WO2024061652A1

WO2024061652A1 - Side gusseted bag

Info

Publication number: WO2024061652A1
Application number: PCT/EP2023/074722
Authority: WO
Inventors: Jens Kösters
Original assignee: Mondi Ag
Priority date: 2022-09-22
Filing date: 2023-09-08
Publication date: 2024-03-28
Also published as: EP4342812A1

Abstract

The invention relates to a side gusseted bag comprising a bag body (3) having a first front wall (1a), a second front wall (1b) and two side gussets (2), wherein the side gussets (2) are arranged on longitudinal edges of the bag body (3) between the front walls (1a, 1b) and are connected to the front walls (1a, 1b) by longitudinal sealing seams (5), wherein the first front wall (1a) is formed by an inner film (10) and an outer film (11) with regions that are not connected to one another. According to the invention, the second front wall (1b) and the side gussets (2) are each formed by an inner film (10) and an outer film (11) with regions that are not connected to one another.

Description

Side gusset bag

Description:

The invention relates to a gusseted bag with a bag body having a first front wall, a second front wall and two side gussets, the side gussets being arranged on longitudinal edges of the bag body between the front walls and connected to the front walls by longitudinal sealing seams, the first front wall being composed of an inner film and an outer film , which are partially unconnected to each other, is formed.

The gusseted bag is intended in particular as a packaging bag. The gusseted bag is then suitable, for example, for the provision, storage and transport of various foods, pet food, household chemicals and other everyday goods.

Depending on the design, the gusseted bag can be used for solid, lumpy, granular or powdery as well as liquid or pasty products that are protected by the bag body. The gusseted bag intended as a packaging bag is sealed tightly or largely tightly after filling, so that safe transport and storage are possible. In the usual way, valves can optionally also be provided, for example to enable a controlled escape of gases formed. If the gusseted bag has a resealable closure, further storage is possible even after it has been opened for the first time.

Conventional film packaging bags are used in practice as mass-produced items, whereby the typical structure of such film packaging bags is known, for example, from EP 2 032 454 B1 and EP 2 364 848 B1. The material for the bag body is often a laminated composite with an inner film made of polyethylene (PE) and an outer film based on polyethylene terephthalate (PET) or biaxially oriented polypropylene (BO-PP), whereby a printing layer in such a laminated composite is applied to the inside of the contact surface either on the outer film or the inner film before the inner film is bonded to the outer film and is then visible through the transparent outer film.

Such conventional film packaging bags are characterized by a particularly high-quality appearance and good functional properties. However, due to the lamination of the different polymer materials, pure plastic recycling is not possible, which is why corresponding foil packaging bags as disposable items are often landfilled or burned after use, although thermal recycling is at least still possible. In principle, chemical recycling can also be considered, although this is comparatively complex.

From EP 2 987 744 B1 a gusseted packaging bag is known, the bag body of which has an outer layer and an adjoining inner layer. At least the outer layer is oriented, with special advantages in terms of sealability being achieved when the outer layer is laminated with a non-oriented inner layer. The entire gusseted bag can be made of one type or essentially of one type, in particular from polyethylene, in which case recycling of the corresponding polymer material is then possible.

According to EP 2 987 744 B1 it is proposed that a print is arranged as a counterprint on the inside at the transition from the inner film to the outer film. The printing inks then remain in the recycled material and lead to a discoloration. Furthermore, printing inks are often questionable from a physiological point of view, so the use of the recycled material in direct contact with food is not easily possible. In practice, corresponding recycled materials are often used for lower-quality plastic products, which is why downcycling is also referred to in this context.

In a generic gusseted bag according to DE 10 2019 117 119 A1, only one of the front walls is formed by an inner film and an outer film, which are partially unconnected to one another. The bag body is formed from a bag film, which forms the inner film on one of the front walls, where the outer film is attached in the form of a printed material section with a non-separable connecting seam. The bag film itself is unprinted, and the usually significantly thinner printed material section can preferably be removed manually by a user. This can be done, for example, within the frame-shaped connecting seam with the bag film along a weakening line

Even if mechanical shredding is generally considered and different waste fractions can then be separated from one another, according to DE 10 2019 117 119 A1, manual separation of the material section as the outer film from the bag film as the inner film should also be possible. Accordingly, it is advantageous if the material section is only present on one of the front walls in order to keep the effort required for manual removal to a minimum. The remaining bag body is then unprinted and can be easily recycled. In terms of recyclability, it is generally also advantageous if the unprinted material does not contain any dyes, pigments or the like in the polymer matrix, which is why the bag body is often clear or at least opaquely translucent, depending on the plastic used.

