CA1157825A

CA1157825A - Web comprising a plurality of plastics bags, having two block bottoms

Info

Publication number: CA1157825A
Application number: CA000288716A
Authority: CA
Inventors: Kornelis Herder
Original assignee: Wavin BV
Current assignee: Wavin BV
Priority date: 1976-10-14
Filing date: 1977-10-14
Publication date: 1983-11-29
Also published as: IT1087590B; JPS5742510B2; DK455477A; DE2746125A1; FR2367672A1; AT365515B; BE859675A; CH627701A5; ATA739077A; NL7611388A; SE7711439L; FR2367672B1; BR7706890A; GB1592905A; SU704445A3; JPS5383874A

Abstract

Abstract of the Disclosure A web comprises two layers of foil in the form of a flattened tube and divided transversely into a plurality of sections. Each of the sections when separated from the web and opened out forms a plastic bag of rectangular parallelopepidal shape. The web has along each of its longitudinal edges a gusset folded inwardly so as to lie between said two layers, each gusset defining an inner gusset fold and two outer gusset folds inter-connected by respective gusset parts. Each section has a trans-verse bottom seal at one end thereof connecting the two layers together at least in the region between the inner folds of the gussets at opposite sides of the web. First gusset seals at said one end of each section extend obliquely towards the one end from each outer gusset fold to the inner gusset fold at each side of the web, and each first gusset seal connects one gusset part to the web layer in contact therewith. The first gusset seals or extensions thereof intersect the transverse bottom seal substan-tially in the region near the intersection of the transverse bottom edge with the inner gusset folds. The transverse bottom seal is arranged to close the bag bottom either alone or in co-operation with the first gusset seals, and second gusset seals at said other end of each section extend obliquely inwardly and towards the other end from each outer gusset fold to the inner gusset fold at each side of the web. Each second gusset seal connects one gusset part to the web layer in contact therewith, and further gusset seals extend from the free inner ends of the second gusset seals or near thereto towards the outer web and connect the gusset parts to the respective web layers in contact therewith. A transverse incision is formed in one of the web layers at the other end of each section to allow each section to be filled and formed into a bag while on the web.

Description

1 ~5'7~5 'L'hi'; inventioll re:la~es to a web comprisiny a plurality of plastic bags of the type having gusset folds a:LoncJ the long~
itudinal sides, at least comprisiny a central lonqitudinal gusset fold edge and two outer longitudinal gusset fold edges which bound a first and seconcl yusset Eold with a ~irst transverse bo-t-tom seal which extends at least in the area between the central longitudinal gusset fold elges.
When known p]astlcs bags of this -type have been ~illed, they are provided with a second transverse bottom seal at -their other side which extends over the whole width of -the bay.
Such a bag has the disadvantage tha-t it ~oes no-t have a real block or parallelopepidal shape when heing filled, so that stacking may give rise to difficul-ties.
In the e~isting market there is a great demand for plastics bags, both ends of which have a real block shape when the bag has been filled.
Though this could be realised by providing the bags with two normal block bottoms, this involves great expenditure owing to longitudinal incisions, folding operations, and the like, which are required when a bag of this type is produced.
The present invention provides a web of plastics bags of the aforementioned type which can be comple-tely closed by means of one single second transverse bottom seal after filling the bag, whereafter the flat]y positioned filled bag is given a rectangular parallelopepidal shape, hereinafter referred to has a block-shape.
Accordingly, the present invention provides a web com-prising two layers of foil in the form of a flattened tube and divided transversely in-to a plurality of sections, each of which when separated from the web and opened out forms a plastic bag of rectangular parallelepipedal shape, said web having along each of its longitudinal edges a gusset folded inwardly so as to lie be-1 1 5 '~ 5 t~/ecl-l sa:id two klyers, c~ac~ sai(l (~ s.set ~efinirl(J arl inner yus-set :folcl and two outer gu6set ol.ds interconnected by respective yusset par-ts, each section havlng a tran.sverse bo-ttom seal at one end thereof connectlng sai.d two layers together at least in -the region between the inner folds oE the gussets at opposite sicles of the web, first c~usset seals at said one en~ of each sec-tion extendi.ny obliquely towards said one end from each outer gusset fold to the inner gusse-t fold at each side of the web, each said first gusset seal connecting one said gusset part to the web layer i.n contact therewith, sa:id first gusse-t seals or e~tensions thereof intersectiny the transverse bottom seal substantially in the region near the intersection of the -transverse bottom edge with the inner gusset folds, said transverse bottom seal beiny arranged to close the bag bottom either alone or in co-operation with the first gusset seals, and second gusset seals at said other end of each section extending obliquely inwardly and to-wards said other end from each outer gusset fold to the inner gusset fold at each side of the web, each said second gusset seal connecting one said gusset part to the web layer in contact therewith, and further gusset seals extending from the free inner ends of the second gusset seals or near thereto towards\the--out-e-web and connecting the gusset parts to the respective web layers in contact therewith, and a transverse incision formed in one of the web layers at said other end of each section to allow each on section to be filled and formed into a bag while ~ the web.
A web o:E this type has the great advantage that the bag to be filled does not have to be handled separately but can be filled when it is still connected with the web. Furthermore, each bag can be easily filled by forming a filling opening of a very determined clrcumference, that is to say a filling opening which is defined by the two innermost end sections of the second gusset fold part seals, whilst a subsequent filling of the bag ~ 157~

