EP2284090B1 - Bag and method for its production - Google Patents

Description

The invention relates to a bag made of a flexible material with opposite front walls, arranged between the front walls side walls and the front walls with the side walls connecting longitudinal edges, wherein the longitudinal edges are stiffened by sealing seams and extending in the direction of the longitudinal edges reinforcing strips, wherein at the longitudinal edges in each case an associated Front wall forming material portion and a side wall forming material portion are directly connected to the sealed seam. The flexible material is in particular a plastic film, preferably a multilayer plastic film. The term also includes composite materials having a sealable layer, e.g. B. Composite materials of film and paper and films with fabric reinforcements. The invention also provides methods for producing such bags.

The bags are used as packaging, for example, for particulate, granular or powdery bulk material, which have an approximately rectangular cross-section. The bags are often formed by forming a bottom as a stand-up pouch. Under the invention but also bags for packaging to fall, which can be stored lying on a side or front surface and stacked on each other. In all cases, there is the problem that the bags bulge outwardly due to the contents contained therein on the front and side walls, thereby significantly deforming the bag body. This has the consequence that the packaging gives an overall low-quality impression. Due to the lack of dimensional stability also a space-saving storage is difficult and impairs the stability. In order to increase the overall strength of the bag, it may be provided to use a thicker foil or a stiffer material for the formation of the front and side walls. However, this is associated with a significantly higher cost of materials and thus with higher costs and a larger amount of waste.

In order to achieve a high dimensional stability despite a per se flexible film as a starting material, is from the DE 42 03 798 C2 a bag which, according to the features described above, has sealing seams for reinforcement on the longitudinal edges connecting the front walls with the side walls. The bag is formed by folding and heat sealing of a material web, wherein the longitudinal edges of the material web are sealed at one of the two front walls to each other to close the bag circumferentially. The sealing seams are designed accordingly as blind seals, so do not serve the closure of the bag, but only the stiffening. In order to further increase the dimensional stability of the bag, it is proposed already aufzusiegeln on the web from which the bag is formed, reinforcing strips, in which case the longitudinal edges are generated in the region of the reinforcing strip. The reinforcing strips are made of a foil and cover the entire area from which the reinforced longitudinal edges are subsequently formed. In the formation of the longitudinal edges, respectively, a material section forming the associated front wall and a material section forming the associated side wall are superimposed and welded to one another via the reinforcing strip provided there. The sealing seam formed in this way welds the reinforcing strip, which is provided for stiffening, onto itself, folded on its side facing the inside of the bag with itself, this sealing seam being directly adjacent to the interior of the bag.

By known, reinforced with a reinforcing strip design, the dimensional stability of the bag can be significantly increased. However, there is a risk that the sealing seams are torn open again at the occurrence of peeling forces on the respective self-folded reinforcing strip. Such peel forces may occur, for example, if, upon compression of the bag by stacking or due to momentary shocks, for example, dropping the bag, the internal pressure in the bag increases. If in the known design of the bag, the seal is separated, there is a risk that the bag completely bursts under load. Although the additional reinforcing strip represents a material reinforcement, there is also a danger with blindseal seams because weak spots can be formed by heat sealing and buckling of the bag forming material as well as the reinforcing strip. A bursting of the bag should be avoided as possible even with extreme force effects, since not only the contents contained in the damaged bag is affected, but also the environment, such as collectively stored bags or other goods, can be significantly contaminated.

From the US Pat. No. 6,065,873 is a side gusseted bag known, in which at the longitudinal edges reinforcing strips are placed from the outside. In this embodiment, too, there is a risk that the formed sealing seams will be separated by peeling forces. The from the US Pat. No. 6,065,873 known bag is provided as a carrying bag, which should not be sealed airtight and / or moisture-proof. The manufacture of the bag, in which the reinforcing strips must be placed around the longitudinal edges, is expensive.

Against this background, the invention has for its object to provide a bag with the features described above for packaging, the are characterized by an increased mechanical strength, in particular a higher fall resistance.

The object of the invention and solution of this problem is a bag according to claim 1.

At the longitudinal edges, respectively, a material portion forming the associated front wall and a material portion forming the associated side wall are directly connected to one another at the sealing seam. According to the invention, the associated reinforcing strip on the inside of the bag covers a corner formed between the two material sections.

