EP3519312B1 - Valve bag and method and system for producing a valve bag - Google Patents

Description

The invention relates to a valve sack according to the preamble of claim 1, a method for producing a valve sack according to the preamble of claim 11 and a system for producing a valve sack according to the preamble of claim 16.

Valve bags are those bags that are completely finished before filling and are later filled via the valve, so that no subsequent closing of the bag is necessary. Such bags can be filled particularly quickly and efficiently in filling machines. Filling goods are often powdery goods such as building materials, especially cement. The documents DE102013000038A1 and DE4303894A1 disclose valve sacks. The documents DE102010028394A1 and DE10232136A1 reveal more sacks.

The filling material is often introduced into the sack, in particular blown into it, while being mixed with air. It is therefore necessary that the bag can be deflated.

The present invention relates to such valve bags as described in the opening paragraph, which comprise a first and a second wall which are connected to one another by side edges or gussets. At the ends there are floors, via which the two walls are also connected to one another. The walls delimit the interior of the sack, together with the bottoms and possibly together with the side gussets.

The valve is arranged in one of the floors; this base can therefore be referred to as the valve base. The other bottom is completely closed, that is, the inside of the sack cannot be reached from the outside via this floor. This floor can also be referred to as valveless floor. Since the sack is suspended and / or set up vertically, at least during filling, with the valve base at the upper end, the end of the sack which comprises the valve base can simply be referred to as "top" or "upper end". The second end is therefore "below" or it is the "lower end".

In order to enable filling with simultaneous ventilation, ventilation openings are provided in the first and / or in the second wall.

It is always a challenge to provide a high ventilation capacity, but also to design the sack in such a way that, on the one hand, no filling material can escape through the ventilation openings and, on the other hand, no moisture can penetrate the inside of the sack. This is because leaking filling material leads to a loss of product or, depending on the type of filling material, damage to the health of the people who, for example, carry such filled bags. Moisture entering the inside of the sack can make the contents unusable in the long run.

The object of the present invention is therefore to propose a generic sack and a production method for such a sack which, in spite of the great ventilation required, offers improved retention of contents. In addition, improved protection against moisture is desirable.

The object is achieved by the features mentioned in the preamble of claim 1 with the addition of the features listed in the characterizing part of claim 1.

Accordingly, provision is made for at least one channel to be provided on the outside of at least one wall which covers the ventilation openings and which is formed by at least two parallel fastening strips and a cover strip, the cover strip also comprises ventilation openings and wherein the shortest path between the parallel fastening strips along the cover strip is longer than the shortest path along the at least one wall.

A channel that covers the ventilation openings is thus formed by a cover strip which is arranged on the outside of at least one wall, and at least two fastening strips with which the cover strip is fastened to the wall. This means that the air that is brought into the interior of the bag with the filling material can initially escape into the channel.

According to the invention it is now further provided that the shortest path between the parallel fastening strips, that is to say the path across the fastening strips, along the cover strip is longer than the shortest path along the at least one wall. This means that the covering strip is limp between the fastening strips when the area of the wall between the fastening strips is flat. This means that even in the flat area of the wall, the channel can form a cavity. It is advantageous that the air can flow into this cavity via the ventilation holes, even if the wall arches outward during the filling process. Furthermore, it is advantageous that the cavity or the channel can absorb and store a great deal of air from the interior space in a short time and can release it again over a longer period of time, preferably to the environment. Due to the fact that a large amount of air is taken up in the cavity, rapid venting is ensured, with a small amount of product being able to get into the cavity. However, a discharge of filling material into the environment is prevented. In particular, when the air escapes slowly into the environment, no filling material is entrained.

The same effect can be achieved with an alternative to the invention in which the cover strip and / or the parallel fastening strips are made of stretchable material. Instead of a sloppy cover strip, a cover strip with a stretchable Kick material. Instead or in addition, at least one of the fastening strips can comprise a stretchable material. A stretchable material can be elastic or deformable, for example stretchable, as is known, for example, from films that can be elongated under the action of force. Due to the air emerging from the inside of the sack through the ventilation openings, the cover strip and / or the fastening strips can now be stretched so that the channel can provide an enlarged volume compared to the initial state. This again ensures that a large volume of air can be removed from the inside of the sack in a short time.

