GB1592905A

GB1592905A - Methods of manufacturing webs comprising a plurality of serially interconnected plastics bags

Info

Publication number: GB1592905A
Application number: GB42675/77A
Authority: GB
Original assignee: Wavin BV
Current assignee: Wavin BV
Priority date: 1976-10-14
Filing date: 1977-10-13
Publication date: 1981-07-08
Also published as: DE2746125A1; NL7611388A; JPS5742510B2; JPS5383874A; SE7711439L; CH627701A5; FR2367672B1; DK455477A; SU704445A3; IT1087590B; BE859675A; FR2367672A1; BR7706890A; AT365515B; CA1157825A; ATA739077A

Abstract

The tubular web of film has a plurality of plastic bags which can be separated from this web of film. This provides the advantage that the plastic bags can be made available to the user in a coiled form. This form is very easy to use, in contrast to a stack of loose plastic bags. In this case, each plastic bag is provided with first corner fold welding seams (8, 9, 10, 11). Each of these welding seams connects an outer web of film (1a, 1b) in each case to the fold part (5, 5a, 6, 6a) located immediately below it and to second corner fold welding seams (13, 14, 15, 16). The first corner fold welding seams (8, 9, 10, 11) are connected to a plastic bag closure welding seam (12). When the web of film is produced, the corner fold welding seams are firstly produced from a tubular film and the closure welding seam (12) is produced subsequently. <IMAGE>

Description

(54) IMPROVEMENTS IN OR RELATING TO METHODS OF MANUFACTURING WEBS COMPRISING A PLURALITY OF SERIALLY INTERCONNECTED PLASTICS BAGS (71) We, WAVIN B.V., a Netherlands limited liability company of 251 Handellaan, Zwolle, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to improvements in or relating to webs comprising a plurality of serially interconnected plastics bags and includes methods of manufacturing such webs and plastics bags detached from such webs when filled and sealed closed.

The invention, the scope of which is defined in the appended claims, includes a method of manufacturing a web comprising a plurality of serially interconnected plastics bags, a first end of one bag lying adjacent the second end, which is either open or adapted to be open for filling when the bag is detached from the web, of the next bag in the series, from a flattened tube of plastics film having two opposed outer layers and a gusset fold formed along each longitudinal side, each gusset fold comprising a central and two outer longitudinal fold edges, first and second gusset fold parts of each gusset fold being defined between the central and a respective one of the outer fold edges, the method comprising the steps of: forming between each of the first and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one respective first seal in the region of the first end of each pastics bag to be formed in the web; forming a transverse seal between said outer layers at the first end of each bag, each transverse seal joining the inner ends of each of the respective first seals or extensions thereto and extending at least from one central fold edge to the other; and forming between each of the thirst and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one second seal in the region of the second end of each plastics bag to be formed in the web.

The invention also includes a bag detached from a web produced by a method as defined in the above paragraph, the bag being filled and provided with a further transverse seal between the outer layers and joining the inner ends of each of said second seals or their extensions to close the bag In order that the invention may be well understood some embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings in which:: Figure 1 is a portion of a web of serially interconnected plastics bags; Figure 2 is a bag detached from a slightly modified type of web; Figure 3 is a bag detached from another type of web; Figure 4 is a portion of the bag of Figure 3 when sealed closed; Figure 5 is a perspective view of a filled and sealed bag; Figure 6 shows a partial cross-section of a device for forming first and second seals in the web; Figure 6a shows a portion of the web after the first and second seals have been formed therein; Figure 7 shows a cross-section of a device for forming transverse seals; and Figure 7a shows a portion of the web after the first, second and transverse seals have been formed therein.

A web of serially interconnected plastics bags 1 is shown in Figure 1. The bags 1 are arranged with the first or closed end of one bag lying adjacent a second end which is either open or adapted to be open for filling, when the bag is detached from the web, of the next bag in the series. The web is manufactured from a flattened tube of plastics film having two opposed outer layers la and lb. The flattened tube has a gusset fold formed along each longitudinal edge. Each gusset fold comprises a central longitudinal fold edge 4, 4a and two outer longitudinal fold edges 2, 3 and 2a, 3a (see Fig. 2).A first gusset fold part 5, 5a is defined between one longitudinal outer fold edge 2 or 2a and the respective central fold edge 4 or 4a and a second gusset fold part 6, 6a is defined between the other longitudinal outer fold edge 3 or 3a and its respective central fold edge 4 or 4a.

A set of four first seals is formed in the region of the first or closed end of each bag.

