Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR FOLDING AND SEALING BAGS
FIELD OF THE INVENTION
[0001] This invention relates to a method and system for folding and
sealing
polymeric bags.
[0002] This invention relates to polymeric bags made by the method and
system for
folding and sealing polymeric bags.
BACKGROUND OF THE INVENTION
[0003] US 2010/0154362 Al discloses a method and system for closing
and sealing
bags, wherein each bag after filling with contents is conveyed along a hot air
manifold which
applies hot air under pressure to heat an adhesive layer on a first panel of
the bag and to heat
an adhesive layer on a second panel of the bag. Each of the adhesive layers is
heated to an
adhesive state at a temperature below the softening point temperature of the
polymeric
material of the bag. Then the bag is folded to contact the adhesive layers to
one another, and
the adhesive layers form an adhesive-to-adhesive seal upon application of
pressure. The
adhesive material can transfer to the hot air manifold and associated
mechanisms, causing
equipment contamination. It would be desirable for the bags to have the
adhesive material
located in positions that will minimize transfer of adhesive material to the
hot air manifold
and associated mechanisms.
[0004] US 2010/0158418 Al discloses a bag made form a polymeric woven
tube.
One end of the tube is closed and then sealed by being conveyed along a hot
air manifold
which applies hot air under pressure to heat an adhesive layer on a first
panel of the tube and
to heat an adhesive layer on a second panel of the tube. Each of the adhesive
layers is heated
to an adhesive state at a temperature below the softening point temperature of
the polymeric
material of the tube. Then the tube is folded to contact the adhesive layers
with one another
and form an adhesive-to-adhesive seal. It would be desirable to fold the tube
without
displacing or expelling adhesive from the fold, in order to minimize adhesive
contamination
on surfaces of the tube.
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SUMMARY OF THE INVENTION
[0005] The invention relates to a bag to be filled with contents, the
bag including a
polymeric tube having a first panel, a second panel and side gussets, and the
first panel
having a first section and a second section. An end of the tube has a stepped
construction,
which includes the second section, and portions of the side gussets extending
beyond the
second section and a portion of the second panel extending beyond the side
gussets. First
adhesive material on the first section and second adhesive material on the
stepped
construction attain adhesive states by heating to a temperature below the
softening point
temperature of the polymeric material. The tube has a third section between
the first section
and the second section. The first adhesive material and the second adhesive
material are
absent from the third section wherein the third section is free of adhesive.
The end of the
tube is closed. The tube is folded along the third section without displacing
or expelling
adhesive from the third section in order to minimize adhesive contamination on
surfaces of
the tube, and the adhesive material on the stepped construction and the
adhesive material on
the first section meet in contact and under pressure below the third section
and provide an
adhesive-to-adhesive seal at the end of the bag.
[0006] Another embodiment of the invention relates to a bag
constructed of
polymeric material and adapted to be closed and sealed after being filled with
contents. The
bag includes a first panel, a second panel and side gussets, the first panel
having a first
section and a second section. The bag has one closed end. An end of the bag
through which
the bag is to be filled with contents has a stepped construction, which
includes the second
section, portions of the side gussets extending beyond the second section and
a portion of the
second panel extending beyond the portions of the side gussets. First adhesive
material on
the first section and second adhesive material on the stepped construction
attain adhesive
states by heating to a temperature below the softening point temperature of
the polymeric
material. The first panel has a third section between the first section and
the second section.
The first adhesive material and the second adhesive material are absent from
the third section,
wherein the third section is free of adhesive. The end of the bag is closable
and the bag is
foldable along the third section without displacing or expelling adhesive from
the third
section in order to minimize adhesive contamination on surfaces of the tube,
and the adhesive
material on the stepped construction and the adhesive material on the first
section meet in
contact and under pressure below the third section and provide an adhesive-to-
adhesive seal
at the end of the bag.
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[0007] Another embodiment of the invention relates to a method for
closing and
sealing an end of a bag taken from multiple bags each made of polymeric
material. The bag
has a first adhesive material on a first section of a first panel, and has a
second adhesive
material on a stepped construction, which includes a second section of the
first panel,
portions of side gussets extending beyond the first panel and a portion of a
second panel
extending beyond the side gussets. Further, the method includes, heating the
first adhesive
material and the second adhesive material to their adhesive states, while
conveying the bag
along a hot air manifold after the bag has been filled with contents, and the
bag closed and
creased. The first adhesive material and the second adhesive material are
absent from a third
section of the first panel, wherein the third section is free of adhesive. The
method includes
conveying the third section free of adhesive along a section of the hot air
manifold, which
minimizes adhesive contamination. Further, the method includes folding the bag
along the
third section without displacing or expelling adhesive from the third section,
which
minimizes adhesive contamination of surfaces of the tube, and applying
pressure to contact
the first adhesive material and the second adhesive material and form an
adhesive-to adhesive
seal, which seals the end of the bag through which the bag has been filled
with contents.
BRIEF DESCRIPTION OF THE DRAWINGS
100081 Embodiments of the invention will now be described by way of
example with
reference to the accompanying drawings.
[0009] FIG. 1 is an isometric view of an embodiment of a tube of polymeric
material
to be made into a bag.
[0010] FIG. 2 is an isometric view of another embodiment of a tube of
polymeric
material to be made into a bag.
[0011] FIG. 3 is an isometric view of a bag made from a tube of either
FIG. 1 or
FIG. 2.
[0012] FIG. 4 is a schematic view of a portion of a hot air sealer
apparatus and a
woven polymeric bag conveyed from right to left as viewed in the Figure.
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[0013] FIG. 5 is a schematic view of a creasing apparatus of the hot
air sealer
apparatus of FIG. 4. Further, FIG. 5 discloses a folding section of the hot
air sealer
apparatus of FIG. 4.
[0014] FIG. 6 is a schematic view of the hot air manifold of FIG. 7 in
the folding
section of FIG. 5.
