Note: Descriptions are shown in the official language in which they were submitted.
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BAG AND ARTICLE OF MANUFACTURE
FIELD
The invention relates generally to bags for containing particulate, flowable
compositions.
More particularly, embodiments of the present invention relate to bags that
can be made of
laminates.
BACKGROUND
Industries that use and sell large quantities of bulk, particulate, flowable
compositions,
such as animal food, bulk foods, coffee, fertilizer, detergent, and the like
are often faced with the
task of packaging and shipping such compositions in containers suitable for
shipping, handling,
retail sale, and consumer transport and use. For compositions such as bulk
animal foods, such
containers are typically paper or plastic bags containing up to about 75
pounds of food
composition. Such containers therefore must be able to withstand shipping and
handling without
breaking open.
Bags for containing and handling bulk compositions are made from various
materials and
secured closed in various ways depending on the properties of the bag
materials, the properties of
the closure systems, and cost considerations. Materials used for such bags
include burlap, paper,
multi-layer, and plastics. Closure for one-time use can be accomplished by
stitching, taping,
gluing, heat sealing, and/or ultra sonic welding the containers closed after
the containers are
filled with the composition. The cost to produce such bags and closures varies
with the type of
bag material and type of closure used. In the retail pet food industry, such
bags have typically
been made from multiple layers of paper, plastic, and/or foil, and stitched,
taped, glued, heat
sealed, and/or ultrasonically welded closed.
The materials and closures of such bags are typically selected to provide the
most cost-
effective container, considering material cost, material properties, closure
cost, closure
properties, damage and lost product due to bag breakage, etc. Bags for
containing quantities of
15 or more pounds of dry pet food composition are typically multiple layered
paper bags, often
lined with plastic or foil on an interior surface thereof, that are stitched,
taped and/or glued
closed.
However, paper bags do not keep the food compositions contained therein
particularly
fresh over time. Oxygen, moisture, and even perhaps organisms can enter the
bags. Thus, in
time, the food may oxidize, become stale, become infested, and generally
become less palatable
to the animal and less desirable by the animal owner. Additionally, bags that
are stitched, taped
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and/or glued closed can not be resealed once opened. Therefore, many animal
owners resort to
emptying the contents of the paper bag into a storage container that can be
easily accessed, easily
reclosed, and that keeps the food fresh.
Furthermore, such feed bags are typically rectangularly shaped with very small
depth
versus height of such bags. Thus, the bags must be stacked and displayed
laying flat on one of
the largest surfaces, typically the front or back surface. Such orientation,
particularly for bags
containing 15 or more pounds of composition, makes the bags difficult to
display and to remove
and lift. If such bags are successfully removed from a store shelf, they are
often deposited on a
narrow bottom surface of the bag, and often fall over. The instability of the
bags can be
bothersome if one must keep righting the bag. In addition, if the bag has been
taken home and
opened, extensive spillage can result when the bag tips over.
Recently, manufacturers have attempted to provide bags that are reclosable and
that
provide enhanced spoilage protection for the contents over time, such that a
user does not have to
empty a large, heavy bag into a separate container. Therefore, manufacturers
have begun to
supply plastic bags, or paper bags with plastic or foil linings, and having
reclosable features.
Plastic, and plastic or foil lined materials are better moisture and
air/oxygen barriers than, for
example, paper or burlap, and provide better protection from spoilage and
infestation.
However, it has been found that many such plastic bags burst open, when filled
with
about 15 or more pounds of bulk composition, and dropped off of a truck, a
store shelf, out of a
user's vehicle or grip, or when tipped over. The bursting problem is often
exacerbated when
such bags are formed with a reclosable feature. Such bags can burst at the
site of the reclosable
feature or at one or more seals or seams of the bag, or the material forming
the bag itself can tear
and cause the bag to burst open. In addition, plastic bags can be slippery to
the touch, and can
result in a greater amount of bags dropped versus other materials such as
paper or burlap.
Some manufactures have attempted to solve the problem of bags bursting at a
reclosable
feature by placing and sealing a material over or across the reclosable
feature, which the
consumer then removes once the bag is safely at its final destination. Such an
approach is
feasible with various paper bags, and quantities of composition over about 15
pounds in weight.
However, many plastic bags still burst when they contain over about 15 pounds
of material and
fall from a height of about 3 feet, whether or not the bags contain a
reclosable feature. Thus, the
majority of bags used for containing greater than about 15 pounds of dry pet
food are various
types of paper bags. Other approaches include sealing the inside of the bag in
addition to having
a reclosable feature. Using a double thickness in the reclosable feature is
another option.
However, cost can increase prohibitively as more components are added to the
bag.
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Therefore, there is a need for a plastic bag that can contain amounts of
compositions and
can withstand a drop from heights without bursting open. There is also a need
for such a bag to
be reclosable. There is a need for such a bag to also provide moisture and
oxidation barrier
protection for the contents. There is also a need for the bag to be stable
when situated upright on
a bottom surface of the bag, and for the bag to be easily grippable.
SUMMARY
Embodiments of the present invention relate to articles of manufacture
comprising a bag.