According to the invention, the cover strip comprises a U-shaped fold on at least one of the fastening strips, i. the cover strip is folded over in such a way that its folded outer side is fastened to the wall with the fastening strip. This ensures that the fastening strip can easily bulge without its material being unduly stressed or the covering strip has a z-fold as an alternative or in addition to the u-fold.

The valve bag according to the invention can comprise paper, but also a material made of one or more plastics. Plastics can be a film web, but also a fabric made of plastic tapes, in particular made of such plastic tapes that comprise a stretched polyolefin. A plastic in the sense of the invention can also be a fleece material. The aforementioned materials can also be combined. For example, one wall of the sack can comprise two layers, one layer consisting of paper and the other layer consisting of a plastic. The aforementioned materials can also be laminated, laminated or otherwise coated. The cover strip can consist of the same material or the same materials as the sack, but also of at least one different material.

The cover strip can be a separate strip, which preferably runs in the longitudinal direction of the bag. The cover strip preferably extends over the entire length of the bag.

The fastening strips can be adhesive strips such as cold adhesive, hot-melt or dispersion, or extrusion strips. In particular, extrusion strips or - in other words - longitudinal extrusion seams offer advantages because they are inexpensive. A fastening strip can, however, also be a joining strip in which the wall and the covering strip are connected to one another by welding or sealing, in particular by ultrasonic, infrared or hot air welding or sealing.

The overlap strip can be a separate workpiece. As an alternative or in addition, the cover strip can be an area of at least one wall which covers another area of the wall. Such a coverage area can be produced in a very simple and efficient manner by forming a tube from a flat web material. The walls and the cover strip are thus formed in one piece. The overlapping part then only needs to be fastened with two or more fastening strips, which run parallel but are spaced apart in the transverse direction, in order to form said channel.

It is advantageous if the sack according to the invention has a ventilation capacity of at least 5 m ³ / h, in particular of at least 10 m ³ / h. This venting performance relates to air, but does not deviate significantly from it for other gases either.

In a preferred embodiment of the invention, it is provided that the shortest path between the parallel fastening strips along the cover strip is at least 3% longer than the shortest path along the at least one wall. In this case, sufficient storage is made available for the air escaping from the inside of the sack, with the slackness of the covering strip being kept small at the same time. This helps in avoiding damage to the Covering strip. Furthermore, it can be provided that the invention provides that the shortest path between the parallel fastening strips along the covering strip is at most 20%, in particular at most 10% longer than the shortest path along the at least one wall.

In an advantageous development of the invention, a layer made of a filter material is provided within the channel. This filter material serves as a further filter to further reduce the release of filling material to the environment. In particular, the filter material has small pores that offer air permeability, but block the path of filling material particles and dust. The filter material is preferably attached to the covering strip, the filter material preferably covering all of the ventilation openings of the covering strip, which are described in more detail below. The possible ways of attaching the filter material to the cover strip can be the same as those for attaching the cover strip to the wall. At least one fastening strip for the filter material can coincide with a fastening strip for the cover strip. However, it is preferred that the fastening strip for the filter material is spaced apart from the fastening strip for the cover strip, since the production of the sack is then made easier. The filter material can include papers or plastics, these being in particular in the form of fleece.

In a further preferred embodiment of the invention, at least one layer of a filter material is provided in the sack interior, the filter material also covering the ventilation openings here. The filter material can be the same as the filter material, as has been described in connection with the cover strip. The types of attachment can also be the same. Alternatively, the filter material can replace the ventilation openings. In other words, the at least one wall can comprise at least one cutout in certain regions, which is then completely covered by the filter material.

In an advantageous embodiment of the invention, the air permeability of the ventilation openings in the at least one wall is greater than the air permeability of the cover strip. Basically, also in connection with all of the features and properties of the invention described above and below, it is also possible that the cover strip is free of ventilation openings and that instead the fastening strips have interruptions through which the air can flow. However, a combination of both of the aforementioned venting options is also conceivable. If the covering strip has a lower air permeability, in particular a slow escape of the air into the environment is possible, so that the escape of filling material is again reduced. A micro or nano perforation of the covering strip is advantageous in this context. Micro-perforations, for example with a density of 10 to 30, in particular 13, ventilation openings per square centimeter (cm ³ ), and nano-perforations, for example with a density of 50 to 100, in particular 64, ventilation openings per square centimeter (cm ³ ), can often be separated from one another distinguish. The perforations can be produced, for example, with essentially conical needles or with essentially cylindrical needles. The ventilation openings are preferably small enough so that no moisture can enter the sack or the channel from the outside. This is usually the case when the vents are smaller than 0.8 mm in diameter.