Compared to a conventional gusseted bag, the difference is that the filling material is visible at least on partial surfaces of the bag body. A consumer will immediately notice these differences compared to a conventional bag and, in many cases, find them disadvantageous. For example, with a granular filling material in the form of cereals, pelleted pet food or the like, fragments, crumbs and other small components may be present, which are hardly noticeable in conventional foil bag packaging, but can affect the appearance of a transparent or translucent bag body.

The present invention is based on the object of providing a gusseted bag, particularly in the form of a gusseted packaging bag, which has good functional properties and a high-quality appearance and at the same time can be recycled in an efficient manner.

The subject of the invention is a gusseted bag according to claim 1.

Starting from a generic side-gusseted bag, it is therefore provided that in addition to the first front wall, the second front wall and the side gussets are each formed by an inner film and an outer film, which are partially unconnected to one another. A double-layer design with the inner film and the outer film arranged on top of it is therefore provided around the circumference of the bag body on all four sides. The front walls and the side folds are connected to one another by the longitudinal sealing seams, which join the corresponding sections together, with the longitudinal sealing seams also providing a cuboid shape and stabilizing the bag body.

In particular, it is provided that the front walls and the side folds are formed from separate blanks, which are only connected to one another by the longitudinal sealing seams. The longitudinal sealing seams are then also necessary in order to form the bag body and to seal it tightly on the circumference.

Corresponding gusseted bags can be produced, for example, by a method which is described in EP 2 857 323 B1, with reference also being made to EP 1 541 332 A1 for the technological background. Corresponding methods are also referred to in practice as transverse methods, with separate material webs being supplied for the formation of the first front walls and the second front walls of several gusseted bags following a production direction, which are, for example, previously cut from a wider web. In the transverse method, it can be provided that the side folds end below an upper edge of the bag body, for which purpose the side folds are bent outwards there and are thus fastened and closed on the longitudinal sealing seams.

The integration of a floor is also easily possible using a transverse method. In the context of the invention, it is in particular provided that the bag body has a usually rectangular bottom, which is connected to the front walls and the side folds via bottom sealing seams, wherein the bottom is preferably also formed by an inner film and an outer film, which are partially unconnected to one another.

According to the invention, it is provided that both front walls and both side folds are each formed by an inner film and an outer film, which are partially unconnected to one another. An optional floor is also preferably designed accordingly.

However, the invention is not limited to gusseted bags formed in a transverse process. In principle, taking into account the general idea of the invention, another manufacturing process, for example a so-called longitudinal process, can also be considered.

When the bag is shredded in a recycling process, separate fragments of the inner film and the outer film are formed in the unconnected areas, which can then be separated.

In the interests of good functionality and simple production, it is preferably provided that the inner film and the outer film are arranged over the entire surface of the front walls and the side folds and possibly also the bottom, i.e. both films extend over the entire surface. The described sections of the bag body and thus preferably the entire bag body are then designed to be double-walled, but the inner film and the outer film are unconnected to a large extent overall and separate fragments are then formed in the unconnected areas after shredding.

According to a preferred embodiment of the invention it is provided that only the outer film with one is attached to the front walls and/or the side folds imprint is provided. Such a print on the back of the outer film along the line of sight is also referred to as counter-printing. As explained further below, it is particularly advantageous if there is only a print on the outer film on the front walls and the side folds, so that the inner film is free of printing ink, at least in the unconnected areas, which means high-quality and comparatively simple recycling appropriate components. To select the different types of particles, it can be determined, for example, after crushing, whether individual particles are provided with printing ink or otherwise colored. Sorting is then possible using air nozzles, among other things.

In principle, however, it is also possible, in addition or as an alternative, for the inner film to be printed.

With regard to good recyclability of the bag body, further preferred embodiments can be provided. For example, a color can be provided for a print which can be separated from the polymer material during a recycling process. It should also be noted that after the bag body has been shredded and the particles of the inner film on the one hand and the outer film on the other hand have been separated, the side of the outer film is also exposed, which initially faces the inner film in the bag body itself and which is thus initially protected on the inside. A print on the side-gusseted bag is then protected against mechanical damage, abrasion or removal by water, solvents or other liquids.

Especially against this background, a color can also be used, which can be removed relatively easily after being exposed in the recycling process can. For example, water-based and/or water-soluble colors are suitable. For example, suitable colors can also be removed in a heated alkaline solution at a temperature of, for example, 60°.