Each of the first seals is between two layers of film, an outer layer and the next adjacent gusset fold part. Thus, in the bags illustrated, a first seal 8 is formed between first gusset fold part 5 and the outer layer la on one side of the bag, on the other side another first seal 10 is formed between outer layer la and first gusset fold part Sa.

The other first seals 9 and 11 arc between outer layer Ih and respective second gusset fold parts 6 and 6a. The seals 8 and 9 and the seals 10 and 11 lie one above the other while the bag is flattened in the web. All the first seals 8, 9, 10, 11 are illustrated as extending across the entire width of the gusset folds from the outer fold edge 2, 2a, 3 or 3a to the respective central fold edge but can stop short of the central fold if desired. The first seals 8, 9, 10 and 11 are shown extending at 45" to the longitudinal direction of the tube, but other angles could be used.

Transverse seals 12 are formed across the width of the tube to define closed ends of the plastic bags 1 to be formed in the web.

Each seal 12 joins the inner ends 8, 8a or extensions to the first seals 8, 9, 10, 11 where the first seals do not extend as far as the relative central fold edge, and may extend only between the inner ends of the first seals, or their extensions, that is only across the central part of the flattened tube between the two central fold edges 4, 4a, or alternatively across the entire width of the tube as shown and in this case sealing together four layers of foil at each gusset fold.

In the region of the second ends of the bags a plurality of second seals is formed.

Each of these seals is formed between a gusset fold part and its adjacent outer layer.

In the type of web illustrated in Figure I a first set of four second seals 13, 14, 15, 16 only is formed extending preferably at an angle of 45" to the longitudinal direction of the tube from a point on the respective outer fold edge to an inner end of the seal located inwardly of the central fold edge. In the region beyond the central fold edge the two outer layers la, lb are sealed together to reinforce the open end of the bag during filling. In the type of web illustrated in Figure 2 the first set of second seals extend only as far as the central fold edge and also a set of further second seals 20a, 20h, 21a, 21b is formed which extend transversely between their respective outer fold edge and central fold edge and join with the inner end 17, 18 of the diagonal second seal in the same gusset part.In order to ensure a good seal when the bag is closed, seals 20a, 20b, 21a, 21b preferably extend beyond the central fold edges. In a still further type of web as illustrated in Figures 3 and 4 another set of four second seals 25, 26, 27, 28 is formed. The seals 25, 26, 27, 28 together with the seals 15, 16, 17, 18 define four triangles with bases along respective portions of the outer fold edges and their apixes 17a, 18a on central fold edges 4, 4a.

The angle at which the seals 25, 26, 27, 28 extend to the longitudinal direction of the tube may be 45" or a sharper angle. With this type of web the transverse further second seals 20a, 20h, 21a, 21b are not essential.

This arrangement of second seals allows a reinforced funnel shaped opening to be formed for the bag I when it is detached from the web and its mouth spread, which facilitates filling and allows easy centering of a bag above the filling machine.

In order that the bags may be detachable from the web the entire periphery of the tube may be perforated at the second end.

In order that the bags may be filled whilst still on the web an opening 23 may be formed in pne of the outer layers. As shown in Figure I this opening may be provided with extensions 23a, 23b into the gusset fold parts at either side of the tube. When such an opening is provided perforations 24 may extend around the remainder of the periphery of the tube in this region to allow the bag to be detached from the web either before or after filling.

When a bag 1 of any of the described webs has been filled it is necessary for it to be sealed. A further transverse seal 19 is formed across the open end of the bag I to close it. The seal 19 joins the inner ends 17 and 18 or 17a and 18a or extensions to the second seals if all or some of the second seals do not extend as far as the relative central fold edge. Seal 19 may extend only between those inner ends or may extend across the entire width of the bag. If the set of further transverse seals 20a, 20b, 21a, 21h is provided then when seal 19 is extended right across the bag it only has to secure two parts together that is outer layers la and Ib in the region between central fold edges 4 and 4a, the seals 20a and 20b in the region of one gusset fold, and the seals 21a and 21b in the region of the other gusset fold. This overcomes the difficulty of sealing four separate film layers together in the region of the gusset folds.

A bag from any web as described above takes on a convenient block shape when filled and sealed closed as shown in Figure 5 by virtue of the presence of the preferably inclined first and second seals 8, 9, 10, 11 and 13, 14, 15, 16 which assist in forming rectangular end faces of the block. The gusset fold parts 5, 6 and 5a, 6a are opened out to define side watts of the block while outer layers la and lh form the top and bottom surfaces of the block and also the end walls of the block. Such a block shape is convenient for stacking and of good appearance.