In a preferred embodiment of the embodiment, the ventilation openings of the at least one wall are spaced apart from the ventilation openings of the cover strip in the longitudinal direction of the bag. This distance is preferably at least one third of the bag height. It is advantageous that the air from the inside of the sack has to travel a longer distance in order to get into the surroundings. As a result, moisture that could penetrate the channel does not get into the interior of the bag, or at least only very slowly.

In general, the ventilation openings can be designed as holes or as slots. Holes are often created by needles, whereas slots can often be created by knives. In an advantageous embodiment, the slots are provided in the at least one wall. in order to provide a large ventilation capacity here. The ventilation capacity can be increased again if at least two slots are at an angle to one another, in particular at a right angle (90 °). The length of the slots is preferably between 1 mm and 30 mm.

In an advantageous embodiment of the invention it is provided that the ventilation openings in the at least one wall are spaced a maximum of half a bag length, in particular a maximum of a third of the bag length, particularly preferably a quarter of the bag length, from the valve base. In this way, the air that is introduced into the interior of the sack during filling can escape undisturbed in the upper area. Only when the filling is almost complete does the product level reach these ventilation openings. In this way, a very high ventilation rate is guaranteed for almost the entire filling process.

It is advantageous if the ventilation openings of the cover strip are at most half a sack length, in particular at most a third of the sack length and particularly preferably a quarter of the sack length, from the valveless bottom. In this way, a good protection against penetrating moisture is achieved, because any moisture that may penetrate has to travel a long way into the inside of the bag. In this connection it is worth mentioning that the surface of the sack that is provided with ventilation openings is a maximum of 15% of the total surface of the sack.

It is also preferred if the valve bottom comprises two bottom flaps, the first bottom flap comprising parts of the covering strip, the second bottom flap at least partially covering the first bottom flap when viewed from the outside. This prevents that moisture gets into the channel via the bottom flap and from here on a short way via the ventilation openings in the at least one wall into the interior of the bag. The moisture protection is thus increased.

It is also advantageous if the valveless bottom comprises two bottom flaps, the first bottom flap comprising parts of the covering strip, the first bottom flap at least partially covering the second bottom flap as seen from outside the sack. In this way it can be prevented that moisture which penetrates through the ventilation openings into the channel gets into the bag interior via the bottom flap over a short distance. The moisture protection is thus increased.

The moisture protection can be further improved if at least one base is covered with a base cover sheet from the outside and / or with an inner bar from the inside of the bag.

The above-mentioned object is also achieved by a method according to claim 11.

• eine Flachbahn zur Verfügung gestellt wird
• aus der Flachbahn ein Schlauch mit einer ersten und einer zweiten Wand gebildet wird,
• der Schlauch zu Schlauchstücken vereinzelt wird
• an beiden Enden eines jeden Schlauchstücks ein Boden angeformt wird, wobei Entlüftungslöcher eingebracht werden.

The inventive method is based on a method for producing a valve bag in which

• a flat track is made available
• a tube with a first and a second wall is formed from the flat web,
• the hose is separated into hose pieces
• a base is formed on both ends of each tube piece, ventilation holes being introduced.

The stated object is achieved according to the invention in that at least one cover strip is produced on the first or the second wall, with which the ventilation holes are covered, the cover strip being provided with at least one longitudinal fold.

This method achieves the same advantages as have already been described in connection with a sack according to the invention. In order to be able to produce a sack in which at least one channel is provided on the outside of at least one wall which covers the ventilation openings and which is formed by at least two parallel fastening strips and a cover strip, the cover strip also includes ventilation openings and the shortest path between the parallel fastening strip along the cover strip is longer than the shortest path along the at least one wall, the cover strip is provided with at least one fold running in the longitudinal direction. This is, for example, the edge of the cover strip, which is folded once so that the edge area is then designed with two layers. The folded edge is preferably fastened to the wall with the fastening strip.

