Note: Descriptions are shown in the official language in which they were submitted.
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SIDE-GUSSET BAG MADE OF A PLASTIC FABRIC LAMINATE
The invention relates to a side-gusset bag made of a
plastic film/fabric laminate.
The side-gusset bag has a front panel, a rear panel, and
side gussets between the front panel and the rear panel and
connected to the front and rear panels by respective edge folds.
The side-gusset bag is made of a plastic film/fabric laminate that
comprises a polymer film on the outer surface of the bag and fabric
connected to the polymer film and made of polymer ribbons on the
inner surface of the bag. The fabric and the polymer film on the
outer surface of the bag are connected flatly to each other and
form a fixed plastic film/fabric laminate. The side-gusset bag
that lies flat is closed on one end by a flap of the front panel,
and side gusset flaps between the flap of the front panel and the
rear panel and folded onto the rear panel to form a bottom gusset
and connected thereto. The front and rear panels form surfaces of
equal size. The designation of these bag surfaces as "front panel"
and "rear panel" is intended to facilitate understanding of the
teaching according to the invention, and not to present any
technical restriction. For the purpose of facilitating
understanding of the technical teaching as claimed, in the scope of
the disclosure of the invention, the bag surface onto which film
flaps are folded and attached, thereby forming the bottom gusset,
is termed the "rear panel."
The flattened side-gusset bag can be filled through the
open end thereof, and is closed following filling. The filled
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side-gusset bag is configured as a packaging bag, particularly for
loose fill materials such as pelletized animal feed, litter for
animals, or similar materials. As a result of the use of a plastic
film/fabric laminate, the side-gusset bag is particularly suitable
for large packages that have a significant filled volume and a
significant filled weight. Corresponding side-gusset bags are also
termed "side fold bags" in practice. No differentiation is made
between these two terms in the context of the present invention.
Side-gusset bags made of single- or multi-layer films
not reinforced by a fabric typically have a bottom face formed by
welds. The welds extend from a edge fold on longitudinal sides of
the front or rear panels, at an acute angle, toward the bottom
gusset. The welds, also termed "corner seals", function such that
the base of the side-gusset bag better forms a flat bottom face
when the side-gusset bag is filled with a product.
In practice, side-gusset bags manufactured from a
plastic film/fabric laminate do not have any welds to shape the
base, because the fabric surface on the inner surface of the bag
cannot be welded, or cannot be welded well. High welding
temperatures are necessary to produce a weld, and there is the risk
that the polymer structure and the orientation of the polymer
ribbons of the fabric will be destroyed by to much heat. A further
problem in the creation of welds between the flanks of the side
gussets and the adjacent front panel or rear panel is the poor
contact between the surfaces being connected, due to their fabric
structure. Side-gusset bags made of plastic film/fabric laminate
materials, and without corner seals on the bottom face, have a base
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shape that is visually poor following filling. The poor base shape
also has negative influences on the volume of the container,
because the fill height increases if the base does not sit
correctly. This then needs to be taken into account by increasing
the height of the bag. The problem occurs particularly in the case
of side-gusset bags that lie flat, and have deep side gussets that
form rectangular packages after filling.
In order to make it possible to create welds on side-
gusset bags manufactured from a plastic film/fabric laminate, the
fabric must be equipped over its entire surface or at least
sectionally with a coating capable of producing a weld - produced
by way of example by an extrusion coating or by the application of
a hot-melt glue. The use of coated fabrics made of uniaxially
oriented polymer ribbons, and a coating made of a sealable polymer,
for the purpose of producing bags, is known from EP 2 188 438
[US 2010/0209024]. The coating of the fabric surface of a plastic
film/fabric laminate material, for the purpose of improving the
seal properties, involves a complex manufacturing process, and
requires an additional application of material that involves
accordingly higher costs.
