U.S. patent application number 14/859414 was filed with the patent office on 2017-03-23 for drawstring trash bag.
The applicant listed for this patent is Poly-America, L.P.. Invention is credited to Brad A. Cobler, Wade Morgan Moody.
Application Number | 20170081084 14/859414 |
Document ID | / |
Family ID | 58163415 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170081084 |
Kind Code |
A1 |
Moody; Wade Morgan ; et
al. |
March 23, 2017 |
DRAWSTRING TRASH BAG
Abstract
The present invention is directed to a drawstring bag comprising
a first panel and a second panel. The first panel and the second
panel are joined along a first side, a bottom, and a second side.
The first panel and the second panel thereby define an upper
opening of the bag. The drawstring bag may further comprise a first
pair of drawstrings disposed within a first hem along the upper
opening of the bag in the first panel and a second pair of
drawstrings disposed within a second hem along the upper opening of
the bag in the second panel. The first pair of drawstrings may
comprise a shorter elastic drawstring and a longer inelastic
drawstring.
Inventors: |
Moody; Wade Morgan; (Fort
Worth, TX) ; Cobler; Brad A.; (Irving, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Poly-America, L.P. |
Grand Prairie |
TX |
US |
|
|
Family ID: |
58163415 |
Appl. No.: |
14/859414 |
Filed: |
September 21, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65F 1/002 20130101;
B31B 70/8137 20170801; B65D 33/28 20130101; B31B 70/8135
20170801 |
International
Class: |
B65D 33/16 20060101
B65D033/16 |
Claims
1. A drawstring bag comprising: a first panel and a second panel,
the first panel and the second panel joined along a first side, a
bottom, and a second side, the first panel and the second panel
thereby defining an upper opening of the bag, a first hem located
along the upper opening of the bag in the first panel, a first
drawstring disposed within the first hem, a second drawstring
disposed within the first hem, the first panel, the second panel,
the first drawstring, and the second drawstring welded together
proximate to the first side by one or more first short seals, the
first panel, the second panel, the first drawstring and the second
drawstring welded together proximate to the second side by one or
more second short seals, the first drawstring having a working
length greater than a working length of the second drawstring, and
the second drawstring having an elongation at yield of less than
100% such that the second drawstring experiences a permanent
deformation when elongated less than 100%.
2. The drawstring bag of claim 1 further comprising: a first end of
the first drawstring located approximately above a first end of the
second drawstring.
3. The drawstring bag of claim 2 further comprising: the first end
of the first drawstring not overlapping the first end of the second
drawstring so that the entire height of the first end of the first
drawstring is welded to an upper edge of the first and second
panels.
4. The drawstring bag of claim 1 further comprising: a width of the
first drawstring approximately one-half inch or less, and a width
of the second drawstring approximately one-half inch or less.
5. The drawstring bag of claim 1 further comprising: a thickness of
the first drawstring less than a thickness of the second
drawstring.
6. The drawstring bag of claim 1 further comprising: an inner bag
opening length defined by an out-stretched distance between an
inner edge of the one or more first short seals and an inner edge
of the one or more second short seals, the working length of the
second drawstring less than the inner bag opening length, and the
working length of the first drawstring equal to or greater than the
inner bag opening length.
7. The drawstring bag of claim 1 further comprising: the first
drawstring inelastic, and the second drawstring elastic.
8. A drawstring bag comprising: a first panel and a second panel,
the first panel and the second panel joined along a first side, a
bottom, and a second side, the first panel and the second panel
thereby defining an upper opening of the bag, a first hem located
along the upper opening of the bag in the first panel, a first
drawstring disposed within the first hem, a second drawstring
disposed within the first hem, the first panel, the second panel,
the first drawstring, and the second drawstring welded together
proximate to the first side, the first panel, the second panel, the
first drawstring and the second drawstring welded together
proximate to the second side, the first drawstring having a working
length greater than a working length of the second drawstring, and
the second drawstring having an elongation at yield of less than
100% such that the second drawstring experiences a permanent
deformation when elongated less than 100%.
9. The drawstring bag of claim 8 further comprising: a first end of
the first drawstring located approximately above a first end of the
second drawstring.
10. (canceled)
11. The drawstring bag of claim 8 further comprising: the second
drawstring having a yield strength of at least approximately five
pounds and a thickness of approximately 3 mils or less.
12. The drawstring bag of claim 11 further comprising: a thickness
of the first drawstring less than a thickness of the second
drawstring.
13. The drawstring bag of claim 8 further comprising: an inner bag
opening length defined by an out-stretched distance between an
inner edge of the first side and an inner edge of the second side,
the working length of the second drawstring less than the inner bag
opening length, and the working length of the first drawstring
approximately equal to the inner bag opening length.
14. The drawstring bag of claim 8 further comprising: the first
drawstring inelastic, and the second drawstring elastic.
15. The drawstring bag of claim 14 further comprising: the second
drawstring having a yield strength at least 50% and less than 100%
of a yield strength of the first drawstring.
16-20. (canceled)
21. The drawstring bag of claim 1 further comprising: the second
drawstring comprising a blend of LLDPE and LDPE.
22. The drawstring bag of claim 1 further comprising: the second
drawstring subjected to cold stretching.
23. The drawstring bag of claim 8 further comprising: the second
drawstring comprising a blend of LLDPE and LDPE.
24. The drawstring bag of claim 8 further comprising: the second
drawstring subjected to cold stretching.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to improvements in polymeric
bags. Specifically, the present invention relates to polymeric bags
utilizing a drawstring and typically used for trash or refuse
disposal. Moreover, the present invention relates to polymeric bags
utilizing both an elastic and inelastic drawstring in the same hem
of the bag.
[0004] 2. Description of the Related Art
[0005] Polymeric bags are ubiquitous in modern society. Polymeric
bags can be manufactured using woven polymeric materials or
manufactured using thin polymeric films with one or more material
layers. Applications for which polymeric bags may be utilized are
numerous with variations of polymeric bags used in a number of
different industries. Moreover, some polymeric bags may exhibit
certain properties depending on the specific polymeric materials
used in the manufacturing process.
[0006] The present invention relates primarily to thin-film bags,
typically polyethylene bags, used for trash or garbage collection.
Such bags are typically manufactured using a blown-film extrusion
process, providing a film material for the trash bag body which is
subsequently converted into a final product. Polyethylene trash
bags are available in different sizes, thicknesses, and colors and
typically incorporate one of three different closure methods:
straight top bags with twist tie closures; flapped bags where the
flaps can be used to secure, tie, and carry the bag; and drawstring
trash bags where a drawstring is provided within each hem to
provide a method for securing, tying, and carrying the trash bags.
