EP3606835B1 - Multiple ply bag and method for manufacturing a multiple ply bag - Google Patents

Description

The invention relates to a multi-layer bag for bulk goods such as. E.g. cement, plaster, granules, cocoa powder or other powdered foods or chemicals.

Such bags are well known and are typically formed from two or more layers of a flat or web-shaped material, preferably paper and/or plastic. They are used in particular for the packaging and distribution of powdery or fine-grained bulk goods. Common sizes are 5 kg, 10 kg and 25 kg. A multi-layer bag is e.g. B. in the DE 20 2014 000 194 described.

To produce such bags, material webs made of flat material, e.g. B. paper and/or film webs, placed one on top of the other in a so-called tube machine, formed into an endless tube and divided into tube pieces of suitable length, from which the bag is finally formed, for example by means of a cross or block bottom fold. The multi-layer hose pieces include several single-layer hose pieces, which typically have the same length and are placed one inside the other in such a way that their ends are flush with one another. A two-layer paper web section with such flush ends according to the prior art is in Figure 1a shown, a piece of hose formed from it in Figure 1b . At the ends of the hose pieces will be the bag bottoms are formed, e.g. B. in the form of a cross or block bottom fold. In Figure 1a a cross-bottom fold is indicated at the top and bottom ends of the hose section by dashed fold lines. Towards the end of the sack manufacturing process, the bottom fold is usually fixed using suitable gluing. Due to the flush material layers, when gluing the bottom fold, the outermost material layer is usually glued to inner material layers, such as. B. out Figure 2 visible.

From the DE 23 60 142 A1 A multi-layer cross or block bottom bag is known, with a tubular shaped bag outer wall and a tubular inner lining arranged staggered to this, with the bag outer wall and inner lining being glued together in the bottom area. The CH 339804 A describes a multi-layer sack and a process for its production, in which individual sack layers are arranged staggered to one another. From the FR 2,028,049 A1 A multi-layer valve bag with staggered layers and glued bottoms is known. The FR 1,073,031 A describes a multi-layer cross-bottom valve bag made of paper with alternating staggering of the material layers in the side flaps and corner folds. From the DE 357123 A paper bag made of several layers is known, in which the bottom is glued together by a reinforcing flap.

The bags described above are increasingly used for bulk or filling goods that are processed under clean room conditions, e.g. B. in the food or pharmaceutical industry. With such filling material there is a need to remove as much of the outer layer of the bag as possible shortly before it is introduced into the clean room, but without opening the bag in the process. This is referred to below as stripping or stripping the bag. Any contaminants that may adhere to the outer skin of the bag should be removed before it is brought into the clean room, although the bag should remain closed as much as possible and then only be opened and emptied in the clean room.

It is therefore the object of the present invention to propose a multi-layer sack in which the outer layer can be easily removed over as large an area as possible, while at the same time the sack should remain largely closed. In addition, the bag according to the invention should be simple and inexpensive to produce.

According to the invention the object is achieved by a bag according to claim 1.

According to the invention, a method with the features of independent claim 9 is proposed for bag production. Advantageous refinements are the subject of the subclaims.

It is envisaged that the hose pieces of the individual material layers do not end flush with one another at their ends, but that at least one inner hose piece, hereinafter referred to as the inner hose piece, has a protrusion at at least one end compared to the outermost hose piece, hereinafter referred to as the outer hose piece. It is therefore provided that at least one inner hose piece protrudes beyond the outer hose piece at at least one end. For typical bag formats, the overhang is suitably a few centimeters, preferably at least 1cm, more preferably at least 2cm and even more preferably at least 3cm. Advantageously, the projection is at most 8cm, more advantageously at most 6cm and even more advantageously at most 4cm.

At the ends with a protruding inner tube piece, a bag bottom can be formed in a simple manner, in which the inner tube piece is closed by gluing to close the bottom, without the outer hose piece being included in this bonding. Due to the protrusion of the inner hose piece, bonding of the outer hose piece to the inner hose piece in the floor area can be avoided and, nevertheless, a bond closing the floor can be achieved in a simple manner. Bonding in this sense should also include any similar fixing of the closed floor, e.g. B. welding or otherwise fixing the closed floor.