[0015] FIG. 7 is an isometric view of a hot air manifold to be
incorporated in the
folding section of FIG. 5.
[0016] FIG. 8 is a top plan view of the a hot air manifold of FIG. 7.
[0017] FIG. 9 is a view of a back wall of the a hot air manifold of
FIG. 7.
[0018] FIG. 10 is a cross section along the line 10-10 of FIG. 8.
100191 FIG. 11 is a schematic view of a pinch closing and cooling
apparatus of the
hot air sealer apparatus of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Bags to be used for bulk packaging of granular or finely ground
materials,
such as nutrients including, but not limited to, whole and ground grains,
seeds, dry pet food,
chemical fertilizers, other bulk food and non-food products, and growing plant
treatments,
must be durable to resist material degradation, abrasion, puncture,
contamination and leakage
of contents, and must withstand a drop test while sealed and filled with
contents weighing up
to about 50 pounds, and even up to about 80 pounds. Moreover, such bags are
typically
disposed of after use, which requires an inexpensive and light-weight
construction that is
environmentally friendly, may be recyclable, and reduces waste in the supply
chain from
production, use of the bag, to disposal in either a recycling stream or
landfill.
[0021] Currently, multi-walled paper and polymer layer bags,
consisting of multiple
paper layers and layers of polymer film, are heavy, expensive to produce and
ship, easy to
tear and puncture, and create waste in the supply chain. Multi-wall
paper/polymer layer bags,
traditionally used to package bulk products, are not recyclable and add
significant amounts of
materials to landfills. This invention overcomes many of the significant
drawbacks of multi-
wall paper/polymer layer bags, by offering a lighter weight bag that is less
expensive, more
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durable and tear-resistant, resulting in significantly reduced waste in the
supply chain, and is
100% recyclable in a suitable recycling stream. Moreover, this invention can
function
essentially in the same way on existing bag filling and sealing equipment to
perfect a pinch-
sealed bag filled with product.
[0022] A typical manufacturing production line provides apparatus to fill
the bags
with contents, and further provides apparatus to close the bag in a simple
manner by pinch
closing, and further provides equipment to seal the pinch closed bag. Bags of
traditional
construction can be close by sewing or alternatively, sealed with a hot melt
sealant instead of
sewing. Such bags of traditional construction include multi-wall bags
fabricated of paper and
polymeric film laminates. The bag construction must allow quick filling of the
bag with
contents and thereafter must allow closing and sealing the bag.
[0023] The traditional bag construction has layers of polymer laminated
with a paper
layer or layers. Sealing of the traditional bags after filling is accomplished
by re-melting a hot
melt adhesive and/or meltable polymer layer at an elevated temperature while
the paper
resists damage to the bag construction. The high flash point inherent to paper
is relied upon
to withstand the application of heat at an elevated temperature and thereby to
protect the bag
from damage due to the heat and temperature. Further, a thin polyethylene, PE,
polymer
coating on the paper surface can melt or soften together with the hot melt
adhesive to adhere
to the paper and form a secure seal. Existing end-user production line
equipment applies hot
air onto the bag to melt and activate the hot melt adhesive and/or meltable
polymer layer,
following the bag filling operation. The heat must be applied at a temperature
that melts the
hot melt adhesive, and further, to at least partially melt the polymer coating
on the paper
surface, while relying on the paper to withstand the heat and temperature, and
to prevent bag
weakening or burning due the heat and temperature. However, a major drawback
of the
multi-wall paper and polymer laminates is that they are composite materials
not capable of
recycling as either paper or plastic as a single material classification.
Further, the multi-wall
laminates of the traditional bag are not compostable, and consequently remain
in one piece in
landfills. Further, the multi-wall laminates are heavy, and add unnecessary
shipping costs.
[0024] In an end-user's manufacturing production line, apparatus is
provided to fill
the bags with contents through an open end of the bag, followed by closing and
sealing the
filled bag. Traditional production lines have employed stitching equipment to
sew the bags
shut. Alternative production lines have heated air jets to apply heat at an
elevated temperature
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to melt and activate pre-applied hot melt adhesives that have been pre-applied
to traditional
bags of thick multiwall paper and polymer film laminate construction.
Thereafter, a closure
mechanism closes the bags in an advantageous manner simply by pinch closing
the open
ends. The closure mechanism applies pressure on the bags to close and hold the
bags closed
while the hot melt adhesive adheres to the closed bag and until the adhesive
cools and
hardens.
[0025] The heat must be applied at a temperature that melts the hot
melt adhesive,
and further, which can melt portions of the polymer coating on the paper
surface, while
relying on the paper to withstand the heat and temperature, and prevent
weakening or burning
due the heat and temperature. The traditional bags have a construction of
thick multi-wall
paper and polymer film laminates. The one or more, thick paper layers of the
traditional bags
withstand the heat applied at elevated temperatures without weakening the bag
strength and
without burning the paper. Further, a laminated film coating of polyethylene,
PE, on the
paper surface partially melts while in contact with the melted, hot melt
adhesive to form a
heat seal with the adhesive.
[0026] The embodiments of the invention provide a sustainable solution
to the long
existing need for bags that replace traditional bags of multi-wall paper and
polymer
laminates, and yet can withstand the application of heat and temperature to
seal the bags,
which continue to be prevalent in existing production equipment.
[0027] Accordingly, there has been a long existing need for a bag
fabricated of
structural components capable of being recycled or resulting in less landfill
material
compared to traditional bags, and capable of being sealed by existing
production equipment
to avoid expensive replacement of existing production line equipment.
Accordingly, to
replace the existing structural components of a laminated paper and polymer
bag with an
improved bag, the improved bag must be heat sealed by existing production
equipment while
withstanding the application of heat and/or pressure to melt the adhesive and
seal the bag.
Moreover, there has been a long existing need to eliminate a paper and polymer
laminate as
one of the structural components of the bag, which is incapable of recycling
and/or
degradation in a land fill, and which add significantly higher weight and
quantities of
materials in a landfill.