The present invention is of particular relevance to drawtapes used
in drawstring trash bags.
[0007] Over the past decade drawstring trash bags have enjoyed
increasing commercial success as consumers recognize such bags
increased utility. This is particularly true with respect to
domestic household use where drawstring trash bags are now the most
popular type of trash bags used in kitchen settings.
[0008] Such drawstring bags typically feature a drawstring located
within each hem and anchored to the upper corners of the bag. The
drawstrings can be used to pull the trash bag closed, to secure the
trash bag mouth closed by tying the drawstrings closed, and to
provide handles for carrying the closed, filled trash bag.
Traditionally, such drawstrings were manufactured using primarily
high density polyethylene, which offers increased tensile strength
when compared to linear low density polyethylene or low density
polyethylene. However, new improved drawstrings are emerging which
provide other features and functions, particularly with respect to
securing the top of the drawstring trash bag onto a trash
receptacle.
[0009] One solution for gripping the top of a trash receptacle is
described in U.S. Pat. No. 5,133,607 (the '607 patent) entitled
"Plastic Liner Bag with Elastic Top Tie Strip." The '607 patent,
which is incorporated herein by reference, describes using an
elastic drawstring or band within the top of the drawstring bag.
The elastic drawstring can be pulled outward at the top corners of
the bag. Unfortunately, the elastic tie top requires relatively
expensive elastomeric materials and a thicker gauge than
traditional high density drawstrings.
[0010] Solutions have also been described for securing the top of
the drawstring trash bag onto a trash receptacle using multiple
drawtape elements. For instance, U.S. Pat. No. 6,164,824 (the '824
patent) entitled "Garbage Bag with Elastic Rim Edge Support,"
describes an elastic loop with a rest diameter, the elastic loop
located within an upper edge of a loop space of a trash bag. The
elastic loop is pulled over an outer rim of a trash receptacle to a
stretch diameter. The bag is described as being fixed to the
garbage receptacle as the elastic element attempts to resume its
rest diameter. The '824 patent also describes a loop shaped plastic
cinch element located in the same upper edge of the loop space that
may extend outside an opening of the upper edge of the loop space
which may be used to tie the top end of the garbage bag. Both the
cinch element and the elastic element are described as a continuous
loop. The '824 patent discloses costly and difficult to manufacture
materials for the cinch element, such as a band of fibrous
material. The '824 patent also discloses relatively expensive and
bulky materials for the elastic element, such as natural rubber,
that is only capable of carrying a small fraction of the weight of
a full trash bag.
[0011] Another solution involving multiple drawstring elements
includes U.S. Pat. No. 6,585,415 (the '415 patent) entitled
"Expandable Garbage Bag." The '415 patent describes a drawstring
garbage bag with inextensible ribbons disposed within hems at an
upper opening of both sides of the bag. Further described is an
elastic ribbon inserted into one of the two hems. Provided in at
least the hem containing the elastic ribbon is a hole for accessing
the ribbon. The elastic ribbon is configured so that it may be
pulled out of the hem, once the bag has been placed in a container,
and the hem wrapped over the top edge of the container, twisted,
and wrapped around the outer circumference of the bag around the
container to affix the bag to the container. The elastic ribbon
requires a highly elastic material for stretching over the entire
outer rim of a receptacle, adding considerable manufacturing costs
to the garbage bag.
[0012] Another approach to improving drawstring trash bags is
described in United States Published Patent Application No.
2011/0052103 (the '103 application) entitled "Elastic Drawstring
for Trash Bags," assigned to Applicant and hereby incorporated into
this disclosure by reference in its entirety. The '103 application
discloses a blend of linear low-density polyethylene (LLDPE) and
low-density polyethylene (LDPE) to provide a drawstring with
elastic-like properties. Specifically, when the two polyethylene
resins are used together as described in the patent application,
the resultant material provides limited elastic properties, with
the blended drawtape exhibiting a greater percentage of elongation
before yielding than either of the two materials would exhibit
alone. Moreover, a 3 mil drawtape according to the '103 application
can provide elastic recovery of approximately 80%, which is greater
than either the LLDPE or the LDPE materials would exhibit
individually.
[0013] A further improvement to the blended LLDPE and LDPE
drawstring of the '103 application is described in United States
Published Patent Application No. 2014/0254958 (the '958
application) entitled "Cold-Stretched Drawstring Trash Bag",
assigned to Applicant and hereby incorporated by reference in its
entirety into this disclosure. The '958 application discloses a
cold-stretch process applied to drawtape film that strain hardens
the film, increasing the tensile strength at yield, and decreasing
the elongation at yield of the film.
[0014] It would be advantageous to further improve the properties
of the drawstring trash bag described in the '103 application. For
instance, it would be advantageous to improve the range of
containers that a drawstring trash bag may be affixed to by using
common polyethylene materials, such as high density polyethylene,
linear low density polyethylene, and low density polyethylene. The
above described '103 and '958 applications describe a bag that is
capable of adhering to receptacle openings within a limited range.
The below described invention provides a drawstring bag capable of
easily adhering to a greater range of container openings while
still being manufactured with the aforementioned common and
low-cost polyethylene materials.
SUMMARY OF THE INVENTION
[0015] The present invention is directed to a drawstring bag
comprising a first panel and a second panel. The first panel and
the second panel are joined along a first side, a bottom, and a
second side. The first panel and the second panel define an upper
opening of the bag. The drawstring bag may further comprise a first
hem located along the upper opening of the bag in the first panel.
A first drawstring and a second drawstring may be disposed within
the first hem. One or more short seals may weld together the first
panel, the second panel, the first drawstring, and the second
drawstring proximate to the first side. The second drawstring may
have a working length greater than a working length of the first
drawstring. The first drawstring may have an elongation at yield of
less than 100%.
[0016] In at least one embodiment of the present invention, the
first drawstring may have a first end located approximately above a
first end of the second drawstring. The first end of the first
drawstring may not overlap the first end of the second drawstring
so that the entire height of the first end of the first drawstring
is welded to an upper edge of the first panel and the first panel.
A second end of the first drawstring may not overlap the second end
of the second drawstring so that the entire height of the second
end of the first drawstring is welded to an upper edge of the first
panel and the first panel. A width of the first drawstring may be
approximately one-half inch or less and a width of the second
drawstring may also be approximately one-half inch or less. A
thickness of the first drawstring may be less than a thickness of
the second drawstring.