Since the outer tube piece is not included in the bottom bonding of the inner tube piece or is not glued to the inner tube piece in the area of the bottom bonding, the outer tube piece can be easily removed from the bottom of the finished or filled bag without the bond closing the protruding inner tube piece being released becomes. In the area of the bag wall between the floors, gluing the outer layer to inner layers of the bag material according to the prior art is not necessary anyway. The invention thus enables a multi-layer bag that can be stripped or stripped in a simple manner, ie in which the outer layer of material can be easily removed In this way, a large area - including floor areas - can be removed from a filled bag without opening the bag and releasing the contents.

In an advantageous embodiment, the protrusion of the inner hose piece relative to the outer hose piece is achieved in that the protruding inner hose piece is made longer than the outer hose piece.

According to the invention, a protrusion of an inner hose piece relative to the outer hose piece is formed at both ends of the outer hose piece. Then bottoms can be formed at both ends of the hose piece, which are glued to an inner hose piece without gluing the outer hose piece. This makes it possible to design the outer layer in the area of both bottoms to be removable in a simple manner in order to be able to strip or strip a bag with two bottoms over as large an area as possible. This can be realized particularly advantageously in that an inner hose piece is designed to be longer than the outer hose piece in such a way that it has a protrusion, advantageously a protrusion of the same length, at both ends of the outer hose piece.

In another preferred embodiment according to claim 3, the bag has two inner tube pieces which are inserted telescopically into one another. Advantageously, the inner hose pieces have the same length as the outer hose piece. Further advantageously, each of the two inner hose pieces protrudes beyond the outer hose piece at a different end, particularly advantageously by a protrusion of the same length. This configuration is particularly advantageous in terms of production technology because a protrusion can be created at both ends with outer and inner hose pieces of the same length. Of course, in addition to the two inner hose pieces mentioned above, there can be other inner hose pieces of the same or different lengths.

The bag according to the invention has two opposite bottoms, which are formed at the ends of the tube pieces in a cross or block bottom fold.

According to the invention, at least one base is additionally reinforced by a cover sheet which is glued to the outer tube piece and has no bonding to the inner tube piece. With a cover sheet attached in this way, the stability of the base and the bag can be increased, while the outer layer is easy to remove. Particularly advantageously, the outer tube piece forms a frame in the area of the base, which is glued to the cover sheet.

Preferred cross or block floors have side flaps that run essentially parallel to the longitudinal axis of the floor and corner indentations at the ends of the longitudinal axis of the floor. Such floors are typically closed by closing the overlapping side flaps, and the overlapping side flaps are usually glued. Advantageously, with such floors, the protrusion of the inner tube piece is designed such that the outer tube piece does not extend into the overlap area of the side flaps. This makes it particularly possible to glue the side flaps in the overlap area without including the outer tube piece in this bonding, and the outer tube piece forms a frame in the floor area that runs along the edges of the finished floor. In another preferred embodiment, the outer tube piece and/or the bottom cover sheet(s) have at least one tear strip in order to be able to tear open the outer layer of the bag easily and in a defined manner and remove it from the bag.

Particularly advantageously, the tear strip is designed in at least three parts, with two parts of the tear strip running lengthwise over the two floors and a tear strip between the floors over the side wall of the bag. Further advantageously, the three parts of the tear strip are arranged in a U-shape. This makes it particularly easy to tear open and remove the outer layer of the bag.

Instead of or in addition to tear strips, the outer layer of the bag may also have suitable perforation lines and/or grooves and/or other suitable means to facilitate tearing open the outer layer and removing it. Such perforation lines and/or grooves and/or other suitable means are particularly advantageously designed and/or arranged in several parts in a similar manner to the tear strips.

The bag advantageously has a bottom designed as a valve base, into which a valve hose is inserted for filling the bag. Another advantage is that the valve tube is not glued to the outer tube piece, so that the outer layer can be removed from the bag comparatively easily without removing the valve. The closed valve remains on the bag so that it remains closed. Even if the outer part of the valve was in contact with the outside, the affected area is small compared to the total surface of the bag, so that the bag can be stripped over a very large area, even if the valve tube remains on the bag.

In another advantageous embodiment, the valve hose can be divided into two pieces of hose, for example. B. can be inserted telescopically into one another. Alternatively, the divisibility can also be achieved through a circumferential perforation, e.g. B. can be made approximately halfway along the valve hose. With a valve hose that can be divided in this way, the outer end of the valve hose can be separated without the inner end of the valve hose being removed from the bag or torn out of it. The closed inner part of the valve tube can continue to keep the bag closed, while the outer part of the valve tube is removable with the remaining outer layer of the bag. In this design The outer parts of the valve hose can also be glued to the outer hose piece, while the inner part of the valve hose is glued to the inner hose piece.

