SAC A PLIURES LATERALES

BAG WITH LATERAL FOLDS

Abrégé français

La présente invention concerne un sac à pliures latérales réalisé à partir d'un film flexible multicouche dont la couche intérieure est soudable, ledit sac comprenant une extrémité de fond fermée et une extrémité de tête dotée d'un système de fermeture, et des pliures latérales (3;4) disposées des deux côtés entre les deux parois latérales de sac qui forment la paroi avant (1) et la paroi arrière (2) du sac, lesdites pliures latérales s'étendant de l'extrémité de fond à l'extrémité de tête, et se terminant à distance en-dessous des arêtes marginales supérieures (5) des parois (1, 2) du sac. Selon l'invention, les parois de sac sont soudées avec les pliures latérales et dans le partie tête du sac, dépourvue de pliure latérale, l'une en-dessous de l'autre le long de leurs arêtes marginales, et les parties d'extrémité supérieures (12) des pliures latérales, sont repliées vers une paroi du sac, par rapport à une ligne de pliure (13) qui est inclinée vers l'intérieur et vers le bas vers l'extrémité de fond, les parties d'extrémité repliées sont soudées au niveau de leur côté intérieur, avec le côté intérieur des moitiés de pliures latérales voisines, et refermées au niveau des arêtes marginales côté tête (17). L'invention se caractérise en ce que les parties d'extrémité repliées des pliures latérales, sont soudées en surface au niveau de leur côté extérieur, avec la paroi de sac voisine, une partie (16) des moitiés de pliures latérales, qui est adjacente aux parties d'extrémité repliées des pliures latérales, est également soudée en surface à la paroi de sac voisine, et la liaison de soudure (14, 15, 16) englobe les bords marginaux des parties d'extrémité repliées des pliures latérales.

Abrégé anglais

The invention concerns a bag with lateral folds made from a multilayer
flexible film whereof the inner layer is sealable, said bag comprising a
closed bottom end and a top end provided with a closure system, and lateral
folds (3, 4) arranged on both sides between the two side walls of the bag
which form the front wall (1) and the rear wall (2) of the bag, said lateral
folds extending from the bottom end to the top end, and terminating spaced
apart from the top marginal edges (5) of the walls (1, 2) of the bag.
According to the invention, the bag walls are bonded with the lateral folds
and in the top part of the bag, not containing any lateral fold, one beneath
the other along their marginal edges, and the top end parts (12) of the
lateral folds, are folded towards the bag wall, relative to a folding line
(13) which is inclined inwards and downwards towards the bottom end, the
folded end parts are bonded at their inner side, with the inner side of the
halves of neighbouring lateral folds, and closed at the marginal edges on the
top side (17). The invention is characterized in that the folded end parts of
the lateral folds, are surface-bonded at their outer side, with the
neighbouring bag wall, one part of the halves of the lateral folds, which is
adjacent the folded end parts of the lateral folds, is also surface-bonded to
the neighbouring bag wall, and the bonding link (14, 15, 16) encompasses the
marginal edges of the folded end parts of the lateral folds.

Revendications

The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A gusseted bag comprised of a flexible, multi-layer film having an inner
layer, wherein only the inner layer is fusible, the gusseted bag comprising:
a bottom end that is closed before or after filling with bulk material;
a top end with a closure device;
bag walls forming a front wall of the gusseted bag and a rear wall of the
gusseted bag;
gussets inserted at opposed sides between the bag walls and extending
from the bottom end to the top end and ending at a spacing below upper edges
of the bag walls so that a top area free of the gussets is provided; and
wherein the bag walls are fused with the gussets and, in the top area free
of the gussets, the bag walls are mutually fused with one another along edges
of
the bag walls;
wherein upper end areas of the gussets have top edges and are folded
over toward one of the bag walls at a folding line and form folded-over end
areas,
wherein the folding line is oriented in a direction toward the bottom end at a
first
slant inwardly and downwardly and the top edges in the folded over end areas
extend also toward the bottom end at a second slant inwardly and downwardly;
wherein the folded-over end areas each have an inner side where the
inner layer of the multi-layer film is folded on itself and fused to itself by
a first
welding seam;
wherein the folded-over end areas each have an outer side where the
inner layer of the multi-layer film is facing a neighboring bag wall and is
areally
fused by a second welding seam to said neighboring bag wall, respectively;
wherein an area of a gusset half neighboring the folded-over end areas,
respectively, is areally fused with the inner layer of the multi-layer film
facing said
neighboring bag wall by a third welding seam to said neighboring bag wall,
respectively; and
wherein the first, second, and third welding seams form a fused
connection in the form of a complete seal in which the top edges are embedded
so that the top edges are closed.
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2. The gusseted bag according to claim 1, wherein the end areas are folded
over toward the rear wall.
3. The gusseted bag according to claim 1 or 2, wherein the closure device is
a reclosable closure device that extends at a spacing above the folded-over
end
areas across an entire bag width of the gusseted bag.
4. The gusseted bag according to claim 3, wherein the reclosable closure
device is a three-layer closure strip having outer layers fused to an inner
side of
the bag walls and having a central layer that is separable by cohesion
fracture in
two partial layers, wherein the two partial layers, when being placed against
one
another, are returned into a state of adhesive connection.
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Description