Within the scope of the invention, it should also be taken into account that in many cases in practice different recycling methods with different approaches and a different level of effort can be provided, at least currently and in the foreseeable future. A design of the gusseted bag that enables good results even with different and, in particular, differently complex recycling processes is particularly advantageous.

According to a further aspect of the invention, it can be provided that an edge section of the outer film in the area of the longitudinal sealing seams is unprinted on the front walls or the side folds, preferably on the front walls and the side folds.

This takes into account the fact that in the area of the longitudinal sealing seams, the inner film is generally not separated from the outer film, even in the recycling process. So if the inner film as a whole and the outer film are unprinted at least at the longitudinal sealing seams, the particles of the composite of outer film and inner film formed at the longitudinal sealing seams are also free of dyes.

According to a preferred embodiment of the invention, it can be provided that the bag body, based on its polymeric film components, consists of at least 80% by weight, in particular 90% by weight, particularly preferably at least 95% by weight, of polymer of a material class, in particular of polyethylene or made of polypropylene. Non-polymeric materials such as For example, inorganic fillers or polymeric substances such as adhesives and printing inks, which do not form direct film components, are not taken into account.

Due to the amount of polymeric film components made from polymer of a material class, appropriate criteria for single-variety or largely pure-variety recycling can be met if the material is sorted appropriately. However, as part of a recycling process, high and/or fluctuating proportions of additional materials such as fillers can lead to impaired quality of the recycled material or the products formed from it.

According to a particularly preferred embodiment of the invention, it is provided that the bag body is made of at least 80%, in particular at least 90%, particularly preferably at least 95%, based on its weight, that is to say its total weight, of polymer of a material class, in particular of polyethylene or polypropylene , is formed. Accordingly, the overall proportion of foreign organic or inorganic materials is low.

It is particularly preferably provided that the inner film and the outer film are essentially made of one type of polymer of one material class and in particular of polyethylene or polypropylene.

Particularly in the context of such a design, it is advantageous if the particles that remain as a composite are free of dyes during recycling, because then corresponding particles are usually processed together with the inner film, which is also not printed, into high-quality products and in particular packaging such as new gusseted bags can. In particular, with regard to gusseted bags as packaging, a certain amount can be achieved Circulation of the material can be achieved, with an at least partially closed circuit being conceivable if the purity is sufficient.

If the outer film is unprinted on the front walls and/or the side folds in the area of the longitudinal sealing seams, then according to a preferred embodiment of the invention it can be provided that the printing extends up to the longitudinal sealing seam. It can be provided that the print ends directly on the longitudinal sealing seams or at a small distance of a few millimeters, for example a distance of 0.5 mm to 8 mm, in particular 1 mm to 5 mm.

If, however, the print extends into the longitudinal sealing seams, various aspects must be taken into account. If the overhang is small and therefore only small amounts of printing ink are used, the associated contamination of the recycling material can be negligible. Otherwise, the particles containing printing ink formed during the recycling process can also be handled separately, in particular with other printed particles.

The advantage is that the bag body is then opaque or largely opaque. Except for narrow, transparent gaps, the interior of the bag body is then covered, which results in a particularly high-quality appearance and the gusseted bag according to the invention cannot be distinguished by a user from a conventional gusseted bag or can only be distinguished with difficulty. Fragments of granular filling goods such as cereals, pelleted pet food, rice or the like are not noticed. This usually also applies to remaining transparent columns if they are sufficiently narrow as described. If the print reaches up to the longitudinal sealing seams, fragments can remain in the area of the longitudinal sealing seams during recycling, which are not only formed from a longitudinal sealing seam but also in front of an adjacent printed section of the outer film. It should be taken into account that a shredding process produces fragments of different sizes and a certain statistical distribution. However, if such a fragment with a partial print is sorted out as printed and the ink is then subsequently washed off, very high-quality recycling is again possible. Because the print is preferably not inserted into the longitudinal sealing seam, such fragments can also be easily washed off after the initially hidden print has been exposed.

According to the invention, it is provided that the inner film and the outer film are partially unconnected to one another on the front walls and the side folds in order to be able to form separate particles or fragments there during recycling. Of course, it is an advantage if the proportion of unconnected areas is as large as possible. In principle, it can be sufficient if a connection between the outer film and the inner film is only provided at the edges of the front walls or the side folds. A kind of frame is then created on the front walls, with a usual rectangular shape of the front walls, a rectangular surrounding frame.

