EP0291128A1

EP0291128A1 - Valve bag with venting means

Info

Publication number: EP0291128A1
Application number: EP88200922A
Authority: EP
Inventors: Piet Van Eerden
Original assignee: Wavin BV
Current assignee: Wavin BV
Priority date: 1987-05-11
Filing date: 1988-05-10
Publication date: 1988-11-17
Also published as: AU1718188A; WO1988008816A1; EP0367769A1

Abstract

A valve bag made of plastic film is provided with a tubular filling valve (2) which comprises an air-permeable and dust-filtering section (13) which extends essentially over the length of the section of the filling valve (2) extending within the bag(1). The filling valve is provided at the end located inside the bag with a constriction which can embrace a filling spout inserted in the filling valve. Thus, the filling valve can be pulled tight so that during filling of the bag an optimal venting of the bag is ensured. The air-permeable and dust-filtering material (13) consists of a nonwoven, particularly a spunbonded nonwoven. The nonwoven may be mounted on a relatively stiff carrier film to facilitate mechanical processing of the nonwoven. A filling spout for filling a valve bag according to the invention is provided with means for keeping the filling valve at distance from the wall of the filling spout.

Description

The present invention relates to a valve bag, in particular made of plastic film, provided with a filling valve and at least one venting opening which is covered by at least an air-permeable and dust-filtering material.
When filling valve bags with pulverulent material such as starch powder, cocoa and cement, the filling material is fluidized with the aid of air and the air/filling material mixture is blown into the bag via a filling spout inserted in the filling valve. Since the required air/filling material ratio in the mixture depends on the type of filling material, the venting capacity of the sack necessary for satisfactory filling during filling is also dependent on the type of filling material. The venting capacity of the bag in many cases has a great influence on the filling speed to be attained.
When filling a valve bag with fluidized pulverulent material the following three phases can be distinguished, i.e. a first phase in which the bag is not yet completely filled with air and filling material, a second phase in which the bag is completely filled with air and filling material but in which the bag does not yet contain sufficient filling material, and a third phase in which the bag is completely filled with filling material but in which filling material is still present in the filling spout. In the first phase, the filling speed does not depend on the venting capacity of the bag. In the second phase, the air which is additionally blown into the bag has to be discharged via the vent of the bag. The filling speed then depends on the venting capacity of the bag. Finally, in the third phase the filling material present in the filling spout has to be blown into the bag by means of an air blast. This does not work without satisfactory venting of the bag.
Valve bags of the type mentioned at the outset are known in various embodiments. The venting opening or openings covered by an air-permeable and dust-filtering material serves or serve to allow the air present in the bag to escape from the bag during filling of the bag with, in particular, pulverulent or more or less fine-grained material, without filling material escaping from the bag.
In a particular embodiment of a known valve bag the wall of the bag is provided over a given area with perforations serving as venting openings and covered by an air-permeable and dust-filtering material.
In another embodiment, a venting tube is fitted in the bag and consists completely or partially of an air-permeable and dust-filtering material such as non-woven.
In yet another embodiment known from Dutch Patent Application 78.11426 a small air-permeable filter pocket is provided in the bag opposite the filling valve and consists of a non-woven.
Dutch Patent Application 78.04027 discloses a valve bag having a tubular filling valve which consists of film material and is surrounded by a filter layer consisting of an air-permeable and dust-filtering material, through which the interior of the bag is in connection with the exterior of the bag. In another embodiment of this known valve bag the entire filling valve consists of a tube of air-permeable and dust-filtering material.
However, it has been found practice that the venting capacity of the known valve bags is often limited and as a result only a limited filling speed can be achieved. This may be the consequence of the fact that the air-permeable and dust-filtering material, such as a non-woven, has the tendency during filling of the bag become blocked, i.e. that the pores in the filter material are blocked by the filling material particles entrained in the air escaping from the bag. The fact that during filling of the bag under production conditions it is difficult to provide the filter with a sufficiently large open venting surface may be another cause of the limited venting capacity.
It is the object of the invention to provide a valve bag which does not have the disadvantages of the known bags and which always has sufficient venting capacity during filling.