The practice of connecting a fabric made of polymer
ribbons to a polymer surface, by ultrasound welding, is known from
US 4 373 979. The fact that the ultrasound welding method can be
used to close the end of the film tube is described using the
example of a side-gusset bag. The weld points produced by
ultrasound welding are in multiple rows that extend perpendicularly
to the longitudinal direction of the film tube. In this case, the
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distance between the weld points is selected such that each polymer
ribbon of the fabric is captured by one weld point.
Proceeding from the above, the object of the invention is
that of designing a side-gusset bag made of a plastic film/fabric
laminate in such a manner that it has a flat and stable bottom face
after being filled.
The object is attained by a side-gusset bag according to
claim 1, the subject matter of the invention.
The invention is a side-gusset bag made of a plastic
film/fabric laminate, having a front panel, a rear panel, and side
gussets between the front panel and the rear panel and connected to
the front panel and rear panel by edge folds. One flap of the
front panel and side gusset flaps between the front panel and the
rear panel are folded onto the rear panel and connected thereto,
thereby forming a bottom gusset. The side-gusset bag, which can be
produced by folding a flat material web, consists of a plastic
film/fabric laminate that comprises a polymer film on the outer
surface of the bag and a fabric connected to the polymer film and
made of polymer ribbons on the inner surface of the bag. The
fabric and the polymer film are connected to each other and form a
fixed laminate. The fabric is untreated and does not comprise a
sealable coating on the inner surface of the bag. According to the
invention, the fabric surfaces of the side gussets on the inner
surface of the bag are connected to the adjacent fabric surfaces of
the front panel or rear panel by corner weld seams that extend at
an acute angle from a edge fold on longitudinal sides of the front
or rear panels toward the bottom gusset. It is essential to the
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invention that the corner weld seams have a structure generated by
ultrasound welding with a grid pattern consisting of a plurality of
punctiform or linear weld points. A grid pattern made of a
plurality of weld points one behind and adjacent to each other is
advantageous. As a result of a local connection at a plurality of
weld points or lines oriented for example parallel to or across
each other, the strength of the seam of the corner weld seams is
the same in the longitudinal and transverse directions of the
corner weld seams. Specifically, no significant brittleness arises
at the seam edges of the corner weld seams, as can often be
observed in the case of heat seals of polymer films produced using
hot weld tongs.
The corner welds advantageously extend up to the bottom
gusset. In this case, the corner weld seams are oriented in such a
manner that they form an angle between 30E and 60E with the bottom
gusset. According to one preferred embodiment of the invention,
the corner weld seams each enclose a equilaterally triangular
surface together with the bottom gusset and one edge fold on the
side.
The fabric of the plastic film/fabric laminate can
particularly consist of a mesh of ribbon-shaped polymer strips.
The polymer ribbons of the mesh preferably have a width between
2 mm and 5 mm in the longitudinal direction and the transverse
direction of the bag such that the polymer strips of the mesh,
extending in the longitudinal direction and the transverse
direction of the bag can also particularly have substantially the
same width.
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The corner weld seams are advantageously 2 mm to 10 mm
wide and the grid pattern can have 10 to 500 weld points per
surface area of 100 mm2. The weld points of the corner weld seams
are preferably on parallel lines oriented at an angle of 45E with
respect to the longitudinal extension of the corner weld seams. In
this case, at least three weld points are on each line, next to
each other with equidistant spacing.
The plastic film/fabric laminate is typically made of
polyolefinic components, and the polymer film on the inner surface
of the bag is preferably a polypropylene film and particularly
consists of a biaxially oriented polypropylene (BOPP). As an
alternative, the polymer film on the inner surface of the bag can
consist of a polyester or polyamide (OPET, OPA). The fabric on the
inner surface of the bag comprises uniaxially oriented polymer
ribbons woven together and welded on the surface thereof. The
fabric therefore is oriented in the longitudinal and transverse
directions.
