable
to provide
a secure and reliable seal as the bag becomes less full.
SUMMARY OF THE INVENTION
The present invention meets the aforementioned needs by providing an easy to
open flexible bag. The bag is further provided with a means for re-closing,
which means
may also be adjustable.
In accordance with a first aspect of the invention a flexible bag comprising a
front
panel, back panel and two inwardly folded side panels, each panel having an
upper and
lower edge, a top portion and a bottom portion which are sealed by joining of
the front
panel to the back panel, the top portion being further defined by a line of
weakness,
wherein at least a portion of one panel of the bag remains un-weakened by the
line. The
line of weakness allows a clean and controlled rupture of the bag.
The bag may further comprise a means to re-close the bag after initial opening
by
the consumer. The re-closeable means may be adjustable to provide an effective
and
reliable closure as the contents of the bag are depleted.
All percentages, ratios, and proportions herein are on a weight basis unless
otherwise indicated. All documents cited herein are hereby incorporated by
reference
in their entirety.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a horizontal perspective view of a first embodiment of a bag of
the present
invention.
Figure 2 is a vertical perspective view of a first embodiment of a bag of the
present
invention.
Figure 3 is a vertical perspective view of a first embodiment of a bag of the
present
invention.
Figure 4 is a horizontal perspective view of a second embodiment of a bag of
the
present invention.
Figure 5 is a horizontal perspective view of a second embodiment of a bag of
the
present invention.
Figure 6 is a horizontal perspective view of a third embodiment of a bag of
the present
invention.
Figure 7 is a vertical perspective view of a third embodiment of a bag of the
present
invention in the closed position.
Figure 8 is a representation of a typical graph obtained using ASTM D-882 for
measuring tensile strength.
Figure 9 is a representation of a typical graph obtained using ASTM D-5733 for
measuring trapezoidal tear strength on a single specimen.
Figure 10 is a vertical perspective view of a fourth embodiment of the present
invention.
Figure 11 is a vertical perspective view of a fourth embodiment of the present
invention
in the closed position.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the present preferred embodiments of
the
invention, examples of which are illustrated in the accompanying figures. As
will be
understood, the terms front and back as used herein to describe panels of the
bag are for
orientation purposes only and are otherwise interchangeable. As discussed more
fully
hereafter, the present invention is directed to a flexible bag for containing
granular,
powdered or other contents, preferably granular detergent, provided with a
line of
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weakness to facilitate opening. A particularly preferred bag 10 made in
accordance with
the present invention is illustrated in Figure 1. The bag 10 is illustrated
having front
panel 12, back panel 14, and side panels 16 and 18 with each panel having an
upper edge
20 and a lower edge 22. The bag 10 also has a top section 24 and a bottom
section 26,
which are sealed by joining front panel 12 to back panel 14 along upper edges
20 and
lower edges 22. The bag 10 is provided with a line of weakness 28, wherein at
least a
portion of at least one of panels 12 or 14 is not weakened by the line 28. In
a preferred
embodiment the line 28 spans both side panels 16 and 18 and one of either
front panel 12
or back panel 14.
Figure 2 illustrates the same bag 10 as Figure 1 wherein the line of weakness
28
has been opened by pulling on either side of the line 28.
Figure 3 represents the same bag 10 as Figure 1 and additionally comprises re-
closeable means 30 (not shown in Figure 3) and 32. Re-closeable means 30 and
32 can
be any mechanical fastening mechanism and are preferably comprised of a hook
and loop
fastening system, wherein one of the means 30 or 32 is the hook component and
the other
is the loop component. It is within the scope of this invention that the two
are
interchangeable. Figure 4 shows the re-closeable means 30 as a small strip
adjacent to
upper edge 20 and affixed to front panel 12. It is also within the scope of
this invention
that the re-closeable means is comprised of a hook and hook system rather than
a hook
and loop system.
Figure 5 shows re-closeable means 32 as a vertical strip affixed to back panel
14.
Figure 6 illustrates another representation of re-closeable means 30. Figure 7
is a
representation of the bag in the closed position.
Another preferred embodiment of the re-closeable system is illustrated in
Figures
and 11. One component 30 of the re-closeable system is attached with the hook
or
loop portion facing the panel that is attached to, either front panel 12 or
back panel 14. A
portion of component 30 is left unattached. Closing of the bag occurs by two
consecutive
folds of the top section 2 of the bag 10. The first fold leaves the unattached
part of the re-
closeable system sticking out and enables it to match to the second component
of the
system. The second fold actually matches the mechanical fasteners together.
Figure 11
represents this alternative embodiment in the closed position.