The seal seam arranged on the longitudinal edges, which connects the material sections of the front wall and the side wall, is concealed on the inside of the bag by the reinforcing strips running in the direction of the longitudinal edges and thus protected against mechanical loads. The reinforcing strip is connected at the side of the sealing seam connecting the material sections to both the associated front wall and the associated side wall. While in the embodiments known from the prior art, the longitudinal edges are strongly stressed in a mechanical force acting on a peeling, these peeling forces are converted according to the embodiment of the invention by the reinforcing strips in shear forces, whereby a significantly higher load capacity is achieved. In addition, there is a uniform, larger-area force distribution, so that overall the stability of the bag and in particular the drop resistance can be greatly increased.

The bag has as an essential part plastic, wherein the bag provided for the formation of flexible material at least on one side must have heat sealable properties so that the seal seams can be produced. Preferably, the bag is made of a plastic film. In a multilayer configuration of the foil provided for bag production, however, it should not be ruled out that a thin metal layer, a metallized plastic layer, a tissue of a paper layer and the like is provided inside or on a non-heat sealing side of the foil.

The invention relates in particular to gusseted bags in which the side walls are formed as gussets, each with a fold line extending between the longitudinal edges. In the case of gusseted bags, there is the advantage that they are initially prefabricated and filled later, both the not yet sealed prefabricated bags and the subsequently filled and sealed, preferably air- and / or moisture-tight sealed bags are included in the present invention , By forming gussets the bags can be easily stacked and transported with folded gussets in the flat state. It is also important in addition that the lightest possible filling should be possible. By virtue of the stiffening provided according to the invention at the longitudinal edges and the associated increased dimensional stability, it is easier to introduce a filling funnel of a filling device into the prefastened side-folding bag which is open on one side.

Furthermore, in practice, it has been observed in practice that transverse elements which are sealed on the inside of the bag, such as reclosing strips, contribute to a further increase in the dimensional stability and thus additionally facilitate the filling. In order to make targeted use of this effect, it is provided according to a preferred embodiment of the invention, a stiffening element running in the transverse direction of the sealing seams in the form of a stiff piece of film is provided on the inside of the bag, which extends on one of the side or front walls or preferably substantially around the entire circumference. However, it may be expedient to omit at least the areas in which sealing seams are to be produced. The strip-shaped section can be formed, for example, from polyethylene or a multilayer film, for example a polyethylene terephthalate / polyethylene (PET / PE) composite. It is also possible an embossing of this stiffening element, an embossment of the bag wall and / or an arrangement of additional sealing seams, to further increase the strength. In prefabricated bags that are to be filled later, can be achieved by the additional stiffening element in particular a better and faster bag opening of the initially folded areas of the bag held, which allows very short cycle times at filling systems. It should be noted that the filling itself can be done very quickly depending on the contents partially, the entire process speed is then essentially determined by the handling of the bag, so in particular the opening behavior of the bag.

In the context of the invention is not excluded in principle the front and side walls each of separate material blanks, z. B. film blanks, which are then connected to each other at the longitudinal edges. However, an embodiment is preferred in which the bag is formed by folding and heat sealing from a material web, wherein the longitudinal edges are then formed at least partially as folding edges. The edges of the material web can be connected to one another to form a circumferentially closed tube either on one of the front or side walls or on one of the longitudinal edges. In the first case, all sealing seams at the longitudinal edges as Blind seal seams, in the second case be formed on three of the four longitudinal edges as blind seal seams. In the context of the invention, blind seal seam is understood to mean a sealed seam which is not provided for closing the pouch, but essentially only for its stiffening. A complete tightness of the blind seals is therefore not absolutely necessary. The blind seals also need not extend the entire length of the bag. To achieve the effect of the present invention, it is sufficient if the blind seals and the reinforcing strips extending in the longitudinal direction extend over most of the length of the bag. In addition, it is also possible to form the longitudinal edges, at least in part, as folding edges and then to trimming them, that is to say to cut off an outer edge after the formation of the sealing seams. A trimming can be provided in particular for optical reasons.