This object is achieved, according to the invention, by a valve bag of the type mentioned at the outset which is characterized in that the filling valve comprises an air-permeable and dust-filtering section which extends essentially over the length of the filling valve section extending within the bag and in that the filling valve is provided at the end located inside the bag with a constriction.
In a valve bag having such a filling valve the innermost part of the filling valve embraces the filling spout during insertion of the filling spout in the filling valve and the filling valve can be pulled tight. By matching the shape of the filling spout with that of the filling valve it is possible to ensure that, during filling, there is always a certain space between the wall of the filling spout and the air-permeable and dust-filtering section of the filling valve, so that the venting can take place perpendicularly to the surface of that section of the filling valve. This leads to a considerable increase in the venting capacity of the bag.
The filling valve is advantageously designed as a tubular sleeve which narrows towards the interior of the sack, so that the filling valve can be uniformly pulled tight.
The filling valve is preferably assembled from two strips of material which are joined to each other along the edges, at least one of the two strips consisting at least partially of an air-permeable and dust-filtering material.
A tubular filling valve of this type can be manufactured in a simple manner.
It has been found, surprisingly, that the nonwoven in a valve bag of the type mentioned at the outset in which the air-permeable and dust-filtering material is a nonwoven, does not have the tendency to become blocked when it consists of spunbonded nonwoven. By using a spunbonded nonwoven as air-permeable and dust-filtering material a bag having a high venting capacity can be obtained. As a result, the filling time of the bag can be shortened and the range of application of valve bags made of plastic film can be considerably increased.
A nonwoven is frequently applied mechanically. The nonwoven material at the same time usually has a sufficient stiffness to be processed mechanically. Certain nonwoven materials such as spunbonded nonwoven which are extremely suitable for serving as cover for venting openings in valve bags because they have very good filter properties and do not become blocked with the material particles entrained in the air escaping from the bag have, however, a very low stiffness compared with the film material of the bag and other conventional non-woven materials and as a result are very difficult to process mechanically.
In order to make mechanical processing of a non-woven having low stiffness nevertheless possible, the nonwoven is mounted on a carrier film having a sufficient stiffness to be processed mechanically.
Such a construction is particularly expedient if the nonwoven is a spunbonded nonwoven but can, of course, also be used with other nonwovens and air-permeable and dust-filtering materials having low stiffness.
The invention also relates to a filling spout for filling valve bags which is characterized in that the filling spout is provided on the outside with means for keeping the wall of the filling valve at a distance from the wall of the filling spout when the filling spout is inserted.
The invention will be explained in more detail hereinafter by means of the description of an exemplary embodiment, with reference to the drawings, in which:

Figure 1 diagrammatically shows a part of a valve bag having a filling valve according to the invention;
Figure 2 to 6 incl. diagrammatically show various stages during manufacture of a valve bag according to the invention;
Figure 7 is a diagrammatic section of a corner of a valve bag according to the invention in the region of the filling valve;
Figure 8 is a view along line VIII-VIII in Figure 7;
Figure 9 is a diagrammatic section of a corner of a modified embodiment of a valve bag according to the invention in the region of the filling valve;
Figure 10 is a view along line X-X in Figure 9;
Figure 11 gives a diagrammatic picture of the manufacture of a filling valve for a valve bag according to the invention;
Figure 12 shows a filling valve, manufactured according to Figure 11, for a valve bag according to the invention;
Figure 13 shows another embodiment of a filling valve for a valve bag according to the invention;
Figure 14 diagrammatically shows the manufacture of a filling valve according to Figure 13;
Figure 15 shows yet another embodiment of a filling valve for a valve bag according to the invention;
Figure 16 shows yet another embodiment of a filling valve for a valve bag according to the invention;
Figure 17 diagrammatically shows a filling spout preferably to be used during filling when this filling spout is inserted in a filling valve;
Figure 18 is a cross section through a filling spout according to Figure 17 at the position of the ribs;
Figure 19 diagrammatically shows an alternative embodiment of a filling spout to be used during filling when this is inserted in a filling valve;
Figures 20 and 23 incl. diagrammatically show the consecutive steps during manufacture of a valve bag according to the invention with the venting tube.