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[0028] Traditional multi-wall paper and polymer laminate bags each
have about 275
grams of paper and 50 grams of polypropylene polymer, and a carbon footprint
of about 11 as
a measure of carbon emissions. Lighter weight bags of about 150 grams results
from
embodiments of the invention with fewer raw materials than those used in
making the
traditional bags, and result in a substantially reduced carbon footprint of
about 5.
[0029] According to embodiments of the invention, woven bags are
fabricated
entirely of a recyclable polypropylene, and with structural components
including a tubular
woven (mesh) bag laminated inside of a non-porous polymeric film of a single
layer or of
laminated layers. The bags are fabricated entirely of a recyclable
polypropylene material that
is recyclable and may be compostable due to having resin additives such as
metallocene, and
further that is free of recycled or contaminated polymers of unknown chemistry
and unknown
material mixtures. Moreover, the bags according to embodiments of the
invention are less
heavy and are more resistant to abrasion, tearing and puncture, and are
reusable compared
with traditional multi-wall paper and polymer laminates that are susceptible
to abrasion and
damage. The bags according to embodiments of the invention reduce waste due to
shipping
costs, damaged bag contents and increased shelf life of the contents.
[0030] The embodiments of the invention fulfill a long existing need
for lighter
weight, strong bags having structural components that eliminate traditional
non-recyclable
paper-polymer laminates, and moreover, that are durable for reuse, and are
degradable by
composting in a landfill and are recyclable as a single material. Moreover,
the recyclable
and/or compostable bags include water soluble adhesive materials as structural
components
of the bags. Embodiments of the adhesive materials can be pre-applied while
soluble in
water, a nontoxic solvent. The adhesive materials are applied onto opposed
surfaces of the
bags, followed by curing by exposure to radiant or entrained heat, electron
beam, EB,
radiation, air or other curing medium and/or to evaporate the nontoxic
dispersion for
environmentally safe removal from the activatable adhesive components of the
dispersion
mixture that attain a non-adhesive hardened state, which is non-reactive to
water or humidity,
and is nontoxic by incidental contact with nutrients being filled in the bags.
An opposite end
of each of the bags has a pinch bottom or alternatively, a flat bottom
configuration that is
closed and sealed by sewing, or by an adhesive preferably a nontoxic adhesive
or by plastic
welding or by a material including, but not limited to polymeric, paper or
nonwoven tape.
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The bags are folded flat for shipment to another manufacturing facility where
the bags are
filled with contents and closed and sealed.
[0031] The adhesive materials to seal the bag are activatable to a
melted adhesive
state using existing production line equipment that apply heat at a
temperature sufficiently
below the softening point temperature Tg of the polymeric structural
components of the bag,
and to melt the adhesive materials to an adhesive state without damaging the
other structural
components of the bag.
[0032] While a traditional multi-wall paper/polymer layer bag can be
sealed with a re-
melted hot melt adhesive, these hot melt adhesives are not suitable for
sealing polymeric
.. bags, which typically are comprised of one or more polymeric layers of
recyclable
polypropylene, or a recyclable and/or compostable polypropylene woven bag and
an outer
polymeric layer or laminate of two or more polymeric layers of recyclable
polypropylene or
other polymer material, but not including either paper or an outer layer,
which is not beat-
sealable on traditional bag manufacturing production equipment. The heat
required to
activate a hot melt adhesive to an adhesive state would be detrimental to a
polymer woven
bag and would destroy the structural integrity of the bag. A traditional multi-
wall
paper/polymer layer bag can be sealed with a hot melt adhesive, whereas on a
polymeric bag
the heat applied by existing end-user equipment to reactivate or re-melt a hot
melt adhesive
would further heat the polymer material of the bag above its softening point
Tg temperature
causing the polymer material to soften, lose tensile strength or even undergo
plastic
deformation. Accordingly, typical known hot melt adhesives are not suitable
for forming a
seal on a polymeric bag.
[0033] The hot melt adhesive is reactivated by a stream of hot air
coming from a hot
air sealer equipment. The equipment is designed to blow hot air only on the
1.5 inch width of
pre-applied adhesive to render the adhesive to a heat activated adhesive
state. Typical heat
settings on a hot air sealer equipment for multi-wall paper bags often exceed
204.44 C
(400 F). However, woven polypropylene bags will deform at approximately 148.89
C
(300 F). A need exists to modify the equipment to seal woven polymeric bags at
a reduced
heat activation temperature. During the development of a pinch bottom closure
for woven
polymeric bags, it became clear that hot air scaler equipment that typically
seal multi-wall
paper bags needed to be modified.
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[0034] Each of FIGS. 1 and 2 discloses an alternative embodiment of a
bag 100
formed from a polymeric tube, which includes an outer layer 104 having a
single polymeric
film or a laminate of polymeric films, and an inner polymeric woven bag layer
102. The tube
is formed with first panel 106, a second panel 108 and an open end 122 of the
bag that is
pinch closed by closing the first panel 106 and the second panel 108 against
each other at
their end edges adjacent the open end 122. A portion of the woven bag layer
102 is depicted
with a woven appearance.
[0035] The polymeric woven bag 100 has a stepped, or step cut,
construction at the
open end 122, wherein a portion of the first panel 106 is removed by severing,
cutting or hot
knife, and wherein the first panel 106 is made shorter than a longer portion
502 of the second
panel 108 at the open end. The longer portion 502 provides a foldable flap
portion 502 on the
second panel 108. Further, the inner woven layer 102 of the foldable flap
portion 502 is
exposed. The first panel 106 and the second panel 108 are joined along their
side edges along
sides 110 of the bag 100.
[0036] Further, in FIGS. 1 and 2, the bag 100 has sides 110 in the form of
side gussets
110. Longitudinal end folds or creases 112 join the side gussets 110 with the
first panel 106.
Longitudinal end folds or creases 114 join the side gussets 110 with the
second panel 108.