According to a preferred embodiment of the invention, it is provided against this background that the inner film and the outer film are unconnected over 80%, in particular 90%, of the covered area on the front walls and the side folds. With a simply designed bag body, connections outside the edges are often not necessary. However, it may be useful to connect the inner film and the outer film in certain areas, for example in order to be able to form or arrange a functional structure.

For example, if the bag body is provided with a weakening line, a local connection of the inner film and the outer film can ensure that they tear together. Along the weakening line, it can then be provided, for example, that only the inner film or the outer film is weakened, removed or notched, for example with a laser, with the sectional connection in the area of the weakening line then resulting in a uniform, as linear as possible crack propagation in the area of the weakening line outer film and the inner film is achieved.

For example, it can be provided that on the front walls the inner film and the outer film are connected to one another, in particular glued and/or connected by heat sealing, at least along a strip running along the transverse direction, the bag body having the previously described functional structure in the area of the strip. It is then also possible for an imprint to be left out locally in such an area. The missing print can then also visually highlight a corresponding functional structure to make it easier for the user to operate. It is also conceivable that the outer film is printed on the weakening line, particularly on its outer sides, i.e. in a face print, in order to identify the weakening line in a precise position. In a washable design, the beautiful print is then exposed on the outside of the bag body. In order to be able to form the weakening line described above as a possible functional structure, the outer film or the Inner film or a layer of the inner film or the outer film can also be used a laser additive.

Regardless of the arrangement of functional structures, when producing the gusseted bag on a film web with the inner film and the outer film, a sectional, in particular linear connection of the inner film and the outer film can be useful in order to be able to handle the film web easily. If, for example, adhesive is applied to the edges of such a film web and/or in areas of subsequently formed separating or folding lines, the glued areas can optionally also be subsequently removed by trimming the edges of the gusseted bag, for example to a largely or completely adhesive-free Provide side gusset bags.

Another functional structure that can be considered is, for example, a reclosure, which is applied to the inner film on the inside of the front walls. Such a reclosure can optionally be particularly highlighted by omitting the print.

The bag body is limited on the periphery by the front walls and the side folds. According to a preferred embodiment, the previously mentioned base is provided, which is then connected to the front walls and the side folds via base sealing seams. The base sealing seams for connecting to the front walls then run in a transverse direction of the bag, while the base sealing seams for connecting to the side folds run along a depth in a filled, erected side-fold bag.

Alternatively, depending on the manufacturing process, a standing area can also be formed simply by folding the films, which also form the front walls that the transition from the front walls to the bottom is formed by edges or folded edges.

When producing the gusseted bag in the previously described transverse process (see also EP 2 857 323 B1), the bottom can be folded, for example, from a section adjoining one of the front walls, with the bottom sealing seams connecting the bottom with the side gussets then being essentially two-dimensional Arrangement along the longitudinal direction of the individual gusseted bags, in particular simultaneously with the longitudinal sealing seams, can be created. During production, a first film web can be supplied to form one of the front walls with the adjoining base and a second, correspondingly narrower film web can be supplied for the further front wall. The gussets are then supplied separately for the successive gusset bags.

As already stated above, the invention is not limited to gusseted bags which are produced in a transverse process. So-called pre-made bags, which are usually first laid flat and then filled, can also be produced in a longitudinal process. In principle, the invention is also suitable for FFS processes (form, fill and seal), in which the bag body is formed and filled immediately one after the other in an integrated process.

Within the scope of the invention it is preferably provided that the inner film is significantly thicker than the outer film on the front walls and/or the side folds. The thickness ratio can be, for example, between 2:1 and 10:1. By making the inner film thicker, several advantages are achieved within the scope of the invention. First of all, it should be noted that the inner film is sealed at the longitudinal sealing seams and, if necessary, at other sealing seams and is therefore essential for the closure and the resilience of the bag body. Sufficient thickness is necessary to provide sufficient stability, although the outer film may contribute some stabilization to the bag body.

In addition, the inner film is preferably unprinted, so that a larger proportion of the material of the bag body, which is formed in particular by the inner film, can be easily recycled simply due to the thickness ratios. Against this background, it should be taken into account that the use of soluble colors for the outer film is only optional, so that recycled material obtained from the outer film can then have a lower quality due to remaining dyes. In principle, with insoluble printing inks, it is also possible to accept corresponding discolorations when the corresponding particle fraction is recycled separately, for example in order to produce lower-quality products in which the coloring is of minor importance or is subsequently changed by adding further dyes in the manufacturing process. Dark gray or black coloring is usually also possible with colored recycled particles.