In another preferred embodiment, the bag according to the invention has an inner bar which is inserted into the open base(s) with a protruding inner tube piece in such a way that the inner bar is glued to the inner tube piece and has no bonding to the outer tube piece. This configuration enables a particularly good sealing of the bag bottom with the inner bar, while at the same time ensuring that the outer layer can be easily removed. Furthermore, with this embodiment it is possible to close the inner tube piece in the floor area simply by gluing the inner bar, so that further gluing of the inner tube piece in the floor area is not necessary. The closed side flaps can be held in the closed position using a cover sheet that is simply glued to the outer tube piece.

At least one material layer of the bags according to the invention is made of paper or a paper-like material. Paper-like materials include: B. coated or laminated papers should be considered, or other fibrous flat materials with comparable properties to paper. Other material layers of the bags according to the invention can, for. B. be designed as plastic films.

The method according to the invention according to claim 9 is based on the previously known use of a tubing machine in bag production. Material layers of a web-shaped flat material, for example paper and/or Plastic film webs, placed on top of each other in a tubing machine, cut to a suitable length and formed into tubing pieces.

Advantageously, the supernatant can be produced by making the inner tube piece longer or cutting it to a greater length than the outer tube piece. This can e.g. B. can be realized in that the material web from which the protruding inner tube piece is formed runs faster in the tubing machine than the material web from which the outer tube piece is made.

In another preferred embodiment of the method, the bag is produced with at least two inner tube pieces, the length of which corresponds to the outer tube piece, the outer tube piece and the inner tube piece being arranged staggered in the tubing machine in such a way that the one inner tube piece faces the outer tube piece forward in the conveying direction of the web-shaped material and that other inner hose piece is moved backwards. Further advantageously, the outer tube piece and the two inner tube pieces are brought into the aforementioned staggered arrangement by staggered cutting of the associated material webs. So it is possible to use material webs running at the same speed for outer and inner tube pieces to form a protrusion of the inner tube pieces on both sides compared to the outer tube piece, with the protrusion being particularly advantageously the same size on both sides.

In the method according to the invention, floors are formed at the ends of the multi-layer hose pieces in a so-called floor laying machine, whereby when the floors are closed or glued together with the inner hose piece protruding, the inner hose piece is not glued to the outer hose piece.

Fig. 1a/b:

Bündig abschließende Papierbahnabschnitte bzw. Schlauchstücke für die Sackherstellung gemäß Stand der Technik

Fig. 2:

Das Zulegen eines aus dem Stand der Technik bekannten Sackbodens

Fig. 3a:

Einen Papierbahnabschnitt für einen erfindungsgemäßen zweilagigen Sack

Fig. 3b:

Ein Schlauchstück für einen erfindungsgemäßen zweilagigen Sack

Fig. 4:

Eine Draufsicht auf den offenen Kreuzboden eines erfindungsgemäßen Sackes

Fig. 5:

Eine Schrägansicht des teilweise zugelegten Kreuzbodens eines erfindungsgemäßen Sackes

Fig. 6:

Den geschlossenen Kreuzboden eines erfindungsgemäßen Sackes

Fig. 7:

Einen Papierbahnabschnitt für einen erfindungsgemäßen dreilagigen Sack

Fig. 8:

Den geschlossenen Boden eines erfindungsgemäßen Sackes mit Deckblatt

Fig. 9:

Eine Schrägansicht eines erfindungsgemäßen Sackes mit Aufreißstreifen

Fig. 10:

Den offenen Ventilboden eines erfindungsgemäßen Sackes mit eingeklebtem Ventilschlauch

Fig. 11

Den offenen Ventilboden eines erfindungsgemäßen Sackes mit eingeklebtem, zweiteiligen Ventilschlauch

Fig. 12:

Den zugelegten Ventilboden eines erfindungsgemäßen Sackes

Fig. 13:

Den offenen Kreuzboden eines erfindungsgemäßen Sackes mit Innenriegel

Fig. 14:

Den offenen Kreuzboden eines erfindungsgemäßen Sackes mit Ventilschlauch und Innenriegel

Fig. 15:

Eine schematische Darstellung des Zuschneidens von Papierbahnen für einen erfindungsgemäßen zweilagigen Sack

Fig. 16:

Eine schematische Darstellung des Zuschneidens von Papierbahnen für einen erfindungsgemäße dreilagigen Sack.