carl be easlly ~er~orllled by provicl:inq a secorl(l transverse bottom seal, wherea~te~r the combination oE second tran.sver~e bottom seal and the aforementior,ed second gusset fold par-t seals provides a second block bot-tom when the bag i.s filled.
Preferably, the t~bular foil is ~irst provided with at least one first and at least one seconcl gusset fold part seal on either sicle of the foil, and aft:er having moved the foil over a distance greater than the yreatest distance between the second and first gusset fold part seals, a transverse seal is applied.

This measure is very important Eor the continuous pro-duction of a web oE bags. For forming the first and second gusset fold part seals, a separation means must be held between the first and second gusset folds.
If now a transverse bottom seal connecting all four layers in the gusset folds is Eormed before the zone where the gusset fold part seals are formed, the separation means have to be removed from between the gusset fold in order to let pass the transverse bottom seal, and immediately thereafter the separation means must be reintroduced between the gusset folds. This remo~val and reintroduction of the separation means is not necessary if the transverse bottom seal is formed after the formation of the gusset fold part seals. In that case the separation means can be held in a fixed position.
So as to obtain an optimum block bottom shape, the first and second fold part seals extend under an angle of 45.
In order to simplify the filling operation of the bags when introducing the filling nozzles, third gusset fold part seals are provided which adjoin the second gusset fold part seals, where-by the second and the first gusset fold part seals form a triangle together with the longitudinal gusset fold edges.
The third gusset fold seals create a funnel shaped open-ing of the bag which facilitates the filling operation.

:

1 157~

l~reEer:a))ly, ~o~l~th gusset Eold part seals extend per-pendiclllar to the longitucl:irlal gusset fold edcJes. Two fourth gusset fold part seals .situated on the same side are pre~erably united to form one seal.
Such a fourth seal oFfers the great advantage that the sides of the bag are consiclerably streng-thenecl and that four foil layers do no-t have to be connected lo each other in the slcle region of the bag. In the central par-t of ~he bag only two foil layers need be conn~cted during -tlle sealing opera-tion.
By providing one of the foil layers of -the tubular foil of the web with anlincision or opening in -the region be-tween the second gusset fold part seals and the nearest firs-t transverse bot-tom sea], -the bags can be easily filled while maintaining the connection of the bag with the web. The bag is separated from the web after the filling operation.
When the tubular foil is still flat the other foil side of the tubular foil may then be provided with a per~oration so as to facilitate removal o~ the bag from the web.
A perforation running over the entire cirucmference of the tubular foil may also be provided in the region between the first bottom seal and the nearest second gusset fold part seals.
This embodiment lends itself well for removing a bag from a web.
The invention in another aspect relates to a method for filli~g a plastics bag having gusset folds along the longitudinal sides, at least comprising a central and two outer longitudinal gusset fold edges which bound a first and a second gusset fold part with a first transverse bottom seal which extends at least between the central longitudinal gusset fold edges. The plastics bag is filled and subsequently a second transverse bottom seal is provided in such a manner that the second gusset fold part seals or their extensions intersect the second transverse bottom seal principally in a region near the intersection of the second trans-1 157~32~