The bag can be used for containing large quantities of particulate, flowable
compositions such as
dry pet food. The bags can comprise a multi-layer laminate having a thickness
of from about 130
to about 200 microns; wherein the plastic laminate comprises a polyamide. The
plastic laminate
can have a dart drop resistant of at least about 5 grams/mil and a tear
resistance of at least about 6
grams/mil and 9 grams/mil in the machine direction and cross direction,
respectively. The bag
having a height between about 18 inches and 40 inches, a width between 11
inches and 18
inches, and a depth between 2.5 inches and 9 inches and can contain at least
about 10 liters of a
particulate, flowable composition contained in the bag.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a bag of one embodiment of the present
invention.
FIG. 2 is a perspective view of an alternative embodiment of the present
invention.
FIG. 3 is a perspective cutaway view showing a bag of one embodiment of the
present
invention filled with particulate, flowable composition.
FIG. 4 is a top perspective view of a bag illustrating a non-reusable closure
of one
embodiment of the present invention.
FIG. 5 is a cross-sectional side view of the membrane of one embodiment of the
invention.
FIG 6 is a perspective view of a bag having a non-reusable closure partially
installed
therein.
FIGS 7a-c are perspective views of the non-reusable closure of one embodiment
of the
present invention illustrating the targeted openable region.
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DETAILED DESCRIPTION
All measurements made herein art made at 25 C unless otherwise designated.
The term "particulate, flowable compositions", as used herein and usable with
the present
invention, means compositions including animal feeds including rodent, dog,
cat, horse, goat,
cattle, pig, bird, and the like; detergents; fertilizers; cat litter; bulk
foods including grains, nuts,
beans, fruits, and the like.
The term "slack fill", as used herein, means to fill a container with a
composition during
manufacturing and/or packaging such that the composition occupies a volume
less than the
interior volume of the container, thereby leaving a "head space", meaning
empty portion of
volume, in the container.
The term "seal", as used herein, means the seal or seals that form the bag
itself, and which
can be formed by sealing the surfaces, such as the inner surfaces, of the
plastic laminate together;
and in addition means the seals formed when sealing a non-reusable closure to
the top of the bag,
if such a non-reusable closure is used.
The term "seal strength", as used herein, refers to a measure of tensile
strength at each
seal made and used in footling the bag.
Article of Manufacture
Bag
One embodiment of the present invention encompasses articles of manufacture
illustrated
in FIGS 1-7. As shown in FIGS 1 and 2, the article of manufacture comprises a
bag 10
comprising a front surface 12 and a rear surface 14 extending upwardly from a
bottom surface
16, which can be flattenable, especially when formable material is used to
construct the article.
Two side surfaces 18 each can be an expandable gusset 20, which can include a
region of the side
surface that folds to form a crease, therein connecting front surface 12 and
rear surface 14 at
opposite sides of bag 10. The bag 10 also can have a flattenable bottom
surface 16 that can be
formed by connecting front surface 12, rear surface 14, and side surfaces 18.
Bag 10 also can
have a top surface 22 formable by connecting front surface 12, rear surface
14, side surfaces 18,
and located opposite flattenable bottom surface 16. The bag has a height H, a
width W, a depth
D. The height H, width W, and depth D of bag 10 are defined and measured as
internal
dimensions of bag 10, measured from the inside surfaces of the bag. The height
H is measured
along the front or rear face of the bag from the inside edge of the bottom
seal to the top edge of
the bag, not including any closure. The width is measured across the front or
rear face of the bag
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from inside of edge seal to inside of edge seal at a midpoint of the height of
the bag. The depth is
measured across either side surface from edge seal to edge seal at a midpoint
of the height of the
bag. The height H, width W, and depth D define an internal volume V.
The bag 10 can be sealable by methods commonly known in the art, such as, for
example,
5 heat sealing, along at least one edge of a side surface 18a, 18b, bottom
surface 16, and top
surface 22. The bag can also be sealed at each edge 18a, 18b. Such a bag,
sealed at each of the
four side edges, can be commonly referred to as a "quad seal" bag. A quad seal
bag is one
embodiment described herein. The seals of the bag can have a seal strength of
at least about
1,600 pounds per square inch. The bag can comprise a plastic laminate having a
thickness of
from about 130 to about 200 microns. The plastic laminate can have an impact
dart-drop
resistance of at least about 6.2 grams/mil, and a tear resistance of at least
about 7.9 grams/mil and
10.8 grams/mil in the machine direction and cross direction respectively.
The article of manufacture can comprise, in addition to the bag, at least
about 15 pounds
of a particulate, flowable composition contained therein.
Alternatively, the article of
manufacture can comprise at least about 20 pounds of the particulate, flowable
composition,
alternatively at least about 30 pounds of the particulate, flowable
composition, and alternatively
at least about 40 pounds of the particulate, flowable composition. The article
of manufacture can
comprise up to about 75 pounds of particulate, flowable composition. From a
volume
perspective, the article, alternatively or additionally with respect to the
weight above, can contain
at least about 10 liters of a particulate, flowable compositions, or at least
about 15 liters, or at
least about 20 liters, or at least about 30 liters, or at least about 40
liters, or at least about 75
liters.
The bag 10 of the article of manufacture of the present invention can be
formed to have
any particular dimensions and any particular shape. An embodiment of bag 10 of
the present
invention, as shown in FIGS 1 and 2, can have a ratio of width W to height H
of from about 0.4
to about 0.8. Alternatively, the ratio of width W to height H can be about
0.6. Such a ratio of
width W to height H can help to ensure that bag 10 is stable and resistant to
tipping such that bag
10 can be easily placed and stored on its bottom surface 16. Such a ratio can
result in more of the
composition contained inside the container to be situated such that the
potential for tipping can
be decreased. Furthermore, such a width W to height H ratio can help
distribute forces generated
on the plastic laminate and seals if the bag is dropped, such that the width W
to height H ratio
aids in making the bag resistant to breaking or bursting if dropped. Such a
ratio can allow forces
to distribute by providing more surface area for the forces to contact and
dissipate through.