[0017] In at least one embodiment of the present invention, an
inner bag opening length may be defined by an out-stretched
distance between an inner edge of the one or more first short seals
and an inner edge of the one or more second short seals. The
working length of the first drawstring may be less than the inner
bag opening length. The working length of the second drawstring may
be equal to or greater than the inner bag opening length.
Furthermore, in at least one embodiment, the first drawstring may
be relatively inelastic and the second drawstring may be relatively
elastic. The first drawstring may be comprised of a cold-stretched
blended LLDPE/LDPE film and the second drawstring may be comprised
of a HDPE film.
[0018] In another embodiment of the present invention, a drawstring
bag may comprise a first panel and a second panel. The first panel
and the second panel may be joined along a first side, a bottom,
and a second side. The first panel and the second panel may define
an upper opening of the bag. The drawstring bag may further
comprise a first hem located along the upper opening of the bag in
the first panel. A first drawstring and a second drawstring may be
disposed within the first hem. The first panel, the second panel,
the first drawstring, and the second drawstring may be welded
together proximate to the first side. The second drawstring may
have a working length greater than a working length of the first
drawstring. The first drawstring may have an elongation at yield of
less than 100%.
[0019] In at least one embodiment of the present invention, the
second drawstring may have a yield strength of at least
approximately five pounds. The second drawstring may also have a
thickness of approximately 3 mils. The drawstring bag may also have
an inner bag opening length defined by an out-stretched distance
between an inner edge of the first side and an inner edge of the
second side. In addition, the working length of the first
drawstring may be less than the inner bag opening length. Also, the
working length of the second drawstring may be approximately equal
to the inner bag opening length. Additionally, the second
drawstring may have a yield strength at least approximately 50% and
less than 100% of a yield strength of the first drawstring.
[0020] In an alternative embodiment of the present invention, a
drawstring bag may comprise a first panel and a second panel. The
first panel and the second panel may be joined along a first side,
a bottom, and a second side. The first panel and the second panel
may thereby define an upper opening of the bag. A first hem may be
located along the upper opening of the bag in the first panel. A
first drawstring may be disposed within the first hem and may
comprise a first drawtape and a second drawtape. A first surface of
the first drawtape may be affixed to an adjacent first surface of
the second drawtape. A width of the first drawtape may be greater
than a width of the second drawtape and an elasticity of the first
drawtape may be less than an elasticity of the second drawtape.
[0021] In at least one embodiment, the second drawtape may be
stretched prior to being affixed to the second drawtape.
Additionally, a length of the second drawtape may be stretched at
least 10% and no more than 25% prior to being affixed to the first
drawtape. Furthermore, the first drawtape may be affixed to the
second drawtape with adhesive. The first drawtape may be affixed to
the second drawtape intermittently defining a repeating pattern of
affixed sections of the first drawtape affixed to the second
drawtape and non-affixed sections of the first drawtape not affixed
to the second drawtape.
BRIEF DESCRIPTION OF THE RELATED DRAWINGS
[0022] A full and complete understanding of the present invention
may be obtained by reference to the detailed description of the
present invention and preferred embodiments when viewed with
reference to the accompanying drawings. The drawings can be briefly
described as follows.
[0023] FIG. 1 provides a side view of a drawstring trash bag
according to one embodiment of the present invention.
[0024] FIG. 2 provides an additional side view of the drawstring
trash bag of FIG. 1 with gathering of the first and second hems
shown and the hidden lines of the drawstrings within the first and
second hems not shown.
[0025] FIG. 3 provides a partial cross-sectional view of the
drawstring trash bag of FIGS. 1 and 2 taken along line A-A of FIG.
1.
[0026] FIG. 4 provides a partial cross-sectional view of an
alternative embodiment of the drawstring trash bag of the present
invention.
[0027] FIG. 5 provides a partial side view of an upper corner of
the drawstring trash bag of FIGS. 1, 2, and 3.
[0028] FIG. 6a provides a partial side view of a drawstring trash
bag according to an alternative embodiment of the present
invention.
[0029] FIG. 6b provides a detailed partial view of the drawstring
of the drawstring trash bag of FIG. 6a.
[0030] FIG. 7 provides an illustration of a process for
manufacturing the drawstring of FIG. 6a and FIG. 6b.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The present disclosure illustrates one or more preferred
embodiments of the present invention. It is not intended to provide
an illustration or encompass all embodiments contemplated by the
present invention. In view of the disclosure of the present
invention contained herein, a person having ordinary skill in the
art will recognize that innumerable modifications and insubstantial
changes may be incorporated or otherwise included within the
present invention without diverging from the spirit of the
invention. Therefore, it is understood that the present invention
is not limited to those embodiments disclosed herein. The appended
claims are intended to more fully and accurately encompass the
invention to the fullest extent possible, but it is fully
appreciated that certain limitations on the use of particular terms
is not intended to conclusively limit the scope of protection.
[0032] As the term is used herein, "linear low density
polyethylene," or LLDPE, is a category of polymer, specifically a
category of polyethylene resin with a density below 0.930
g/cm.sup.3 that is comprised of substantially linear polyethylene
molecules with significant short-chain branching. LLDPE is
typically made by copolymerization of ethylene with short-chain
alpha-olefins as known in the art, although alternative methods of
synthesizing LLDPE may be utilized. LLDPE may also include very low
density polyethylene resin (VLDPE), which is also sometimes known
as ultra low density polyethylene resin (ULDPE). VLDPE and ULDPE
are typically defined as an LLDPE with a density of less than 0.906
g/cm.sup.3.
[0033] As the term is used herein, "low density polyethylene," or
LDPE, is a type of polymer, specifically a category of polyethylene
resins with a density between 0.910 g/cm.sup.3 and 0.940 g/cm.sup.3
that is comprised of a high number of both short and long chain
branching along the respective polyethylene molecules. Unlike
LLDPE, LDPE is typically made through free radical polymerization
and has a lower tensile strength than LLDPE but greater
elasticity.
[0034] As the term is used herein, "high density polyethylene," or
HDPE, is a type of polymer, specifically a category of polyethylene
resins with density between 0.940 g/cm.sup.3 to 0.970 g/cm.sup.3
that is comprised of a greater proportion of crystalline regions
than LDPE. The size and size distribution of crystalline regions
are determinants of the tensile strength and environmental stress
crack resistance of the end product. HDPE, with fewer branches than
LDPE, HDPE has a greater proportion of crystals, which results in
greater density and greater strength but also much lower elasticity
in comparison to LDPE.