Furthermore, it is also possible that, even if there is a soluble color on the outer film, depending on the recycling of the gusseted bag, a recycling process is used in which washing is not possible. Even in such constellations, it is of course advantageous if the outer film is made comparatively thin, for which reference is made to the previously mentioned preferred thickness ratios. According to a preferred embodiment of the invention, it can be provided that the thickness of the inner film is between 80 pm and 200 pm. The outer film can, for example, have a thickness between 15 pm and 50 pm.

It should be noted that on the front walls and the side folds and possibly also a bottom, the inner film preferably has the same thickness and is made of the identical material. In particular, the sections can also be at least partially cut from a common film web. For example, it is possible for the front walls and any floor provided to be formed from a first film web and the side folds from a second film web. In principle, variations in the thickness and material of the inner film can also be provided to a certain extent for the front walls, the side folds and/or the bottom fold. Corresponding considerations apply equally to the outer film.

The gusseted bag according to the invention is preferably designed or provided as a gusseted packaging bag. Corresponding gusseted bags are often produced as pre-made bags, particularly in the transverse process described above. The bag body, which is formed from the front walls, the side folds and, if necessary, a bottom fold, is first left open at an upper edge and then filled and closed. The production of the gusseted bag on the one hand and the filling and closing on the other hand are usually carried out at different production sites, whereby the prefabricated gusseted bag can be easily stacked, transported and stored. The present invention relates to both the prefabricated and the fully filled and closed gusseted bag.

Accordingly, according to one embodiment of the invention, it is provided that in a flat state the side folds are folded along a center line between the front walls, with the bag body being open at an upper edge.

The invention equally relates to the gusseted bag when the bag body is filled with a filling material and, in particular, is sealed in an airtight manner. The filling material is then well protected against external influences, although depending on the design of the bag body and depending on the filling material contained, ventilation and/or venting valves, perforation or the like are not excluded.

In order to be able to produce the longitudinal sealing seams and other sealing seams, the inner film should be easily sealable to itself on its side facing a filling space of the bag body. At the same time, it is advantageous if the structure of the outer film is not affected too much during such a sealing process and, in particular, does not melt.

Against this background, it is expedient if the inner film has a lower softening or melting temperature than the outer film, at least on its inside. Corresponding differences in heat sealability can, for example, also be achieved within a single material class by selecting suitable polymer types. Additionally or alternatively, according to a preferred embodiment of the invention, it is provided that the outer film is oriented, in particular monoaxially oriented, whereby the sealing strength is increased.

In particular, the inner film can be designed as a multilayer film, in particular as a multilayer coextrusion film. The inner layer of the inner film located on the inside of the bag body then expediently has a comparatively low melting point and good heat sealability against itself. The outside, which borders the outer film on the opposite side of the inner film, can be made of a material that can be sealed particularly well against the preferably monoaxially oriented outer film. Finally, the inner film can also have a core layer.

In the case of a monoaxially oriented outer film, this results in particular in a MDO-PE/PE layer structure, and based on this representation, multi-layer designs of the outer film and the inner film also come into consideration. A biaxially oriented, possibly multi-layered outer film can also be used, so that a BO-PE/PE layer structure then results. Finally, a PE/PE layer structure is also possible if suitable different types of PE are used with regard to heat sealing and/or further measures are provided for the production of sealing seams, particularly in the area of the side folds. It is conceivable, for example, that separating strips are inserted into the side folds during heat sealing and/or a protective varnish (anti-sealing varnish) is applied.

In a multilayer configuration, a barrier layer can be provided both for the outer film and preferably for the inner film. A layer of ethylene can be used as a barrier layer, especially for oxygen. Vinyl acetate copolymer (EVAL/EVOH) or polyvinyl alcohol (PVAL/PVOH) can be used, the thickness of which can be, for example, between 0.5 pm and 5 pm. For example, a five-layer structure PE/HV/EVOH/HV/PE with adhesion promoter layers, which adjoin a central layer made of EVOH, is conceivable for the inner film. With regard to recycling, a thin barrier layer based on EVOH or PVOH is harmless in many cases.