Figure 1 shows a section of a valve bag 1 made of plastic film and provided with a tubular filling valve 2. The filling valve 2 is located in the region of a bottom of the valve bag 1. The bottom of the valve bag 1 is covered by a cover sheet 3. Figures 2 to 6 incl. diagrammatically show the various stages of manufacture of a valve bag according to Figure 1. Figure 2 shows a tubular film section 4 from which a valve bag according to the invention is manufactured. The top of the tube film section 4 is provided all round its outside with an adhesive layer 5. The uppermost end 6 of the tubular film section is folded in a conventional manner as shown in Figure 3, bottom flaps 7 and 8 and corner flaps 9 and 10 being produced. The filling valve 2 is also arranged in the conventional manner at the position of the corner flap 10 on the unfolded upper part of the tubular film section 4 as shown in Figure 4. The construction of the filling valve will be described in detail in the text below.
After fitting the filling valve, the two bottom flaps 7 and 8 are folded as shown in Figure 5 after which the cover sheet 3 is finally fitted at the bottom of the valve bag as shown in Figure 6.
Figure 7 diagrammatically shows a section of a corner of a valve bag in the region of the filling valve 2, while figure 8 is a bottom view along line VIII-VIII in Figure 7. Figure 7 and 8 also show diagrammatically the construction of the filling valve 2. The filling valve 2 is tubular and comprises and air-permeable and dust-filtering section which extends essentially over the length of the section, extending within the bag, of the filling valve. In the embodiment shown here, the filling valve 2 is built up from two strips of material 12 and 13, the strip 12 located at the side of the adjacent bag bottom consisting of film material and the other strip 13 consisting of an air-permeable and dust-filtering material. The two strips are joined to each other and their sides by means of connecting seams 14. At its end 15 located within the bag the filling valve 2 is provided with a constriction 16. In the embodiment shown this is achieved by constructing the filling valve 2 as a tubular sleeve which narrows towards the interior of the bag. When the filling nozzle is inserted in the filling valve 2 the constriction 16 will fit tightly around the outside of the filling spout inserted in the filling valve, and as a result the entire filling valve can be pulled tight. Matching the shape of the filling valve to that of the filling spout makes it possible to ensure that a certain space is produced between the outer wall of the filling spout and the air-permeable and dust-filtering material, which is pulled tight, of the filling valve. In this manner, optimum venting can be obtained during filling of the bag since the air can escape from the bag perpendicularly to the plane of the air-permeable and dust-filtering section of the filling valve and can flow outwards via the space between the filling spout and the filling valve.
By manufacturing one of the two strips of the filling valve of film material which is relatively stiff compared to the air-permeable and dust-filtering material a certain stiffness is imparted to the filling valve as a whole, as a result of which it is possible to process the filling valve in a trouble-free manner, on machines for manufacturing valve bags.
Figures 9 and 10 essentially correspond to Figures 7 and 8 with the difference that the edges of the bottom flaps 7 and 8 of the bag do not touch each other, so that a so-called "negative overlap" 17 is produced.
In Figure 7 to 10 incl., as mentioned, the strip 12 of film material of the filling valve 2 is located on the side of the adjacent bag bottom and the air-permeable and dust-filtering strip 13 is located on the side of the interior of the bag. This embodiment has the advantage that the filter is located on the side where there is the most space. Furthermore, the filling material which arrives at the filter during filling will have the tendency to fall downwards again so that the tendency for the filter layer to block up is low.
It is, however, also possible to fit the filling valve 2 the other way round in the valve bag, namely with the air-permeable and dust-filtering strip on the side of the adjacent bag bottom and the strip of film material on the side of the interior of the bag. This embodiment has the advantage that, during "inflation" of the bag during filling, the air present in the bag can escape from the bag via the space between the bag bottom and the filling valve. Furthermore, this embodiment achieves the result that, after the bag has been filled, the filling valve is sealed very tightly by the relatively stiff film layer which is pressed against the bottom of the bag.
In order to obtain a very high venting capacity the two strips of the filling valve may consist of air-permeable and dust-filtering material, so that venting can take place via both sides of the filling valve.
In order, at the same time, to impart sufficient stiffness to the filling valve so that it can be processed without trouble on a machine for manufacturing valve bags, at least one of the two strips may be provided with a cover layer of relatively stiff material, which cover layer is provided with perforations such that the strip provided with a cover layer is sufficiently air-permeable.