According to the invention, the cover strip is provided with a u-fold and / or with two folds, the two folding directions running in opposite directions. This creates a z-fold. This means that the cover strip is in three layers in the area of the fold.

The folds mentioned are preferably produced by guide plates, along which the flat web transported by a transport device, such as transport rollers, is guided. In addition, pre-break rollers and / or pressure rollers can be provided with which the folded edge is pre-embossed and / or the folded edge that has been formed is fixed again.

In a preferred embodiment of the invention, ventilation holes are made in the flat web before it is processed into a tube. Making vent holes at this point is very easy. It can be done, for example, by a roller, the outer circumference of which is fitted with needles and / or knives.

In an advantageous embodiment of the invention, the flat web and the cover strip are connected to one another, in particular also before the tube is formed. In other words, the covering strip is part of the flat sheet and develops its actual functionality after the tube has been formed by being attached to the wall by two fastening strips.

In a further advantageous embodiment of the invention, a filter material is applied to the flat web and / or to the cover strip and fastened there. The filter material is preferably in web form and is drawn off and applied from a roll. It is preferably fastened with a dispersion adhesive, with a cold adhesive or with a hot-melt adhesive. It is advantageous if the filter material is applied to the flat web before a tube is formed from the flat web. In this case, the application and attachment of the filter material is particularly simple.

The above-mentioned object is also achieved by a system for producing valve sacks according to claim 16.

• eine Bereitstellungseinrichtung, insbesondere eine Abwickeleinrichtung, zur Bereitstellung einer Flachbahn.
• Schlauchbildungswerkzeuge zum Bilden eines Schlauches mit einer ersten und einer zweiten Wand aus der Flachbahn,
• einer Vereinzelungseinrichtung zum Vereinzeln des Schlauches zu Schlauchstücken vereinzelt wird
• Bodenbildungseinrichtungen zum Anformen jeweils eines Bodens an beiden Enden eines jeden Schlauchstücks
• wenigstens eine Perforations- oder Schneideinrichtung zum Einbringen von Entlüftungslöchern.

The system according to the invention is based on a system for the production of valve bags, comprising:

• a supply device, in particular an unwinding device, for providing a flat web.
• Hose forming tools for forming a hose with a first and a second wall from the flat sheet,
• a separating device for separating the hose into hose pieces
• Bottom forming devices for forming a bottom each at both ends of each hose section
• at least one perforation or cutting device for introducing ventilation holes.

• dass eine Einrichtung zur Erzeugung eines Überdeckungsstreifens auf der ersten oder der zweiten Wand vorgesehen ist, wobei mit dem Überdeckungsstreifen die Entlüftungslöcher abdeckbar sind,
• dass eine Umfalteinrichtung vorgesehen ist, mit welcher der Überdeckungsstreifen mit wenigstens einer in Längsrichtung verlaufenden Umfaltung versehbar ist.

To achieve the stated object, the invention provides

• that a device for generating a cover strip is provided on the first or the second wall, the ventilation holes being able to be covered with the cover strip,
• that a folding device is provided with which the cover strip can be provided with at least one fold extending in the longitudinal direction.

Further advantages, features and details of the invention emerge from the following description, in which various exemplary embodiments are explained in detail with reference to the figures.

Fig. 1

Querschnitt durch eine erste Ausführungsform eines erfindungsgemäßen Ventilsacks;

Fig. 2

Querschnitt durch eine weitere Ausführungsform eines erfindungsgemäßen Ventilsacks;

Fig. 3

Querschnitt durch eine weitere Ausführungsform eines erfindungsgemäßen Ventilsacks;

Fig. 4

Querschnitt durch eine weitere Ausführungsform eines erfindungsgemäßen Ventilsacks;

Fig. 5

Die Bearbeitung einer Flachbahn vor der Schlauchbildung;

Fig. 6

Die Bildung eines Schlauches aus der Flachbahn;

Fig. 7

Fertig ausgebildeter Schlauch;

Fig. 8

Perspektivische Darstellung eines erfindungsgemäßen Ventilsacks;

Fig. 9

Schnitt IX-IX der Figur 8.

