Valve bag and method and system for producing a valve bag

Abstract

The invention relates to 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, comprising a valve, which is arranged in one of the bottoms and via which the bag interior can be filled with a filling material, and comprising venting openings in the first and/or in the second wall for venting the bag interior. At least one channel is provided on the outside of at least one wall, which channel covers the venting openings and is 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 strips consist of stretchable material.

Claims

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 first side latch and a second side latch, wherein the first and second side latches are folded over such that they partially overlap, a valve, which is arranged in one of the bottoms and via which the bag interior can be filled with a filling material, and venting openings in the second wall for venting the bag interior, wherein: at least one channel is provided on the outside of the second wall, said channel covering the venting openings and being formed at least by two parallel fastening strips and by a cover strip comprising an outer surface, the cover strip likewise comprising venting openings within the outer surface, the venting openings in the at least one wall are no more than half a bag length away from the bottom in which the valve is arranged, the venting openings of the cover strip are no more than half a bag length away from the bottom in which no valve is arranged, the second wall continues into the first side latch, and 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, and the cover strip comprises a u-shaped or a z-shaped fold.

2. The valve bag according to claim 1, wherein 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 claim 1, wherein the venting capacity is greater than 5 m.sup.3/h and particularly greater than 10 m.sup.3/h.

4. The valve bag according to claim 1, wherein a layer comprising a filter material is provided within the channel.

5. The valve bag according to claim 1, wherein a layer comprising a filter material is provided in the bag interior, wherein the filter material covers the venting openings in the outer surface of the cover strip.

6. The valve bag according to claim 1, wherein 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 claim 1, wherein the venting openings in the at least one wall are no more than one-third the bag length away from the bottom in which the valve is arranged.

8. The valve bag according to claim 1, wherein the venting openings of the cover strip are no more than one-third the bag length away from the bottom in which no valve is arranged.

9. The valve bag according to claim 1, wherein 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 claim 1, wherein 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 claim 1, 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, the valve bag comprises a first side latch and a second side latch, wherein the first and second side latches are folded over such that they partially overlap, and wherein venting openings are placed, wherein: at least one cover strip is created on the first or the second wall, with which the venting openings are covered, wherein the cover strip comprises an outer surface likewise having venting openings and is equipped with at least one u-shaped or z-shaped fold extending in the longitudinal direction, the venting openings in the at least one wall are no more than half a bag length away from the bottom in which the valve is arranged, the venting openings of the cover strip are no more than half a bag length away from the bottom in which no valve is arranged, and at least one channel is provided on the outside of the second wall, and the second wall continues into the first side latch.

12. The method according to claim 11, wherein the venting openings are placed before a tube is formed from the flat strip.

13. The method according to claim 11, wherein 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 claim 11, wherein a filter material is applied to the flat strip and/or to the cover strip and attached therein.

15. The method according to claim 11, wherein 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 claim 1, 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, and at least one perforation or cutting device for placing venting openings, wherein that a device for creating a cover strip is provided on the first or the second wall, wherein the venting openings can be covered with the cover strip, that a folding device is provided, with which the cover strip comprising an outer surface likewise having venting openings can be equipped with at least one u-shaped or L-shaped fold extending in the longitudinal direction.

17. The valve bag according to claim 1, wherein the cover strip comprises a u-shaped fold.

18. The valve bag according to claim 1, wherein the cover strip comprises a z-shaped fold.

Description

(1) Further advantages, features, and details of the invention result from the subsequent description, in which various exemplary embodiments are explained in detail with reference to the figures. In doing so, the features mentioned in the claims and in the description may each individually be essential to the invention per se or for any combinations of features mentioned. Within the scope of the entire disclosure, the features, details, and advantages, which are described in connection with the method according to the invention, obviously also apply in connection with the valve bag according to the invention and vice versa, so that reference is always made or can be made mutually regarding the disclosure for the individual aspects of the invention. The features, details, and advantages, which are described in connection with the system according to the invention, also apply in connection with the valve bag according to the invention and/or the method according to the invention and vice versa such that a mutual reference is also possible here. In addition, features, which are described or have been described in connection with other features, may also be features according to the invention, including independently of these other features alone or in combination with any other features, such that mutual reference can be made to these feature combinations. The individual figures show the following:

(2) FIG. 1 is a cross-section through a first embodiment of a valve bag according to the invention;

(3) FIG. 2 is a cross-section through another embodiment of a valve bag according to the invention;