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Bag 10 also can have a ratio of depth D to height H of from about 0.17 to
about 0.4.
Alternatively bag 10 can have a depth D to height H ratio of from about 0.17
to about 0.3. The
depth D can be represented by side surface 18. The depth D to height H ratio
can also aid in
ensuring that bag 10 can be easily placed and stored on its bottom surface 16
and be resistant to
tipping. In addition, the depth D to height H ratio can also help distribute
forces generated on the
plastic laminate and seals if bag 10 is dropped, such that the depth D to
height H ratio aids in
making bag 10 resistant to breaking or bursting if dropped. Such a ratio
allows forces to
distribute by providing more surface area for the forces to contact and
dissipate through.
Such ratios are not commonly found in commercially available bags. Most
commercially
available side gusseted bags have rather small side gussets, and thus, very
small depth to height
ratios. Such small depth to height ratios result in bags that have small
bottom surfaces, and
which effectively can not be stood on the bottom surface without tipping over.
Therefore,
conventional pet feed bags must be displayed laid down on either the front or
rear surface and
cannot effectively be used throughout the period of use of the composition
contained therein
because they do not stand up well. In addition plastic laminate bags with
small side gussets are
much less burst-resistant due to the small surface area of the sides having
the gussets. When
such bags are dropped, particularly on the small, gusseted sides, they are
likely to burst due to the
forces created due to the small surface area of the gusseted sides.
Therefore, an example combination of ratio of width W to height H, and ratio
of depth D
to height H, of a bag of one embodiment of the present invention, is about 0.6
and about 0.20. A
bag 10 of one embodiment of the present invention, when formed as described,
can withstand a
drop from at least about 4 feet, on one of gusseted sides 18, when filled with
at least about 15
pounds of particulate, flowable composition, and can be very stable and
resistant to tipping.
Thus, such a bag can be displayed and sold in an upright, vertical position
and can be easily used
as the storage container for the composition contained therein, throughout the
use of the
composition.
Bags of embodiments of the present invention can have varying absolute
dimensions for
height, width, and depth. The height can range from about 18 inches to about
40 inches, or from
about 20 inches to about 40 inches, or from about 20 inches to about 39
inches, and all numeric
ranges therebetween. The width can range from about 11 inches to about 18
inches, or from
about 13 inches to about 18 inches, or from about 13 inches to about 17.75
inches, and all
numeric ranges therebetween. The depth can range from about 2.5 inches to
about 9 inches, or
from about 3 inches to about 9 inches, or from about 3 inches to about 8.5
inches, and all numeric
ranges therebetween. Any combination of these dimensions can be used.
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As shown in FIG 3, bag 10 of one embodiment of the present invention also
defines an
internal volume V, which can be at least about 20% greater than a volume Vc
occupied by the
composition contained within bag 10, thus creating a head space volume Vh. The
bags can be
slack filled such that the composition does not occupy the entire internal
volume V of the bag.
The head space volume Vh allows bag 10 to be easily and securely sealed after
filling, helps to
distribute forces generated if bag 10 is dropped to help ensure bag 10 is
burst resistant, and, in
combination with the depth D and gussets 20, provides a grippable portion 24,
as seen in FIGS 1
and 2 near the top surface 22 by which bag 10 can be grasped for lifting.
An embodiment of bag 10 can comprise a non-reusable closure 26, shown in FIG
4, that
can aid in ensuring bag 10 is burst resistant and can provide a tamper evident
indicator. Non-
reusable closure 26 can have a length that extends along said width W of bag
10. Non-reusable
closure 26 can comprise a membrane 28 disposed, such as by connected or
otherwise attached,
between front surface 12 and rear surface 14 of bag 10. The membrane 28 can
have a thickness
of from about 170 to about 200 microns. In one embodiment, non-reusable
closure 26 can be
utilized on bag 10 in the machine direction of the material of membrane 28.
Membrane 28 can have a user-facing surface 30, an outer surface 32 (as shown
in FIG 5),
and a tear strength of at least about 15 pounds per square inch (PSI), as
measured in the
transverse or cross machine direction, by ASTM Method D-882 Standard Test
Method for
Tensile Properties of Thin Plastic Sheeting. Non-reusable closure 26 can be
disposed at a top
edge 34 of bag 10 or, alternatively, can be disposed inward a distance from
top edge 34 of bag
10. In FIG 4, non-reusable closure 26 is shown located at top edge 34 of bag
10.
As shown in FIG 5, membrane 28 can have a plurality of ribs 36 on outer
surface 32 of
membrane 28, which enable outer surface 32 to be sealed to front surface 12 of
bag10, and a
plurality of ribs 36 on outer surface 32 of membrane 28 which enable outer
surface 32 to be
sealable to rear surface 14 of bag 10 to seal bag 10 closed.
