EP1232954A1 - Bag chain with drawstrings and method of its manufacture - Google Patents

Abstract

The sacks are made in a line joined together edge to edge. The sack openings are located along one side of the line and have hemmed edges with drawstrings. Each drawstring is fixed to one edge of a sack and accessed through a cut-out at the opposite edge. The sacks (1a - 1e), e.g. for domestic refuse, are made in a line joined together edge to edge (4, 4a, 5a, 5b, 4b, 4c, 5c, 5d, 4d, 4e). The sack openings (6a, 6b, 6c, 6d) are located along one side of the line and have hemmed edges (7) with drawstrings (8). Each drawstring is fixed to one edge of a sack and accessed through a cut-out (9) at the opposite edge. The cut-outs are made at regular intervals along the line corresponding to the width of the sacks, and the drawstrings are in two strands joined at the point of the cut-outs.

Description

The present invention relates to a chain of bags, especially of plastic, in particular of bags for storage household waste, of the so-called "sliding link" type, comprising a opening bordered by a sheath in which a sliding link is arranged grippable from the outside.

In general, in industrialized countries, waste and garbage, especially household garbage, is stored in plastic bags. These plastic bags have generally two plastic faces connected to each other on their periphery by providing an opening area. These bags have the most often a rectangular shape, although other shapes are possible: for example, the bottom of the bag can have a rounded shape. In the following description, for ease of reference, reference will be made to bags of rectangular shape, but it is understood that the bags according to the present invention are not limited to this form.

The bags can be prepared from two sheets rectangular plastic, by welding three sides of the rectangle and leaving the fourth side open. They can also be prepared from a single sheet of plastic that is folded, either form the bottom of the bag, or to form a lateral side of the bag, two of the other sides being heat sealed. As is known, in the bags, the faces can be connected together by a bellows at the bottom and / or at a lateral side, preferably on two lateral sides.

It is also known to manufacture so-called "link bags sliding "in which the opening of the bag, whatever it is, is bordered a sheath in which a link is likely to slide. The link can be made of a single strand, the two ends of the link being fixed between them. It can also consist of two strands, each strand being fixed by each of its ends to the sheath. The link is, from preferably a plastic tape capable of being heat sealed.

The sheath is generally prepared by folding the sheet of plastic material parallel to the opening and by heat sealing parallel to the edge of the film. The sheath can be continuous or formed from two separate parts. This is particularly the case when the bags are formed by heat sealing the lateral sides and that the sheath is formed by folding the plastic sheet before heat sealing the sides side.

We know in particular from document DE 36 43 503 a heat-sealable plastic bag with two welded strands by their ends to form a closing ring, movable in the sheath on both sides of the bag. This bag has two indents in the sheath at the lateral sides of the bag to allow gripping of the closing ring and allow it to slide in the sheath to close the bag. In a known manner, the recesses can also be provided in the middle of the opening, equidistant from two lateral sides, especially when the link consists of two strands fixed at each of their ends to the sheath by heat sealing together with the side edges of the bag.

This bag has drawbacks: in bags of this type, to close the bag, the user pulls the link by grabbing it by everyone of the two recesses so as to slide the link and close the bag. He then makes a knot with the two link portions that were drawn and released by sliding to ensure that the bag does not risk accidentally open during subsequent handling.

For ecological reasons, we tend to make a selective sorting garbage, especially household garbage. For this purpose, we ask the user to put the different types of garbage: glass, paper, plastics, .... in separate bags for processing the sorted materials separately, in particular for the purpose of recycling them. When the bags have two indentations in the sheath, the knot made with the two drawn link portions is difficult to undo to open the bag and the time thus lost increases the cost of treatment, in particular recycling of the different sorted materials.

According to the present invention, it has been found that, to close a "sliding link" bag, when users could not pull that a portion of the link by a single recess of the sheath containing the tie, they didn't tend to tie a knot, but just pull the link to close the bag. Under these conditions, when the sorting operation, just loosen the link to open the bag. It is not therefore generally no longer necessary to untie a knot, which constitutes time saving.