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Bay Materials
The bags of the present invention are formed from elastic materials including
but
not limited to polymeric film, woven materials, non-woven materials,
preferably
polyethylene film, more preferably monolayers, coextrusions, two-layer
laminations,
three- layer laminations and metalized laminations, all materials with or
without lacquer
coatings. Bags according to the present invention can be formed by any method
known
in the art. One method for forming flexible bags from a continuous web of
material is
well known in the art and described in U.S. Pat. No. 5,054,619, issued to
Muckenfuhs.
Line of Weakness
The easy opening feature of bags according to the present invention results
from
the weakening of the film material in the desired trajectory of bag rupture or
separation.
The line of weakness is such that at least a portion of one panel of the bag
remains
un-weakened by the line. This prevents the entire top of the bag from being
separated
upon opening. After opening, the flap that results from the line of weakness
being broken
provides the bag with a handle or grasp area for the consumer to hold onto
while dosing
the product. This feature provides better maneuverability of the bag and
allows easier
dosing.
The line of weakness will deteriorate the strength of the film in such a way
that it
can withstand normal filling, packing and handling operation and yet be easily
opened by
the consumer. This behavior is achieved by reducing the trapezoidal tear
strength of the
original film. Reduction of the trapezoidal tear strength is also most likely
accompanied
by loss of tensile strength.
The line of weakness is characterized by the following test methods: a)ASTM D-
882 Standard Test Method for Tensile Properties on Thin Plastic Sheeting and
b) ASTM
D-5733 Standard Test Method for Tearing Strength of Nonwoven Fabrics by the
Trapezoidal Procedure. The resultant graphs of these test methods are
exemplified in
Figures 8 and 9. The samples used to generate Figures 8 and 9 are taken from
the line of
weakness 28 as shown in Figure 1. In accordance with ASTM D-882 and ASTM D-
5733, the line of weakness 28 must be parallel to the shortest side of the
sample (i.e.;
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width). The line of weakness 28 must cover the entire width of the sample and
must be
centered with respect to the sample length. The slot for initiating the cut of
the
trapezoidal tear sample must be on top of the line of weakness 28.
The line of weakness is characterized by three parameters obtained from the
above-mentioned standard tests. The first parameter is yield stress value.
Referring to
Figure 8, this graph is illustrative of the approximate yield stress value of
a weakened
film (shown in Figure 8 as Yz) versus the approximate yield stress value of an
unweakened film (shown in Figure 8 as Y,). The yield stress value of the
weakened film
in the ASTM D-882 tensile test should be no less than 90% of the yield stress
value of the
un-weakened film. Second, the final or rupture stress value of the weakened
film (shown
as RZ in Figure 8) should be no lower than 90% of the yield stress value of
the
unweakened film Y,:
Third, the average trapezoidal tearing force according to ASTM D-5733, of the
weakened film should be less than 4Kgf. Figure 9 is illustrative of a typical
graph
obtained using ASTM D-5733 for measuring trapezoidal tear strength on the
weakened
film of a single specimen. With regard to both Figures 8 and 9, the values
indicated
therein for force, elongation (Figure 8), and extension (Figure 9), should be
considered as
merely exemplary and in no way limiting to the present invention.
Additionally, the line of weakness may possess a pattern. Those patterns may
take the form of a continuous line, a dashed line, or a combination thereof.
However the
most preferred pattern is the dashed line, wherein the dashed line is
comprised of a
plurality of scored segments. The length of each scored segment varies from
about 0.12
mm to 4.4 mm, preferably varies from about 0.3 mm to 2 mm, and most preferably
varies
from about 0.6 mm to 1 mm. The distance between adjacent scored segments
varies from
about 0.4 mm to 4 mm, preferably varies from about 1 mm to 3 mm, and most
preferably
varies from about 1.5 mm to 2 mm. The score depth will vary depending upon the
thickness of the film.
A starting notch may be provided at some point along the line of weakness. The
starting notch provides an area, which is easier to tear because the scoring
is deeper. If
the line of weakness spans the back panel wherein there is also a vertical
seal, the starting
notch provides easy tearing through the multiple plies of the vertical seal to
the line of
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weakness.
Method of Producing the Line of Weakness
The line of weakness can be produced using methods including but not limited
to
scoring, perforating, chemical treatment, preferably laser scoring, laser
perforation,
mechanical scoring, mechanical perforation, embossing methods, or combinations
of
these methods. The line of weakness is preferably made in the film before it
is formed
into a bag.
One method of making a line of weakness in a flexible fihn uses at least one
laser.
First a laser bean with sufficient wattage to evaporate a portion of the film
material is
focused onto the film. The use of laser technology allows for very accurate
control of the
depth or penetration from very slight scoring to complete perforation of the
film. A laser
using any form of electromagnetic radiation can be used. Suitable lasers for
use in the
present invention include those based on COZ gas.