(4) FIG. 3 is a cross-section through another embodiment of a valve bag according to the invention;

(5) FIG. 4 is a cross-section through another embodiment of a valve bag according to the invention;

(6) FIG. 5 shows the processing of a flat strip before tube formation;

(7) FIG. 6 shows the formation of a tube from the flat strip;

(8) FIG. 7 shows the tube completely finished;

(9) FIG. 8 shows a perspective view of a valve bag according to the invention;

(10) FIG. 9 shows section IX-IX from FIG. 8;

(11) FIG. 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 represents the back wall in the present example. Said first wall is connected to the second wall 5, which represents the front wall, via the side edges 3, 4. The front wall 5 is formed by a first area 6 and a second area 7. The edge 8 of the first area 6 is attached at the surface facing the bag interior 10 using a fastening strip 9. The strip encroaching on the fastening strip 9 forms a cover strip 11, which covers the venting holes 12 of the second wall 5. The edge 13 of the cover strip 11 is connected on the outer surface of the first area 6 of the second wall 5 by means of a fastening strip 14. In this case, the outer surface of the cover strip is attached to the first area 6 such that a u-shaped fold 15 is formed or a double-layer area of the cover strip is formed when it is in the flat state. In this manner, a channel 16 is formed, the volume of which can be modified within a very large range. Said channel further comprises venting holes 17 so that the air from the bag interior that reaches the channel can be released to the environment.

(12) The fastening strip 9 functions to delimit the cover strip 11 from h area 7 of the front wall 5.

(13) A filter material 18, which is attached to the cover strip by means of two fastening strips 19, is preferably provided on the surface of the cover strip 11 facing the channel.

(14) FIG. 2 shows another exemplary embodiment of a valve bag 1 according to the invention. Instead of the u-shaped fold in the cover strip 11, a z-shaped fold 21 is provided in this exemplary embodiment, said fold resulting such that a double fold is created. The z-shaped fold is characterized in that three layers are formed in this case. Even if FIG. 2 shows that the z-shaped fold 21 is arranged in the area of fastening strip 14, the z-shaped fold can be arranged at any position between fastening strip 9 and fastening strip 14. Multiple z-shaped folds 21 are also conceivable.

(15) In the embodiment from FIG. 3, the cover strip 11 of the valve bag 1 even comprises a z-shaped fold 21 and a u-shaped fold 15.

(16) The features of the exemplary embodiments according to FIGS. 1 to 3 may be combined as desired. However, in all cases, it is important that the length of the path that is established by the line, visible in the figures, of the cover strip 11 between fastening strip 9 and fastening strip 14 is greater than the length of the path that is established by the line, visible in the figures, of the second wall 5 between fastening strip 9 and fastening strip 14. It is preferable here when the length difference is at least 3%.

(17) FIG. 3 shows another embodiment option, which can also be combined with all of the other exemplary embodiments disclosed in this patent application. In this case, the cover strip 11 is attached to the area 6 of the front wall with a third fastening strip 22. Said third fastening strip 22 divides the channel 16 into a first sub-channel 23 and a second sub-channel 24, wherein the venting holes 12 lead from the bag interior 10 to the first sub-channel 23. The venting openings 17 then lead from the second sub-channel 24 to the environment. To ensure that the air from the first sub-channel 23 can then reach the second sub-channel 24, the fastening strip comprises at least one gap. Preferably, the at least one gap is long enough such that the venting capacity of the bag is not impacted.

(18) In contrast with the exemplary embodiments according to FIGS. 1 to 3, the cover strip 11 is formed as a separate workpiece in the exemplary embodiment according to FIG. 4. Accordingly, it is not formed in one piece with a part of the front wall 5. This separate cover strip 11 is attached on the front wall 5 of the valve bag by means of two fastening strips 9, 14. As the example shows, the cover strip 11 comprises u-shaped folds 15 at its two edges. The front wall 5 and the back wall 2 of the valve bag 1 may already be produced as a tube, for example by means of a blown film extrusion process or a circular weaving process. However, a tube may also be produced from a flat strip, in which the two side areas have been folded with the formation of an overlap and in which the overlapping edges are connected by means of a weld seam.