In principle, a barrier layer, in particular for oxygen, can also be applied as a barrier coating, in particular as a barrier varnish. Such a barrier lacquer can be formed, for example, based on PVOH. It should be noted that the external barrier coating usually impairs heat sealability. To take this into account, it is possible not to apply the barrier varnish to the entire surface and to at least partially leave it out where heat-sealed seams are created. So if an edge strip on one edge of the front walls and/or side folds and/or the bottom is not covered with the barrier paint, a reliable production of a heat-sealed seam is possible there. A corresponding sealing tool can be designed so wide that it also overlaps the edge of the barrier varnish. This then ensures that the barrier varnish extends directly to the corresponding sealing seam.

In combination with the previously described print, it can be provided, for example, that at the internal transition from the outer film to the inner film, the outer film is in a counterprint with the print and the inner film is in a face print with the barrier varnish.

The invention is explained below using an exemplary embodiment. Show it: 1 shows a filled and closed gusseted bag,

Fig. 2 shows the gusseted bag according to Fig. 1 in an unfilled, flat state.

3 shows a horizontal section through a gusseted bag according to FIG. 2,

4, starting from FIG. 2, shows a detailed view of a transition from a front wall into a side fold,

5 shows a material web from which the front walls and a bottom of gusseted bags are formed,

6 shows a material web according to FIG. 5 in an alternative embodiment.

Fig. 1 shows a side-gusseted bag with a bag body 3 having a first front wall 1a, a second front wall 1b and two side gussets 2. In the illustrated embodiment, the bag body 3 also has a rectangular base 4 on which the bag body 3 is placed.

The front walls 1a, 1b are connected to the side gussets 2 via longitudinal sealing seams 5. The bottom 4 connects to the front walls 1a, 1b or the side folds 2 via bottom sealing seams 6a, 6b.

From Fig. 1 it can be seen that the side folds 2 end below an upper edge of the bag body 3, which is closed with a top seal seam 7 running along a transverse direction of the bag. Below The top seal seam 7 has a weakening line 8 for tearing off an upper bag section and an internal reclosure 9.

Fig. 2 shows the gusseted bag with the bag body 3 in a flat state, with the upper edge of the bag not yet closed with the top seal seam 7 and therefore accessible. As explained in detail below, the front walls 1a, 1b, the side folds 2 and the bottom 4 are each formed from an inner film 10 and an outer film 11, which are partially unconnected to one another.

Preferably - as in the exemplary embodiment shown - it is provided that the inner film 10 and the outer film 11 are unconnected over a large part of the covered area and in particular over at least 80% of the covered area.

In the case of the side gussets 2 and the bottom 4, a connection of the inner film 10 with the outer film 11 is only provided at the longitudinal sealing seams 5 or the bottom sealing seams 6a, 6b.

In the case of the front walls 1 a, 1 b, the inner film 10 and the outer film 11 are additionally glued to one another in an area 12 that runs in strips along the transverse direction or, alternatively, sealed to one another. The strip-shaped area 12 immediately adjoining the upper edge of the bag is small compared to the total area of the front walls 1a, 1b.

By gluing or sealing, the strip-shaped area 12 can be opened with suction cups or the like, starting from the flat state shown, in order to then be able to fill the bag body 3 and then close it. Without gluing or one Connecting the inner film 10 to the outer film 11 in another way would pose the risk that the inner film 10 and the outer film 11 would not be grasped together during handling, so that reliable opening of the bag body 3 would then not be possible or would at least be more difficult.

The weakening line 8 and the reclosure 9 are also located on the strip-shaped area 12. By connecting the inner film 10 to the outer film 11, it is sufficient if the weakening line as material removal, notch, incision or the like only in the inner film 10 or preferably the Outer film 11 is formed, with the weakening line 8 then ensuring a controlled tearing of the interconnected inner film 10 and outer film 11. Bonding can also be useful in the area of the reclosure 9 in order to enable safe and intuitive handling there.

In the flat state shown, the side folds 2 and the bottom 4 are inserted between the front walls 1a, 1b. So that the side gussets 2 can end below the upper edge of the bag, the side gussets 2 are bent outwards at an angle. The side folds 2 are thereby tightly integrated into the longitudinal sealing seams 5 at their upper end.

Fig. 3 shows a highly schematic horizontal section through the flat side-gusseted bag according to Fig. 2. As already explained above, both front walls 1 a, 1 b and the side gussets 2 are formed in the same way from the inner film 10 and the outer film 11, with the inner film 10 having a greater thickness than the outer film 11. The thickness ratio can, for example, be in a range between 2:1 and 10:1. The inner film can in particular have a thickness between 80 pm and 200 pm, while the outer film 11, for example, has a thickness between 15 pm and 50 pm. can have.