Exemplary embodiments of the invention are explained in more detail using the figures below. Show:

Fig. 1a/b:

Flush paper web sections or tube pieces for bag production according to the state of the art

Fig. 2:

Adding a bag base known from the prior art

Fig. 3a:

A paper web section for a two-layer sack according to the invention

Fig. 3b:

A piece of tubing for a two-layer bag according to the invention

Fig. 4:

A top view of the open cross bottom of a bag according to the invention

Fig. 5:

An oblique view of the partially closed cross bottom of a bag according to the invention

Fig. 6:

The closed cross bottom of a bag according to the invention

Fig. 7:

A paper web section for a three-layer sack according to the invention

Fig. 8:

The closed bottom of a bag according to the invention with a cover sheet

Fig. 9:

An oblique view of a bag according to the invention with tear strips

Fig. 10:

The open valve bottom of a bag according to the invention with a glued-in valve tube

Fig. 11

The open valve base of a bag according to the invention with a two-part valve hose glued in

Fig. 12:

The closed valve base of a bag according to the invention

Fig. 13:

The open cross bottom of a bag according to the invention with an inner bar

Fig. 14:

The open cross bottom of a bag according to the invention with a valve tube and inner latch

Fig. 15:

A schematic representation of the cutting of paper webs for a two-layer bag according to the invention

Fig. 16:

A schematic representation of the cutting of paper webs for a three-layer sack according to the invention.

Figure 1a shows a two-layer paper web section 1 for producing a two-layer paper bag according to the prior art. The upper paper layer 3 forms the outer layer of the finished bag, the paper layer 4 underneath forms the inner layer of the bag wall. The right and left edges 5 and 6 of the material layers 3 and 4 are each connected to form a tube, which in Figure 1b is shown. In Figure 1a the left edge 6 can be seen from both material layers 3 and 4, while the right edge can only be seen from material layer 3. The two-layer paper section is formed into a tube Figure 1b a two-layer hose piece 1 with the outer hose piece 3 and inner hose piece 4, with the two paper or hose piece layers 3 and 4 flush with one another at the ends 7 and 8. The bottom fold of the bag is formed in the areas of the two ends 7 and 8, whereby in Figure 1a in dashed lines a cross-bottom fold is indicated. Figure 2 shows the closing of the base 9 when made from the paper web section or tube piece 1 according to Figure 1a /b a cross-bottom bag is formed according to the prior art. The inside of the inner paper layer 4 is marked by cross hatching. As can be seen, when gluing the floor using the adhesive contour 2 shown in dotted lines, the outside of the outer hose piece 3 is glued to the inside of the inner hose piece 4. Therefore, the outer layer 3 cannot be removed from the bag without loosening the bond 2 of the bottom.

Figure 3a shows a two-layer paper web section 15 for producing a two-layer bag according to the invention. The upper paper layer 22 forms the outer layer and the lower paper layer 32 forms the inner layer of the bag. By connecting the respective left and right side edges 24, 34 and 25, 35, a two-layer hose piece 15 is formed with the outer hose piece 22 and the inner hose piece 32, as in Figure 3b shown schematically. The inner tube piece 32 has a projection U at its two ends 37 and 38 relative to the respective end 27 and 28 of the outer tube piece 22, and the outer layer 22 is provided with a tear strip 29. Suitably, the projection (U) is between 3cm and 5cm.

Figure 4 shows the open cross bottom 50 of a bag according to the invention, which is from the in Figure 3a /b shown two-layer paper web section 15 or tube piece 15 is formed. Characteristic of the cross bottom fold are the corner folds 52 and 53 as well as the side flaps 55 and 56, which are folded around the side fold lines 58 and 59 to close the bottom. The outer hose piece 22 is in Figure 4 provided with a dot/angle pattern, and the inner tube piece 32 with a crossed hatching. Due to the protrusion U of the end 37 of the inner hose piece 32 compared to the end 27 of the outer hose piece 22, there is a central area in the area of the floor in which the corner folds 52 and 53 and the side flaps 55 and 56 are formed only by the inner hose piece 32 and not by the outer hose piece 22 are covered. Due to the overhang U when closing the side flaps 55 and 56 and their bonding with a suitable adhesive contour 51 prevents the inner tube piece 32 from bonding to the outer tube piece 22.