Longitudinal folds or creases 116 are between foldable first portions 118 and
foldable second
portions 120 of respective side gussets 110. The panels 106, 108 are joined
along their side
edges and end edges by plastic welding of the edges or by an adhesive.
Alternatively the bag
100 is tubular, and the panels 106, 108 are defined by making folds or creases
in the bag 100.
The stepped, or step cut, construction exposes respective side gussets 110,
wherein each of
the side gussets 110 includes a first gusset portion 118 joining the first
panel 106 and a
second gusset portion 120 joining the second panel 108.
[0037] In FIG. 1, the first gusset portion 118 and the second gusset
portion 120
extend at different lengths beyond a panel second section 204. The first
gusset portion 118
extends beyond the second section 204. The second gusset portion 120 extends
beyond the
first gusset portion 118. In FIG. 2, the first gusset portion 118 and the
second gusset portion
120 extend the same length beyond a panel second section 204.
[0038] In FIGS. 1 and 2, a structural component of the first panel 106
includes a first
adhesive layer 600 applied on the first section 202 of the first panel 106. A
structural
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component of the second panel 108 includes a second or further adhesive layer
602 on a
portion of the second panel 108. Further, the second adhesive layer 602 is on
the second
section 204 of the first panel 106, and on the exposed portions 118, 120 of
the side gussets
110 exposed by the stepped or step cut construction. The adhesive layers 600,
602 are dried
to a non-adhesive stable state by passage through a heated oven or directing
fan blown heated
air onto the adhesive layers. According to an embodiment of the invention, the
adhesive
layer 600 and the adhesive layer 602 are applied simultaneously. According to
another
embodiment of the invention, the adhesive layer 600 and the further adhesive
layer 602 can
be of the same material applied simultaneously on the bag 100 or,
alternatively, applied
separately.
[0039] An end 122 of the bag is open through which contents can be
introduced into
the bag 100. After filling the bag with contents, the end 122 is adapted to be
pinch closed
between end edges of the first panel 106 and the second panel 108. An opposite
end 124 of
the bag 100 is closed by being sewn, taped, glued or plastic welded.
Advantageously, the bag
100 is fabricated entirely of compostable polypropylene, PP.
[0040] The bag 100 is foldable along a fold line 206 extending across
the bag 100,
wherein the fold line 206 extends across the first panel 106 between a panel
first section 202
adjacent to a panel second section 204. The bag 100 is foldable without
creasing, or
alternatively is foldable along a crease formed along the fold line 206 by a
creasing
apparatus.
[0041] An adhesive-to-adhesive seal is formed by applying heat to
activate the
adhesive layers 600, 602 (FIG. 3) to adhesive states, which attain adhesive
states by heating
to a temperature below the softening point temperature of the polymeric
material. In FIG. 3,
the bag 100 is foldable along the fold line 206 to fold the first panel 106 on
itself and to urge
the adhesive layer 602 into contact with the adhesive layer 600 below the fold
line 206 and
form an adhesive-to-adhesive seal. The sealing flap portion 502 is folded onto
the panel
second section 204 of the panel 106 to hold the bag 100 in a folded
configuration.
Preferably, the adhesive layers 600, 602 are the same width, or the same
height relative to the
height of the bag, to form an adhesive-to-adhesive seal of the same width.
[0042] Another embodiment of the bag 100 has the end 122 closed and sealed,
as
disclosed by FIG. 3, to form a bottom of a bag 100, while the opposite end 124
is an open
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end through which the bag is to be filled with contents. The bag 100 is made
from a
polymeric tube, wherein the opposite end 124 is an open end of the polymeric
tube. The
opposite end 124 has the same construction as one embodiment of the end 122,
previously
described, such that the opposite end 124 can be closed and sealed after
filling the bag with
contents.
[0043] Then, the embodiments of the bag 100 are prepared for storage
and shipment.
The end 122 of the bag 100 is pinch closed by closing the first panel 106 and
the second
panel 108 against each other at their end edges adjacent the open end 122. The
end 122 of
the bag 100 is folded flat while remaining unsealed, and the bag 100 is folded
flat for storage
and shipment to another manufacturing facility wherein the end 122 of the bag
100 is opened,
the bag 100 is unfolded and expanded from the flat configuration, and the bag
is filled with
contents. Then, the end 122 is closed and sealed. Each of the adhesive layers
is heated to an
adhesive state at a temperature below the softening point temperature of the
polymeric
material of the bag. Then the bag is folded to contact the adhesive layers to
one another, and
the adhesive layers form an adhesive-to-adhesive seal upon application of
pressure. It would
be desirable to fold the tube without displacing or expelling adhesive from
the fold, in order
to minimize adhesive contamination on surfaces of the tube. Thus, the first
panel 106 of the
polymeric tube has a third section 208 between the first section 202 and the
second section
204. The tube is folded along the third section 208, wherein the adhesive
material 602 on the
stepped construction and the adhesive material 600 on the first section 106
meet in contact
and under pressure below the third section 208 and provide an adhesive-to-
adhesive seal at
one closed end of the bag 100.
[0044] The first adhesive material 600 and the second adhesive
material 602 are
absent from the third section 208, wherein the third section 208 between the
first section 202
and the second section 204 is free of adhesive. As a result, the tube is
folded and pressure is
applied, without displacing or expelling adhesive from the third section 208,
in order to
minimize adhesive contamination on surfaces of the tube.
[0045] Development of a pinch bottom closure on woven polymeric
(polypropylene)
bags discovered that the polypropylene materials that the bag is constructed
of could not
withstand the heat required to re-activate a hot melt via typical hot air
sealers. Theoretically,
hot melts could be used but would need much longer sealing equipment in order
to 1) run at
much lower air temperatures, and 2) allow the bag more time to seal under the
reduced heat.