The lower edge of the front panel, the lower edge of the
flanks of the side gussets adjacent the front panel, the lower edge
of the flanks of the side gussets adjacent the rear panel, and the
lower edge of the rear panel are advantageously offset with respect
to each other in a fan shape such that the layers of the plastic
film/fabric laminate folded along the bottom gusset each have a
flap that directly abuts the rear panel and is preferably glued to
the rear panel. In this manner, the side-gusset bag has a stable
bottom face that forms a substantially flat and stable bottom
surface following filling of the side-gusset bag. As a result of
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the use of a plastic film/fabric laminate, the side-gusset bag
according to the invention is suitable for large containers and for
packaging of bulk goods with high bulk weight.
The invention is described below in greater detail with
reference to a drawing showing only one embodiment, wherein:
FIG. 1 is a view of the front panel of a side-gusset bag
lying flat,
FIG. 2 is a view of the rear panel of the side-gusset bag
shown in FIG. 1,
FIG. 3 is a detauk view of the inner surface of the bag
of the side-gusset bag shown in FIGS. 1 and 2,
FIG. 4 is a large-scale view of a corner weld seam for
the purpose of shaping the bottom face when the side-gusset bag is
filled,
FIG. 5 shows the the method of making the corner weld
seam shown in FIG. 4,
FIG. 6 shows a side-gusset bag closed following the
filling thereof, resulting in a package,
FIG. 7 shows the profile of a cut edge of the film layers
of a side gusset tube prior to gluing of the film layers to form a
bottom face, and
FIG. 8 shows a variant of the subject matter as shown in
FIG. 4.
FIGS. 1 and 2 show a side-gusset bag lying flat, having a
front panel 1, a rear panel 2, and side gussets 3 between the front
panel and the rear panel and gussets connected to the front panel 1
and rear panel 2 by edge folds 4. The side-gusset bag is formed
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from a flat material web by folding. An overlap region 5 on the
rear panel 2 in the embodiment is closed by gluing. The side-
gusset bag is open at its upper end and can be filled in machines
with a loose bulk material. The side-gusset bag has a closed lower
end forming a flat bottom face when the side-gusset bag is filled.
The bottom face is formed by a flap 6 of the front panel, and side
gusset flaps 7 between the flap 6 of the front panel 1 and the rear
panel 2 and folded onto the rear panel 2 so as to form a bottom
gusset 8 connected to the rear panel 2.
So that the bottom face is shaped better, when the side-
gusset bag is formed, corner weld seams 9 are made that extend at
an acute angle from the outer edge fold 4 on the respective
longitudinal outer edges of the front or rear panels 1, 2 toward
the bottom gusset 8. The corner weld seams 9 can form an angle
between 30E and 60E with the bottom gusset 8. In this embodiment
and according to one preferred embodiment of the invention, the
corner weld seams 9 each enclose a equilateral-triangular surface,
together with the bottom gusset 8 and one edge fold 4 on the side.
The side-gusset bag shown in the drawing is made of a
plastic film/fabric laminate. The plastic film/fabric laminate has
at least two layers, and comprises a polymer film 10 on the outer
surface of the bag and a fabric 11 connected to the polymer film 10
and made of polymer ribbons 12 and 13 on the inner surface of the
bag. The polymer film 10 is permanently glued to the fabric 11.
The plastic film/fabric laminate is made for example of
polyolefinic components.
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FIG. 3 shows that the fabric 11 consists of a mesh of
polymer ribbons 12 and 13 including longitudinal polymer ribbons 12
and transverse polymer ribbons 13 having a width for example
between 2 mm and 5 mm. Here, the polymer ribbons 12 and 13 of the
mesh have substantially the same width in the longitudinal
direction of the bag and the transverse direction of the bag.