Figure 5 shows the closing of the bottom 50 of a bag according to the invention, with first the front side flap 56 and then the rear side flap 55 being closed. As can be seen, the areas of the inside of the side flaps formed solely by the inner tube piece 32 rest solely on areas of the inner tube piece in the area of the adhesive contour 51, so that the outer tube piece 22 is not included in this bonding 51 when gluing the closed floor.

Figure 6 shows the closed and glued bottom 50 of a bag according to the invention. The outer tube piece 22 forms a frame that runs along the edge of the base 50 and leaves a window in the middle in which the overlap of the protruding area of the side flaps 55 and 56 can be seen. In the closed floor, only areas of the inner tube piece 32 are glued together, without including the outer tube piece 22 in this bonding. The outer tube piece 22 is provided with the tear strip 29 to make it easier to tear open the outer layer of the bag to undress it.

Figure 7 shows a three-layer paper web section 15 for a three-layer bag according to the invention, the upper paper layer 22 forming the outer layer of the bag or the outer tube piece 22, and the two underlying paper layers 32, 42 forming inner layers or inner tube pieces 32, 42. As already for the embodiment according to Figure 3 explained, tube pieces are formed from the paper layers 22, 32, 42 by connecting the respective left and right edges 24, 34, 44 and 25, 35, 45 to one another. The inner paper layer or the inner tube piece 32 has a projection U at its upper end 37 relative to the upper end 27 of the outer layer or the outer tube piece 22. Likewise, the inner layer or the inner tube piece 42 has a projection U at its lower end 48 relative to the lower end 28 of the outer layer or the outer tube piece 22. The projections U are at both ends of the outer tube piece is essentially the same size, and all three paper layers or tube pieces 22, 32 and 42 have essentially the same length L between the ends 27, 37, 47 and 28, 38 and 48. Accordingly, the projections U are realized in that the paper layers or tube pieces 22, 32, 42 are arranged offset from one another in the direction of the length L, which corresponds to the conveying direction F of the paper web in the tube machine. The offset arrangement of the inner paper layers 32 and 42 in the tube formation means that the tube pieces 32 and 42 are telescopically inserted into one another, the telescopic extension corresponding to twice the projection U, and the two inner tube pieces inserted telescopically into one another are arranged in this way relative to the outer tube piece that the projection U is formed at both ends 27 and 28 of the outer hose piece. Also in the exemplary embodiment of the invention Figure 7 The bottom of the bag is added as in the Figures 4 to 6 illustrated, and a tear strip 29 is also provided in the outer tube piece 22 in order to make it easier to tear open and remove the outer layer of the bag. The embodiment according to Figure 7 can be implemented particularly easily in terms of production technology because the paper layers 22, 32 and 42 can be cut to the same length in the tubing machine, i.e. web sections of the same length are required for all material layers.

Figure 8 shows a bag base 50 formed according to the invention, which is additionally reinforced by a cover sheet 60. The adhesive contour 61 of the cover sheet is designed in such a way that the cover sheet is only glued to the outer tube piece 22 or the frame formed by it in the area of the base. Accordingly, the cover sheet 60 is not glued to inner tube pieces, so that it can be removed from the bag bottom 50 with the outer tube piece 22 without tearing open the inner layers. In order to make it easier to tear open the cover sheet, a tear strip 69 is provided in it, in addition to a tear strip 29 in the outer tube piece.

Figure 9 shows a bag 17 according to the invention in the filled state with a valve base 50 and an opposite base 70, both ends of the multi-layer hose piece or both bases 50, 70 being designed according to the invention, ie with an inner hose piece protruding from the outer hose piece. The bottoms 50, 70 are reinforced with cover sheets 60, each of which is provided with a tear strip 69. Furthermore, the outer tube piece 22 is provided with a tear strip 29. Overall, the arrangement of the tear strips on the bag body forms a U-shaped structure. This allows the outer layer of the bag to be torn open particularly conveniently and removed from the bag without the inner layers of the bag being destroyed and the bag being opened.

Figure 10 shows an opened bag bottom 50 according to the invention, into which a valve hose 80 is inserted for filling the bag. The valve hose 80 is only glued to the inner hose piece 32 by a suitable arrangement of the adhesive contour 81. The outer layer 22 can thus be removed from the bag without the valve being torn out of the remaining bag. After removing the outer layer, a comparatively small area remains with the outer end of the valve hose 80 on the remaining or stripped bag, which was in contact with the outside space.