FIG 6 illustrates a membrane 28 employed on a bag 10. A plurality of ribs 36
(as shown
in FIG 5) on outer surface 32 of membrane 28 can be sealable to an inner
surface 12a of front
surface 12 and to a top portion 20a of an inner surface 20b of gussets 20. A
plurality of ribs 36
on outer surface 32 of membrane 28 can be sealable to an inner surface 14a of
rear surface 14 and
to a top portion 20a of an inner surface 20b of gussets 20. When membrane 28
is sealed to bag
10, the seal can seal to the top portion 20a of gussets 20 as well as front
and back surfaces 12 and
14. Such a seal can be accomplished by methods commonly known in the art, such
as, for
example, heat sealing.
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When the article of manufacture is being manufactured, bag 10 can be formed,
the top
portion thereof open. Ribs 36a of outer surface 32 of membrane 28 can then be
sealed to inner
surface 12a of front surface 12 and top portions 20a of gussets 20. The bag 10
can be filled, and
then ribs 36b of outer surface 32 can be sealed to inner surface 14a of rear
surface 14 and top
portions 20a of gussets 20 to seal bag 10 closed and form top surface 22.
Such a closure allows for top filling of bags. However, such a closure could
also be
completely sealed at the top of the bag, and form the top surface 22, before
filling and be used
with a bottom fill process without having the closure break or burst during
the bottom fill
process.
Although membrane 28 provides excellent burst resistance, a tear strength of
greater than
about 15 pounds per square inch proves difficult for a user to open by hand.
Because it can be
desired that the article of manufacture of the present invention also be easy
for an ultimate
consumer or user to open by hand, membrane 28 comprises a targeted opening
region 38.
Targeted opening region 38 can have a tear strength, measured in the
transverse or cross machine
direction by ASTM Method D-882, of from about 1 to about 15 pounds per square
inch,
alternatively of from about 3 to about 12 pounds per inch, alternatively from
about 4 to about 10
pounds per inch, alternatively from about 4 to about 9 pounds per inch, and
alternatively from
about 5 to about 7 pounds per inch.
During development of the bags of some embodiments of the present invention,
it was
found that known non-reusable closures and tamper evident features have
opening regions that
extend the entire length of the membrane, i.e. essentially the entire width of
the bag. Such
opening regions typically consist of one or more score lines, perforations, or
other material-
weakening features. However, it was found that such opening regions, while
being easily opened
by a consumer, by hand, also can become a region of weakness and bursting when
bags filled
with for example, 15 or more pounds of dry pet food, are dropped, sometimes
from as low as 18
inches. Such drops are common in the shipping and handling of large, heavy
bags containing
various particulate, flowable compositions and cause damage and loss of
product, and annoyance
to retailers and consumers.
Therefore, the burst-resistant bag 10 of one embodiment of the present
invention
comprises targeted opening region 38 that comprises from about 1% to about 90%
of a length L
of membrane 28. Alternatively targeted opening region 38 comprises from about
1% to about
50% of the length L of membrane 28, alternatively from about 1% to about 30%
of the length L
of membrane 28, and alternatively of from about 1% to about 10% of the length
L of membrane
28. Furthermore, it was found that when the opening region extends to, or is
located within,
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about 5% of either end 28a, 28b of the length L of membrane 28, even if the
opening region only
comprises a small percentage, for example about 10-20%, of the length L of
membrane 38, burst
resistance is decreased. Thus, even small opening regions, when located at the
end(s) 28a, 28b,
of membrane 28, decrease burst resistance. Therefore, the "targeted opening
region" 38 of one
embodiment of the present invention means, and has the proviso that, the
opening region does
not extend to within about 5% of either end 28a, 28b of membrane 28. Targeted
opening region
38 can be located anywhere along the length L of membrane 28, within the
definition of the
targeted opening region, or can be centered at a midpoint M along the length L
of membrane 28
and width W of bag 10. Targeted opening region 38 can be located at or near a
midpoint m of
the width w of membrane 28 and can be disposed inboard a distance from top
edge 34 of bag 10.
FIGS 7a-c illustrate various locations and sizes of one embodiment of targeted
opening region
38.
As can be seen in FIGS 7a-c, targeted opening region 38 can comprise a
plurality of
perforations 40 in membrane 28. Targeted opening region 38 can also comprise
and be formed
by laser scoring, heat scoring, or mechanical weakening of any type such as
removing a portion
of material.
Also shown in FIGS 7a-c, membrane 28 can also comprise instructional indicia
42 on
user-facing surface 30 of membrane 28. Such instructional indicia 42 can
comprise printing
including words, pictures, symbols, illustrations, and the like, to indicate
to the user where and
how to open the non-reusable closure 26.
Membrane 28 can be formed from a material selected from the group consisting
of
ethylene derived polymer, polypropylene, polyester, polyolefins, homopolymer
and/or co-
polymer polyolefins, and combinations thereof. Particularly, membrane 28 can
comprise an
ethylene-derived polymer selected from the group consisting of low density
polyethylene, high
density polyethylene, ultra-low density polyethylene, and combinations
thereof. The particular
combination of material can be selected based on balancing strength of the
material for burst
resistance with openability for ease of use of the bag 10. The material can be
devised and formed
based on its ability to seal securely to the plastic laminate of bag 10 to
provide the required seal
strength of at least about 1,600 pounds per square inch. The material of the
membrane can be a
co-extruded blend of low density polyethylene, high density polyethylene, and
ultra low/very low
density polyethylene, with ultra low/very low density polyethylene forming
ribs 36 and 36 such
that the ribs seal to the inner surfaces of the bag at a temperature that can
be less than about
68 C. The number of ribs 36 can depend on the width w of the membrane. The
spacing of the
ribs 36 on membrane 28 can depend on the type and strength of seal desired.