The speed of the film and the movement of the laser beam are dependent upon
the
pattern and depth of score desired as well as the type of film used. Suitable
methods for
Iaser scoring films are disclosed in US Patent Nos. 3,626,143, 3,790,744,
3,909,582 all to
American Can Company and US Patent Nos. 5,158,499 and 5,229,180 to Americail
National Can Company, US Patent No. 5,001,325 to LPF Verpakkingen B.V, US
Patent
No. 4,743,123 to Wavin B. V., Japanese Patents 09133018, 07008283 and 06103200
all
to Dainippon Printing Company.
Another suitable method for producing the line of weakness is the use of
blades.
The blades are installed on an engraving cylinder, which is mounted directly
on the film
processing machinery so that the cuts are made prior to formation of the bag.
Different
blade patterns can be used to get different patterns in the line of weakness.
The pressure
applied to the blades is also varied during the process to control the
dimensions and depth
of the cuts to ensure the bag opens easily.
Embossing is another alternative method for production of the line of
weakness.
The embossing technology weakens the film in specific areas by means of
pressure,
temperature, time and a deforming profile. The desired results are achieved by
changing
the caliper and/or material structure at the embossed trajectory. The basic
equipment
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used for embossing consists of a sealing jaw capable of pressing against a
back plate. A
deforming profile or pattern is fixed to the jaw and heated. The film is
pressed between
the deforming profile and the back plate. The main variables known to affect
this process
are: heating temperature, cooling temperature, pressure, heating time, cooling
time, film
tension while embossing, film tension after embossing, back plate material,
back plate
thickness, back plate temperature, jaw pattern and jaw thickness. The
embossing.unit
would be installed after an unwinding station of film, preferably incorporated
into the
packaging equipment line. Suitable examples of embossing are described in US
Patent
No. S,g7~,549 to American National Can Company.
Re-closeable S, s
The re-closeable system is resistant to contamination by the contents of the
bag.
Its main objective is to protect granule products contained in bags from
spillage,
humidity, and other external factors that might affect the integrity of the
product. This re-
closeable system comprises a mechanical fastener, preferably hook and loop or
hook and
hook type, attached to a flexible bag that allows consumers to open and
securely close the
bags as many times as product uses in the bag.
The system consists of placing fastening materials on opposite panels of the
bag.
In a preferred embodiment, the panels are the front and the back panel
although other
configurations are contemplated. The fasteners can be either disposable or
industrial
materials. It is desired to use disposable materials to optimize costs. The
mechanical
fasteners can be of any shape and size, and in any disposition. The particular
configuration of the re-closeable system components should be such that the
bag can be
sealed throughout the entire use of the product contained therein. By sealed
is meant that
no product spills out when the bag is tipped on its side. Specifically, the re-
closeable
system is characterized by the energy required to peel off one component of
the fastener
from the other component. This energy must not be less than 2.4Kgfmm per each
Kg of
product contained in the bag.
The re-closeable system is intended to work with the easy opening feature
described above which facilitates the opening of the bag. At least one (1)
piece of the
mechanical fastener is placed on one panel of the bag while a piece of the
matching
fastener is placed on the opposite panel of the bag. Preferably one piece of
the mechanical
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fastener is a vertical strip. The top of the bag (with the small piece of
fastener) is rolled
over for the two fasteners to match and tightly close the bag as the product
is being
consumed. As more product is consumed, the fasteners close farther down
vertically to
allow the tight seal. A variation of this design is also a button-to-button
closure. This
means that the mechanical fasteners can also consist of two individual buttons
that
perform the seal. In this case, the seal is a stationary one, instead of an
adjustable one.
These mechanical fasteners can be adhered to the bag by the means of
adhesives.
The adhesive can be either a hot melt or pressure sensitive adhesive. A hot
melt adhesive
is applied to the mechanical fastener right before the piece is to be applied
to the bag. The
pressure sensitive adhesive is adhered to the fastener as one piece.
The application of these mechanical fasteners to the bag can be accomplished
in different
ways. One way is to adhere these fasteners to the film before the bag is
produced. In this case,
the pieces of mechanical fasteners are attached to the film either while the
roll of film is being
prepared or while the roll of film is being unwound at the machine. The
mechanical fasteners
may also be adhered to the bag after it has been formed.
While particular embodiments of the present invention have been illustrated
and
described, it would be obvious to those skilled in the art that various other
changes and
modifications can be made without departing from the spirit and scope of the
invention.
It is therefore intended to cover in the appended claims all such changes and
modifications that are within the scope of this invention.
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