In the embodiment according to Figure 11 the valve hose 80 is designed to be divisible, in which the valve hose is formed from an inner and outer section 84, 85, which are inserted telescopically into one another. As in Figure 11 shown, in this embodiment the inner part 84 of the valve hose is glued to the inner hose piece via the adhesive contour 81, and the outer part 85 of the valve hose 80 is glued to the outer hose piece via the adhesive contour 82. Due to the divisibility of the valve tube 80, it is possible to remove the outer part of the valve 85 with the outer layer from the bag, with the inner tube 84 remaining on the remaining bag due to the advantageously stronger adhesive bond 81. The valve closure is arranged in the inner part 84 of the valve, so that the valve remains closed even after the outer part 85 has been removed. In total This embodiment makes it possible to also remove the outer part 85 of the valve 80, which was in contact with the outside space, with the outer layer from the bag, so that the remaining or stripped bag no longer has any surface areas that were in contact with the outside space before stripping.

Figure 12 shows an added valve base 50 designed according to the invention, into which a valve hose 80 is inserted. As can be seen, the valve hose 80 is in contact with the outside space in the left area, so that with the removal of this outer part, the surface of the bag in contact with the outside space can be removed even more extensively. In addition, the in Figure 12 shown valve base 50 in the in Figure 8 illustrated manner can be reinforced by a cover sheet 60.

Figure 13 shows an opened base 50 according to the invention, which is additionally covered by an inner bar 90. Due to the circumferential adhesive contour 91, the inner bar is glued all around to the inner tube piece, so that on the one hand a particularly good seal of the bag is achieved with the inner bar, and on the other hand the outer tube piece 22 is prevented from sticking to the inner tube pieces. Since the inner tube piece and thus the interior of the bag is already completely closed by gluing the inner bar 90, further gluing of the inner tube piece in the bottom area is not necessary. After closing the side flaps, they can be held in the closed position by a cover sheet, the cover sheet only being glued to the outer tube piece 22. This makes it possible in Figure 13 shown embodiment of the invention a particularly tight bag with an inner bar, the outer layer 22 being removable in a simple manner.

As in Figure 14 shown, the inner bar 90 can also be combined with a valve hose 80, which is glued into the open bag bottom below the inner bar 90.

The Figures 15 and 16 illustrate a stage of the manufacturing process according to the invention for bags according to the invention, namely the production of multi-layer paper web sections 15 or tube pieces 22, 32, 42, the inner layer or inner tube pieces having a protrusion U relative to the outer layer or the outer tube piece. Figure 15 explains the production of a two-layer paper web section 15 according to Figure 3 . Paper webs are unwound from rolls 20 and 30 and placed on top of each other in the tubing machine. The paper web 20 is for the outer layer or the outer tube piece 22, and the paper web 30 for the inner tube piece 32 of the bags according to the invention. In a first station 95 of the tubing machine, the paper webs are provided with a straight transverse perforation 27, 28, 37, 38, which later form the upper and lower edges 27, 28, 37, 38 of the outer and inner tube pieces 22, 32. The paper web sections 22 and 32 are then separated in a second station 96 of the tubing machine. As can be seen, two-layer paper web sections 22, 32 are formed, in which the upper and lower ends 37 and 38 of the inner tube piece 32 each have a projection U relative to the upper and lower ends 27 and 28 of the outer tube piece 22.

Figure 16 shows the production of a three-layer paper web section 15 according to Figure 7 . The paper from the paper roll 20 forms the outer layer or the outer tube piece, the paper from the paper rolls 30 and 40 forms the inner layers or inner tube pieces 32, 42. In station 95 of the tube machine, the paper webs 20, 30, 40 are provided with straight transverse perforations , and in station 96 the paper web sections are separated so that the inner layers or inner tube pieces 32, 42 form a protrusion U at both ends of the outer tube piece 22. The paper web sections or tube pieces 22, 32, 42 have the same length L in the conveying direction F of the tubing machine. Only the perforation or cutting lines are offset from one another, with the paper web section 32 being shifted backwards in the conveying direction relative to the section 22, and the Section 42 opposite section 22 to the front. In this way, it is possible to produce a sack with paper web sections of the same length or tube pieces of the same length for the outer and inner layers in which there is a protrusion of an inner tube piece at the ends of the outer tube piece, so that both bottoms of the bag can be glued according to the invention in such a way that the outer tube piece is not glued to an inner tube piece.