Document FR 1 397 298 discloses a sachet with sliding closure of this type and its manufacturing process. This sachet has a front face and a rear face which each have side of a sachet opening, a hem with a drawstring in which one end of these cords is attached to the edge side of the bag or in the vicinity thereof inside the hem; the other end being detached or made detachable from the hem by a line of least resistance or discovered by a notch in the hem, to be able to be grasped by the fingers.

This bag has drawbacks: in fact, the lines of perforations to make the end of the cord detachable are near the boundary between two bags, so that they may tear when the bags are separated at the end of the manufacturing process. These perforation lines must therefore meet specifications precise: too fragile, they are damaged at the end of the manufacturing process; too resistant to tearing, they make, on the contrary, the cord unusable. These specifications complicate the manufacturing process and increase its cost.

In the continuous manufacturing processes disclosed by DE 3643 503 and FR 1 397 298, the notches or the lines of perforations are formed by a cutting tool like a utility knife reciprocating at intervals corresponding to the width of a bag. The process therefore reaches a rate of production of bags relatively low compared to the operating rate of machines used, which corresponds to a scrolling of the chain of manufacturing equal to the width of a bag, which increases the costs of operation, maintenance and replacement of said machines.

The object of the present invention is to provide link bags sliding in which only one portion of the link is graspable, said bags not having the above drawbacks.

For this, the invention relates to a chain of plurality of bags assembled by adjacent side sides, each bag of said chain comprising two faces connected together over their entire periphery, with the exception of a longitudinal edge of said chain, each bag of said chain having an opening opening on said edge longitudinal, each side of each bag having a sheath bordering said opening, a sliding link being disposed in each sheath, each link being fixed in said sheath at one of the two sides lateral of said bag and grippable from the outside by a recess formed in said sheath at the other lateral side of said bag, characterized by the fact that the bags in the bags of the said chain are cut along said longitudinal edge at regular intervals corresponding to the width of two bags, the bags of said chain being precut transversely between their lateral edges adjacent to the right of each embrace and halfway between two embraces successive to be able to be separated.

Advantageously, said transverse precut at the level of each recess is carried out substantially on an axis transverse of symmetry of said recess, so that said embrace be able to separate into two embraces of forms substantially symmetrical and specific to each respective bag after separation of the bags on both sides of said precut.

Preferably, the link arranged in each sheath of a bag consists of two strands connected together at said recess.

Advantageously, when said chain comprises at least three consecutive bags, the middle bag among said three bags has a first side side adjacent to the opposite side side of a second bag among said three bags, the two adjacent lateral sides of the middle bag and the second bag ending at said longitudinal edge in the bottom of a recess, said recess being astride said bag middle and said second bag; the second lateral side of the median sac being adjacent to the opposite lateral side of the third bag among said three bags, the two adjacent lateral sides of the middle bag and the third bag do not communicating with no embracing of said chain.

Preferably, the chain is in the form of a winding around a substantially transverse direction, for facilitate its packaging, storage and transport.

a) découper un fourreau continu constitué d'un film de matière plastique, par exemple de polyéthylène, sensiblement selon deux axes longitudinaux transversalement opposés dudit fourreau, pour obtenir deux demi-fourreaux séparés,

b) écarter les deux demi-fourreaux l'un de l'autre,

c) découper des portions de film au voisinage des deux bords longitudinaux de chaque demi-fourreau, à des intervalles réguliers correspondant à deux fois la largeur d'un sac le long de chaque bord longitudinal, lesdites portions découpées étant sensiblement appariées dans la direction transversale dudit demi-fourreau,

d) disposer à l'intérieur de chaque demi-fourreau deux brins (8) constitués chacun d'un ruban de matière plastique, lesdits brins étant disposés le long de chacun des deux bords longitudinaux dudit demi-fourreau, au droit desdites portions découpées,

e) replier vers l'intérieur chaque bord longitudinal de chaque demi-fourreau autour du brin correspondant, sensiblement le long d'un axe longitudinal passant sur lesdites portions découpées, de façon que chaque brin reste accessible de l'extérieur par un embrèvement résultant du pliage sur lui-même de l'emplacement de chaque portion de film découpée précitée,

f) thermosouder les bords repliés, parallèlement à la direction longitudinale dudit demi-fourreau, pour former sur chaque bord du film une gaine dans laquelle est logé un brin de lien,

g) effectuer, à intervalles réguliers correspondant à la largeur d'un sac, une pluralité de paires de thermosoudures transversales adjacentes, correspondant aux côtés latéraux d'une pluralité de sacs adjacents formant une chaíne, chaque paire de thermosoudures étant formée alternativement au droit d'un embrèvement, et à mi-distance entre deux embrèvements successifs,

h) prédécouper les sacs entre les thermosoudures de chaque paire de thermosoudures précitée.