(19) FIG. 5 then shows some steps of a method according to the invention for producing a valve bag. To this end, a flat strip 50 is initially unrolled by a roll-off device, which is not shown. Subsequently, the venting openings 17 are placed, which are also not shown. Said venting openings are preferably not placed in the longitudinal direction of the flat strip continuously but rather in cycles. To this end, a roller, the peripheral surface of which is prepared with needle, cutting, or punching tools, can be unrolled on the flat strip. An alternative or additional provision may be that such a roller is placed in contact with the flat strip 50 at the points on which venting openings 17 are intended to be placed. To this end, an actuating mechanism may be provided, which places the roller in contact with the flat strip in cycles. The flat strip preferably runs by means of a mating-roller in this case.

(20) The venting openings 12 can be placed in the flat strip 50 in the same manner. In this case however, a roller 51 is shown with which individual, short sections are created in the flat strip 50. The circumferential surface 52 of the roller 51 is provided with blades 53 for this, wherein every two adjacent blades form an angle to one another, particularly a right angle. An actuating mechanism, which places the roller in contact with the flat strip in cycles, may be provided as well for the roller 51. The actuating mechanism for the roller 51 functions independently of the actuating mechanism mentioned in the previous paragraph, because the venting openings, 12 and 7, are preferably placed offset in transport direction of the flat strip.

(21) After placement of venting holes 17 and before or after the placement of venting holes 12, the flat strip 50 is provided with a filter material 55, which is attached to the flat strip 50. Said filter material may be applied to the flat strip in the form of a strip. To this end, the filter material may be provided as a roller and be unrolled within a roll-off device. In order to attach the filter material, a provision may be that the filter material is provided with two lateral adhesive strips in its roller form. It is advantageous, however, when two adhesive tracks 56, 57 are applied to the flat strip and/or to the strip-shaped filter material, wherein the venting openings 17 lie completely within said adhesive tracks. The adhesive tracks may comprise a dispersion adhesive, a hot-melt adhesive, or a cold adhesive; however, they may also comprise an extrudate. In the latter case, plastic in an extruder is transitioned to a melt form and applied as tracks through tubes in this form. Directly after application of the adhesive tracks, the flat strip and the strip-shaped filter material are combined, which is indicated by arrows 58, and pressed together, for example by means of a pair of pressing rollers, and optionally cooled as well.

(22) In another embodiment, the filter material 55 may also be applied to the flat strip in form of slips, wherein the filter material should be dimensioned such that it completely covers the venting openings 17 concentrated on a section of surface. In order to provide the filter material in form of slips, prefabricated slips can be used. However, it is preferable when the filter material is present in roller form and is separated into slips by means of a separating tool, for example a cutting tool. Adhesive tracks are then preferably applied to the flat strip 50, wherein a circumferential adhesive track is created so that the air, which should go through the filter material, cannot escape through a gap in the adhesive track.

(23) The described procedures for applying filter material may also be used when the venting openings 12 are to be covered with a filter material.

(24) FIG. 6 next shows the folding of the side areas of the flat strip 50 around the edges of the fold, 3 and 4, wherein the back wall 2 and the two areas, 6 and 7, of the front wall 5 are formed. In doing so, it is advantageous when area 6 is already more folded at a fixed position than area 7. The u-shaped fold 15 is preferably created before or even during the folding of area 7. Alternative or additional folds may also be placed at this time. However, it is also possible for the described folds to be placed after folding of areas 6 and 7.

(25) FIG. 7 shows the already folded areas 6 and 7, which are then attached to one another with fastening strips 9 and 14. To this end, there are two extrusion tubes, which place at least one melted plastic material in the form of at least two parallel tracks between areas 6 and 7 and thus delimit channel 16. Using at least one pressing device, which is not shown, for example a press-on roller, areas 6 and 7 can be connected to one another along fastening strips 9 and 14 such that a permanent and long-term connection can be created. At least one cooling device may be provided in order to cool down the fastening strips, particularly when they were created with the development of heat. The cooling device may consist of the pressing device. Thus, for example, press-on rollers may be cooled.

(26) FIG. 8 next shows a valve bag 101, characterized simply as bag, which preferably is produced from a tube according to the exemplary embodiments in FIGS. 1 to 7. In order to produce a bag 101 from such a tube, said tube is separated into tube pieces, a bottom opening is formed at both its ends, and subsequently said bottom opening is sealed forming one bottom. In the exemplary embodiment shown, the bottoms, of which only one bottom 102 can be seen, are formed as cross-bottoms. To this end, during production, one bag end is fitted by forming a bottom rectangle and two bottom triangles 103. Subsequently, the side latches, 104 and 105, are folded over such that they partially overlap. Preferably, a bottom cover sheet 106 is subsequently affixed to the already-formed bottom, wherein it is preferably connected with both bottom triangles 103 and with both side latches 104 and 105.