The fabric surface on the inner surface of the bag cannot
be easily welded. High weld temperatures would be required, and
the risk would exist that orientations in the polymer ribbons 12
and 13 would be destroyed. The corner weld seams 9 are generated
according to the invention by ultrasound welding, and have a
structure produced by ultrasound welding with a grid pattern of a
two-dimensional array of weld points 14. The weld points 14
connect the fabric surface of the side gussets 3 on the inner
surface of the bag with the adjacent fabric surface of the front
panel 1 or rear panel 2. The scope of the invention also includes
a system in which the structure of the corner weld seam generated
by ultrasound welding consists of lines of weld points that extend
for example parallel to, or across each other.
The method of making the corner weld seams 9 by
ultrasound welding is shown in FIG. 5. High-frequency alternating
current is produced by a generator and transmitted to an ultrasound
converter that generates an ultrasonic vibration therefrom. The
high-frequency mechanical oscillations of a sonotrode 15 are
transmitted under pressure to the polymer layers being connected.
The oscillations in ultrasound welding cause molecular friction and
boundary surface friction in the joint zone. In the process, the
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heat needed for the weld is created and the polymer material is
plasticized at the weld points 14. According to FIG. 5, counter
bearings 16 for the sonotrode 15 engage laterally with the expanded
side gussets 3. The ultrasound seal has the advantage that the
welding times are short, and thermal energy is limited as much as
possible to the contact regions such that other laminate regions,
and particularly the oriented polymer ribbons 12 and 13 of the
fabric 11, are exposed to lower heat stress.
The corner weld seams 9 each have a width as shown in
FIG. 4, between 2 mm and 10 mm with a grid pattern advantageously
of 10 to 500 weld points per surface area of 100 mm2. Here, the
corner weld seam 9 is about 4 mm wide and is composed of about 100
weld points per surface area of 100 mire. FIG. 4 shows that the
weld points 14 of the corner weld seams 9 are on parallel lines 17
oriented at an angle p of 45E to the longitudinal extension of the
corner weld seams 9. At least three weld points 14 are on each
line 17, next to each other with equidistant spacing.
In the embodiment of FIG. 8, a ventilation hole 24 is in
at least one triangular bag flap 7' bounded by a corner weld seam
9. An exchange of air is ensured between the bag flap 7' formed
with the ventilation hole 24 and the interior fill space of the
side-gusset bag. The exchange of air is indicated by arrows.
Here, the exchange of air is possible because the corner weld seam
9 maintains a space between the bottom gusset 8 and the edge fold 4
on the longitudinal side of the bag. As an alternative or in
addition thereto, the corner weld seam can for example be
discontinuous in order to ensure or facilitate the exchange of air
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between the triangular bag flap 7' and the fill space of the side-
gusset bag.
The corner weld seams 9 provide a good base shape during
filling of the side-gusset bag. After filling and the closure of
its upper end, the side-gusset bag forms a substantially
parallepipedal package with a flat, stable bottom face, as shown in
FIG. 6.
The side-gusset bag made of a plastic film/fabric
laminate can be used for the package of loose bulk goods such as
pelletized animal feed, litter for animals, or similar materials,
and is suitable as a bag particularly for large packages that have
a significant filled volume and a significant filled weight. In
addition to the fact that the package has a well-shaped flat bottom
face as a result of the corner weld seams 9, the bottom face must
also be able to bear a great load during filling and during
handling of the bag. Because the fabric surfaces on the inner
surface of the bag are not capable of welding, the material layers
are preferably glued to each other. As regards the permanent glued
bond, it is advantageous if the film layers being glued to each
other to form a bottom face have an edge profile with the shape
shown in FIG. 7. FIG. 7 shows a view of the rear panel 2 with a
lower edge 18 of the front panel 1, a lower edge 19 of flanks 20 of
the side gussets 3 adjacent the front panel 1, a lower edge 21 of
flanks 22 of the side gussets 3 adjacent the rear panel 2, and the
lower edge 23 of the rear panel 2 are offset to each other in a fan
shape. As a result, the layers of the plastic film/fabric laminate
folded along the bottom gusset 8 each have a flap that lies
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immediately against the rear panel 2 and is glued or welded to the
rear panel 2.
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