[0035] As the term is used within this particular disclosure,
"elastic," describes a relative physical property of a material. A
relatively elastic material is a material that may be elongated by
tension and recover to a greater percentage to its original length
than a material that is relatively inelastic. Elasticity of a
polymer film may be measured by an industry accepted test, such as
ASTM D-5449, known as the "Permanent Set Test." The relative
elasticity of various common materials used by Applicant has been
tested according to the Permanent Set Test to provide objective
criteria for materials that are relatively elastic and relatively
inelastic. As used herein in this particular disclosure, the term
relatively elastic, or elastic in general, shall refer to a
material that recovers at least 80% after a 20% elongation and a
relatively inelastic, or inelastic in general, material shall refer
to a material that recovers less than 80% after a 20% elongation,
with elastic recovery as measured by ASTM D-5449.
[0036] As the term is used herein, "yield strength," describes the
maximum tensile force a material may withstand without experiencing
a permanent elongation and "elongation at yield" describes the
elongation of a material when stretched to its yield strength
versus its initial unstretched length.
[0037] It is customary for Applicant to refer to a drawstring trash
bag when referring to the final product itself. However, when
referring to the physical structure of the "drawstring," it is
typically referred to as a drawtape. Therefore, although such usage
may not necessarily be universal, even within this application, the
term drawtape is frequently used when referring to the material
used for the drawstring before the conversion process, i.e. before
the process by which the drawstring is incorporated into a trash
bag.
[0038] Looking at FIG. 1 and FIG. 2, side views of a drawstring bag
100 are depicted illustrating an embodiment of the present
invention. In the depicted embodiment, the drawstring bag 100 is
manufactured from a first panel 102 and a second panel 104. A fold
forms the bag bottom 108 and seals 106a and 106b are provided along
a first side 107a and a second side 107b of the respective first
panel 102 and second panel 104. While this construction method is
the preferred method for manufacture, the invention disclosed
herein is not necessarily limited to any particular manufacturing
method or construction.
[0039] As part of the drawstring trash bag 100, drawstrings 116a,
116b, 118a and 118b are provided within hems 112 and 114, each hem
encompassing a pair of drawstrings, a first pair comprising
drawstrings 116a and 116b and a second pair comprising drawstrings
118a and 118b. To provide the hems 112 and 114, an upper edge of
the first panel 102 is folded over and sealed to form the first hem
112. Similarly, an upper edge of the second panel 104 is folded
over and sealed to form the second hem 114. First and second
drawstrings 116a and 116b are disposed within the first hem 112 and
extend across the width of the first panel 102 while third and
fourth drawstrings 118a and 118b are disposed within the second hem
114 and extend across the width of the second panel 104. For ease
of illustration, FIG. 1 utilizes a different dashed line style to
differentiate between the two drawstrings encapsulated in each
hem.
[0040] In a preferred embodiment, the first and third drawstrings
116a and 118a are relatively inelastic while the second and third
drawstrings 116b and 118b are relatively elastic. The second and
fourth drawstrings 116b and 118b provide the necessary elasticity
for the drawstring bag to fit snugly over a wide range of trash
receptacle openings. The first and third drawstrings 116a and 118a,
working in conjunction with the second and fourth drawstrings 116b
and 118b, provide the necessary lifting capacity for a user to lift
a full bag 100 out of a trash receptacle, close and tie the bag,
and to carry it for disposal. In at least one preferred embodiment,
the necessary lifting capacity is only provided by both pairs of
drawstrings, 116a/b and 118a/b working in parallel; only a single
drawstring in each hem does not provide the lifting capacity needed
to remove a fully loaded bag from a container and to carry it
away.
[0041] In a preferred embodiment, the respective ends of the first,
second, third, and fourth drawstrings 116a, 116b, 118a and 118b are
secured within the hems 112 and 114 by a pair of short seals 120
and 121 provided in the upper corners of the drawstring trash bag
100. The short seals 120 and 121 may generally be formed by
applying a combination of heat and pressure in the locations shown
in FIGS. 1 and 2. Each short seal seals or welds together an upper
edge of the first panel 102, the first panel 102, an end of the
four drawstrings 116a, 116b, 118a and 118b, the second panel 104,
and the upper edge of the first panel 104. In an alternative
embodiment, the respective ends of the first, second, third, and
fourth drawstrings 116a, 116b, 118a and 118b are secured within the
hems 112 and 114 only by the side seals 106a and 106b that secure
the sides of the first panel 102 to the second panel 104. In some
embodiments, including a depicted preferred embodiment, a
drawstring bag 100 includes central access cutouts 110a and 110b.
The central access cutouts 110a and 110b allow a user to pull the
drawstrings 116a, 116b, 118a and 118b through the cutouts 110a and
110b to close the opening of the bag 100.
[0042] FIG. 3, which is not to scale, is a fractional cross-section
of bag 100 that depicts drawstrings 116a, 116b, 118a and 118a
disposed within hems 112 and 114 formed in the drawstring trash bag
100. To provide the hems containing the drawstrings 116a, 116b,
118a and 118a, the uppermost portion of the first and second panels
102 and 104 are folded over the drawstrings 116a, 116b, 118a and
118a, respectively. The first hem 112 is created after forming a
hem seal on the first panel 102 while the second hem 114 is sealed
by the hem seal on the second panel 104, encapsulating the
drawstrings 116a, 116b, 118a and 118a within the respective hems
112 and 114. The hem seals may generally be formed by applying a
combination of heat and pressure to each panel, sealing the two
layers of polyethylene film together on each respective panel 102
and 104.
[0043] As shown in FIG. 3, first and second drawstrings 116a and
116b are arranged above and below each other within hem 112.
Similarly, third and fourth drawstrings 118a and 118b are arranged
above and below each other within hem 114. Shown in FIG. 4 is an
alternative arrangement for each pair of drawstrings with each pair
of drawstrings shown in a side-by-side arrangement within each hem
112 and 114. The arrangement of the drawstrings in FIG. 3 may be
preferable since such an arrangement limits the number of layers
welded by the short seals 120 and 121.
[0044] As known to a person having ordinary skill in the art,
difficulty arises when attempting to weld multiple layers of
polyethylene film together. Thus, it is desirable to limit the
number layers of film that are welded together at a single
location. As shown in FIG. 5, a preferred embodiment of the present
invention limits the number of layers of film welded together at
both ends of the hems. FIG. 5 illustrates an anchoring location of
the drawstrings of the embodiment of the invention shown in FIG.
3.
[0045] FIG. 5 shows a first end of the first drawstring 116a welded
to a first end of hem 112 of the bag 100 at a first upper short
seal 120a and a first end of the second drawstring 116b welded to
the first end of hem 112 at a first lower short seal 120b. A first
end of the third drawstring 118a is welded to a first end of the
second hem 114 at the upper short seal 120a and a first end of the
fourth drawstring 118b is welded to the lower short seal 120b.