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In addition to finding a particular material for the membrane 28 that provides
burst
resistance and allows for openability, the dimensions of membrane 28 can be
important with
respect to burst resistance, seal strength, ease of sealing during
manufacturing, and openability.
Membrane 28 can have a width w of from about 1.5 inches to about 3 inches.
Alternatively,
5 membrane 28 can have a width of from about 2 inches to about 3 inches.
Alternatively,
membrane 28 can have a width of about 3 inches. When the total width w of the
membrane 28 is
about 3 inches, there can be about ten to fifteen (10-15), alternatively about
fourteen (14) ribs 36
on outer surface 32, as illustrated previously in FIG. 5.
Production and creation of the particular plastic laminate can be advantageous
such that
10 when the laminate is used for bags that contain particulate, flowable
compositions are often
dropped during shipping and handling. Conventional, commercially available
such bags often
burst when dropped from a height of as low as 18 inches, when filled with as
little as 15 pounds
of composition. Such bursting causes damage and lost product as well as messes
and annoyance
to retailers and consumers. In particular, bags that have reclosable features
tend to burst at the
site of the reclosable feature. Thus, currently available resealable feed bags
are generally not
available in capacities greater than about 15 pounds, and/or have the
reclosable feature taped
over, or otherwise additionally reinforced.
When bags containing large amounts, such as the amounts disclosed herein, such
as up to
75 pounds or up to 75 liters, of particulate, flowable compositions burst,
several elements of the
bag can fail. If the bag has a reclosable feature, the forces generated by a
drop of the bag can
cause the composition contained therein to burst through the reclosable
feature. The seals that
form the bag can separate and fail. The material from which the bag itself is
made, for example,
the plastic laminate, can tear or burst open. The material from which the
laminate is made, as
well as the thickness of the laminate affect its burst resistance.
Therefore, in some embodiments of the present invention it can be advantageous
to create
an appropriate laminate having a balance of strength and stretchability
(measured by tensile
strength), flexibility and stiffness (measured by secant modulus), texture,
thickness, and cost-
effectiveness. Particular laminates may have a high tensile strength, and
therefore a high
resistance to stretching, which can be useful. However, in some instances,
such a laminate may
be brittle or stiff (i.e. have a high secant modulus), and because it resists
stretching, may burst
easily and therefore may not be useful or particularly preferred in some bags
of the present
invention. In addition, a laminate usable with embodiments of the present
invention can also
have a suitable texture and not be extremely slippery. Bags containing at
least about 15 pounds
of a particulate, flowable composition can be difficult to pick up and carry
because of the weight
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of material contained therein, especially when the materials used for
construction of the bag are
slippery or difficult to grip. Thus, bags containing such materials should
ideally not be slippery
or difficult to grip.
In addition, the laminate can be securely sealable to form the bag by methods
known the
art such as heat sealing. The laminate can be cost-effective as well, and
plastic laminate bags are
more costly than traditional paper feed bags. Thus, in one embodiment, as thin
a layer of
laminate as possible can be used from a cost-effective standpoint. However,
the thickness of the
laminate in combination with its composition affects its likelihood to burst
if dropped. Thus,
material composition and thickness can also be considered.
Bag 10 of embodiments of the present invention can have a seal strength of at
least about
1,600 pounds per square inch as measured by ASTM Method D-882. Alternatively,
bag 10 can
have a seal strength of at least about 1,800 pounds per square inch.
The plastic laminate forming the bag can have an impact dart-drop resistance
of at least
about 5 grams/mil as measured by ASTM Method D-1709-04, and a tear resistance
of at least
about 6 grams/mil and 9 grams/mil as measured in both the machine direction
(MD) and
transverse or cross machine direction (CD), respectively, by ASTM Method D-
1922.
Alternatively, the plastic laminate can have an impact dart drop resistance of
at least about 5.5
grams/mil and a tear resistance of at least about 7 grams/mil (MD) and about
10 grams/mil (CD).
Alternatively, the plastic laminate can have an impact dart drop resistant of
at least about 6.2
grams/mil and a tear resistance of at least about 7.9 grams/mil (MD) and
10.8grams/mil (CD).
The plastic laminate of the bag can have a secant modulus of from about 30,000
to about
110,000 pounds per square inch, as measured in both the machine and transverse
or cross
machine directions by ASTM Method D-882.
Bag 10 can be formed from a plastic laminate selected from the group
consisting of
ethylene-derived polymer, polypropylene, polyester, teraphthalates,
polyolefins, homopolymer
and or co-polymer polyolefins, woven polypropylene, ployamides, and
combinations thereof.
More particularly, the plastic laminate can be selected from the group
consisting of ethylene-
derived polymers such as polyethylenes in combination with a polyamide, such
as Nylon 6,6. In
order to be sealable to itself and to the material of a non-reusable closure,
if one is employed, the
material of the inner surface of the laminate can have a relatively low
melting point such that it
melts to enable heat sealing, whereas the outer surface can have a higher
melting point such that
it does not melt during heat sealing. Thus, an outer layer can be Nylon 6,6,
and an inner layer
can be a co-extruded blend of linear low density polyethylene, medium density
polyethylene, and
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linear low density polyethylene. As used herein the densities of polyethylene,
"low", "medium",
"high", "ultra low/very low", have meanings as used and understood in the art
for such materials.