Figure 11 diagrammatically shows the manner in which a filling valve 2 for a bag according to the invention can be manufactured. The starting point is formed by a roll of film material 18 and a roll of air-permable and dust-filtering material 19. The width of the two rolls 18, 19 corresponds to the width of the filling valve 2 to be manufactured. The strips obtained from the two rolls are joined to each other along their edges with the aid of a welding roller 20 and a backing roller 21 and are cut into pieces by means of a knife 22 mounted on the welding roll. In this manner, a filling valve 11 is produced which is built up of a strip of film material 12 and strip of air-permeable and dust-filtering material 13, which two strips are joined to each other by means of connecting seams 14 (see Figure 12).
Figure 13 shows an alternative embodiment of a filling valve for a valve bag according to the invention. The filling valve 2 shown in Figure 13 is composed of a first strip of film material 24 having a length which is greater than the length of the section, extending within the bag, of the filling valve 2′ and a second strip 25 which is joined along the edges to the strip of film material 24 by means of connecting seams 26. The second strip 25 consists of a strip part 27 of air-permeable and dust-filtering material and a doubly folded strip part 28 made of film material which, along the folding edge 29 transverse to the longitudinal direction of the filling valve 2′ is joined with the strip part 27 made of air-permeable and dust-filtering material. The length of the second strip 25 is essentially equal to the length of the first strip of film material 24, the length of the strip part 27 essentially corresponding to the length of the section, extending within the bag , of the filling valve 21. Such an embodiment of a filling valve has the advantage that, after filling of the bag , the extension piece 30 of the filling valve 21 can be doubly folded and can be arranged in a space below the filling opening of the bag , so that a satisfactory seal of the filling valve is achieved and water leakage into the bag and backflow of filling material via the filling valve is prevented.
Figure 14 diagrammatically shows the manner in which a filling valve 2 according to Figure 13 can be manufactured. In manufacturing filling valves according to Figure 13, the starting point is formed by a roll of film material 31, a roll of air-permeable and dust-filtering material 32 and a second roll of film material 33 for the doubly-folded part strip 28. After the web, of dust filtering and air-permeable material fed from the roll 32 has been joined with the web, of film material fed from roll 33, the web assembled and the web of film material fed from roll 31, are joined to each other and cut into pieces in the manner shown in Figure 14, so that filling valves 2′ as shown in Figure 13 are formed.
Figures 15 and 16 show two other possible embodiments of a filling valve for a valve bag according to the invention.
In the filling valve 2˝ according to Figure 15, the strips 34 and 35 of which the valve is assembled each consist of a strip part 36 of air-permeable and dust-filtering material and a strip part 37 made of film material which is joined along edge 38 with a strip part 36. The two strips 34 and 35 are joined to each other along the sides by means of connecting seams 39.
The filling valve 2‴ according to Figure 16 is assembled of two strips 40 and 41 which each correspond to the strip 25 of the valve according to Figure 13. The two strips 40 and 41 are joined to each other along the sides by means of connecting seams 42. This valve also has an extension piece 43 which, after filling of the sack, can be doubly-folded so that the filling valve is sealed tightly.
Figure 17 and 18 diagrammatically show a filling spout which is preferably used during filling of a valve bag according to the invention. In Figure 17, the filling spout is inserted in a filling valve 2 of a bag. The filling spout 44 is provided over at least part of the outer wall 46 with spacers 45 which extend outwards and which serve to keep the wall of a filling valve 2 at a distance from the wall 46 of the filling spout 44 when the filling spout 44 is inserted. In the embodiment shown here, the spacers consists of raised ribs which extend in the longitudinal direction of the filling spout 44.
Using such a filling spout guarantees that the air which escapes from the bag via the air-permeable and dust-filtering section of the filling valve 2 always has sufficient space also to flow outwards unhindered.
Figure 19 shows an alternative embodiment of a filling spout. The filling spout 47 is surrounded by a tubular sleeve 49 which is arranged at a distance from the outer wall 48 and is made of a material provided with openings such as gauze or perforated sheeting. The wall of the filling valve is held by this tubular sleeve at a distance from the wall 48 of the filling spout 47. The filling valve 2 can be held firmly on the tubular sleeve 49 by means of a clamping member 50. Here again it is ensured that the air present in the bag can always flow outwards unhindered during filling.