CA 02563328 2011-04-01
Bag with Lateral Folds
The invention relates to a bag having lateral folds, which bag is made of
flexible
multi-layer film whose inner layer is fusible.
In a know bag of this type (DE 20017182 U1) the halves of the lateral folds
are
connected at their exterior along the upper edges in order to provide a
sealing
action that is additionally improved by folding over the end areas and by
securing
the folded-over end areas to the neighboring gusset half.
The invention concerns the problem of a further improvement of the sealing
action
of the gussets at their upper ends.
In one aspect, the invention provides a gusseted bag comprised of a flexible,
multi-
layer film having an inner layer, wherein only the inner layer is fusible, the
gusseted bag comprising:
a bottom end that is closed before or after filling with bulk material;
a top end with a closure device;
bag walls forming a front wall of the gusseted bag and a rear wall of the
gusseted bag;
gussets inserted at opposed sides between the bag walls and extending
from the bottom end to the top end and ending at a spacing below upper edges
of
the bag walls so that a top area free of the gussets is provided; and
wherein the bag walls are fused with the gussets and, in the top area free of
the gussets, the bag walls are mutually fused with one another along edges of
the
bag walls;
wherein upper end areas of the gussets have top edges and are folded over
toward one of the bag walls at a folding line and form folded-over end areas,
wherein the folding line is oriented in a direction toward the bottom end at a
first
slant inwardly and downwardly and the top edges in the folded over end areas
extend also toward the bottom end at a second slant inwardly and downwardly;
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CA 02563328 2011-04-01
wherein the folded-over end areas each have an inner side where the inner
layer of the multi-layer film is folded on itself and fused to itself by a
first welding
seam;
wherein the folded-over end areas each have an outer side where the inner
layer of the multi-layer film is facing a neighboring bag wall and is areally
fused by
a second welding seam to said neighboring bag wall, respectively;
wherein an area of a gusset half neighboring the folded-over end areas,
respectively, is areally fused with the inner layer of the multi-layer film
facing said
neighboring bag wall by a third welding seam to said neighboring bag wall,
respectively; and
wherein the first, second, and third welding seams form a fused connection
in the form of a complete seal in which the top edges are embedded so that the
top
edges are closed.
In one embodiment, the end areas are folded over toward the rear wall. In one
embodiment the closure device is a reclosable closure device that extends at a
spacing above the folded-over end areas across an entire bag width of the
gusseted bag. In one embodiment, the reclosable closure device is a three-
layer
closure strip having outer layers fused to an inner side of the bag walls and
having
a central layer that is separable by cohesion fraction in two partial layers,
wherein
the two partial layers, when being placed against one another, are returned
into a
state of adhesive connection.
Embedding the upper edges in a fused connecting area after folding over the
upper end areas of the lateral folds ensures that a complete and safe sealing
action of the gussets at the upper end is present even when no special
closure,
be it by fusing or by an adhesive, is provided along the upper edges of the
lateral folds. This is so because the fused connecting area forms a complete
seal that, independent of additional measures, provides a reliable closure of
the gussets at their upper edges. At the same time, by connecting the gusset
areas to the bag wall, preferably the rear bag wall, it is ensured that the
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CA 02563328 2011-04-01
upper ends of the gussets no longer project in a disturbing way into the
filling space.
Further details and effects result from the following description and the
drawing in which two embodiments. of the subject matter of the invention are
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CA 02563328 2006-10-10
schematically shown in more detail. The drawings show in:
Fig. 1 a broken-away view of the upper end area of a bag according
to the invention,
Fig. 2 a section approximately along the section line II-II of Fig. 1,
Fig. 3 a view similar to Fig. 1 of a modified bag embodiment,