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[0046] To seal a multi-wall paper bag, its flap portion or sealing
flap is coated with a
3.81 cm. (1.5 inches) width of hot melt adhesive. After filling the bag with
contents, the
adhesive is heated to an adhesive state and the sealing flap is folded to
adhere the adhesive
against an adjacent 3.81 cm. (1.5 inches) width of the bag. A typical hot air
sealer equipment
(apparatus) heats the hot melt adhesive to its melt temperature, while the
paper materials of
the bag withstand the hot melt temperature without heat damage. A pinch
closure of the
sealer equipment folds the sealing flap and pinches the bag to seal the
sealing flap against the
bag while the adhesive cures and dries. However, a typical hot air sealer
equipment produces
hot melt temperatures that would cause heat damage to woven polymeric
(polypropylene)
bags disclosed herein.
[0047] An embodiment of the invention provides a woven polymeric
(polypropylene)
bag 100 with a pinch closure without requiring new capital equipment for
sealing the bags.
The adhesives 600, 602 disclosed herein for sealing woven polymeric
(polypropylene) bags
100 will reactivate to an adhesive state at much lower temperatures than
higher melt
temperatures required to melt a hot melt adhesive, and will do so within the
current dwell
times provided by today's typical hot air sealer equipment. A problem was that
the lower
melt temperature adhesives disclosed herein provide an adhesive-to-adhesive
seal while the
sealing flap 502 is folded against the panel section 204. The adhesive-to-
adhesive seal
requires adhesive coatings 600, 602 over a wide area across the polymeric bags
100. More
specifically, a full 7.62 cm. (3 inches) width of adhesive coatings 600, 602
is needed, which
provides a problem for the typical hot air sealer equipment. The typical hot
air sealer
equipment is capable of heating a 3.81 cm. (1.5 inches) width of hot melt
adhesive on a
sealing flap of a multi-wall paper bag. However, hot air distribution is
needed over a 7.62
cm. (3 inches) wide area across the woven polymeric bag 100. For this reason,
the hot air
sealer equipment is modified with an air manifold to distribute hot air to
where it is needed
over a 7.62 cm. (3 inches) wide area across the woven polymeric bag 100. This
modification
provides a capability of the same hot air sealer equipment to seal both multi-
wall paper bags
and woven polymeric bags 100 on the same equipment.
[0048] The modification is capable of heating adhesive material having
a dimension
up to 3.81 cm (1.5 inches) in width on the first section of the first panel,
and heating the
adhesive material to its adhesive state while having a dimension up to 3.81 cm
(1.5 inches)
in width on the stepped construction of the bag.
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[0049] FIG. 4 discloses a system performing a method for closing and
sealing an end
of bag taken from multiple bags each made of polymeric material. FIG. 4
discloses a portion
of a pinch sealing unit 400 or hot air sealer apparatus 400 and a woven
polymeric bag 100
conveyed from right to left as viewed in the Figure. The apparatus 400 has a
stationary guide
plate 402 against which the bag 100 is supported. The stationary guide plate
402 has a
vertical orientation.
[0050] FIG. 5 discloses a creasing apparatus 500 of the hot air sealer
apparatus 400.
The bag 100 is conveyed past a rotatable creasing wheel 504. A circumference
of the creasing
wheel 504 rolls over the bag 100 to pinch close the bag end 122 while the bag
end 122 is
conveyed between the creasing wheel 504 and the guide plate 402, FIG. 4. The
creasing
wheel 504 has a projecting circumferential rim flange 506 to press against the
fold line 206,
disclosed by FIG. 3, of the bag 100, and to crease the bag 100 along its fold
line 206. The
creased bag 100 folds along the fold line 206, which pivots the flap portion
502 and the
section 202 of the panel 106 along the fold line 206.
[0051] In FIG. 5, after passing the creasing wheel, the stepped
construction of the
bag 100 enters a folding apparatus 600 of the hot air sealer apparatus 400.
The stepped
construction of the bag 100 first passes under a diagonal flared leading edge
604 of a folding
blade 606. The folding blade 606 is formed lengthwise along a bent stationary
blade, such
that the bent stationary blade extends behind the stepped construction of the
flap portion 502
and the section 202 of the panel 106. The flared leading edge 604 guides the
stepped
construction of the flap portion 502 and the section 202 of the panel 106
under the folding
blade 606. With reference to 6, the stepped construction of flap portion 502
and the section
202 of the panel 106 continues to pass under and against the folding blade
606. The folding
blade 606 extends lengthwise rearward of its flared leading edge 604 and bends
downward
progressively of its length until it is parallel to a top wall 702, disclosed
by FIG. 6, of a hot
air manifold 700.
[0052] The adhesive layer 602 is heated to an adhesive state by hot
air blown through
a top wall 702 of a hot air manifold 700, disclosed by FIG. 7. The adhesive
layer 600 is
heated by hot air blown through a back wall 704 of the hot air chamber 716.
For example, the
adhesive layer 602 on the flap portion 502 and the section 202 of the panel
106 of the bag
100 is approximately 3.81 cm. (1.5 inches) in width and extends across the bag
100.
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Similarly, the adhesive layer 602 is approximately 3.81 cm. (1.5 inches) in
width and extends
across the bag 100.
[0053] FIG. 7 discloses the hot air manifold 700 of the hot air sealer
apparatus 400
having a hollow hot air chamber 716, disclosed by FIGS. 8, 9 and 10. The hot
air chamber
716 is provided by the top wall 702, the back wall 704, a bottom wall 706 in
FIG. 9, a front
wall 710 in FIG. 8 and end walls 712, 714, for example, made by stamping and
forming
individual pieces and welding or brazing the pieces together to form the hot
air chamber 716.
An inlet 718 to the hot air chamber 716 is provided through the front wall
710. Hot air under
pressure is supplied through the inlet 718 to pressurize the hollow chamber
716.