The floors are folded, added and glued according to the invention in one Figure 15 / 16 Floor laying machine, not shown.

Claims (11)

1. A multi-ply sack (17) for bulk goods having at least one material ply of paper or paper-like material, manufactured from an outer tube section (22) that forms the outer material ply of the sack wall in the finished sack (17) and having one or more inner tube sections (32, 42) that are arranged within the outer tube section (22), wherein a projection (U) of an inner tube section (32, 42) is present at both ends (27, 28) of the outer tube section (22),
   characterized in that
   the bottoms without any adhesive bonding of the outer tube section are adhesively bonded to an inner tube section, with at least one bottom having a projecting inner tube section being additionally reinforced by a top sheet (60) that is adhesively bonded to the outer tube section and does not have any adhesive bonding to an inner tube section.
2. A sack in accordance with claim 1, wherein at least one inner tube section (32) has a projection with respect to the outer tube section at both ends of the outer tube section.
3. A sack in accordance with one of the preceding claims, wherein the sack comprises two inner tube sections (32, 42) that are inserted into one another in the manner of a telescope, with the one inner tube section (32) having a projection with respect to the one end (27) of the outer tube section (22) and the other inner tube section (42) having a projection with respect to the other end (28) of the outer tube section (22), with the two inner tube sections (32, 42) inserted into one another in the manner of a telescope having substantially the same length (L) as the outer tube section (22).
4. A sack in accordance with one of the preceding claims, wherein the bottoms (50, 70) are configured as cross bottoms or square bottoms having side flaps (55, 56) that extend substantially in parallel with the longitudinal bottom axis, and wherein, with bottoms having projecting inner tube sections (32), the outer tube section (22) does not reach into the overlap region of the side flaps of the bottom fold.
5. A sack in accordance with one of the preceding claims, wherein the outer tube section (22) is provided with at least one tear strip (29) to tear open the outer ply of the sack and to remove it from the sack, and wherein the tear strip (29, 69) is preferably configured in at least three parts, with two parts of the tear strip extending longitudinally over the bottoms and one tear strip (29) extending between the bottoms (50, 70) over the sack wall.
6. A sack in accordance with one of the preceding claims, wherein at least one perforation line, grooves and/or other suitable means are provided in the outer ply to facilitate the tearing open and the removal of the outer material ply.
7. A sack in accordance with one of the preceding claims, wherein a bottom (50) having a projecting inner tube section (32) is configured as a valve bottom into which a valve hose (80) is inserted for filling the sack, with the valve hose either having no adhesive bond to the outer tube section or being divisible such that an outer section (85) of the valve hose is removable from the sack with the outer ply of the sack without the sack being opened in so doing.
8. A sack in accordance with one of the preceding claims, wherein an inner latch (90) is inserted into the open bottoms having projecting inner tube sections (32), with the inner latch having an adhesive bond (91) to the inner tube section (32) and not having any adhesive bond to the outer tube section (22).
9. A method of manufacturing a multi-ply sack in accordance with claim 1 from at least two plies of a sheet-like areal material (20, 30, 40), in particular paper and/or plastic, in which the material plies are placed over one another in a tubing machine and are cut into sections and are shaped into multi-ply tube sections (15) such that the multi-ply tube section comprises an outer tube section (22) that forms the outer material ply of the sack wall and one or more inner tube sections (32, 42) that are arranged within the outer tube section, characterized in that at least one inner tube section (32, 42) has a projection (U) in and/or against the conveying direction (F) of the tubing machine with respect to the end of the outer tube section (22), wherein the bottoms are formed at the ends of the multi-ply tube sections in a bottoming machine, with the inner tube section not being adhesively bonded to the outer tube section on the closing or gluing closed of the bottoms with a projection of the inner tube section.
10. A method in accordance with the preceding claim, wherein the sack is formed with at least two inner tube sections (32, 42) whose lengths (L) correspond to the outer tube section, wherein the outer tube section and the inner tube sections are arranged staggered such that the one inner tube section (42) is displaced to the front in the conveying direction (F) of the sheet-like material with respect to the outer tube section and the other inner tube section (32) is displaced to the rear.
11. A method in accordance with the preceding claim, wherein the outer tube section (22) and the inner tube sections (32, 42) are brought into the staggered arrangement by a staggered cutting of the associated material sheets.

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