Fig. 4 a section view along the section line IV-IV of Fig. 3, and
Fig. 5 a section illustration similar to Fig. 4 showing a reclosable
closure device at the top of the bag in open position.
The gusseted bag illustrated in the drawing is comprised of a flexible, multi-
layer, at least two-layer, film that is preferably made from thermoplastic
material. The inner. layer of the film is fusible and is comprised, for
example, of a polyolefin such as polyethylene or polypropylene. One or several
layers can adjoin outwardly and, depending on the requirements, respectively,
can be a metal foil, for example, aluminum foil, and/or a polyester layer
that,
in turn, is not fusible but has high strength and excellent printability.
The illustrated bag has a front wall 1 and a congruent rear wall 2 as well as
lateral folds 3, 4 inserted between them and extending from a bottom end, not
illustrated, to the top end of the bag and ending in this connection at a
spacing below the upper edge 5 of the bag walls 1, 2. The bag walls 1, 2 are
fused with the gussets 3, 4 as well as with the top area of the bag that is
free of gussets along their edges, in particular, by longitudinal fusing seams
6, 7 at the edges. Also, the bottom end is closed by a transverse fusing seam
(not illustrated): this can be carried out before or after filling of the bag
with the bulk material.
In the area of the top end of the bag there is usually a closure device that
is
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CA 02563328 2006-10-10
formed by a welding seam that can be provided before or after filling the bag
with the bulk material. It can also be comprised of a reclosable closure
device that, in the embodiment according to Fig. 1 and Fig. 2, is formed by
pressure lock strips embodied like tongue and groove. In detail, this
reclosable closure device 8 is comprised of lock strips 9, 10 extending across
the width of the bag; one is attached to the front wall 1 of the bag and the
other to the rear wall 2 of the bag by fusing or hot sealing. The lock strips
9, 10 support locking members 11 that, when pressure is applied, are
transferred into a state of mutual engagement and, when a pulling force is
io applied, their mutual engagement is released.
The upper end area 12 of both gussets 3, 4 is folded over along an inwardly
and
slantedly downwardly extending folding edge 13 wherein folding can be done
toward the front wall 1 or toward the rear wall 2. The folded-over end areas
12 of the gussets 3, 4 have the shape of a right triangle and are connected by
fusing to the corresponding half of the gussets 3, 4 facing them, as
illustrated in Figs. 2, 4, and 5; this is schematically illustrated by welding
seam 14. Moreover, the folded-over end areas 12 are fused with their outer
side to the neighboring bag wall, in the illustrated embodiment to the rear
wall 2 of the bag, as schematically illustrated by the welding seam 15 in
Figs.
2, 4, and 5. Moreover, an area 16 of the same-side gusset halves that adjoins
the folded-over end areas 12 of the gussets 3, 4 is also areally fused to the
neighboring bag wall 2 so that the fused connecting areas include the top
edges
17 of the folded-over end areas 12.
In this way, it is ensured that the upper ends of the lateral folds 3, 4 are
closed off absolutely tightly independent of whether or not the outer surfaces
of the gussets 3, 4 resting against one another are additionally closed off at
the top edges 17 by a closure device, for example, an adhesive closure.
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CA 02563328 2006-10-10
In the bag embodiment illustrated in Figs. 3 to 5, a reclosable closure device
18 that is formed as a three-layer lock strip extending across the entire bag
width is provided in the top area of the bag. The two outer layers 19, 20 are
fused to the inner side of the neighboring bag wall 1 or 2, respectively, as
illustrated schematically by the fused connections 21, 22. The central layer
23 is comprised of a resin or plastic material that is permanently adhesive or
sticky and can be separated by cohesion fracture into two partial layers when
the central layer 23 is exposed to a pulling force by pulling apart the bag
io walls 1, 2. After removal of bulk material, the two separated partial
layers
can again be combined to a closed central layer 23 by applying pressure. In
other respects, the configuration according to Figs. 3 to 5 corresponds to the
bag embodiment of Figs. 1 and 2.
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Dessin représentatif