In a valve bag made of plastic film of the type having a filling valve and a venting opening covered by an air-permeable and dust-filtering nonwoven very good venting is obtained when the nonwoven consists of a spunbonded nonwoven. A spunbonded nonwoven is particularly suitably manufactured from continuous fibres having a thickness of 5-10 µm which are joined to each other thermally or mechanically without use of additional material. A spunbonded nonwoven of this type is marketed under the tradename Lutravil®. The fibre material may be polypropene, polyethene, polyamide or polyethene terephthalate. It is preferable to manufacture the film of the bag and the nonwoven of the same material so that the film material and the nonwoven material can be recycled together after use of the bag. In view of the fact that the bag is usually manufactured from polyethene film it is preferable to manufacture the nonwoven from polyethene fibres.
The thickness of the nonwoven can be chosen on the basis of requirements to be met by the venting. Depending on the requirements, a nonwoven can be chosen having a weight between 5 and 10 g/m².
A bag of the type described in Dutch Patent Application 78.11426 having a small filter pocket manufactured of spunbonded nonwoven can be filled within a filling time of 8 to 12 seconds with a large variety of powders, it being possible for the particle size to vary between 1 and 200 µm, without the small filter pocket becoming blocked and without dust penetration taking place.
A high venting capacity can also be achieved by using a spunbonded nonwoven as cover material for the venting opening or openings in other types of valve bags , for example those in which the venting takes place via perforations provided in the wall of the bag over a certain area and covered by a nonwoven or those in which venting takes place via a venting tube or venting valve.
A spunbonded nonwoven as described above generally has too low a stiffness to be provided readily mechanically in a valve bag. Before being attached to the bag, the spunbonded nonwoven is therefore mounted on a carrier film which has sufficient stiffness to be able to be processed mechanically.
Figures 20 and 23 incl. show how a dust-filtering and air-permeable nonwoven having low intrinsic stiffness can be fitted in a valve bag with venting tube in one of the bottoms.
After a tubular film section 4 shown in Figure 2 has been folded in the manner shown in Figure 3 a filling valve 51 of film material is fitted in the conventional manner at the position of the corner flap 10 on the unfolded upper section of the tubular film section (Figure 20). The filling valve 51 is for this purpose provided all round with an adhesive layer 52 which is bonded to the adhesive layer 5 of the corner flap 10.
Figure 21 shows the manner in which the venting tube of the valve bag is manufactured and fitted on the pre-formed bag section of Figure 20. A film web 60 made of the same material as the material of the tube film section 4 is unrolled from a roll 61. Parallel thereto, a web 62 of the nonwoven material for covering the venting opening of the valve bag to be manufactured is unrolled from a roll 63 and joined to the film web 60 by means of two longitudinal seams 64. The film web 60 serves as a carrier for the nonwoven 62. The thus formed, assembled web is cut into sections having the desired length as a result of which sheets 65 are produced. The nonwoven 62 is at the same time joined to the carrier film 60 by means of a transverse weld 67 at the end 66 of each sheet 65 which will be fitted at the position of the filling valve 52 on the bag. A tubular section open at one end is thus produced which will serve as venting tube for the valve bag. The sheet 65 is subsequently provided at the two ends 66 and 68 on the upper and lower side with an adhesive layer 70, the adhesive being provided at the end 68 on the lower side of the nonwoven 62. This ensures that at this position no adhesive gets between the nonwoven 62 and the carrier film 60. The sheet 65 provided with adhesive layers 70 is adhered on the pre-formed bag end of figure 20, adhesive layers 70 adhering to adhesive layers 5. As a result, a bag end as represented in figure 22 is produced. The bottom flaps 7 and 8 are subsequently folded inwards. Finally, the bag end is covered in the usual manner with a cover sheet 71 as shown in figure 24.
The other bag end is formed in the conventional manner.
In the example a certain manner of mounting the nonwoven on a carrier film and the manufacture of the valve bag having a venting tube is described. It will be clear that the nonwoven can also be joined to the carrier film in another manner, for example by welding. Furthermore, it is possible to use various types of carrier film such as continuous carrier film and carrier film provided with perforations. A combination of a nonwoven having low stiffness with a carrier film can be used for various types of valve bags, for example in a tubular filling valve described above made of two strips, the nonwoven functioning separately from the carrier film during filling of the bag.
A carrier film can also be used with other air-permeable and dust-filtering materials having low stiffness.
By using a carrier film a valve bag can be manufactured mechanically with a venting hole or venting holes which is or are sealed by a nonwoven having excellent properties in respect of air-permeability and dust-filtration but which per se has only very low stiffness.