The individual figures show:

Fig. 1

Cross section through a first embodiment of a valve sacks according to the invention;

Fig. 2

Cross section through a further embodiment of a valve bag according to the invention;

Fig. 3

Cross section through a further embodiment of a valve bag according to the invention;

Fig. 4

Cross section through a further embodiment of a valve bag according to the invention;

Fig. 5

The processing of a flat web before the tube formation;

Fig. 6

The formation of a tube from the flat sheet;

Fig. 7

Pre-formed hose;

Fig. 8

Perspective view of a valve bag according to the invention;

Fig. 9

Section IX-IX of the Figure 8 .

The Figure 1 shows the cross section through a first embodiment of a valve bag 1 according to the invention. It comprises a first wall 2, which in the present example represents the rear wall. This first wall is connected via the side edges 3, 4 to the second wall 5, which represents the front wall. The front wall 5 is formed by a first region 6 and a second region 7. The edge 8 of the first region 6 is fastened with a fastening strip 9 to the surface facing the bag interior 10. The strip crossing over the fastening strip 9 forms a cover strip 11 which covers the ventilation holes 12 in the second wall 5. The cover strip 11 is connected with its edge 13 via a fastening strip 14 on the outer surface of the first area 6 of the second wall 5. Here, the outer surface of the cover strip is attached to the first area 6, so that a U-shaped fold 15 or, in the flat state, a double-layer area of the cover strip is formed. In this way, a channel 16 is formed, the volume of which can be changed over a very large area. This channel also includes ventilation openings 17 so that the air that has entered the channel from the inside of the bag can escape into the environment.

The covering strip 11 can be delimited from the area 7 of the front wall 5 by the fastening strip 9.

On the surface of the cover strip 11 facing the channel, a filter material 18 is preferably provided, which is fastened to the cover strip via two fastening strips 19.

The Figure 2 shows a further exemplary embodiment of a valve bag 1 according to the invention. Instead of the U-shaped fold of the covering strip 11, a z-shaped fold 21 is provided in this exemplary embodiment, which is created by producing a double fold. The z-shaped fold is characterized by the fact that three layers are formed here. Even if in the Figure 2 it can be seen that the z-shaped fold 21 is arranged in the area of the fastening strip 14, so the z-shaped fold can be arranged at any position between the fastening strip 9 and the fastening strip 14. Several z-shaped folds 21 are also conceivable.

In the embodiment of Figure 3 the cover strip 11 of the valve bag 1 even comprises a Z-shaped fold 21 and a U-shaped fold 15.

The features of the embodiments according to Figures 1 to 3 can be combined with each other as required. In all cases, however, it is important that the length of the path, which is defined by the line of the cover strip 11 between the fastening strip 9 and the fastening strip 14 visible in the figures, is greater than the length of the path which is visible in the figures Line of the second wall 5 between the fastening strip 9 and the fastening strip 14 is set. It is preferred if the difference in length is at least 3%.

The Figure 3 shows a further configuration option which can also be combined with all of the other exemplary embodiments disclosed in this patent application. In this case, the covering strip 11 is fastened to the area 6 of the front wall with a third fastening strip 22. This third fastening strip 22 divides the channel 16 into a first partial channel 23 and a second partial channel 24, with the ventilation openings 12 from Guide the inside of the sack 10 into the first partial channel 23. The ventilation openings 17 lead from the second sub-channel 24 into the environment. So that the air can now also pass from the first partial channel 23 into the second partial channel 24, the fastening strip comprises at least one interruption. The at least one interruption is preferably so long that the ventilation capacity of the bag is not impaired.

In the embodiment according to Figure 4 is in contrast to the embodiments according to Figures 1 to 3 the cover strip 11 is designed as a separate workpiece. It is therefore not formed in one piece with part of the front wall 5. This separate cover strip 11 is attached to the front wall 5 of the valve bag via the two attachment strips 9, 14. As an example, it is shown that the cover strip 11 comprises U-shaped folds 15 on its two edges. The front wall 5 and the rear wall 2 of the valve bag 1 can already have been produced as a tube, for example by a blown film extrusion process or a circular weaving process. However, a tube can also be made from a flat web in which the two side areas have been turned over to form an overlap and in which the overlapping edges are connected by a joint seam.