The subject of the invention is also a method for manufacturing the aforementioned bags, said method being characterized in that it comprises the following steps consisting in:

a) cutting a continuous sheath made of a plastic film, for example of polyethylene, substantially along two transversely opposite longitudinal axes of said sheath, in order to obtain two separate half-sheaths,

b) move the two half-sleeves apart from one another,

c) cutting portions of film in the vicinity of the two longitudinal edges of each half-sheath, at regular intervals corresponding to twice the width of a bag along each longitudinal edge, said cut portions being substantially matched in the transverse direction said half-sheath,

d) placing inside each half-sheath two strands (8) each consisting of a plastic tape, said strands being arranged along each of the two longitudinal edges of said half-sheath, in line with said cut portions,

e) fold inwards each longitudinal edge of each half-sheath around the corresponding strand, substantially along a longitudinal axis passing over said cut portions, so that each strand remains accessible from the outside by a recess resulting from the folding on itself of the location of each aforementioned cut film portion,

f) heat-sealing the folded edges, parallel to the longitudinal direction of said half-sheath, to form on each edge of the film a sheath in which is housed a strand of link,

g) perform, at regular intervals corresponding to the width of a bag, a plurality of pairs of adjacent transverse heat seals, corresponding to the lateral sides of a plurality of adjacent bags forming a chain, each pair of heat seals being formed alternately at right angles to '' a kiss, and halfway between two successive kiss,

h) pre-cut the bags between the heat seals of each pair of aforementioned heat seals.

This process according to the invention is advantageous compared to prior art method according to FR 1 397 298, in which the material first of the bag manufacturing process is a strip of material flexible or a flat sheath with a W-fold and split on one side. During the process of the prior art, such a strip must run with a well-controlled orientation; as well as the W-fold of the sheath must be kept in constant shape and orientation. The process according to the invention overcomes these costly constraints.

Advantageously, in step c) above, cutting of substantially circular portions, so as to obtain in step h) above, bags each having a single recess substantially in the form of quarter circle.

a) découper longitudinalement un fourreau continu constitué d'un film de matière plastique, par exemple de polyéthylène, sensiblement en son milieu pour obtenir deux demi-fourreaux séparés,

b) écarter les deux demi-fourreaux l'un de l'autre,

c) replier vers l'intérieur chaque bord longitudinal de chaque demi-fourreau,

d) découper le long des deux bords longitudinaux repliés de chaque demi-fourreau, à intervalles réguliers correspondant à la largeur de deux sacs, des portions de film,

e) introduire à l'intérieur de chaque bord replié du demi-fourreau, un brin constitué d'un ruban de matière plastique, de façon que chaque brin soit accessible de l'extérieur par l'embrèvement résultant de chaque portion de film découpée,

f) thermosouder les bords repliés, parallèlement à la direction longitudinale dudit demi-fourreau, pour former une gaine sur chaque bord du film, dans laquelle est logé un brin de lien,

g) effectuer, à intervalles réguliers correspondant à la largeur d'un sac, une pluralité de paires de thermosoudures transversales adjacentes, correspondant aux côtés latéraux d'une pluralité de sacs adjacents formant une chaíne, chaque paire de thermosoudures étant formée alternativement au droit d'un embrèvement, et à mi-distance entre deux embrèvements successifs,

h) prédécouper les sacs entre les thermosoudures de chaque paire de thermosoudures précitée.