Claims

1. Valve bag , in particular made of plastic film, provided with a filling valve and at least one venting opening which is covered by at least an air-permeable and dust-filtering material, characterized in that the filling valve (2; 2′; 2′♂; 2′♂♂) comprises an air-permeable and dust-filtering section which extends essentially over the length of the section of the filling valve extending within the bag and in that the filling valve is provided at the end (15) located inside the bag with a constriction (16).

2. Valve bag according to claim 1, characterized in that the filling valve (2; 2′; 2′♂; 2′♂♂) is designed as a tubular sleeve which narrows towards the interior of the bag.

3. Valve bag according to claim 1 or 2, characterized in that the filling valve (2; 2′; 2′♂; 2′♂♂) is assembled from two strips (12, 13; 24, 25; 34, 35, 35; 40, 41) of material joined to each other along the edges, at least one of the two strips (13; 25; 34, 35; 40, 41) consisting at least partially of an air-permeable and dust-filtering material.

4. Valve bag according to claim 3, characterized in that the two strips (12, 13; 24, 25) consist of different material, one of the two materials being relatively stiff.

5. Valve bag according to claim 4, characterized in that the strip (12) located at the side of an adjacent bag wall consists of film material and the other strip (13) consists of an air-permeable and dust-filtering material.

6. Valve bag according to claim 4, characterized in that the strip located at the side of an adjacent bag wall consists of an air-permeable and dust-filtering material and the other strip consists of a film material.

7. Valve bag according to claim 3, characterized in that the two strips consist of an air-permeable and dust-filtering material.

8. Valve bag according to claim 7, characterized in that at least one of the two strips is provided with a covering layer of a relatively stiff material, which covering layer is provided with perforations, such that the strip provided with the covering layer is sufficiently air-permeable.