The method of manufacturing a web of serially interconnected plastics bags is now described with reference to Figures 6, 6a, 7 and 7a. The web is made from a flattened tube of plastics film in which seals may be formed by the application of heat and pressure. The tube has longitudinal gusset folds as previously described. In order to form the first and second seals heat sealing members 29a, 29b which extend over the gusset fold above and below outer layers la and lb respectively as far as the first and second seals are to extend across the tube are used. The heat seal members may be such that they can form all the first and second seals of one bag at a single application.An insulating separating means 30, for example a Pertinax (Registered Trade Mark) plate is inserted between the gusset fold parts 5 and 6 on one side and Sa and 6a on the other side to prevent the seals being formed through more than the requisite two film layers. A period of 1.5 seconds is typically necessary to form the first and second seals. The tube is then advanced through a distance at least as great as the greatest distance A between the seals already formed before the first and second seals for the next bag are formed. By forming all the necessary first and second seals in the web as shown in Figure 6a it is not necessary to remove and reinsert the insulating plate 30 while transverse seals 12 are formed in between.The transverse seals 12 are formed in the web by heat sealing members 31 and 32, one of which may serve merely as a support, the members are pressed towards each other in the regions in which the seals are to be formed for a typical duration of 2 to 4 seconds, the tube being advanced the required distance between each seal formation. Figure 7a shows the tube after seals 12 have been formed. The openings 23 and perforations 24 may be formed at any convenient stage ot the manufacture to complete the web. The bags may be filled and then sealed closed by a further transverse seal 19 which can be formed by further heat seal members (not shown).

WHAT WE CLAIM IS: 1. A method of manufacturing a web comprising a plurality of serially interconnected plastics bags, a first end of one bag lying adjacent the second end, which is either open or adapted to be open for filling when the bag is detached from the web, of the next bag in the series, from a flattened tube of plastics film having two opposed outer layers and a gusset fold formed along each longitudinal side, each gusset fold comprising a central and two outer longitudinal fold edges, first and second gusset fold parts of each gusset fold being defined between the central and a respective one of the outer fold edges, the method comprising the steps of: forming between each of the first and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one respective first seal in the region of the first end of each plastics bag to be formed in the web; forming a transverse seal between said outer layers at the first end of each bag, each transverse seal joining the inner ends of each of the respective first seals or extensions thereto and extending at least from one central fold edge to the other; and forming between each of the first and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one second seal in the region of the second end of each plastics bag to be formed in the web.

2. A method as claimed in claim 1, wherein the steps of forming said first and second seals for a given bag in the web precede said step of forming said transverse seal for that bag.

3. A method as claimed in claim 1 or 2, wherein each transverse seal is formed such that it joins inner ends of said first seals at the relative central fold edge.

4. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend at least from a respective one of the outer fold edges to the corresponding central fold edge.

5. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend at an angle of substantially 45" to the longitudinal direction of the tube.

6. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend from respective points on the respective longitudinal outer fold edges.

7. A method as claimed in any one of the preceding claims, wherein each transverse seal is formed to extend across the entire

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Claims

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separate film layers together in the region of the gusset folds.

A bag from any web as described above takes on a convenient block shape when filled and sealed closed as shown in Figure

5 by virtue of the presence of the preferably inclined first and second seals 8, 9, 10, 11 and 13, 14, 15, 16 which assist in forming rectangular end faces of the block. The gusset fold parts 5, 6 and 5a, 6a are opened out to define side watts of the block while outer layers la and lh form the top and bottom surfaces of the block and also the end walls of the block. Such a block shape is convenient for stacking and of good appearance.

The method of manufacturing a web of serially interconnected plastics bags is now described with reference to Figures 6, 6a, 7 and 7a. The web is made from a flattened tube of plastics film in which seals may be formed by the application of heat and pressure. The tube has longitudinal gusset folds as previously described. In order to form the first and second seals heat sealing members 29a, 29b which extend over the gusset fold above and below outer layers la and lb respectively as far as the first and second seals are to extend across the tube are used. The heat seal members may be such that they can form all the first and second seals of one bag at a single application.An insulating separating means 30, for example a Pertinax (Registered Trade Mark) plate is inserted between the gusset fold parts 5 and 6 on one side and Sa and 6a on the other side to prevent the seals being formed through more than the requisite two film layers. A period of 1.5 seconds is typically necessary to form the first and second seals. The tube is then advanced through a distance at least as great as the greatest distance A between the seals already formed before the first and second seals for the next bag are formed. By forming all the necessary first and second seals in the web as shown in Figure 6a it is not necessary to remove and reinsert the insulating plate 30 while transverse seals 12 are formed in between.The transverse seals