Similarly, second ends of the first drawstring 116a and third
drawstring 118a can be welded to a second end of hem 112 of the bag
100 at a second upper short seal (not shown) and second ends of the
second drawstring 116b and fourth drawstring 118b can be welded to
the second end of hem 112 at a second lower short seal (not
shown).
[0046] The arrangement of the drawstrings 116a, 116b, 118a and 118a
depicted in FIG. 5 limits the number of layers welded together at
the short seals 120 and 121 and also places the drawstrings within
the hems 112 and 114 above and below each other for easy access by
a user of the drawstring trash bag 100. The short seals 120a and
120b may be formed by two separate welds or may also be formed by a
single weld for ease of manufacturing. Furthermore, the short seals
120a and 120b may be separated by a certain amount of distance as
shown in FIG. 5, may be placed so that a lower edge of seal 120a is
in contact with an upper edge of seal 120b, or may be positioned
where a limited amount of seal 120a overlaps with seal 120b.
[0047] In a preferred embodiment, if short seal 120a overlaps short
seal 120b, the overlap is limited. For instance, upper short seal
120a can have an upper short seal height extending from an upper to
a lower edge of short seal 120a and lower short seal 120b can have
a lower short seal height extending form an upper to a lower edge
of short seal 120b. Preferably, less than one-half of the upper
short seal height overlaps with less than one-half of the lower
short seal height. This overlap arrangement then leads to at least
one-half of the upper short seal height in contact with both panel
102 and upper edge of panel 102 within hem 112. In a likewise
fashion, at least one-half of the lower short seal height is then
placed in contact with both panel 102 and the upper edge of panel
102 within hem 112.
[0048] In at least one preferred embodiment, the elastic second and
fourth drawstrings 116b and 118b may be formed from a blend of
LLDPE and LDPE as disclosed by the previously discussed '103
application. This particular blend of polyethylene film provides
the necessary elastic recovery, force-to-stretch (the effort
required to stretch the film over a trash receptacle), and tensile
strength at yield while utilizing cost-effective materials. The
cold-stretched blend of LLDPE/LDPE, due to it comprising primarily
LLDPE, is still capable of carrying a significant load in tension,
with the addition of the LDPE surprisingly only negligibly
affecting its yield strength and its elongation at yield. In
another preferred embodiment, the drawtape film formed according to
the '103 application may further undergo a cold-stretched process
as described in the previously discussed '958 application. Use of
the cold-stretch process increases the yield strength of the film
and decreases the film's elongation at yield. For instance, a
one-inch wide and approximately 3 mil thick film made from the
aforementioned polyethylene blend according to the '103
application, has been shown to have approximately a 7.4 pound yield
strength and approximately a 104% elongation at yield. In contrast
to this, the same material after undergoing the cold-stretch
process has been shown to have a yield strength of approximately
10.4 pounds and an elongation at yield of approximately 54%.
[0049] The cold-stretch process of the '958 application has also
been shown to increase the elastic recovery of the drawtape film.
For example, a one-inch wide and approximately 3 mil thick drawtape
film made according to the '103 application exhibited an elastic
recovery of only 78% when tested according to the Permanent Set
Test while film of the same construction with the cold-stretch
process applied to it exhibited an elastic recovery of 89%. Hence,
the cold-stretch process provides an elastic drawtape film capable
of carrying a heavier load at a more useful length while also
increasing the elastic recovery of the film.
[0050] When the force applied to a drawstring exceeds the yield
strength of the drawstring, the drawstring will begin to stretch
uncontrollably. Exceeding the yield strength results in permanent
deformation and rapid, excessive elongation of the drawstring,
making the yielding drawstring mostly useless to carry the load of
the bag. Therefore, increasing the tensile strength at yield to
10.4 pounds from 7.4 pounds means that a cold-stretched drawtape
film can effectively carry more weight than a drawtape film of the
same material that has not been cold-stretched and having otherwise
identical construction. The elongation at yield for the
cold-stretch drawtape film is essentially half of the comparable
non-cold-stretch drawtape film. Thus, reduced elongation of the
cold-stretch drawtape film makes carrying a fully loaded trash bag
utilizing the cold-stretched drawtape film easier.
[0051] Regarding the inelastic first and third drawstrings 116a and
118a of the present invention, an example of a relatively inelastic
and cost-effective film is HDPE. Common examples of HDPE film are
known to provide 10 to 11 pounds of yield strength for a one-inch
wide film having a thickness of approximately 2.25 mils. The
thickness or width of the inelastic drawtape film may be decreased
if less lifting capacity is required and it also may be increased
if additional lifting capacity is required.
[0052] In a preferred embodiment, the third drawstring 118a of the
second hem 114 has the same structure and composition as the first
drawstring 116a of the first hem 112. In a likewise manner, in a
preferred embodiment, the fourth drawstring 118b of the second hem
114 has the same structure and composition as the second drawstring
116b of the first hem 112. In other words, the construction of the
second hem 114 is identical to the first hem 112. Thus, for the
sake of brevity, only the first pair of drawstrings, drawstrings
116a and 116b are discussed in detail below.
[0053] In a preferred embodiment, a working length of the first
drawstring 116a is longer than a working length of the second
drawstring 116b as shown in FIGS. 1 and 2. The working length is a
path length of a drawstring between its two anchor points of the
first short seal 120 and the second short seal 121. As previously
mentioned, the first drawstring 116a is constructed from a
relatively inelastic material, such as the HDPE drawtape film
discussed above. The second drawstring 116b, as also previously
discussed, is constructed from a relatively elastic material, such
as the cold-stretched LLDPE/LDPE blend discussed above. The working
length of the second drawstring 116b is shorter than the
out-stretched width of the trash bag 100 between short seals 120
and 121 such that the hem 112 of the trash bag 100 gathers due to
the shorter length of the first drawstring 116b pulling short seals
120 and 121 inwards towards each other. This gathering of hem 112
is shown by the surface texture lines of FIG. 1b. The first
drawstring 116a gathers, or bunches up, along with the hem 112 but
due to its greater degree of freedom, and its inherent greater
degree of stiffness, has a tendency to loop outside of cutout 110a,
as shown in FIG. 1a and FIG. 1b rather than bunching up throughout
its length.