The Figure 5 now shows some steps of a method according to the invention for producing a valve bag. For this purpose, a flat web 50 is first unwound from an unwinding device (not shown). This is followed by the introduction of ventilation openings 17, which is again not shown. These ventilation openings are preferably not introduced continuously in the longitudinal direction of the flat web, but rather in cycles. For this purpose, a roller can roll on the flat web, the peripheral surface of which is only partially covered with needle, cutting or punching tools. Alternatively or in addition, it can be provided that such a roller is brought into contact with the flat web 50 at the points at which the ventilation openings 17 are to be introduced. For this purpose, an adjustment mechanism can be provided which brings the roller into contact with the flat web in cycles. The flat web preferably runs over a counter roller.

In the same way, the ventilation openings 12 can be made in the flat web 50. In this case, however, a roller 51 is shown with which individual, short cuts are produced in the flat web 50. For this purpose, the circumferential surface 52 of the roller 51 is covered with knives 53, two adjacent knives at an angle to one another, in particular a right angle. An adjustment mechanism can also be provided for the roller 51, which brings the roller into contact with the flat web in cycles. The adjustment mechanism for the roller 51 works independently of the adjustment mechanism mentioned in the preceding paragraph, since the ventilation openings 12 and 17 are preferably introduced offset in the transport direction of the flat web.

After the introduction of the ventilation openings 17 and before or after the introduction of the ventilation openings 12, the flat web 50 is covered with a filter material 55, which is attached to the flat web 50. This filter material can be applied to the flat web in web form. For this purpose, the filter material can be made available as a roll and unwound within an unwinding device. To fasten the filter material, it can be provided that the filter material is already provided with two lateral adhesive strips in its roll form. However, it is advantageous if two adhesive traces 56, 57 are applied to the flat web and / or to the web-shaped filter material, the ventilation openings 17 lying completely within these adhesive traces. The adhesive traces can comprise a dispersion adhesive, a hot melt adhesive or a cold glue; but they can also comprise an extrudate. In the latter case, plastic is converted into a melt form in an extruder and applied in this form as traces through nozzles. Immediately after the adhesive traces have been applied, the flat web and the web-shaped filter material are joined together, which is indicated by the arrows 58, and - for example by means of a pair of press rollers - are pressed together and optionally also cooled.

In another embodiment, the filter material 55 can also be applied to the flat web in the form of a slip, the filter material being at least dimensioned such that it completely covers the ventilation openings 17 concentrated on a surface section. Ready-made slips can be used to provide the filter material in slip form. It is preferred, however, if the filter material is also present in roll form and is separated into slips of paper by a separating tool, for example a cutting tool. Adhesive traces are now preferably applied to the flat web 50, a circumferential adhesive tracing being generated so that the air that is to pass through the filter material cannot escape through a gap in the adhesive tracing.

The described procedures for applying filter material can also be used if the ventilation openings 12 are to be covered with a filter material.

In the Figure 6 the folding of the side areas of the flat web 50 around the fold edges 3 and 4 is now shown, the rear wall 2 and the two areas 6 and 7 of the front wall 5 being formed. It is advantageous if at a fixed point the area 6 has already turned over further than the area 7. The u-fold 15 is preferably already produced before or during the turning over of the area 7. Alternative or additional folds can now also be introduced. Nevertheless, it is possible that the described folds can also be introduced after the areas 6 and 7 have been turned over.

The Figure 7 shows the areas 6 and 7 which have already been turned over and which are now fastened to one another with the fastening strips 9 and 14. For this purpose, in an advantageous embodiment, there are two extrusion nozzles which introduce at least one molten plastic material in the form of at least two parallel tracks between the areas 6 and 7 and thus delimit the channel 16. With at least one pressing device (not shown), for example a pressure roller, the areas 6 and 7 can be connected to one another along the fastening strips 9 and 14, so that a permanent and durable connection can be generated. At least one cooling device can be provided in order to be able to cool the fastening strips, in particular if they were created under the action of heat. The cooling device can be comprised by the pressing device. For example, pressure rollers can be cooled.