verse bottc)m 5et.~1 Wi.th !:lle ccntraL longituclin~l gusse~ fold edges, whereas the second transverse~ bottom s~al closes -the bay eith~r in or no-t in co-operation wi-th the second g~sse-t fold seal ~arts.
PreEerably, the first and second -transverse bo-ttom seals extend from -the oLl-ter lonyitudinal gusset fold edyes and uniting the superimposed foil layers in the side reyions of the bags to form one single seal.
The invention will now be described in more deta.il by way of example only with referellce to -the accompanying draw-ings, in which;
~ig. 1 shows a web comprising various interconnected plastics bags;
Fig. 2 shows a part of a web of plastics bags;
E'ig. 3 shows parts of a web of plastics bags, illustr-ating various gusset fold part seals;
Fig. 4 shows a closed plastic bag of figure 3;
Fig. 5 shows a ready-made filled bag;
Fig. 6 shows the members for forming first and second gusset fold seals;
Fig. 6a shows a tubular foil with first and second gusset fold seals obtained in this way;
Fig. 7 shows the step of forming the first transverse seals; and Fig. 7a shows the web with transverse and gusset fold seals.
Fig. 1 shows a web of a plurality of plastics bags 1, each bag having gusset folds along the longitudinal sides, com-prising two outer longitudinal gusset fold edges 2 and 3 respect~
ively 2a and 3a, and central longitudinal gusset fold edge is 4, 4a respectively.
The ends of the plastics bags 1 have a first transverse bottom heat-seal 12 so that the superlmposed foil layers la and 3 1~7B2t;

Ib are at leclst :intercollnected in the re~iorl bet~leen the central longitudinal ~uss~t fold edcles 4, 4a.
q'he first tr~nsverse bottom seal :L2 preferably extends onto the outer lonyitudinal gusset fold edges 2, 3, 2a, 3a To form -the seal 12, the superimposed oil layers la and lb are interconnectecl, whereas the foil ]ay~rs la and lb, and firs-t yusset folds parts 5, 5a and second folds par-ts 6, 6a, are all inter-connected in the edge regions. A s~al oE this t~pe produ-es a very strong bag and excellen-t appearance in the filled condition.
To obtain a block-bottom shape in the filled bag a first fold part seal 8 extends from the intersectlon 8a, 8a' oE
the transverse bot-tom seal 12 with the central longitudinal gusset fold edge 4 to the outer longitudinal gusset ~old edge 2. "Seal"
means here a heat-seal. ~lhen the bag is still flat another first gusset fold part seal 9 is formed underneath said seal 8, which extends in the same direction as said gusset fold part seal 8.
On the other side of the bag similar first gusset fold part seals 10, 11 extend between the intersection 8a' of the transverse bottom seal 12 with central longitudinal gusset fold edge 4a and a point on one of the outer longitudinal gusset fold edges 2a, 3a. The first gusset fold part seals 8, 9, 10, 11 extend expediently under an angle of 45 with respect to the outer longitudinal gusset fold edges.
The other end of the bag comprises second gusset fold parts 13, 14, 15 and 16, which extend from the outer longitudinal gusset fold edges 2 and 3 onto the central longitudinal gusset fold edges 2a, 3a respectively, onto the central longitudinal gusset fild edge 4a. The second gusset fold seals 13, 14, 15, 16 extend at an angle of 45 with respect to the extension of the line which connects the end sections 17 and 18 of the aformention-ed four second fold part seals.
As shown in Figure 4 a second transverse bottom seal 19 I I S ~