[0054] FIGS. 7 and 8 disclose the top wall 702 is perforated with a
distribution of air
passages 720 blowing hot air onto the adhesive layer 602 on the flap portion
502 and on the
adhesive layer 600 on the section 202 of the panel 106. The back wall 704 is
perforated with
a distribution of air passages 722 blowing hot air onto the adhesive layer 600
on the panel
section 204 of the bag 100. The back wall 704 has a flared leading edge 724 to
guide the
panel section 204 past the leading edge 724.
[0055] FIG. 6 discloses the hot air manifold 700 in the hot air sealer
apparatus 400.
Further, FIG. 6 discloses a tapered trailing end 732 of the hot air chamber
716. The hot air
chamber 716 tapers inward at 732a along the front wall 710, disclosed by FIGS.
8 and 11,
toward the trailing end 732. The hot air chamber 716 tapers downward at 732b,
disclosed by
FIGS. 9 and 11, along the top wall 702 toward the trailing end 732. In FIG.
11, hot air is
supplied to the hot air chamber 116 by way of a hot air conduit 720 connected
to the inlet
718.
[0056] In FIG. 6, the bag 100 having the flap portion 502 and the
panel section 202 is
conveyed from right to left over the top wall 702 of the hot air chamber 716,
while hot air
under pressure is blown from the hot air chamber 16 through the passages 720
through the
top wall 702 and onto the adhesive layer 602 on the flap portion 502 and onto
the adhesive
layer 600 on the panel section 202. The adhesive layers 600, 602 are heated to
adhesive
states by the hot air, and thereafter pass a trailing end 732 of the hot air
chamber 716.
[0057] According to an embodiment of the invention, the passages 722
are added to
the back wall 704 such that hot air under pressure is blown from the hot air
chamber 116
through the passages 722 through the back wall 704 and onto the adhesive layer
600
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disclosed by FIGS. 2 and 3, on the panel section 204 disclosed by FIG. 3. The
adhesive layer
600 is heated to an adhesive state by the hot air, and thereafter passes a
trailing end 732 of the
hot air chamber 716.
[0058] The adhesive material can transfer to the hot air manifold and
associated
mechanisms, causing equipment contamination. To minimize equipment
contamination,
FIG. 9 discloses the top wall 702 is recessed below the top edge margin 726 to
define a recess
730 along the top wall 702 to space the adhesive layers 600, 602 away from the
top wall 702
and prevent contact therebetween while the adhesive layers 600, 602 are heated
to their
adhesive states. Further, the back wall 704, disclosed by FIG. 10, has
lengthwise outwardly
projecting edge margins 726, 728 formed by bending. The projecting edge
margins 726, 728
form a lengthwise cavity 730 disclosed by FIG. 10, wherein the projecting edge
margins 726,
728 space the adhesive layer 600 on the panel section 204 away from the back
wall 704 to
prevent contact therebetween while the adhesive layers 600, 602 are heated to
their adhesive
states.
[0059] Further, it would be desirable for the bags 100 to have the adhesive
material of
the adhesive layers 600, 602 located in positions, which will minimize
transfer of adhesive
material to the hot air manifold 700 and associated mechanisms. Thus, on the
bag 100, the
first adhesive material 600 and the second adhesive material 602 are absent
from the third
section 208, wherein the third section 208 between the first section 202 and
the second
section 204 is free of adhesive. As a result, the tube is folded and pressure
is applied, without
displacing or expelling adhesive from the third section 208, in order to
minimize adhesive
contamination of the hot air manifold 700 and associated mechanisms. Further,
the third
section 208 of the first panel 106 is conveyed along a section 726 of the hot
air manifold 700
between the back wall 704 and the top wall 716, wherein contact between the
third section
208 and the hot air manifold 700 is absent of adhesive material, which
minimizes adhesive
contamination.
[0060] The hot air sealer apparatus 400 is adapted for pinch closing
and sealing a
multi-wall paper bag, not shown, having a hot melt adhesive. The hot air
manifold 700 is
further capable of heating the hot melt adhesive to a hot melt temperature by
adjusting the
temperature at which the hot air is heated in the hot air chamber 716. The
multi-wall paper
bag can withstand the hot melt temperature. However, the bag 100 of polymeric
material
cannot withstand the hot melt temperature. Accordingly, the temperature at
which the hot air
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is heated in the hot air chamber 116 must be adjusted below the melt
temperatures or
softening point temperatures of polymeric materials used in making the bag
100. Further, a
multi-wall paper bag, not shown, which has a hot melt adhesive layer of about
1.5 inches in
width across the bag can be heated by hot air blown through the top wall 702.
However, the
multi-wall paper bag does not have additional adhesive to form an adhesive-to-
adhesive seal.
For this reason, hot air blown through the back wall 704 of the hot air
chamber 716 impinges
harmlessly against the multi-wall paper bag, wherein the paper material of the
multi-wall
paper bag withstands the hot melt temperature of the hot air.
[0061] FIG. 6 discloses the folding blade 606 biases against the bag
100 to hold the
flap portion 502 and the section 202 of the panel 106 downward toward the top
wall 702 as
the flap portion 502 and the section 202 of the panel 106 are conveyed from
right to left.
Further, the folding blade 606 has a trailing end 606a that extends beyond the
trailing end 732
of the hot air chamber 716. The folding blade 606 progressively bends
lengthwise toward its
trailing end 606a until its trailing end 606a is essentially vertical beyond
the trailing end 732
of the hot air chamber 716. The progressively bending folding blade 606 biases
the flap
portion 502 and the section 202 of the panel 106 progressively downward to
follow the
tapered top wall 732b of the hot air chamber 716. Beyond the trailing end 732
of the hot air
chamber 716, the trailing end 606a of folding blade 606 biases the flap
portion 502 and the
section 202 of the panel 106 essentially vertical. Further, the trailing end
606a of the folding
blade 606 biases the flap portion 502 to fold, as disclosed in FIGS. 2 and 3,
along the fold
line 206, FIG. 3, while the adhesive layer 600 on the panel section 202 has
been heated to an
adhesive state and becomes biased to engage against the heated adhesive layer
600, disclosed
by FIGS. 2 and 3, on the panel section 204 of the bag 100, which has been
heated to an
adhesive state. The folded panel section 202 and folded flap portion 502
emerge from the
trailing end 606a of the folding blade 606 while the bag 100 continues to be
conveyed from
right to left.