In the bag according to the invention, the front and side walls are preferably formed from a multilayer film, wherein the film on the inside of the bag a first heat-sealable film layer and on the outside a second film layer which is not heat-sealable or at least has a higher melting temperature than the first film layer, having. As explained above, in particular the entire bag can be formed by folding and heat sealing from a single material or foil web. Suitable examples are multilayer laminates which have an inner heat-sealable layer of a polyolefin, in particular polyethylene (PE), and an outer layer of a polyester, in particular polyethylene terephthalate (PET). In between, optional connecting and functional layers made of plastic or even thin metal layers may be provided, in particular to improve the barrier properties. Furthermore, a film laminate or a coextrusion film which consists entirely of polyolefin may also be provided to form the bag. For an inside, For example, a biaxially oriented polypropylene (BOPP) is suitable for the second film layer disposed on the outside of heat-sealable first film layer made of polyethylene.

In the context of the invention, the reinforcing strips on the inside of the bag each cover the corner formed between the two adjacent material sections. Multilayered reinforcing strips are preferably used, wherein an outer heat-sealable layer is sealed to the associated front wall and the associated side wall and wherein the opposite layer is not heat-sealable or at least has a higher melting temperature. As will be explained below, the reinforcing strips can be fastened to the adjacent material sections in a particularly simple manner when the bag is folded up. However, it must be avoided that the then folded on reinforcing strips stick inside, so are sealed with itself.

It is advantageous if at the longitudinal edges of each provided there reinforcing strip with sealing seams on the associated front wall and the associated side wall is attached, these sealing seams at a distance from the sealing seam, at the longitudinal edge considered the material portion of the front wall with the material portion the side wall connects directly.

In this case, exactly the middle bending region of the reinforcing strip is recessed. This avoids that new vulnerabilities are created by the sealing. Mechanical loads are thus also kept to a certain extent by the kink as a weak point and the connection arranged behind the front and side wall.

The invention also provides a method according to claim 7 for the production of a bag.

According to the method of the invention, a material web is fed, in which case reinforcing strips are placed on the material web at a distance from one another and connected to the material web. In this method step, the reinforcing strips remain unconnected at least at half their width, wherein initially a prefixing of the reinforcing strips, for example by a rotary sealing tool, is sufficient.

The material web is folded onto itself in the region of the reinforcing strips to form longitudinal edges, so that the reinforcing strips are folded onto themselves there as well. It should also be included that the reinforcing strips are pre-folded prior to placing on the web, so that they can easily be folded over with the formation of the longitudinal edges. The folding of the material web takes place in such a way that the material web extends in the region of the reinforcing strips in the direction of the respective outer edge beyond the associated self-folded reinforcing strip, wherein subsequently the folded bag film directly bears on its inner surface between the outer edge and the respective reinforcing strip itself is heat sealed by a sealed seam. According to the invention, a first side of the reinforcing strip which is located on the outside in the folded state is additionally sealed with the material web, without the reinforcing strips being sealed with themselves in their second side lying on the inside in the folded state. The assignment of the outer first side of the reinforcing strips and the second folded side inwardly of the reinforcing strips refers only to the reinforcing strip itself. Based on the film tube formed from the bag film, the entire reinforcing strips are arranged inside. According to the invention, the folded reinforcing strips are preferably sealed to the material web for the bag film in such a way that a respective bent edge of the reinforcing strips is cut out by a heat seal. As described above, this results in the advantage that a particularly high strength of the bags at the longitudinal edges can be achieved with such a process control.

Usually, after sealing and producing sealing seams, transverse seals are formed and individual bags open at one end are cut off. These bags can then be stored and transported as prefabricated gusseted bags, the bags being filled and sealed subsequently at their open end.

Fig. 1

einen Beutel, der an seinen Längskanten verstärkt ist,

Fig. 2

den erfindungsgemäßen Beutels in einem horizontalen Schnitt,

Fig. 3

eine Detailansicht des Ausschnitts A der Fig. 2,

Fig. 4

einen Verfahrensschritt zur Befestigung von Verstärkungsstreifen auf einer Materialbahn, und

Fig. 5

die Bildung von verstärkten Längskanten durch Heißsiegeln.

The invention will be explained below with reference to exemplary embodiments. They show schematically:

Fig. 1

a bag reinforced at its longitudinal edges,

Fig. 2

the bag according to the invention in a horizontal section,

Fig. 3

a detailed view of the section A of Fig. 2 .

Fig. 4

a method step for fixing reinforcing strips on a material web, and

Fig. 5

the formation of reinforced longitudinal edges by heat sealing.