(27) The non-visible bottom 107 is formed similarly to bottom 102; however, a valve 108 is placed on one of the two bottom triangles and fastened there, before folding of side latches 104 and 105, such that the side latches are folded by means of the valve. Alternatively, a valve slip can be placed on one of the bottom triangles and fastened there, said valve slip forming the valve 108 by means of the folding of the side latches. The optional bottom cover sheet is subsequently connected only with the valve and not with the bottom triangle underneath. The valve 108 ensures access from the environment to the bag interior and thus offers the option of filling the bag with filling material from the outside. In one further development of the shown embodiment, a provision is that the valve 108 is formed to be sealable in order to reduce the penetration of moisture and the escaping of parts of the filling material after filling, during subsequent storage. With reference to valve 108, the bottom 107 can be characterized as a valve bottom, while bottom 102 can be characterized as a valve-free bottom.

(28) It is further discernible that the second wall 5 continues into side latch 104, which is preferably folded via side latch 105. The advantages of this embodiment are explained below in connection with FIG. 9. As previously explained, the wall 5 comprises the channel 16, which is delimited by fastening strips 9 and 14, wherein fastening strip 9 is represented by a dashed line, because it is not visible in a finished bag. It is further discernible that venting openings 17 are arranged closer to the valve-free bottom than venting openings 12. Preferably, the distance between the venting openings 17 and the bottom 102 is no more than one-third, preferably no more than one-fourth, particularly one-fifth the entire bag length L.

(29) Conversely, a provision is that venting openings 17 are arranged closer to the valve bottom than venting openings 12. Preferably, the distance between the venting openings 12 and the bottom 107 is no more than one-third, preferably no more than one-fourth, particularly one-fifth the entire bag length L.

(30) FIG. 9 shows section IX-IX through the bag 101 (see FIG. 8). Thus, sections through bottoms 102 and 107 are now discernible. With the valve-free bottom 102, particularly the folding sequence of side latches 104 and 105 is discernible. Because section IX-IX also forms a section through the channel 16, the side latch 104 appears in three layers, because, in addition to the relevant parts of areas 6 and 7, the filter material 18 is discernible, as well. Side latch 104 is enclosed, i.e., it was folded before the folding of side latch 105. Thus, side latch 105 is on the exterior. Because of the bottom cover sheet 106, the channel 16 is not accessible or barely accessible via latch 105 such that practically no moisture can penetrate the bag via bottom 102. However, if there is moisture nonetheless, this moisture must first be diffused over the entire bag length in order to reach the bag interior.

(31) The valve bottom 107 comprises side latches 109 and 110, wherein side latch 109 is form similarly to side latch 105. Accordingly, side latch 110 is formed analogously to side latch 104. In contrast to bottom 102, the side latch 110 is initially folded with bottom 107, i.e., it is enclosed. Side latch 109 consequently forms the external latch. Because the valve 108 is additionally arranged underneath side latch 110 and, at least during filling, the individual layers of the side latches are pressed together, part of the filling material is prevented from reaching the channel 16.

LIST OF REFERENCE NUMERALS

(32) 1 Valve bag

(33) 2 First wall

(34) 3 Side edge

(35) 4 Side edge

(36) 5 Second wall

(37) 6 First area

(38) 7 Second area

(39) 8 Edge

(40) 9 Fastening strip

(41) 10 Surface

(42) 11 Cover strip

(43) 12 Venting holes

(44) 13 Edge

(45) 14 Fastening strip

(46) 15 u-shaped fold

(47) 16 Channel

(48) 17 Venting opening

(49) 18 Filter material

(50) 19 Fastening strip

(51) 20

(52) 21 z-shaped fold

(53) 22 Fastening strip

(54) 23 First sub-channel

(55) 24 Second sub-channel

(56) 50 Flat strip

(57) 51 Roller

(58) 52 Circumferential surface

(59) 53 Blade

(60) 55 Filter material

(61) 56 Adhesive track

(62) 57 Adhesive track

(63) 58 Arrow

(64) 101 Valve bag

(65) 102 Bottom

(66) 103 Bottom triangle

(67) 104 Side latch

(68) 105 Side latch

(69) 106 Bottom cover sheet

(70) 107 Nonvisible bottom

(71) 108 Valve

(72) 109 Side latch

(73) 110 Side latch

(74) L Bag length