[0062] FIG. 11 discloses a pinch closing apparatus 1200 of the hot air
sealer
apparatus 400. A pair of roller driven belt drives 1202, 1204 pinch on
opposite sides of the
folded bag 100 to pinch close the bag 100, and further, to clamp the second
panel 108 of the
bag 100 against the first panel 106 of the bag and form an adhesive-to
adhesive seal by
contact between the first adhesive layer 600 and the second adhesive layer
602. The belt
drives 1202, 1202 apply clamping pressure transferred to the adhesive layers
600 while they
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become cooled to ambient and form solidified, sealed states, to form an
adhesive-to-adhesive
seal.
[0063] In FIG. 11, the roller driven belt drives 1202, 1204 can
overlap the trailing
end 606a of the folding blade 606 to draw the folded bag 100 out from the
folding blade 606.
The roller driven belt drives 1202, 1204 apply continuous clamping pressure on
the bag 100
as they convey the bag 100 away from the trailing end 606a of the folding
blade 606. After
leaving the belt drives 1202, 1204, the bag 100 can be clamped to continue
with clamping
pressure applied on the opposite sides of the folded bag 100, along the folded
section 202, to
apply clamping pressure against the adhesive layers 600, 602 to adhere them to
each other
while they become cooled to ambient and form solidified, sealed states.
[0064] An adhesive material was required to be developed to provide a
first adhesive
layer 600 of heat activated adhesive material on a portion of the bag 100. The
same or
another adhesive material was required to be developed to provide a second
adhesive layer
602 of heat activated adhesive material on another portion of the bag 100,
wherein heat
activation temperatures of the first adhesive layer 600 and the second
adhesive layer 602 are
below the softening point temperature of the polymeric material of the bag
100, and wherein
the adhesive layer 600 can be urged into contact with the further adhesive
layer 602 and form
an adhesive-to-adhesive seal to close and seal the bag 100 at its end 122.
Sealing was
advantageously to be performed by using existing end-user production line
equipment for
applying controlled temperature heat to activate the adhesive layers 600, 602
to adhesive
states. A soluble adhesive was developed, wherein the adhesive layer 600 and
the adhesive
layer 602 comprise an adhesive material soluble in an air dryable solvent. For
example, the
adhesive layer 600 and the further adhesive layer 602 comprise adhesive
material or materials
soluble in water and air dried to dimensionally stable, non-adhesive states
impervious to
water or water vapor.
[0065] The adhesive layer 600 and the further adhesive layer 602
comprise respective
adhesive materials having a melt temperature below 300 F, which is below the
softening
point temperature Tg of the polymeric materials in the layers 102, 104 of the
bag 100.
Further, each of the adhesive layer 600 and the further adhesive layer 602
comprise adhesive
materials dried in air, at a temperature below the temperature required to
activate to adhesive
states.
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[0066] The adhesive layers 600, 602 are activated to an adhesive state
by applying
heat at a heat activation temperature below the heat activation temperatures
of standard or
traditional hot melt adhesives or solvent based adhesives that can seal
traditional paper and
polymer laminated bags without damaging the paper layers, but which exceed the
softening
point temperature Tg of polymeric bags 100 fabricated without paper layers.
The standard or
traditional hot melt adhesives cannot be combined with polypropylene bags 100
because the
temperatures needed to activate the adhesives are destructive to the PP
material structure.
[0067] Embodiments of the adhesive layers 600, 602 comprise, an
aqueous dispersion
of an adhesive material or a water based adhesive materials applied in liquid
form and air
dried or cured to a stable, non-adhesive state when air dried to ambient
temperature. Further
embodiments of the adhesive layers 600, 602 each are an acrylic based
waterborne adhesive
or a polyurethane dispersion adhesive, or a butyl, synthetic or natural rubber
adhesive. Other
embodiments of the adhesive layers 600, 602 include a polyurethane adhesive
dispersed in
water (PUD). A preferred embodiment is made up of 35 percent solids. It is
applied at 1.75
grams/bag wet, assuming an 18" wide bag, across the 3" sealing area. The
viscosity is
adjusted to correspond with the mass flow rate of the preferred embodiments of
an applicator
apparatus and method, for example, a slot die applicator applying a stripe of
the adhesive
layers each of a viscosity of 800-1000 centipoises and a coating weight
sufficient to form an
adhesive-to-adhesive seal that will withstand bag tests to be described
herein.
[0068] An embodiment of the adhesive layers 600, 602 for pinch sealing of
PP woven
bags 100 is comprised of synthetic polymer or co-polymer emulsions that are
water- or
solvent-based, including without limitation polyurethane dispersion adhesives,
vinyls,
acrylics, or other polymer or co-polymer emulsions, or may include natural or
synthetic
rubber-based adhesives, which are applied wet solubilized and then dried to a
hardened state
impervious to water and water vapor. Known application apparatus to use on a
production
line includes, but is not limited to spray applicators, wheels, or a slot die
applicators. The
adhesive layers 600, 602 form an adhesive-to-adhesive seal when activated to
adhesive states
by heat applied by a hot air jet or other thermal source at an elevated
temperature up to about
and less than about 300 degrees F. which is below the melting point
temperature of the
polymeric, polyolefin films and/or PP woven materials of the bag panels 106,
108 and the
bag gussets 110 when present. Such adhesive layers 600, 602 provide adequate
bond and
adhesion to polyolefin films and/or PP woven materials, are FDA approved for
non-direct
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food contact, and provide adequate sheer, peel and bond strengths to meet bag
testing
parameters to be described herein.