In another embodiment, the laminate can be a multi-layer laminate. The multi-
layer
laminate can include many layers, such as an inner layer and an outer layer,
and even more
layers. In one embodiment, the multi-layer laminate can comprise a 75 gauge
cast F101 Nylon
outer layer and a 6.1 mil PE coex (polyethylene) inner layer. The plastic
laminate can have a
thickness of from about 130 to about 200 microns. Alternatively, the plastic
laminate can have a
thickness of from about 140 to about 170 microns.
In some embodiments, such a laminate can provide other beneficial properties.
This
multi-layer laminate can assist in reducing damage to the bag but can still
provide a relatively
high gloss, high print quality, reclosable, resealable bag than can stand up,
as disclosed herein.
In addition to aiding in enabling bag 10 to be burst-resistant in one
embodiment, the
plastic laminate can provide oxygen and moisture barrier properties. It has
been shown that
plastic can be a better oxygen and moisture barrier than traditional paper for
pet foods. It has
also been shown that fats, carbohydrates, proteins, and other components
commonly found in pet
foods oxidize over time when exposed to air. Furthermore, it has been shown in
some
palatability tests that animals prefer, over time, food stored in plastic bags
versus that stored in
paper bags but not always. Thus, the articles of manufacture of embodiments of
the present
invention can in some embodiments also provide enhanced palatability of the
oxidizable
compositions contained therein.
Therefore, in one embodiment a plastic laminate can have an oxygen
transmission rate of
less than about 6.5 cc/100 in2/24 hours, as measured by ASTM Method D-3985,
and alternatively
of less than about 6.2 cc/100 in2/24 hours. A plastic laminate can also have a
moisture vapor
transmission rate of less than about 0.1 grams/100 in2/24 hours, when measured
by ASTM
Method F-1249, and alternatively of less than about 0.8 grams/100 in2/24
hours.
In another embodiment of the present invention, as shown in FIGS 1 and 2, bag
10 can
further include a reusable closure 44. As described above, the dimensions and
proportions of bag
10 can be such that they provide burst resistance and enhanced stability.
Thus, bag 10 can be
stable when placed on bottom surface 16. The plastic laminate also can provide
oxygen and
moisture barrier properties to enable the composition to be stored in bag 10
over time. Therefore,
providing a reusable closure enables the end user consumer to simply use bag
10 itself as the
storage device for the composition.
Non-limiting examples of reusable closures of the present invention include a
track and a
slider system, a plastic zipper, a metal zipper, a hook and loop fastening
system, a threaded
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13
closure device, a pressable sealing device, a snap sealing device, resealable
adhesive, magnetic
sealing device, electrostatic sealing device, and combinations thereof.
Reusable closure 44 can be disposed at top edge 34 of bag 10, as shown in FIGS
1 and 2.
Alternatively, reusable closure 44 can be disposable a distance inward from
top edge 34 of said
bag.
In another embodiment of the present invention, bag 10 can comprise both a non-
reusable
closure and a reusable closure. As described above, bag 10 can be not only
burst-resistant but
stable as well, such that it can be used as a reusable storage container. As
described above, the
proportions and dimensions of bag 10 can provide stability. Therefore, bag 10
can have a tip
angle of from about 10 to about 50 , alternatively a tip angle of from about
20 to about 30 .
Tip angle is measured using ASTM Method 6179.
Bag 10 can also be provided with features to equalize air pressure within the
bag, to assist
in providing burst resistance, and to provide an appealing visual appearance
to the bag.
However, such features for equalizing air pressure can also prevent oxygen
transmission into the
bag and infestation, i.e. prevent undesirable organisms form entering the bag.
One such feature
can be a valve, such as a one-way valve. Other such features are generally
known to those of
ordinary skill in the art.
Air pressure equalization described the escape of and entrance of air into and
out bag 10.
It can be important to allow air to escape from bag 10 during shipping and
handling of the bags.
When bags are stacked on pallets for shipping, the weight of the bags on top
of each other can
cause the bags to burst if there is no way for air to escape from the bags.
However, once air is
squeezed out of the bags, the bags can have an unappealing, 'vacuum packed',
lumpy
appearance. Thus, it can be desirable to allow air back into the bags once the
bags are unloaded
for display and sale.
Air pressure equalization can be accomplished by providing a plurality of
perforations 46
in at least one side of bag 10, for example in each side gusset 20 as shown in
FIGS 1 and 2.
Perforations 46 can be less than about 150 micrometers in diameter,
alternatively less than about
100 micrometers in diameter, and alternatively less than about 70 micrometers
in diameter, in
order to allow air to pass there through but prevent infestation.
In addition, one or more gaps (not shown) can be provided at a seal of the bag
for
additional passage of air. The gap(s) can be formed by interrupting the heat
sealing process, and
such seals are known in the art as "skip gap" seals. To form such a "skip gap
seal," a non-
continuous seal bar can be used, i.e. a seal bar having one or more gaps
thereon wherein the
gapped part of the seal bar would not touch the material being sealed, thus
leaving an unsealed
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portion or "gap." Such a "skip gap seal" can be formed on the seal formed at
the bottom of the
bag, at the seal formed when attaching a first portion of the membrane to the
front surface of the
bag, or when attaching the second portion of the membrane to the rear surface
of the bag. A
"skip gap seal" can be formed, for example in the final seal sealing the bag
closed once it has
been filled. Each gap can be of from about 70 um to about lOmm in length. If
no non-reusable
closure is used, gap(s) can be formed in any of the seals used to form the
bag, as required for
appropriate desired air equalization.
