Abstract
A method of making a paper bag for containing sanitary products, which includes conveying a paper web having a first side and a second side in a conveying direction; Applying a sealable coating to the first side of the paper web in sections, and applying second coating strips extending substantially transversely to the conveying direction and spaced apart from one another in the conveying direction; folding onto itself the first side of the paper web along the direction of conveyance to form a two-ply web having a folding configuration; and heat sealing the second coating strips to form side seams each defining a bag interior; separating the two-ply web along the heat sealed side seams to separate the two-ply web into individual paper bags.
Claims
1. A method of manufacturing a paper bag (1) for containing sanitary products, comprising: Conveying a paper web (2) having a first and a second side in a conveying direction (X); Applying, section-by-section, a sealable coating (3) to the first side of the paper web (2), said applying comprising the application of first coating strips (4) extending essentially in the conveying direction (X) and spaced apart from one another transversely with respect to the conveying direction (X), and said applying further comprising the application of second coating strips (5) extending essentially transversely with respect to the conveying direction (X) and spaced apart from one another in the conveying direction (X); Folding onto itself the first side of the paper web (2) along the conveying direction (X) so as to form a two-ply web (7) having a folding arrangement (6); Heat sealing the second coating strips (5) to produce side seams (8) each limiting a bag interior; Separating the two-ply web (7) along the heat-sealed side seams (8) to separate the two-ply web (7) into individual paper bags (1); wherein said applying, section-by-section, of the sealable coating (3) to the first side of the paper web (2) further comprises applying in the conveying direction (X) coating sections (12) extending towards one another in the region of the folding arrangement (6), at least two of first coating strips (4), second coating strips (5) and coating sections (12) being produced by different application methods.
2. The method according to claim 1, wherein at least the coating material used for the sealable coating (3) of the first coating strips (4) is different from that used for the second coating strips (5) and the coating sections (12).
3. The method according to claim 1, wherein the coating material used for the first coating strips (4) is heat reactivatable.
4. The method according to claim 1, wherein the application of the first coating strips (4) is carried out by means of an endless roller, which is arranged such that the distance between the two first coating strips (4) can be adjusted.
5. The method according to claim 1, wherein said applying, section-by-section, of the sealable coating (3) to the first side of the paper web (2) comprises applying the first coating strips (4) in a first process step and applying the second coating strips (5) and/or the coating sections (12) in a second process step.
6. The method according to claim 1, wherein the first coating strips (4) are arranged on opposite side edges of the paper web (2), so that the first coating strips (4), in the folded onto itself state of the paper web (4), delimit a bag opening (9) via which the bag interior is accessible.
7. The method according to claim 6, wherein at least one free area (10), which is free of sealable coating (3), is formed between the opposing first coating strips (4) and between two adjacent second coating strips (5).
8. The method according to claim 1, wherein said folding onto itself comprises inserting a head gusset (11) in the region of the folding arrangement (6).
9. The method according to claim 1, wherein the coating sections (12) are directly adjacent to the second coating strips (5).
10. The method according to claim 1, wherein the coating sections (12) are spaced from the second coating strips (5) transversely to the conveying direction (x).
11. The method according to claim 1, wherein the width of the coating sections (12) transverse to the conveying direction (X) substantially corresponds to the width (BK) of the paper web section (13) provided for the head gusset (11).
12. The method according to claim 1, wherein said applying, section-by-section, of the first and/or the second coating strips (4, 5) and/or the coating sections (12) to the first side of the paper web (2) takes place only on one side of one of the paper web sections to be folded onto itself and separated by the folding arrangement (6).
13. The method according to claim 1, wherein the coating pattern applied in sections is formed mirror-symmetrically in the conveying direction (X), so that when the paper web (2) is folded onto itself, sections having a sealable coating (3) are folded onto itself.
14. The method according to claim 1, wherein partially heat sealing the applied sealable coating (3) further comprises heat sealing the coating sections (12) to create head gusset seams (14).