The bag according to the invention comprises according to the Fig. 1 opposite front walls 1, arranged between the front walls 1 side walls 2 and the front walls 1 with the side walls 2 connecting longitudinal edges 3, wherein the longitudinal edges 3 are reinforced by sealing seams 4. The bag is formed in the embodiment as a stand-up pouch and has in a conventional manner a bottom 5 and a top seal 6, which closes the bag at its top. The bag shown is designed as a gusseted bag, wherein the side walls 2 each have a longitudinally extending fold line 7 as gussets between the longitudinal edges 3. The bag can be pre-assembled and folded flat. The filling and the closure at the top seal seam 6 are then made later on a corresponding filling device. Due to the reinforcement on the longitudinal edges 3, the bag has an overall increased dimensional stability, whereby the filling process is facilitated. In addition, a strip-shaped stiffening element 8 is provided on the inside of the bag, which extends in the transverse direction. By the stiffening element 8, the dimensional stability of the bag is further increased. In particular, the prefabricated, initially flattened bag can be opened easier and faster during handling in a filling device, whereby the entire filling process can be significantly accelerated.

According to the invention, reinforcing strips 9, 9 'are provided in the region of the longitudinal edges 3 for further reinforcement, which extend in the longitudinal direction of the bag and consist of a plastic film.

According to Fig. 2 At the longitudinal edges 3, 3 ', a material section forming the associated front wall 1 and a material section forming the associated side wall 2 are directly connected to one another at the sealed seam 4, the associated reinforcing strip 9 covering a corner formed between the two material sections on the inside of the bag.

The Fig. 3 shows a detailed view of this embodiment in the region of one of the longitudinal edges 3. The illustrated longitudinal edge 3 is formed as two further longitudinal edges 3 as a folding edge, which there preferably over the entire length of the bag extending seal seam 4 is designed as a blind seal, so not the closure of Bag but essentially serves only reinforcement.

The entire bag is formed from a single web of material 10, wherein the edges of the material web 10 at the not shown in detail fourth longitudinal edge 3 'merged and according to the illustration of Fig. 3 are sealed together. The material web 10 consists of a preferably multilayer plastic film or a flexible laminate, which has at least one layer of a sealable plastic film.

The detail view of the Fig. 3 It can be seen that the reinforcing strip 9, which covers the corner formed between the front wall 1 and the side wall 2, is fastened to the material web 10 with additional sealing seams 4 '. In the immediate bend region, the sealing seams 4, 4 'are recessed in order to avoid material weakening there.

While in the known from the prior art embodiments, an overpressure in the bag, which may occur intermittently, for example, when dropping the bag, the sealing seam 4 claimed between the front wall 1 forming material portion and the side wall 2 forming material portion on peeling, this is Sealing seam 4 according to the invention covered by the reinforcing strip 9 and thus protected. In a force stress, the sealing seams 4 ', which connect the reinforcing strip 9 with the bag film 10, subjected to shear, in addition, a large-area distribution of the applied force is generated. Through the combination of these measures, the stability and in particular the drop resistance is significantly increased in the region of the longitudinal edges 3, 3 '. The bags can be designed for a higher load. Finally, there is also the advantage that compared to the known from the prior art versions, even with the use of a thinner bag film consistent or even increased drop resistance can be achieved because the longitudinal edges 3, 3 'because of the inventive design no longer as in the Known bags constitute a weak point limiting the overall strength.

The bag film 10 has a multilayered construction and has on the inside of the bag a first heat-sealable film layer 11 and on the outside a second film layer 12 which is not heat-sealable or has at least a higher melting temperature than the first film layer 11. The first film layer 11 is preferably a polyolefin having a low melting point, for example PE. For example, PET or BOPP may be provided as the second, outer film layer 12. Between the first film layer 11 and the second film layer 12, additional intermediate layers can also be provided without restriction.

Also in the Fig. 3 illustrated reinforcing strip 9 is formed as a multilayer plastic film and has an outer heat-sealable layer 13 and an opposite layer 14 which is not heat-sealable or at least has a higher sealing temperature.