The gap(s) can be straight sided and can have a cylindrical or tubular shape
or can be
shaped and/or curved and of a length that would still allow air to pass there
through, but which
would provide a barrier to infestation (i.e. provide a longer, more
complicated path for
potentially infesting organisms). Any shaped gap can be incorporated or formed
into the seal bar
of the heat sealing apparatus, as would be understood by those skilled in the
art.
Method of Enhancing Palatability
Embodiments of the present invention also can include methods of enhancing
palatability
of an oxidizable particulate, flowable composition after storage comprising
the steps of:
a. providing a plastic laminate bag comprising:
i.) two side surfaces each having a gusset therein and connecting the front
and rear surfaces;
ii.) a closure system comprising a reusable closure and a non-reusable
closure, wherein said non-reusable closure comprises a membrane having a
targeted opening region, the targeted opening region having a tear strength of
from about 4 to about 10 pounds per square inch;
wherein the plastic laminate has a predetermined oxygen transmission rate and
a
predetermined water vapor transmission rate;
b. filling the plastic laminate bag with at least about 15 pounds of an
oxidizable, particulate, flowable composition;
c. sealing the plastic laminate bag closed; thereby preventing oxidation and
spoilage and enhancing the palatability of the composition contained therein.
The plastic laminate usable with the method can have an oxygen transmission
rate of less
than about 6.5 cc/100 in2/24 hours, alternatively less than about 6.2 cc/100
in2/24 hours. The
oxygen transmission rate is measured, as described above, by ASTM Method D-
3985. The
plastic laminate can have a moisture vapor transmission rate of less than
about 0.1 grams/100
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in2/24 hours, alternatively less than about 0.8 grams/100 in2/24 hours. The
moisture vapor
transmission rate is measured, as described above, by ASTM Method F-1249.
Examples
5 ASTM
Method 5276-98 (Reapproved 2004) "Standard Test Method for Drop Test for
Loaded Containers by Free Fall" contains provisions for dropping variously
shaped containers to
assess various parameters such as finding an average drop height to failure,
or for attaining
pass/fail data. Bags of the present invention are subjected to these tests
from heights of up to 6
feet, as a specification for shipping and handling requirements.
10 See
in particular sections A1.1, A1.3. When testing bags of embodiments of the
present
invention, the test is a pass/fail test because required drop heights are
specified. Based on
experience packaging, shipping, and handling such bags, a specification is set
that such bags
containing at least about 20 pounds of particulate, flowable material, must
pass a free fall drop
from at least about 6 feet. When the bags contain at least about 40 pounds of
particulate,
15
flowable material, they must pass a free fall drop from at least about 4 feet.
Failure occurs if any
of the seals of the bag, any closures (whether reusable or non-reusable), or
the bag material tears,
splits, separates, punctures, deforms, bulges, and/or leaks.
The apparatus used for such a drop conforms to section 5 of ASTM Method 5276-
98.
Specifically the apparatus used is a L.A.B. Model 160A Drop Tester. The bags
can be dropped
on each of the six surfaces of the bag, and in particular must pass the drop
test from the given
drop height on at least one of the side surfaces. Single drops are performed,
as in section A2.2.1,
and drops on all six surfaces are performed, as in section A2.2.8. In
particular, drops are
performed on one or both of the two side surfaces, as in section A2.2.10,
because the two side
surfaces are those determined most likely to fail. The impact surface is
concrete, as specified in
section 5.1.5.1, and complies with sections 5.1.5.3-5. When the bags are
dropped on each
surface, they are dropped such that the drop complies with sections 8.4.1-8.5.
Example 1
A bag of one embodiment of the present invention can be constructed as
follows.
A plastic laminate film, comprising a 12 micron thick layer of polyethylene
teraphthalate
("PET") bonded by adhesive lamination to a 140 micron thick co-extruded layer
of metallocene
linear low density polyethylene, medium density polyethylene, and metallocene
linear low
density polyethylene, (available for example from Exopack, Spartanburg, SC,
USA) is used for
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forming the bag. Once the bag is formed, the co-extruded polyethylene layer
forms the inner
surface and the PET layer forms the outer surface of the bag.
The sides of the bag are gusseted. The two edges of each side gusset on each
side of the
bag are sealed to form two edge seals on each side, resulting in four edge (4)
seals, thus forming
a "quad seal" bag. The bag is sealed at the bottom by conventional heat
sealing, capturing the
bottom of the side gussets therein and forming a bottom surface. The side
gussets are also sealed
at the bottom of f the bag with a "K-seal" as is known in the art, to allow
the bottom surface to be
flattenable. The side gussets are also sealed at the top of the bag with a "K-
Seal", as is known in
the art, to restrict the flow of air through the connection of the gusset to
the front and back
panels.