ca~ be ~)rovicle(l al~el rilllncJ thc~ i)ag ~rllls seal extends between the a~orementioned sections 17 allcl 1~.
In order to obtain a bag which is ag strong as possible, the seal 19 ex-tends alollg the edge regions where there are the first and seco~ usset fold seals 8, 9; 10, 11; and 13, 14; 15, 16, respectively. rrhe superimposed layers in the edge regions are connected to form combined third gusset ~o:Ld part seals 21-and 20 as will be exp]ained later.
In order to simplify the finaL welding operation, the thircl seals 20, 21 can be provided in -the web. In some cases difficulties may arise when a seal 19, which is contained at both ends by the seals 20 and 21 in the edge regions, has-to be provided at a filling location since the latter seal consists of four foil layers which are interconnected, whereas the seal 19 has only to connect two foil layers la, lb with one another.
In order to obtain a very good Eilling opening, two separate third gusset fold pa~t seals 20a, 20b, 21a and 21b, which -are interconnected in the filled bag is closed, may be provided instead of combined third seals 20, 21 as shown in Fig 3.
The embodiment of Fig. 3 shows a bag which also com-prises fourth gusset fold part seals 25, 26, 27, 28 provided in the same manner as the Eirst fold seals 8, 9, 10, 11, respectively, and which extend moreover approximately in the same direction as the aforementioned first fold seals 8, 9, 10, 11. The fourth gusset fold part seals 25, 26, 27, 28 offer the advantage that on easy centering of the bag below the filling machine can be realiz-ed. The gusset seals may have another sharper angle than 45 with respect to the outer longitudinal gusset fold edge 2. This is true also for the fourth gusset seals.
Fig. 2 shows a web with bags wherein instead of two facing third gusset fold seals 20a, 20b and 21a, 21b only single seals 20, 21 which each interconnect four layers, by heat seal-I 157~5 incl are useclO The sea:ls ~0, 21 extend pre~erably beyond the central longitudinal gusset ~old edyes 4, 4a, sinc~ in that case a very good seal can be obtained by heat~sealing. These seals then adjoin the end sections 17a, 18a.
Fig. 5 shows a ready-made bag which is ob-tained by using a plastic bag of a web according to Fig. 1. setween -two subsequent bags one of the foil layers la may be provided with an incision 23 so as to enable filling said bag (see Fig. 1).
Underneath the incision 23 in the other foil layer lb, a perEor-ation 24 can he made so as to facilitate tearing the bag off the web after the filling operation. The incision 23 can also extend on either side into incisions 23a and 23b, which cut the gusset through folds so as to facilitate filling the bags. The webs can also have a perforation 24 along their entire circumference.
When a web is provided with such a perforation 24, the bag can be easily torn off the web.
It will be self-evident that the perforations are always in the vicinity of the first transverse bottom seal 12 of each bag. The first gusset fold part seals 8, 9, 10, 11 may not e.~tend to the central edges 4 and 4a. It goes without saying that they can also terminate before reaching the outer longitudinal g~lsset fold edges, but this is not preferable.
F'ig. 6 shows the first phase of forming first or second gusset fold seals 8, 9, 10, 11 or 13, 14, 15, 16. In order to prevent heat sealing of, e.g., gusset fold 5a to gusset fold 6a, f~ f~ c ~,~
a separating means 30, e.g., a Pertinax/~tplate, is positioned between fold parts 5a and 6a. The heat sealing members 29a, 29b form the seals as required. These seals can be formed in about 1.5 seconds. Fig. 6a shows the web af-ter forming the gusset fold seals 8, 9, 13, 14, 15, 16, 28, etc.
Fig. 7 shows the step of forming -the first transverse 1 ~7~2~

secl.ls 1.2, ior closirl~J tl~c tub~lL.-Ir oi.].. '~ .is closure i.s ob-tained by means of a transversc heat sea]. bar 31. and support 32.
Ilowever, support 32 may be a heat: seal bar. The transverse scal can be obtainecl in about 2 to 4 seconds.
It should be notecl-th.lt -the assembly 31, 32 will only be active aEter forming at least one palr oE first and second gusset fold par-t seals such as 8, 9 and 13, 14, 10, 11 and 15, 16 and the web part has rnoved from position lb -to position la, over a distance of at least the dist.ance A, which is the cJreatest distance between first and second gusset fold seals at one side of the foil. In this way the separa-ting means 30 may be hek1 continuously in the gusset fold between parts 5, 6 and 5a, 6a as the transverse heat seal bar is only active a~ter formation of the gusset fold part seals.