To the in Fig. 2 and Fig. 3 Preferably, the reinforcing strips are initially prefolded on themselves and then unfolded again to an angle of about 90 °, so as in the Fig. 4 represented, the reinforcing strip 9 on one side of the bend with the Material web 10 can be connected, including, for example, a rotary sealing tool can be provided. In the formation of in Fig. 2 and Fig. 3 The bag 10 shown below is provided that the web 10 is folded in the region of the reinforcing strip 9 to form longitudinal edges 3, 3 'in such a way that there the reinforcing strips 9 are folded onto itself and that the web 10 in the region of Reinforcing strip 9 in the direction of the respective outer edge 17 extends beyond the associated self-folded reinforcing strip 9, where subsequently between the outer edge 17 and the respective reinforcing strip 9, the folded web 10 is heat-sealed at its inner surface directly to itself by a sealed seam 4 and wherein a first side of the reinforcing strip 9 located in the folded state is additionally sealed to the material web 10 without the reinforcing strip 9 being sealed to itself at its second, inside folded side.

The Fig. 5 shows a correspondingly folded on itself material web 10, wherein two opposite front walls 1 are formed with arranged therebetween side walls 2. The side walls 2 are formed as inwardly folded side gussets. In the Fig. 5 Furthermore, a sealing tool 18 is indicated, with which at the longitudinal edges 3, 3 'sealing seams 4, 4' are generated, which are spaced from each other by a recess 19 in the sealing tool 18. The recess 19 is located exactly where the bend region of the reinforcing strip 9 is located.

Claims (9)

1. A bag of a flexible material with opposing front walls (1), side walls (2) arranged between the front walls (1) and the longitudinal edges (3, 3') connecting the front walls (1) with the side walls (2), wherein the longitudinal edges (3, 3') are stiffened by sealing seams (4) and reinforcement strips (9) extending in direction of the longitudinal edges (3, 3'), and wherein on the longitudinal edges (3, 3') a material portion forming the associated front wall (1) and a material portion forming the associated side wall (2), respectively, are directly connected with each other, characterised in that the associated reinforcement strip (9) on the inside of the bag covers a corner formed between the two material portions, and in that on the longitudinal edges (3, 3') the respectively provided reinforcement strip (9) is fastened with sealing seams (4') on the associated front wall (1) and the associated side wall (2), wherein these sealing seams (4') extend at a distance from the sealing seam (4'), which on the regarded longitudinal edge (3, 3') directly connects the material portion of the front wall (1) with the material portion of the side wall (2).
2. The bag according to claim 1, characterised in that the reinforcement strips (9) are respectively constructed of several layers, wherein an outer heat-sealable layer (13) is sealed fast to the associated front wall (1) and the associated side wall (2), and wherein the opposite layer (14) is not heat-sealable or at least has a higher melting temperature.
3. The bag according to claim 1 or 2, characterised in that the front and side walls (1, 2) are formed of a multi-layer composite material, wherein the composite material has a first heat-sealable layer (11) on the inside of the bag and a second layer (12), which is not heat-sealable or at least has a higher melting temperature than the first layer (11), on the outside.
4. The bag according to one of claims 1 to 3, characterised in that the sealing seams (4) are at least partially formed as blind sealing seams.
5. The bag according to one of claims 1 to 4, characterised in that the bag is formed from a material web (10) by folding and heat-sealing.
6. The bag according to one of claims 1 to 5, characterised by a stiffening element (8) which extends in transverse direction to the sealing seams (4).
7. A method for manufacturing a bag from a flexible material, wherein:

   a material web is fed, onto which reinforcement strips (9) are placed at a distance to each other;

   the reinforcement strips (9) are pre-folded onto themselves and are connected with the material web on one side of the bent edge;

   the material web (10), in the area of the reinforcement strips (9), is folded onto itself for forming longitudinal edges (3, 3') such that at this point the longitudinal edges (3, 3') are also folded onto themselves, and in that the material web (10), in the area of the reinforcement strips (9), extends in direction of a respective outer edge (17) beyond the associated reinforcement strip (9) folded onto itself;

   the folded material web is subsequently heat-sealed with itself by a sealing seam (4) on its inside surface between the outer edge (17) and the reinforcement strip (9);

   a first side of the reinforcement strip (9), which in the folded state lies on the outside, is additionally sealed with the material web (10), without the reinforcement strip (9) being sealed to itself on its second side which in the folded state lies on the inside.

   wherein the folded reinforcement strips (9) are sealed with the material web (10) such that the bent edge of the reinforcement strips (9), respectively, is omitted from the heat-sealing.
8. The method according to claim 7, wherein following folding and producing of sealing seams (4) transverse sealings are formed and individual bags are separated which are open at one end.
9. The method according to claim 8, wherein the bags are filled at their open ends and then closed.

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