15. The method according to claim 1, wherein the folding onto itself of the paper web (2) takes place off-center with respect to the paper web width (B), so that one of the layers of the two-layer web (7) has a projecting material section (15).
16. The method according to claim 1, wherein the first coating strips (4) are applied to the paper web (2) without interruption, i.e., as continuous coating strips (4).
17. The method according to claim 1, wherein the distance (A1) between the first coating strips (4) and/or the respective width (B1) of the first coating strips (4) can be variably adjusted.
18. The method according to claim 1, wherein the distance (A2) between the second coating strips (5) and/or the length (L2) and/or the width (B2) of the second coating strips (5) are variably adjustable.
19. The method according to claim 1, wherein the dimensions (B3, L3) of the coating sections (12) are variably adjustable in and transversely to the conveying direction (X).
20. The method according to claim 1, wherein said applying of the sealable coating (3) is carried out by means of gravure printing and/or flexographic printing and/or nozzle application and/or spraying.
21. The method according to claim 1, wherein, prior to the sectional application of a sealable coating (3) to the first side of the paper web (2), the second side of the paper web (2) is printed with a motif.
22. The method according to claim 1, wherein after separating the two-ply web (7) along the heat-sealed side seams (8) to separate the two-ply web (7) into individual paper bags, the method comprises pinning the individual paper bags onto wicket pins.
Description
DRAWINGS
[0030] Further details of the invention are explained with reference to the figures below. Thereby shows:
[0031] FIG. 1 is a first embodiment of a paper web section coated in sections with sealable coating material;
[0032] FIG. 2 is a front view of an unfilled paper bag;
[0033] FIG. 3 is a second embodiment of a paper web section coated in sections with sealable coating material;
[0034] FIG. 4 is a third embodiment of a paper web section coated in sections with sealable coating material;
[0035] FIG. 5 is a front view of an unfilled paper bag according to the embodiment shown in FIG. 3 or FIG. 4;
[0036] FIG. 6 is a perspective view of a paper web feeding device;
[0037] FIG. 7 is a perspective view of a device for folding the paper web and inserting a head gusset;
[0038] FIG. 8 is a perspective view of a device for punching the folded paper web; and
[0039] FIG. 9 is a perspective view of a device for separating the folded and sealed paper web into individual paper bags and a stack of paper bags.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0040] FIG. 1 shows a section of a paper web 2 with a paper web width B conveyed in a conveying direction X, to which a mirror-symmetrical coating pattern of sealable coating material 3 is applied. This has first coating strips 4 running in the conveying direction X, which extend continuously on opposite outer sides of the paper web 2. After the bags 1 have been produced, the first coating strips 4 serve as a border around a bag opening 9, which is not initially sealed but is sealed only after the bags 1 have been filled with hygiene articles. For each paper bag section, the first coating strips 4 have a length L1 which, due to the continuous application, are each seamlessly adjacent to the first coating strips 4 of the adjacent paper bag sections. In the embodiment shown, the length L1 is 336 mm. The first coating strips 4 have a width B1, in the example shown of 100 mm, and are slightly spaced in the transverse direction from the outer edges of the paper web 2, so that it is avoided that the coating compound builds up at the edge in the printing process, because this remains stuck on the impression cylinder/medium in the edge region projecting over the paper web. The width B1 of the first coating strips 4 is determined by the tolerance range required by the fillers when closing the bags (e.g. due to filling height variations). In the embodiment shown, this engagement area has a width of 10 mm. The first coating strips 4 are spaced apart from one another by a distance A1 in the transverse direction of the paper web 2. The second coating strips 5 serve to produce side seams 8 of the paper bags 1 and, in contrast to the first coating strips 4, are sealed immediately after folding of the paper web 2. The second coating strips 5 extend substantially transversely to the conveying direction X and are spaced apart from one another in the conveying direction X by a distance A2, which in the example shown is 316 mm. Apart from the projecting material section 15, the second coating strips 5 extend over the entire paper web width and have a length L2, which in the example shown is 825 mm. The width B2 of the second coating strips 5 is 20 mm, as shown by way of example. The first and the second coating strips 4, 5 annularly enclose a free area 10 in which no coating material 3 is applied to the paper web 2. The size of the free area 10 corresponds substantially to the “show” area printed on the outside of the bag, and outside this area the bag is sealed.