[0054] In one particular example, a distance between an inner end
of the first short seal 120 and the inner end of the second short
seal 121 of an outstretched bag 100, i.e. the inner hem width, is
approximately 23 inches while the working length of the second
drawstring 116b is approximately 21 inches and the working length
of the first drawstring is 116a is the same length as the inner
width of the two short seals, 23 inches. These dimensions result in
the hem 112 and first drawstring 116a gathering or bunching up
about two inches as illustrated in FIG. 1b, the texture lines of
the figure illustrating the gathering or bunching of the hems 112
and 114.
[0055] As discussed above, the invention contemplates the elastic
drawstrings 116b and 118b having a shorter working length than a
width between the inner edge of short seals 120 and 121. One method
of manufacturing bag 100 with these properties is to out-stretch
the elastic drawstrings 116b and 118b prior to sealing the
drawstrings within the hems 112 and 114 with short seals 120 and
121. To prevent the short seals 120 and 121 from failing, it is
necessary to stretch an inner length of the elastic drawstrings
116b and 118b so that the ends of the drawstrings are not in
tension when short seals 120 and 121 are made. If the ends of the
elastic drawstrings 116b and 118b are under tension when a the
short sealing operation is performed, there is a risk that the
seals will fail since the molten material formed during the sealing
operation will pull away resulting in the drawstrings 116b and 118b
not sealed to the hems 112 and 114. In contrast to the elastic
drawstrings, the inelastic drawstrings 116a and 118a are not
stretched when incorporated into the bag 100 and hence the working
length of the inelastic drawstrings 116a and 118a is the same as
the out-stretched inner width between the inner edges of short
seals 120 and 121.
[0056] The second drawstring 116b, and in cooperation with it, the
fourth drawstring 118b, having such shorter lengths than known
drawstring trash bags, allows the bag 100 to fit over trash
containers with a greater range of upper lip circumferences or
perimeters (i.e. the opening of the trash container) than other
known drawstring trash bags utilizing similar construction and
materials. For instance, the circumference or perimeter of the
opening of a typical kitchen trash receptacle can vary from at
least 42 to 50 inches. With the initial circumference of trash bag
100 limited to 42 inches, due to the working length of the two
shorter elastic drawstrings 116b and 118b of 21 inches, drawstring
trash bag 100 is capable of snugly adhering to trash receptacles
with an upper lip perimeter as small as 42 inches. In certain
embodiments, the elastic drawstrings 116b and 118b may be formed
even shorter so that bag 100 may fit over receptacles with even
smaller openings.
[0057] Although the shorter drawstrings 116b and 118b allow bag 100
to fit snugly over a greater range of receptacle openings, the
shorter length of the second and fourth drawstrings 116b and 118b
would be expected to require a greater amount of effort to stretch
the drawstrings over receptacles with larger openings than bags
with longer drawstrings of similar construction. However, in at
least one preferred embodiment, the second and fourth drawstrings
116b and 118b are only one-half the width of a typical drawstring,
lessening the otherwise higher effort that would be required to
stretch the drawstring trash bag 100 over trash receptacles with
larger openings. Each drawstring also limits the material cost of
bag 100. In at least one preferred embodiment, the first and third
drawstrings 116a and 118a also have a width of approximately
one-half the width of a typical drawstring so that each pair of
drawstrings, laying side-by-side, have approximately the same width
as a single typical drawstring.
[0058] Throughout the trash bag industry, drawstrings widths are
typically one inch wide while drawstring thickness varies depending
upon drawtape material. For LLDPE drawtapes, a common material used
in the manufacture of drawstrings, a nominal thickness of between 3
and 5 mils is typical and for HDPE drawtapes a nominal thickness of
between 2 and 2.5 mils is typical. These dimensions provide the
necessary yield strength of approximately 10 lbs, depending upon
the particular properties of the materials used. This provides for
a drawstring trash bag capable of lifting a bag weighing
approximately 40 pounds with the weight distributed evenly over the
four sections of the drawstring. The thickness of any particular
drawtape film may be decreased to lower the cost of a drawstring
trash bag if less lifting capacity is required. The thickness of
any particular drawtape film may also be increased if additional
lifting capacity is required. However, the overall weight capacity
of a drawstring trash bag may be limited to other design factors,
such as the strength of the film forming the panels and hems of the
bag, or the strength of the side seals and hem seals welding the
various components of the bag together.
[0059] With the typical drawstring having a width of one inch, in a
preferred embodiment of the present invention, each drawstring of
trash bag 100 has a width of approximately one-half inch. With the
width of the shorter elastic drawstrings 116b and 118b one-half of
a typical drawstring, the initial effort required to pull the
drawstring bag over a typical trash receptacle is lessened to
one-half, since the tensile resistance of the film is directly
related to its cross-sectional area. For trash receptacles of
smaller openings, the inelastic longer drawstrings 116a and 118a do
not factor into the effort required to place the trash bag 100 over
trash receptacles having a perimeter of 48 inches or less, since no
stretching of the inelastic drawstrings is necessary due to the
longer length of these drawstrings.
[0060] Even though the effort required increases as the drawstring
116b and 118b are elongated further, the effort remains less than
is required for a typical one-inch wide drawstring, at least for
trash receptacles having openings of 48 inches or less utilizing a
preferred embodiment of the present invention. For example, testing
shows that as little as 6.5 pounds would be required to stretch
trash bag 100 of the preferred embodiment over a receptacle having
a 48 inch perimeter. However, if the drawstring bag 100 is pulled
over a trash receptacle opening having a perimeter greater than 48
inches, the longer inelastic drawstrings 116a and 118a would be
required to stretch. Testing has shown that a prior art drawstring
trash bag with one-inch HDPE drawstrings and a 24 inch width, such
as the inelastic drawstrings of a preferred embodiment of the
present invention, requires a force of approximately 23 pounds to
be stretched over a trash receptacle with a 50 inch opening.
Testing has also shown that a prior art trash bag with a
cold-stretched elastic drawstring requires a force of approximately
13 pounds to be stretched around the same trash receptacle opening.
Based upon these test results, it is estimated that a preferred
embodiment of trash bag 100 would require a force to stretch around
the same receptacle an average of these two values, approximately
17.5 pounds.
[0061] Drawstring trash bags constructed with HDPE drawtapes often
times are known to poorly grip the openings of many trash
receptacles due to the marginal elasticity of HDPE. For trash
receptacles within a narrow range, HDPE drawstring trash bags may
be able to adhere to a trash receptacle opening. For trash
receptacles larger than the opening of the trash bag, it may be
possible for a user to stretch HDPE drawstring over the
receptacle's opening. However, for receptacles with very larger
openings, once the bag is stretched over the receptacle, it is
possible that the bag will not snugly adhere to the receptacle if
the HDPE drawstrings were overstretched and the limited elastic
recovery of the HDPE drawstrings have been exceeded. However, with
the present invention, even though the HDPE drawstrings may have
exceeded their elastic recovery to fit over a larger receptacle,
the elastic drawstrings, having a much greater range of elastic
recovery, will recover after being pulled around larger receptacles
and provide a snug fit to the receptacle. Furthermore, since the
widths of the inelastic drawstrings 116a and 118a are a fraction of
prior art HDPE drawstrings, the effort to pull the drawstrings over
a large receptacle is significantly reduced.