In the Figure 8 a valve sack 101 - referred to as a "sack" for short - can now be seen, which preferably consists of a tube according to the exemplary embodiments of Figures 1 to 7 is made. In order to produce a sack 101 from such a hose, this hose is separated into hose pieces, a bottom opening is formed on both ends and this bottom opening is then closed to form a bottom. In the exemplary embodiment shown, the bottoms, of which only one bottom 102 can be seen, are shaped as cross bottoms. For this purpose, a sack end is drawn up during manufacture, forming a bottom rectangle and two bottom triangles 103. The side flaps 104 and 105 are then folded over so that they partially overlap. Finally, a base cover sheet 106 is preferably fixed on the base that has already been created, this preferably being connected to both base triangles 103 and to both side tabs 104 and 105.

The bottom 107, which is not visible, is designed similar to the bottom 102, but before the side flaps 104 and 105 are folded over, a valve 108 is placed on one of the two bottom triangles and fastened there so that the side flaps are folded over the valve. Alternatively, a valve label can be placed on one of the bottom triangles and fastened there, which forms the valve 108 by folding over the side flaps. The optional bottom cover sheet is then only connected to the valve and not to the bottom triangle below. The valve 108 creates an access to the inside of the sack from the surroundings and therefore offers the possibility of filling the sack with a filling material from the outside. In a further development of the embodiment shown, provision is made for the valve 108 to be designed to be closable in order to allow moisture to penetrate and parts of the filling material to escape during subsequent storage after filling to reduce. Referring to the valve 108, the base 107 can be referred to as a valve base, while the base 102 may be referred to as a valveless base.

It can also be seen that the second wall 5 continues into the side flap 104, which is preferably folded over the side flap 105. The advantages of this embodiment will be discussed further below in connection with FIG Figure 9 explained. As already explained, the wall 5 comprises the channel 16 which is delimited by the fastening strips 9 and 14, the fastening strip 9 being shown with a broken line since it is not visible in a finished sack. It can also be seen that the ventilation openings 17 are arranged closer to the valveless floor than the ventilation openings 12. The distance between the ventilation openings 17 and the floor 102 is preferably a maximum of a third, preferably a maximum of a quarter, in particular a fifth of the total bag length L.

Conversely, it is provided that the ventilation openings 17 are arranged closer to the valve base than the ventilation openings 12. The distance between the ventilation openings 12 and the base 107 is preferably a maximum of a third, preferably a maximum of a quarter, in particular a fifth of the total bag length L.

The Figure 9 shows the section IX - IX through the bag 101 (see Figure 8 ). Sections through the floors 102 and 107 can now be seen. In the valveless base 102, the folding sequence of the side flaps 104 and 105 can be seen in particular. Since the section IX-IX also forms a section through the channel 16, the side flap 104 appears to have three layers, since in addition to the relevant parts of the areas 6 and 7, the filter material 18 can also be seen. The side flap 104 is on the inside, ie it was folded over before the side flap 105 was folded over. Therefore, the side flap 105 is on the outside. Due to the bottom cover sheet 106, the channel 16 is not or hardly accessible via the tab 105, so that almost no moisture can penetrate into the sack via the bottom 102. Should this be the case, it should Only diffuse moisture over the entire length of the sack in order to reach the inside of the sack.

The valve base 107 comprises the side flaps 109 and 110, the side flap 109 being designed analogously to the side flap 105. Accordingly, the side flap 110 is designed analogously to the side flap 104. In contrast to the base 102, the side flap 110 in the case of the base 107 is first folded over, ie it is on the inside. The side flap 109 thus forms the outer flap. Since the valve 108 is also arranged below the side flap 110 and - at least when filling - presses the individual layers of the side flaps onto one another, it is avoided that parts of the filling material get into the channel 16. List of reference symbols 1 Valve bag 2 First wall 3 Side edge 4th Side edge 5 Second wall 6th First area 7th Second area 8th edge 9 Fastening strips 10 surface 11 Cover strip 12 Ventilation holes 13 edge 14th Fastening strips 15th u-shaped fold 16 channel 17th Vent 18th Filter material 19th Fastening strips 20th 21st z-shaped fold 22nd Fastening strips 23 First sub-channel 24 Second sub-channel 50 Flat track 51 roller 52 Peripheral surface 53 knife 55 Filter material 56 Glue trace 57 Glue trace 58 arrow 101 Valve bag 102 ground 103 Bottom triangle 104 Side flap 105 Side flap 106 Soil cover sheet 107 Invisible floor 108 Valve 109 Side flap 110 Side flap L. Bag length