g

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A web comprising two layers of foil in the form of a flattened tube and divided transversely into a plurality of sections, each of which when separated from the web and opened out forms a elastic bag of rectangular parallelepipedal shape, said web having along each of its longitudinal edges a gusset folded inwardly so as to lie between said two layers, each said gusset defining a central gusset fold and two outer gusset folds inter-connected by respective gusset parts, each section having a transverse bottom seal at one end thereof connecting said two layers together at least in the region between the inner folds of the gussets at opposite sides of the web, first gusset seals said one end of each section extending obliquely towards said one end from each outer gusset fold to the inner gusset fold at each side of the web, each said first gusset seal con-necting one said gusset part to the web layer in contact there-with, said first gusset seals or extensions thereof intersecting the transverse bottom seal substantially in the region near the intersection of the transverse bottom edge with the inner gusset folds, said transverse bottom seal being arranged to close the bag bottom either alone or in co-operation with the first gusset seals, and second gusset seals at the other end of each section extending obliquely inwardly and towards said other end from each outer gusset fold to the inner gusset fold at each side of the web, each said second gusset seal connecting one said gusset part to the web layer in contact therewith, and further gusset seals extending from the free inner ends of the second gusset seals or near thereto towards each side of the web and connecting the gusset parts to the respective web layers in contact therewith and a trans-verse incision formed in one of the web layers at said other end of each section to allow each section to be filled and formed into a bag while on the web.

2. A web according to claim 1, wherein the first trans-verse seal is formed after having formed said first and second gusset seals.

3. A web according to claim 1, wherein the tubular foil is first provided with at least one first and at least one second gusset seal at each side of the foil after having moved the foil over a distance being greater than the greatest distance between the second and first gusset fold part seals, a transverse seal is applied.

4. A web according to claim 1, wherein the first gusset seals or extensions thereof substantially intersect the first transverse bottom seal in the intersection of the first transverse bottom seal with the central longitudinal fold edges whilst the transverse bottom seal closes the bag bottom whether or not in co-operation with the first seals.

5. A web according to claim 1, wherein the first or second gusset seals extend to or beyond the central longitudinal gusset fold edges.

6. A web according to claim 1, wherein the first and/or second gusset seals form an angle of 45° with respect to the outer longitudinal gusset fold edges.

7. A web according to claim 1, wherein the first and/or second gusset fold part seals extend from the outer longitudinal gusset fold edges.

8. A web according to claim 1, wherein other gusset seals in the form of third gusset seals extend substantially perpendicularly to the longitudinal gusset fold edges and form an extension of said transverse bottom seal.

9. A web according to claim 8, wherein the bag also comprises as other gusset fold part seals fourth gusset seals which adjoin the second gusset seals and whereby the second and fourth gusset seals form a triangle together with the outer long-itudinal gusset fold edges.

10. A web according to claim 1, wherein the first trans-verse bottom seal extends over the entire width of the bag from one longitudinal gusset fold edges to the outer longitudinal gusset fold edges on the other side of the bag, while fully uniting the super-imposed layers in the region where there are fold parts.

11. A web as claimed in claim 1, wherein the first trans-verse bottom seal merges into the first gusset seals.

12. A web according to claim 1, wherein always two facing gusset seals are united to one single seal which extends to the area between the inner longitudinal gusset fold edges.

13. A web according to claim 8, wherein said first gusset seals, said outer longitudinal gusset fold edges, and said third gusset form a right-angled triangle.

14. A web according to claim 1, wherein the web comprises a perforation extending along the entire circumference of the tubular foil in the vicinity of the first transverse bottom seal.

15. A web according to claim 1, wherein the gusset fold parts are cut through beside the incision in the foil web.

16. A web according to claim 1, wherein the tubular foil is also provided with a perforation which at least extends in the vicinity of the web layer situated opposite the web layer with said incision.