[0062] While the disclosed invention provides a drawstring trash
bag that fits over a wider range of trash receptacles while
requiring less effort to fit over many of these trash receptacles
than prior art drawstring trash bags, it also provides the
necessary strength to be able to lift a full trash bag out of a
receptacle and to carry it away. As previously mentioned, one
reason that one-inch wide drawstrings have become accepted
throughout the industry is that such a width provides the required
lifting strength with commonly available and cost effective
materials. Thus, it follows that the one-half inch wide elastic
drawstrings 116a and 118b of the present invention, when
constructed out of HDPE, do not provide the necessary lifting
capacity standing alone. Hence, the elastic drawstrings 116b and
118b must provide part of the necessary lifting capacity.
[0063] In an exemplary embodiment, it is estimated that a trash bag
utilizing only one-half inch wide elastic drawstrings 116b and
118b, as contemplated by the invention and constructed from the
previously discussed cold-stretched blend of LLDPE/LDPE, with a
thickness of approximately 3 mils, would have a maximum lifting
capacity of 20 pounds, with each of the four drawstring sections
having approximately a five pound yield strength each. However,
when one-half inch elastic drawstrings 116b and 118b are used in
conjunction with one-half inch wide inelastic drawstrings 116a and
118a constructed from the previously discussed HDPE, the cumulative
effect of both drawstrings working in parallel provides a lifting
capacity of approximately 40 pounds; the maximum expected weight of
a typical kitchen drawstring trash bag.
[0064] Each of the drawstrings, both the elastic and inelastic
drawstrings 116a, 116b, 118a and 118a, work together to carry the
load once the elastic drawstrings 116b and 118b are stretched to
the length of the inelastic drawstrings 116a and 118a. Furthermore,
once the elastic drawstrings 116b and 118b stretch to the length of
the inelastic drawstrings 116a and 118a, the elongation of the
drawstrings 116a, 116b, 118a and 118a decreases significantly, when
a fully weighted bag 100 is lifted, due to the limited elasticity
of the inelastic drawstrings 116a and 118a. Each inelastic
drawstring 116a and 118a, with a thickness of 2.25 mils and a width
of one-half inch, may carry approximately a five pound load each.
The inelastic drawstrings 116a and 118a may also be made wider or
thicker to provide a higher lifting capacity if necessary.
[0065] Shown in FIGS. 6a and 6b is an alternative embodiment of the
present invention. Shown in FIG. 6a is a partial view of drawstring
bag 200 formed from a continuous folded web. Shown incorporated
into bag 200 is drawstring 210. Further shown on both sides of bag
200 are sides of adjacent bags formed from the continuous folded
web. FIG. 6a also shows first short seal 220, second short seal
221, and side seals 206. Also shown are perforations 230 on each
side of bag 200. Drawstring 210 is incorporated into bag 200 by
common converting processes as known to persons skilled in the art.
Drawstring 210 is affixed to bag 200 by short seals 220 and
221.
[0066] The structure of drawstring 210 is shown more clearly in
FIG. 6b, which shows a fragmented length of drawstring 210.
Drawstring 210 is formed by an inelastic drawtape 212 and an
elastic drawtape 214. Elastic drawtape 214 is placed centrally
along inelastic drawtape 212. A longitudinal axis of elastic
drawtape 214 is centered about a longitudinal axis of inelastic
drawtape 212 with a first surface of elastic drawtape 214 affixed
to an adjacent first surface of inelastic drawtape 212. The
surfaces of drawtapes 212 and 214 may be affixed to each other via
adhesive or other means known to a person skilled in the art, such
as heat sealing.
[0067] In at least one preferred embodiment, inelastic drawtape 212
is formed with a relatively inelastic material such as HDPE while
elastic drawtape 214 is formed with a relatively highly elastic
material. The highly elastic material can include
non-heat-shrinkable polymers such as block copolymers which are
elastomeric, such as as A-B or A-B-A block copolymers.
Styrene/isoprene, butadiene, or ethylene-butylene/styrene (SIS,
SBS, or SEBS) block copolymers may also be particularly useful.
Other useful elastomeric compositions can include elastomeric
polyurethanes, ethylene copolymers such as ethylene vinyl acetates,
ethylene/propylene copolymer elastomers or ethylene/propylene/diene
terpolymer elastomers. The relatively inelastic drawtape 212 may be
formed from other common materials such as LLDPE, blends of
HDPE/LLDPE, or other commonly known polymeric materials.
[0068] As shown in FIG. 6b, inelastic drawtape 212 has a width much
greater than a width of elastic drawtape 214. In at least one
preferred embodiment, drawtape 212 can have an approximate nominal
width of one inch while drawtape 214 can have an approximate
nominal width between 1/4 and 1/4 inch. Unlike previous
embodiments, adjacent planar surfaces of drawtapes 212 and 214 are
affixed to each other prior to being incorporated into bag 200.
[0069] Elastic drawtape 214 is stretched prior to being affixed to
drawtape 212. In at least one preferred embodiment, elastic
drawtape 214 is stretched approximately 10% in relation to its
original length. In various embodiments, elastic drawtape 214 may
be stretched as little as 5% and as much as 50%, but ideally
between 15% and 25% prior to being adhered to inelastic drawtape
212. Due to its high elasticity, elastic drawtape 214 is typically
capable of recovering approximately 100% after being stretched.
Hence, once elastic drawtape 214 is adhered to inelastic drawtape
212, it places both drawtapes 212 and 214, now drawstring 210,
under tension. Once drawstring 210 is incorporated into drawstring
bag 200, the hem 222 of bag 200 will have a tendency to gather due
to drawstring 210 attempting to recover to the unstretched length
of elastic drawtape 214.