12 are formed in the web by heat sealing members 31 and 32, one of which may serve merely as a support, the members are pressed towards each other in the regions in which the seals are to be formed for a typical duration of 2 to 4 seconds, the tube being advanced the required distance between each seal formation. Figure 7a shows the tube after seals 12 have been formed. The openings 23 and perforations

24 may be formed at any convenient stage ot the manufacture to complete the web. The bags may be filled and then sealed closed by a further transverse seal 19 which can be formed by further heat seal members (not shown).

WHAT WE CLAIM IS: 1. A method of manufacturing a web comprising a plurality of serially interconnected plastics bags, a first end of one bag lying adjacent the second end, which is either open or adapted to be open for filling when the bag is detached from the web, of the next bag in the series, from a flattened tube of plastics film having two opposed outer layers and a gusset fold formed along each longitudinal side, each gusset fold comprising a central and two outer longitudinal fold edges, first and second gusset fold parts of each gusset fold being defined between the central and a respective one of the outer fold edges, the method comprising the steps of: forming between each of the first and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one respective first seal in the region of the first end of each plastics bag to be formed in the web; forming a transverse seal between said outer layers at the first end of each bag, each transverse seal joining the inner ends of each of the respective first seals or extensions thereto and extending at least from one central fold edge to the other; and forming between each of the first and second gusset fold parts and respective adjacent outer layers on each side of the tube at least one second seal in the region of the second end of each plastics bag to be formed in the web.
2. A method as claimed in claim 1, wherein the steps of forming said first and second seals for a given bag in the web precede said step of forming said transverse seal for that bag.
3. A method as claimed in claim 1 or 2, wherein each transverse seal is formed such that it joins inner ends of said first seals at the relative central fold edge.
4. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend at least from a respective one of the outer fold edges to the corresponding central fold edge.
5. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend at an angle of substantially 45" to the longitudinal direction of the tube.
6. A method as claimed in any one of the preceding claims, wherein the first and/or at least some of the second seals of each bag extend from respective points on the respective longitudinal outer fold edges.
7. A method as claimed in any one of the preceding claims, wherein each transverse seal is formed to extend across the entire

width of the bag between the longitudinal outer fold edges.
8. A method as claimed in any one of claims I to 6, wherein each transverse seal is formed only between inner ends of the first seals.
9. A method as claimed in any one of the preceding claims, wherein the step of forming at least one second seal comprises forming at least two second seals between each gusset fold part and the respective outer layer, one of the second seals between each gusset fold part and the respective outer layer extending transversely of the tube between a respective central fold edge and outer fold edge.
10. A method as claimed in claim 9, wherein adjacent pairs of transverse second seals which pairs of seals are formed between gusset fold parts of the same gusset fold and respective outer layers, are bonded together to form a respective transverse single seal on each side of each bag to be formed in the web.
II. A method as claimed in any one of the preceding claims, wherein at least two second seals are formed between each gusset fold part and respective outer layer for each bag to be formed in the web, two seals which are formed between the same gusset fold part and outer layer being arranged to define a triangle having a base along the respective outer fold edge and an apex on the respective central fold edge.
12. A method as claimed in any one of the preceding claims, further comprising the step of perforating at least a portion of the outer layers and gusset fold parts at the second end of each bag to be formed in the web.
13. A method as claimed in any one of the preceding claims, further comprising the step of forming an opening in one of the outer layers between the second seals of each bag and the transverse seal of the next bag in the web.
14. A method as claimed in any one of the preceding claims, wherein the first and second seals for one bag are formed and the tube of plastics film is then moved through a distance at least as great as the greatest longitudinal distance between those first and second seals before the first and second seals of the next bag in the series are formed.
15. A bag detached from a web produced by a method as claimed in any one of the preceding claims, the bag being filled and provided with a further transverse seal between the outer layers and joining the inner ends of each of said second seals or their extensions to close the bag.
16. A bag as claimed in claim 15, wherein the further transverse seal intersects the second seals or their extensions on respective central fold edges.
17. A bag as claimed in claim 15 or 16, wherein the further ransverse seal extends only between the inner ends of the second seals.
18. A filled and sealed closed bag substantially as herein described with reference to the accompanying drawings.
19. A method of manufacturing a web comprising a plurality of serially interconnected plastics bags substantially as herein described with reference to the accompanying drawings.