Further details can be found in FIG. 4, which shows a transition from one of the front walls 1a to one of the side folds 2.

It can be seen that the inner film 10 is formed in three layers with an inner layer 13, a core layer 14 and an outer layer 15, in particular by coextrusion. The inner layer 13 has good heat sealability against itself in order to close the bag body 3 on the circumference along the longitudinal sealing seams 5. The outer layer 15 adjoins the outer film 11, which is designed as a monoaxially oriented monofilm. The outer layer 15 is selected so that good sealability results from the monoaxially oriented outer film 11.

According to a preferred embodiment of the invention, the bag body 3 is made up of at least 80%, in particular at least 90% and particularly preferably at least 95% polymer of a material class, in particular polyethylene or polypropylene. The inner film 10 and the outer film 11 are expediently made of a single type or essentially a single type of polymer of a material class and in particular the previously mentioned materials polyethylene or polypropylene. Such an embodiment also enables a single type recycling of the entire bag body or the particles formed during shredding.

Furthermore, it can be seen from FIG. 4 that the outer film 11 is provided with an imprint 16 on its side facing the inner film 10. The print 16 ends shortly before the longitudinal sealing seams 5. When the bag body 3 is shredded in a recycling process, the inner film 10 and the outer film 11 are mainly formed into separate, separate particles. because the inner film 10 and the outer film 11 are unconnected over a large part of the bag body 3.

It is preferably provided that the inner film 10 is unprinted, so that after appropriate sorting, the particles formed only from the inner film 10 can then be processed very easily after separation into a high-quality recycled product and in particular also again into a gusseted bag.

If particles are formed during shredding in the area of the longitudinal sealing seams 5, the bottom sealing seams 6a, 6b and possibly also in the strip-shaped area 12 on which the outer film 11 is not printed, then these particles can also be sorted into the high-quality, unprinted fraction .

Within the scope of the invention, the print 16 can also be formed with a soluble ink, which can be removed, for example, in a warm alkaline bath. After the color has been washed out, high-quality recycling of the outer film 11 is then possible.

In principle, the gusseted bag according to the invention allows different procedures for recycling. For example, if, as described, the print 16 is formed by a soluble ink, then after shredding, the entire shredded material can also be subjected to a bath to remove the ink, regardless of whether individual particles are printed or unprinted. The shredding then essentially serves to expose the initially internal printed side of the outer film 11.

If the print 16 on the outer film 11 is not made with a soluble color is formed or if no removal step is provided for an inherently soluble color in a recycling process, the particles of the outer film 11 provided with the imprint 16 are expediently removed and recycled separately, thermally recycled or otherwise used or disposed of. In this context too, the different thicknesses of the outer film 11 and the inner film 10 are advantageous. The different thickness can also make the process easier with regard to different separation processes such as air classifying.

In a specific exemplary embodiment, the outer film 11 can be formed, for example, from a monoaxially oriented transparent monofilm made of HDPE with a thickness of 25 μm. In the context of the specific starting example, the printing ink for the print is water-based or water-soluble and can be removed in a bath in the manner described. The inner film 10 is coextruded in three layers and is transparent. An inner layer 13 is then provided in the three-layer structure, which seals against itself at low temperatures. For a sectional connection, in particular along the strip-shaped areas 12, a two-component PUR laminating adhesive (K2-PUR), for example, can be provided.

Fig. 5 shows a material web from which the first front walls 1a, the second front walls 1b and bottoms 4 are produced for successive side gusset bags. First, the film web shown is cut into two strips, which are assigned to the first front walls 1a on the one hand and to the second front walls 1b with the adjoining bottoms 4 on the other hand.

In the film web shown, a partial connection of the inner film 10 to the outer film 11 is provided by adhesive. Roughly in the middle of the A first adhesive strip 17a is provided for the two front walls 1a, 1b, which, when cut in the middle, then forms the previously described strip-shaped area 12 for the first front walls 1a and the second front walls 1b. Further adhesive strips 17b are then provided where the lower edges of the front walls 1a, 1b and edges of the bottoms 4 are formed in the finished bag body 3. The bottom sealing seams 6a are then created at the corresponding locations.

While the adhesive strip 17a in the exemplary embodiment of FIG. 5 is also relevant for the function of the reclosure 9 and the weakening line 8 and enables the flattened bag body to be opened, the further adhesive strips 17b are primarily intended to provide a certain degree of fixation during production or pre-fixing of the inner film 10 and the outer film 11 to each other.