[0069] Two adhesive layers 600, 602 in particular are an acrylic based
waterborne
adhesive and a polyurethane dispersion adhesive. Each has an adhesive state
activation
temperature below 300 F, and below the softening point temperature Tg of the
polymeric
layers 102, 104 made of compostable polypropylene, for example.
[0070] An embodiment of the adhesive layers 600, 602 includes: a
polyurethane
adhesive dispersion of 35% solids in water, with a viscosity adjusted for
application to the
bags, for example, a viscosity of approximately or about 800 -1000 centipoises
for
application by a slot die applicator, or less than about 800 centipoises for
application by a
spray applicator. The viscosity is varied or adjusted to obtain an optimum
mass flow rate and
attain a desired coating weight as need for application by a specific form of
applicator.
Adhesive 1623-63A, is available commercially from Bostik, Inc., Wauwatosa, WI
53226,
USA , wherein the adhesives per se form no part of the present invention
separate from being
a structural component of the bags disclosed herein. The embodiments of
adhesive layers
660, 602 as a structural component of the bags includes 1.75 grams adhesive
material per bag
applied wet, solubilized in water, assuming an 18 inch wide bag and a 3 inches
wide stripe of
adhesive on the bag, which is equivalent to 0.6 grams per bag dry or about
10.6 lbs per ream
dry weight coating. Once the adhesive layers 600, 602 are applied, they must
pass under a
drying system to evaporate the water and dry the adhesive layers to a stable
state impervious
to water, water vapor and ambient temperatures.
[0071] The bag 100 includes heat sealable material or materials on a
low melt
temperature, woven and solid polyolefin films. The suitable adhesive material
or materials
are applied to the bag surfaces as a solution or emulsion, and are air dried
at temperatures
below their heat activation temperatures to evaporate the volatiles of solvent
or water and
solidify. The solid adhesive materials are not moisture or pressure sensitive
to activate to an
adhesive state, and thereby avoid contamination of the bag contents during bag
filling.
[0072] One suitable adhesive material for heat sealing polyolefin
films of the bag 100
comprises a water based emulsion of triethylamine adhesive commercially
available as
AQUAGRIP 19566F, manufactured by Bostik, Inc., 11320 Watertown Plank Road,
Wauwatosa, WI 53226 USA.
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[0073] Another embodiment of a hot melt adhesive for heat sealing
polyolefin films
of the bag 100 comprises a hot melt adhesive H9463 available commercially from
Bostik,
Inc. Wauwatosa, WI 53226, USA , wherein the adhesives per se form no part of
the present
invention separate from being a structural component of the bags disclosed
herein. The hot
melt adhesive H9463 has a softening point temperature of 148 C (298 F), a
liquid flow
temperature of 177 C (350 F) and a viscosity of 18000 centipoise at 162.8 C
(325 F) and
900 centipoise at 190.6 C (375 F).
[0074] Another embodiment of a hot melt adhesive for heat sealing
polyolefin films
of the bag 100 comprises a hot melt adhesive H9477 Generation II of H9463 now
or soon to
be available commercially from Bostik, Inc. Wauwatosa, WI 53226, USA, wherein
the
adhesives per se form no part of the present invention separate from being a
structural
component of the bags disclosed herein.
[0075] Another embodiment of a suitable adhesive material for heat
sealing
polyolefin films of the bag 100 comprises an aqueous based dispersion or
emulsion as an
opaque liquid or fluid of an ethylene copolymer or ethylene copolymers, butyl
acetate and
acetaldehyde, which is commercially available as the product name ROBOND TM HS
37-140
adhesive material manufactured by Rohm and Haas Company, 100 Independence Mall
West,
Philadelphia, PA 19106-2399 USA, wherein the adhesives per se form no part of
the present
invention separate from being a structural component of the bags disclosed
herein.
[0076] Another embodiment of a suitable adhesive material for heat sealing
polyolefin films of the bag 100 comprises an aqueous based dispersion or
emulsion as an
opaque liquid or fluid, including an ionomer dispersion in water, based upon
Surlyng
ionomer resin, and which can be diluted or thickened or crosslinked for
enhanced properties,
and which is commercially available as the product name ADCOTETm 37-220 Heat
Seal
Coating manufactured by Rohm and Haas Company, 100 Independence Mall West,
Philadelphia, PA 19106-2399 USA, which during oven drying must reach a minimum
temperature of 82 C (180 F) and which must reach a minimum heat seal
temperature 93 C
(250 F), wherein the adhesives per se form no part of the present invention
separate from
being a structural component of the bags disclosed herein.
[0077] Another embodiment of a suitable adhesive material for heat sealing
polyolefin films of the bag 100 comprises an aqueous based dispersion or
emulsion as an
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opaque liquid or fluid, including water, acrylic polymer, polyester
polyurethane resin,
formaldehyde, ammonium hydroxide, alumina and further including ammonia as a
combustion
product, which is commercially available as the product name NWC 23526K (and
NWC
23526KC) FDA WATER BASE HEAT SEAL FOR POLYWOVENTM adhesive
material, product code 728575, manufactured by ASHLAND Inc., P.O. Box 2219,
Columbus,
OH 43216, USA, wherein the adhesives per se form no part of the present
invention separate
from being a structural component of the bags disclosed herein.
[0078] This description of the exemplary embodiments is intended to be
read in
connection with the accompanying drawings, which are to be considered part of
the entire
written description. In the description, relative terms such as "lower,"
"upper,'' "horizontal,"
"vertical,", "above," "below," "up," "down." "top" and "bottom" as well as
derivative thereof
(e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to
refer to the
orientation as then described or as shown in the drawing under discussion.
These relative terms
are for convenience of description and do not require that the apparatus be
constructed
or operated in a particular orientation. Terms concerning attachments,
coupling and the like,
such as "connected" and "interconnected," refer to a relationship wherein
structures are
secured or attached to one another either directly or indirectly through
intervening structures,
as well as both movable or rigid attachments or relationships, unless
expressly described
otherwise.
[0079] 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.
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