[0041] The projecting material section 15 has two wicket pin holes 17 per paper bag section and has a width of 42 mm in the example shown. The second coating strips 5 each have coating sections 12 centrally adjacent thereto or overlapping therewith, which serve to seal the head gusset 11. The head gusset 11 is formed as part of the folding arrangement 6 by a paper web section 13 provided for this with a width BK, in the example shown 115 mm. When the paper web 2 is unfolded, the head gusset 11 is thereby inserted in a W-shape into the folding area. The coating sections 12 are arranged opposite one another at the outer edges of the bag and extend mutually towards one another, the free area 10 extending between the two coating sections 12. The coating sections 12 each have a length L3 in the conveying direction X and a width B3, which in the example shown are 115 mm and 70 mm respectively.
[0042] An alternative embodiment of a coating pattern applied to a paper web section is shown in FIG. 3. The first coating strips 4 applied by means of an endless roll extend over the entire paper bag width, i.e. corresponding to the length L1, and consist of a first coating material which can be heat reactivated. The coating strips 4 have a width B1 and are arranged in an upper region of the bag, and may be immediately adjacent to the material section 15 or spaced therefrom by a slight distance of, for example, 5+/−1 mm. This allows the sealable coating to be adhered to the paper web 2 during the manufacturing process. In the period between bag manufacture and filling of the bag, the coating 4 is inactive as soon as it has cooled down after application, so that it does not develop any adhesive effect. As a result, the bag can be stored easily and layer 4 does not need to be provided with a peel-off strip. The layer 4 can then be heat-activated again for the process of filling the bag 1 with articles, so that an adhesion effect is again provided for closing the bag 1. The second coating strips 5 and the coating sections 12 comprise a second coating material which is suitable for immediate bag production after application, since in the method the bag body is produced immediately after application of the second coating strips 5 and the coating sections 12, that is, it is folded onto one another. As a result, a coating material which cannot be heat reactivated can be used. The second coating strips 5 with a length L2 and a width B2 are spaced from the coating sections 12 transversely to the conveying direction X and directly adjoin or open into the coating area 4. This means that the coating area 4 and the coating strips 5 do not overlap or overlap only slightly. Furthermore, the second coating strips 5 are applied only on the right side of the paper web section, or the coating sections 12 are applied only in the area of the inwardly folded section of the head gusset 6. With sufficient coating application, only one side of each of the two sections to be joined thus needs to be provided with coating material. This has the advantage that the folding does not have to be carried out with the precision that would be necessary if the coating material were applied to both sides.
[0043] FIG. 4 essentially shows the coating pattern according to the second embodiment shown in FIG. 3. However, the third embodiment shown in FIG. 4 differs from the second embodiment in that the coating strips 5 have a greater length L2 and additionally extend over the entire width B1 of the coating area 4. As a result, the coating strips 5 and the coating area 4 overlap in the third embodiment.
[0044] FIG. 5 shows the front view of a paper bag 1 produced from a paper web section as shown in FIG. 1. This has a longitudinal dimension 24 and a transverse dimension 25. The two-ply web 7 of the bag 1 is joined by side seams 8 produced by the second coating strips 5. Opposite the head gusset is a filling opening 9, which is directly adjacent to the wicket section 15 having two wicket holes 17. Surrounding the filling opening 9 from the inside are the first coating sections 4 (not shown), which can be heat reactivated after filling the bag to seal it. After the coating pattern has been applied, half of the paper web 2 is folded on top of each other along a folding arrangement 6 running in the conveying direction X, thereby forming a two-ply web 7 whose plies each represent a bag front and a bag back. Due to the symmetrical arrangement of the coating pattern, uniformly coated areas are folded on top of each other in each case when the paper web is folded. During folding, the head gusset 11 is inserted as described above. Subsequently, the second coating strips 5 are sealed so that in each case bag bases with bag interiors separated from one another are formed. The second coating strips 5 can be sealed up to the areas which overlap with the first coating strips 4. The first coating strips 4 are not sealed and surround a bag opening 9 remaining in the open state. Subsequently, protruding areas of the head gussets 11 are removed by punching. This concerns the corner areas connected to each other and protruding from the bag. After punching, the coating sections 12 are sealed. After sealing the second coating strips 5 and the coating sections 12 and after punching, the paper web 2 is separated into separate bags 1 along separation lines 16. The separation lines 16 run longitudinally in the center of the second coating strips 5, so that these are each separated into two side seams 8 of two adjacent bags 1.