[0070] Shown in FIG. 7 is an exemplary process for forming
drawstring 210. Elastic drawtape 214 and inelastic drawtape 212 are
shown unrolling from feedstock rolls 310 and 312. Elastic drawtape
214 unrolls from roll 312 and then passes through stretching nip
rollers 320. After passing through stretching nip rollers 320,
elastic drawtape 214 passes over adhesive roller 322. The surface
of adhesive roller 322 can be supplied with an adhesive that is
applied to a first surface of drawtape 214 as it comes into contact
with the circumferential surface of adhesive roller 322. The
adhesive may be applied to drawtape 214 continuously or
intermittently. Intermittent application of the adhesive may be
desirable as discussed below. Once elastic drawtape 214 rolls over
adhesive roller 322, it enters affixing nip rollers 324. In at
least one alternative embodiment, an adhesive may be applied to
inelastic drawtape 212 rather than elastic drawtape 214. Adhesive
may also be applied to both inelastic drawtape 212 and elastic
drawtape 214.
[0071] Affixing nip rollers 324, as shown in FIG. 7, rotate faster
than stretching nip rollers 322. The difference in speed between
the sets of nip rollers stretches the elastic drawtape 214 prior to
it being adhered to inelastic drawtape 212. The difference in speed
can be varied based on the amount of stretching desired in drawtape
212. As discussed above, the amount of stretch, and hence the
approximate difference in speed between the sets of nip rollers 320
and 324, can vary between approximately 5% and 50% with an ideal
speed difference between 15% and 25%. Inelastic drawtape 212 rolls
directly from feedstock roll 310 to nip rollers 324. Hence,
inelastic drawtape 212 is not stretched in the construction of
drawstring 210. Drawtapes 212 and 214 are pressed together by nip
rollers 324; bringing a surface of elastic drawtape 212 into
contact with an adjacent surface of inelastic drawtape 214 so that
the adhesive adheres the two drawtapes 212 and 214 together,
forming drawstring 210.
[0072] If adhesive has been applied intermittently to one or more
drawtapes 212 and 214, then the two drawtapes may be affixed to
each other in affixed sections and not affixed to each in
non-affixed sections. This intermittent affixation of drawtapes 212
and 214 may be desirable to control the bunching of inelastic
drawtape 212 once tension in drawstring 210 is released and elastic
drawtape 214 recovers or attempts to recover to its original
unstretched length. The distance between affixed sections and
non-affixed sections may vary greatly, but in one preferred
embodiment, adhesive may be applied to one or more drawstrings 212
and 214 so that a gap of 1/4-inch to 3/8-inch exists between each
affixed section and a length of approximately 1/16-inch to 1/8-inch
of both drawtapes 212 and 214 are affixed to each other with
adhesive between each non-affixed section. In at least a preferred
embodiment, the spacing of affixed and non-affixed sections repeats
evenly for the length of drawstring 210. Furthermore, in an
alternative embodiment, heat sealing can be applied to drawtapes
212 and 214 to achieve the same structure of affixed and
non-affixed sections for drawstring 210.
[0073] Returning to FIG. 6a, due to the stretching of drawtape 214,
drawstring 210 is under tension when assembled into bag 200. A
continuous length of drawstring 210 is inserted onto a continuous
folded web and then a continuous hem 222 is formed from the
continuous folded web, the hem 222 encapsulating drawstring 210.
Short seals 220 and 221 are then formed in hem 222. Once short
seals 220 and 221 are formed, the folded web can be perforated, the
perforations defining first and second sides of bag 200. Since the
continuous drawstring 210 is held by nip rollers (not shown) on
both sides of bag 200 when short seals 220 and 221 are formed,
tension is equalized in drawstring 210 and short seals 220 and 221
may be formed in drawstring 210 and hem 222 without drawstring 210
pulling away from short seals 220 and 221 and causing the seals to
fail.
[0074] Once drawstring bag 200 is completely formed, the
perforations 230 may be broken. Once perforations 230 are broken,
the tension held in drawstring 210 will be released; with the
perforations separated, the nip rollers on both sides of bag 200
will no longer hold any tension in drawstring 210. Once tension in
drawstring 210 is released, hem 222 will begin to bunch when
elastic drawtape 214 attempts to recover to its original
unstretched length. Elastic drawtape 214 returning to its original
length will also cause drawstring 210 to bunch up within hem
222.
[0075] In an alternative embodiment, the perforations 230 may not
be broken, but rather the continuous web of formed drawstring bags
200 may be rolled into a roll of bags with the tension released
once the roll is complete. The roll of bags will attempt to recover
once on the roll but may largely be prevented from recovering due
to friction in the roll of bags. However, once a bag is removed
from the roll, or is on an exterior of the roll of bags, the
removed bag may begin to recover and the hem of the bag will begin
to gather due to the elastic drawtape 212 attempting to return to
its original length.
[0076] Unlike previous embodiments of the invention, due to the
high elasticity of drawtape 214, only inelastic drawtape 212 is
capable of carrying any significant load of drawstring bag 200.
Hence, in at least one preferred embodiment, drawtape 212 has a
nominal approximate width of one-inch and a thickness of
approximately 2.25 mils for an inelastic drawtape 212 constructed
from HDPE. As previously discussed, elastic drawtape 212 with these
dimensions should provide for a total carrying capacity of 40
pounds when incorporated into drawstring bag 200.
[0077] As discussed above, the width of elastic drawtape 214 can
vary greatly, but for ease of manufacturing, a width of 1/4 to 1/2
inch may be desirable. Depending upon the material selected for the
elastic drawtape 214 and the material's corresponding tensile and
elastic properties, a thickness of elastic drawtape 214 may vary
from 0.5 mils to 6 mils. It may be desirable for the elastic
drawtape 214 to have a lower thickness relative to inelastic
drawtape 212 to prevent the elastic drawtape 214 from interfering
with the formation of short seals 221 and 222, and also to limit
the amount of effort required to pull drawstring 210 through hem
222 by limiting the surface contact between drawtape 214 and hem
222.
[0078] Due to the high elasticity of the elastic drawtape 214, the
drawstring 210 may be designed to gather the hem 222 of drawstring
bag 200 a considerable amount. For instance, if drawtape 214 is
out-stretched 20% and the working length of drawstring 210 is 24
inches, gathering of the hem exceeding 4 inches can be expected.
Thus, drawstring bag 200 can adhere to trash receptacles with
openings as small as 20 inches or less. Also, due to its high
elasticity and relatively low tensile strength, drawstring bag 200
should provide relatively low resistance to being stretched over
trash receptacles, at least until the un-gathered length of the
drawstring 210 is met or exceeded.
[0079] As noted, the embodiments depicted herein are not intended
to limit the scope of the present invention. Indeed, it is
contemplated that any number of different embodiments may be
utilized without diverging from the spirit of the invention.
Therefore, the appended claims are intended to more fully encompass
the scope of the present invention.
* * * * *