9. Valve bag according to claim 3, characterized in that the filling valve (2′) is composed of a first strip, located at the side of an adjacent bag wall, of film material (24) having a length which is greater than the length of the section, extending within the bag, of the filling valve (2′) and a second strip (25) which is joined along the edges to the strip of film material and which consists of a strip part (27) of an air-permeable and dust-filtering material and a doubly folded strip part (28) of a film material which, along the folded edge (29) transverse to the longitudinal direction of the filling valve (2′) is joined to the strip part (27) of air-permeable and dust-filtering material, such that the total length of the second strip (25) is essentially equal to the length of the first strip of film material (24).

10. Valve bag according to claim 3, characterized in that the filling valve (2′♂) is assembled of two strips (34, 35) which each consist of a strip part (36) of an air-permeable and dust-filtering material and a strip part (37) of film material joined thereto via a connecting seam (38) transverse to the longitudinal direction of the filling valve (2′♂).

11. Valve bag according to claim 3, characterized in that the filling valve (2′♂♂) is assembled of two strips (40, 41) which each consist of a strip part (27′) of an air-permeable and dust-filtering material and a doubly folded strip part (28′) of a film material which is joined, along the folded edge (29′) transverse to the longitudinal direction of the filling valve (2′♂♂) with the strip part (27′) of air-permeable and dust-filtering material.

12. Valve bag according to one of claims 1 to 11, characterized in that the air-permeable and dust-filtering material consists of a nonwoven.

13. Valve bag , in particular made of plastic film, provided with a filling valve and at least one venting opening which is covered by at least an air-permeable and dust-filtering nonwoven, characterized in that the non-woven consists of a spunbonded nonwoven.

14. Valve bag according to claim 13, characterized in that the spunbonded nonwoven is manufactured of continous fibres.

15. Valve bag according to claim 13 or 14, characterized in that the fibres of the spunbonded nonwoven are joined to each other thermally or mechanically.

16. Valve bag according to one of claim 13 to 15, characterized in that the spunbonded nonwoven is manufactured of fibres having a thickness less than 20 µm.

17. Valve bag according to claim 16, characterized in that the thickness of the fibres is 5-10 µm.

18. Valve bag according to one of claims 13 to 17, characterized in that the weight of the nonwoven is between 5 and 100 g/m².

19. Valve bag according to one of claims 13 to 18, characterized in that the material of the fibres is polypropene, polyethene, polyamide or polyethene terephthalate.

20. Valve bag according to one of claims 13 to 19, characterized in that both the film of the bag and the nonwoven are manufactured of the same material, preferably polythene.

21. Valve bag according to claim 13, characterized in that the nonwoven is mounted on a carrier film which possesses sufficient stiffness to be processed mechanically.

22. Valve bag according to claim 21, characterized in that the nonwoven is mounted on the carrier film by adhesive bonding or welding.

23. Valve bag according to claim 21 or 22, characterized in that the material of the carrier film essentially corresponds to the material of the bag.

24. Valve bag according to one of claims 21 to 23, characterized in that the carrier film is provided with perforations.

25. Valve bag according to one of claims 21 to 24, characterized in that the nonwoven can function during filling of the bag separately from the carrier film.

26. Filling spout for filling valve bags, characterized in that the filling spout (44; 47) is provided on the outside with means to keep the wall of the filling valve (2, 2′, 2′♂, 2′♂♂) at a distance from the wall (46) of the filling spout when the filling spout is inserted.

27. Filling spout according to claim 26, characterized in that the said means consist of spacers (45) arranged over at least a section of the outer wall (46) of the filling spout (45).

28. Filling spout according to claim 27, characterized in that the spacers consist of raised ribs (45) extending in the longitudinal direction of the filling spout (44).

29. Filling spout according to claim 26, characterized in that the said means consist of a tubular sleeve (49) made of material provided with openings and arranged around the filling spout (47) and at a distance from the outer wall (48) thereof, such as gauze or perforated sheeting.