[0045] FIG. 2 shows a bag 1 produced by the process in the unfilled state, without the corners of the head gussets 11 having been punched away. This has a paper layer 2 forming a double-layer web 7 and a sealable coating 3 arranged in sections thereon, which faces a bag interior. The bag has a rectangular shape with a longitudinal dimension 24 corresponding to the length of the second coating strips 5 and a transverse dimension 25 corresponding to the length of the first coating strips 4. The bag 1 has an inlaid head gusset 11 in the region of a folding arrangement 6, so that the web of material forming the bag is folded back onto itself by means of three folds to form a front bag wall and a rear bag wall. The superimposed material web sections have aligned side edges extending along the longitudinal dimension of the bag. In the region of the side edges, the front and the rear bag walls are heat-sealed to one another over a width b corresponding to half the width B2 of the second coating strips 5, so that in each case 1 cm wide sealing seams 8 formed as flat seams join the bag walls to one another. In the region of the head gusset 11, the front and rear bag walls are not welded directly to one another, but the front bag wall is welded to the head gusset section facing it and the rear bag wall is welded to the head gusset section facing it. Opposite the head gusset 11, the bag has an opening 9 which is surrounded on the inside by the first coating strips 4, so that the opening 9 can also be sealed after the bag has been filled with hygiene articles. A projecting material section 15 projecting beyond the bag opening 9 is provided on the rear bag wall. Two holes 17 are provided in the material section 15, which serve to fasten the bag 1 on wicket pins.
[0046] FIGS. 6 to 9 show individual stations of a system for the production of paper bags 1 which can be filled with hygiene articles and which carries out the process. FIG. 6 shows a feed device 18 for conveying a paper web 2. The paper web 2 is thereby provided on a paper roll 19, from which the paper web 2 is continuously unwound and fed to the manufacturing process. FIG. 7 shows a folding device 20 for folding the paper web 2 into a double-layer web 7, which has a folding wedge 26 tapering in the conveying direction X, over which the paper web 2 is guided. Starting from its outer sides in the direction of the web center, the paper web 2 is folded over along the outer edges of the folding wedge 26 in the direction of the rear side of the folding wedge 26. In the course of this, the paper web 2 changes its conveying direction X. An insertion wedge 27 is arranged at the tip of the folding wedge 26 against the folding wedge direction, by means of which the folding arrangement 6 with inserted head gusset 11 is produced. This produces a double-layered web 7, which is guided through the nip of a pair of rollers in which the intended folds are introduced into the paper web 2. On the opposite side of the head gusset 11, it can be seen that the double-layer paper web 7 has a projecting material section 15. After the first and second coating strips 4, 5 have been sealed, the double-layered web 7 is fed to a punching device 21 as shown in FIG. 8, which removes the projecting corner sections of the head gussets 11 in each case. Finally, in FIG. 9, a separating device 22 is shown which separates the double-layered web 7 along the provided separation lines 16 into individual paper bags 1, the separation lines 16 running along the second coating strips 5 as described above and separating them into two side seams 8 of adjacent bags 1. Finally, the made-up, partially sealed, punched and separated bags 1 are deposited on a bag stack 23. Thus, the bags are ready to be filled via the opening 9 in a subsequent process and then sealed along the first coating strips 4.
[0047] The features of the invention disclosed in the foregoing description, in the drawings as well as in the claims may be essential to the realization of the invention both individually and in any combination.