Claims (16)

1. A valve bag, in particular a cross-bottom valve bag, comprising
   a first wall and a second wall, which are joined to each other by means of side edges or side folds and by means of bottoms and which delimit a bag interior,
   a valve, which is arranged in one of the bottoms and via which the bag interior can be filled with a filling material,
   venting openings in the first and/or in the second wall for venting the bag interior,
   characterized in that
   at least one channel is provided on the outside of at least one wall, said channel covering the venting openings and being formed at least by two parallel fastening strips and by a cover strip, the cover strip likewise comprising venting openings, and wherein the shortest path between the parallel fastening strips along the cover strip is longer than the shortest path along the at least one wall, or the cover strip and/or the parallel fastening strip consist of an expandable material.
2. The valve bag according to claim 1,
   characterized in that
   the shortest path between the parallel fastening strips is at least 3 % longer along the cover strip than the shortest path along the at least one wall.
3. The valve bag according to any of the preceding claims,
   characterized in that
   the venting capacity is greater than 5 m³/h and particularly greater than 10 m³/h.
4. The valve bag according to any of the preceding claims,
   characterized in that
   a layer comprising a filter material is provided within the channel.
5. The valve bag according to any of the preceding claims,
   characterized in that
   a layer comprising a filter material is provided in the bag interior, wherein the filter material covers the venting holes.
6. The valve bag according to any of the preceding claims,
   characterized in that
   the air permeability of the venting openings in the at least one wall is greater than the air permeability of the cover strip.
7. The valve bag according to any of the preceding claims,
   characterized in that
   the venting openings in the at least one wall are no more than half a bag length, particularly no more than one-third the bag length, away from the bottom in which the valve is arranged.
8. The valve bag according to any of the preceding claims,
   characterized in that
   the venting openings of the cover strip are no more than half a bag length, particularly no more than one-third the bag length, away from the bottom in which no valve is arranged.
9. The valve bag according to any of the preceding claims,
   characterized in that
   the valve bottom comprises two bottom flaps, wherein the first bottom flap comprises parts of the cover strip, wherein, when viewed from the exterior, the second bottom flap covers the first bottom flap at least partially.
10. The valve bag according to any of the preceding claims,
    characterized in that
    the bottom, which is valve-free, comprises two bottom flaps, wherein the first bottom flap comprises parts of the cover strip, wherein, when viewed from the exterior of the bag, the first bottom flap covers the second bottom flap at least partially.
11. A method for producing a valve bag according to any of claims 1 to 10,
    wherein
    a flat strip is provided
    a tube with a first and a second wall is formed from the flat strip,
    the tube is separated into tube parts,
    a bottom is formed on both ends of each tube piece,
    wherein venting holes are placed,
    characterized in that
    at least one cover strip is created on the first or the second wall, with which the venting holes are covered, wherein the cover strip is equipped with at least one fold extending in the longitudinal direction.
12. The method according to claim 11,
    characterized in that
    the venting holes are placed before a tube is formed from the flat strip.
13. The method according to any of claims 10 to 12,
    characterized in that
    the cover strip is formed from the flat strip, wherein the cover strip and the flat strip are connected to each other.
14. The method according to any of claims 10 to 13,
    characterized in that
    a filter material is applied to the flat strip and/'or to the cover strip and attached therein.
15. The method according to any of claims 10 to 14,
    characterized in that
    a filter material is applied to the flat strip and/or to the cover strip and attached therein.
16. A system for producing a valve bag according to any of claims 1 to 10, comprising
    a providing device, particularly a roll-off device, for providing a flat strip,
    tube-forming tools for forming a tube with a first and a second wall from the flat strip,
    a separating device for separating the tube into tube parts,
    bottom-forming devices for forming a respective bottom at both ends of each tube piece,
    at least one perforation or cutting device for placing venting holes,
    characterized in
    that a device for creating a cover strip is provided on the first or the second wall,
    wherein the venting holes can be covered with the cover strip,
    that a folding device is provided, with which the cover strip can be equipped with at least one fold extending in the longitudinal direction.

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