A non-reusable closure membrane formed from a blend of low density
polyethylene and
ultra low density polyethylene is attached, by co-extrusion therewith, to a
track of a slider and
track zipper, for example a Slide-Rite zipper from Pactive Corp., Lake
Forest, Ii, USA. A track
of a slider track zipper device is formed high density polyethylene. The track
and the membrane
are co-extruded. The membrane has a width w of about 3 inches as measured from
inner edge to
inner edge of the track. The membrane has a targeted opening region of 1.5
inches in length,
disposed along the length of the membrane, and formed form a plurality of
perforations. The
targeted opening region is formed centered at a midpoint m of the width w of
the membrane, and
centered at a midpoint M of the length L of the membrane. See FIG 7C. The
targeted opening
region has a tear strength (as measured by ASTM Method D-882) of between about
5-7 pounds
per square inch.
The non-reusable closure membrane attached to the reusable track and slider
closure is
attached by heat sealing one side of the outer surface of the membrane to an
inner surface of the
front surface of the bag. The inner and outer surfaces of one half of each
side gusset are captured
by the seal. The bag is filled with 20 pounds of dry pet food. With the
dimensions described
herein, 20% headsp ace is provided and results in 5.5 inches of bag height
remaining above the
height of the product, which enables proper sealing of the bag. The second
side of the outer
surface of the membrane of the non-reusable closure is then heat sealed to the
inner surface of the
rear surface of the bag to close the bag. The inner and outer surfaces of the
other half of each
side gusset are captured by the final seal.
The bag has a height of 25 inches, a width of 13.25 inches, and a depth of 6.5
inches.
Height dimensions have a tolerance of about 0.12 inches. Width dimensions have
a tolerance of
about 0.25 inches. Depth dimensions have a tolerance of 0.6 inches. The ratio
of width to height
is 0.6. The ratio of depth to height is 0.25.
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A bag as described in this example will pass a drop test conducted according
to ASTM
Method D-5276-98 (Reapproved 2004) Standard Test Method for Drop Test of
Loaded
Containers by Free Fall, when dropped on any and all six surface, particularly
the two side
surfaces, from a height of 6 feet when filled with 20 pounds of dry dog food.
Example 2
An alternative embodiment of a bag of an article of manufacture of the present
invention
can be made as follows.
A plastic laminate film, comprising a 19 micron thick layer of Nylon 6,6
bonded by
adhesive lamination to a 155 micron thick co-extruded layer of metallocene
linear low density
polyethylene, medium density polyethylene, and metallocene linear low density
polyethylene,
(available for example from Exopack, Spartanburg, SC, USA), is used for
forming the bag. Once
the bag is formed, the co-extruded polyethylene layer forms the inner surface
and the nylon layer
forms the outer surface of the bag.
The sides of the bag are gusseted. The two edges of each side gusset on each
side of the
bag are sealed to form two edge seals on each side, resulting in four edge (4)
seals, thus forming
a "quad seal" bag. The bag is sealed at the bottom by conventional heat
sealing, capturing the
bottom of the side gussets therein and forming a bottom surface. The side
gussets are also sealed
at the bottom of the bag with a "K-seal" as is known in the art, to allow the
bottom surface to be
flattenable. The side gussets are also sealed at the top of the bag with a "K-
Seal" as is known in
the art, to restrict the flow of air through the connection of the gusset to
the front and back
panels.
A non-reusable closure membrane formed from a blend of low density
polyethylene and
ultra low density polyethylene is attached, by co-extrusion therewith, to a
track of a slider and
track zipper, for example a Slide-Rite zipper from Pactive Corp., Lake
Forest, Ii, USA. A track
of a slider track zipper device is formed high density polyethylene. The track
and the membrane
are co-extruded. The membrane has a width w of about 3 inches as measured from
inner edge to
inner edge of the track. The membrane has a targeted opening region of 1.5
inches in length,
disposed along the length of the membrane, and formed form a plurality of
perforations. The
targeted opening region is formed centered at a midpoint m of the width w of
the membrane, and
centered at a midpoint M of the length L of the membrane. See FIG 7C. The
targeted opening
region has a tear strength (as measured by ASTM Method D-882) of between about
5-7 pounds
per square inch.
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The non-reusable closure membrane attached to the reusable track and slider
closure is
attached by heat sealing one side of the outer surface of the membrane to an
inner surface of the
front surface of the bag. The inner and outer surfaces of one half of each
side gusset are captured
by the seal. The bag is filled with 40 pounds of dry pet food. With the
dimensions described
herein, 20% headspace is provided and results in 5.5 inches of bag height
remaining above the
height of the product, which enables proper sealing of the bag. The second
side of the outer
surface of the membrane of the non-reusable closure is then heat sealed to the
inner surface of the
rear surface of the bag to close the bag. The inner and outer surfaces of the
other half of each
side gusset are captured by the final seal.
The bag has a height of 29 inches, a width of 17.5 inches, and a depth of 7.25
inches.
Height dimensions have a tolerance of about 0.12 inches. Width dimensions have
a tolerance of
about 0.25 inches. Depth dimensions have a tolerance of 0.6 inches. The ratio
of width to height
is 0.6. The ratio of depth to height is 0.25.
A bag as described in this example will pass a drop test conducted according
to ASTM
Method D-5276 ¨ 98 (Reapproved 2004) Standard Test Method for Drop Test of
Loaded
Containers by Free Fall, when dropped on any and all six surfaces,
particularly the two side
surfaces, from a height of 4 feet when filled with 40 pounds of dry dog food.
The dimensions and values disclosed herein are not to be understood as being
strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean
"about 40 mm."
The scope of the claims should not be limited by the preferred embodiments set
forth
in the examples, but should be given the broadest interpretation consistent
with the
description as a whole.