Fig. 6 shows a modification based on Fig. 5, whereby the adhesive strips 17a, 17b are made narrower. The adhesive strips 17a, 17b serve to be able to guide the film web formed from several layers in a system and are arranged in sections of the film web, which are removed again during bag production by trimming the edges of the bag body 3, also known as trimming.

The finished bag body 3 is then completely free of adhesive, which can be advantageous for recycling after use. In order to create a strip-shaped area 12 with a connection, a seal (not shown) can be created in accordance with the width of the middle adhesive strip 17a of FIG. 5 in the embodiment according to FIG. 6.

Claims

Patent claims:

1. Side gusset bag with a bag body (3) having a first front wall (1a), a second front wall (1b) and two side gussets (2), the side gussets (2) on the longitudinal edges of the bag body (3) between the front walls (1a, 1b ) are arranged and connected to the front walls (1a, 1b) by longitudinal sealing seams (5), the first front wall (1a) being formed by an inner film (10) and an outer film (11), which are partially unconnected to one another, characterized that the second front wall (1b) and the side folds (2) are each formed by an inner film (10) and an outer film (11), which are partially unconnected to one another.

2. Side-gusseted bags according to claim 1, characterized in that the inner film (10) and the outer film (11) are arranged over the entire surface of the front walls (1a, 1b) and the side gussets (2).

3. Side gusset bag according to claim 1 or 2, characterized in that on the front walls (1a, 1b) and / or the side gussets (2) only the outer film (11) is provided with a print (16).

4. Side gusset bag according to claim 3, characterized in that on the front walls (1a, 1b) and / or the side gussets (2) an edge section of the outer film (11) in the area of the longitudinal sealing seams (5) is unprinted, it being provided that the print (16) extends up to the longitudinal sealing seams (5).

5. Side gusset bag according to one of claims 1 to 4, characterized in that on the front walls (1a, 1b) and the side gussets (2). Inner film (10) and the outer film (11) are unconnected over 80% of the covered area.

6. Side-gusseted bag according to one of claims 1 to 5, characterized in that the bag body (3) has a bottom (4) which is connected to the front walls (1 a, 1 b) and the side gussets (2) via bottom sealing seams (6a, 6b) and that the bottom (4) is formed by an inner film (10) and an outer film (11), which are partially unconnected to one another.

7. Side gusset bag according to one of claims 1 to 6, characterized in that on the front walls (1 a, 1 b), the inner film (10) and the outer film (11) are glued in areas between the longitudinal sealing seams (5).

8. Gusseted bag according to one of claims 1 to 6, characterized in that the bag body (3) is free of adhesive, the inner film (10) and the outer film (11) being connected to one another exclusively by heat sealing.

9. Side gusset bag according to one of claims 1 to 8, characterized in that on the front walls (1a, 1b) the inner film (10) and the outer film (11) are glued along at least one strip-shaped area (12) running along a transverse direction and / or sealed, the bag body (3) having a functional structure on the strip-shaped area (12).

10. Side gusset bag according to one of claims 1 to 9, characterized in that the side gussets (2) end below an upper edge of the bag body (3).

11. Side gusset bag according to one of claims 1 to 10, characterized in that on the front walls (1a, 1b) and / or the side gussets (2) the inner film (10) has a thickness between 80 pm and 200 pm and the outer film (11 ) have a thickness between 15 pm and 50 pm.

12. Side gusset bag according to one of claims 1 to 11, characterized in that the bag body (3) is formed at least 80% from polymer of a material class, in particular from polyethylene or polypropylene.

13. Side gusset bag according to one of claims 1 to 12, characterized in that the inner film (10) and the outer film (11) are essentially made of polymer of one material class, in particular of polyethylene or polypropylene.

14. Side-gusseted bag according to one of claims 1 to 13, characterized in that in a flat state the side gussets (2) are bent along a center line and inserted between the front walls (1a, 1b), the bag body (3) being open at an upper edge.

15. Gusseted bag according to one of claims 1 to 13, characterized in that the bag body (3) is filled with a filling material and closed.

16. Gusseted bag according to one of claims 1 to 15, characterized in that the inner film (10) is designed as a multi-layer film.

17. Side gusset bag according to one of claims 1 to 16, characterized in that the outer film (11) is oriented, in particular monoaxially oriented.

18. Side-gusseted bag according to one of claims 1 to 17, characterized in that the front walls (1a, 1b) and the side walls (2) are formed from separate cuts which are connected to one another by the longitudinal sealing seams (5).