In another embodiment, the bags are produced by a process characterized in that it comprises the following stages consisting in:

a) cutting a continuous sheath longitudinally made of a plastic film, for example of polyethylene, substantially in the middle to obtain two separate half-sheaths,

b) move the two half-sleeves apart from one another,

c) fold inwards each longitudinal edge of each half-sleeve,

d) cut along the two folded longitudinal edges of each half-sheath, at regular intervals corresponding to the width of two bags, portions of film,

e) introduce inside each folded edge of the half-sheath, a strand made of a plastic tape, so that each strand is accessible from the outside by the removal resulting from each portion of cut film,

f) heat-sealing the folded edges, parallel to the longitudinal direction of said half-sheath, to form a sheath on each edge of the film, in which is housed a strand of link,

g) perform, at regular intervals corresponding to the width of a bag, a plurality of pairs of adjacent transverse heat seals, corresponding to the lateral sides of a plurality of adjacent bags forming a chain, each pair of heat seals being formed alternately at right angles to '' a kiss, and halfway between two successive kiss,

h) pre-cut the bags between the heat seals of each pair of aforementioned heat seals.

Advantageously, in step d) above, cutting of substantially semi-circular portions, so as to obtain in step h) above, bags each having a unique shaped recess substantially quadrant.

Halving the frequency of cutting film portions compared to the prior art helps speed up the manufacturing bags and reducing manufacturing costs. Indeed, it causes a reduction in the wear of the machines used for make these cuts and a reduction in their costs of operation, maintenance and replacement. Machines thus operate at two distinct frequencies, one for cutting out dimples every two bags, the other to carry out the pre-cuts at each bag; unlike the prior art where only one frequency identical is used.

• la figure 1 est une vue en élévation d'un sac de la chaíne de la figure 2 ;
• la figure 2 est une vue en élévation de la chaíne de sacs selon l'invention ;
• les figures 3 à 10 représentent les étapes successives du procédé de fabrication de la chaíne de la figure 2 dans deux différents modes de réalisation de l'invention.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the accompanying drawing. On this drawing :

• Figure 1 is an elevational view of a bag of the chain of Figure 2;
• Figure 2 is an elevational view of the bag chain according to the invention;
• Figures 3 to 10 show the successive stages of the manufacturing process of the chain of Figure 2 in two different embodiments of the invention.

The bag shown in Figure 1 is designated in its together by reference 1. It consists of two planar faces symmetrical about a plane obtained by folding a sheet in half of plastic relative to the bottom 3 of the bag. The lateral sides 4 and 5 of the bag are obtained by heat sealing. Both sides are like this interconnected over their entire periphery except for a so-called area opening, opposite the bottom 3.

The opening 6 of the bag is bordered on each side by a sheath 7. This sheath 7 is formed by folding inward of the sheet of plastic on each side of the bag and by welding 10 of this fold on the face, parallel to the edge of the opening 6. The parts of this sheath 7 carried by the two faces of plastic material are also welded between them at the lateral sides 4 and 5. In the sheath 7, is arranged a sliding link 8 consisting of two plastic strands generally different in color from that of the constituent sheet of sides of the bag. On the sheath 7, a single recess 9 is provided at the level of one of the lateral sides 5 of the bag, for manual gripping of the sliding link 8. One end of each strand of the link 8 is fixed by heat sealing in the sheath 7 at the lateral side 4 of the bag, and the two strands are connected together by heat sealing at 11 at the recess 9 formed in the sheath 7, in the extension of the other lateral side 5 of the bag 1. The link formed by the two strands 8 heat-sealed at 11 is accessible in the embossment 9. The link 8 is fixed to the sheath at a point distant from the cutout 9. It is thus more easy to pull on link 8, causing the sheath to pucker at level of the opening 6 of the bag.

The continuous process of manufacturing a chain of bags such that the one described above will now be described with reference to Figures 3 to 10.

As can be seen in FIG. 3, to begin with, a continuous sheath 14 of plastic film, for example polyethylene, is scrolled on a machine (not shown) in the direction indicated by the arrow 15. The sheath 14 is cut longitudinally , substantially along a plane of symmetry P thereof, for example with a cutting knife (not shown), in order to obtain two separate half-sheaths 14 a and 14 b , visible in FIG. 4.

Posteriorly, as visible in figure 6, along the two longitudinal edges 12 of each half-sleeve (only one 14b is shown), are cut circular portions 16, at intervals regulars corresponding to twice the width ℓ of a bag. Portions 16 are cut in pairs at the same longitudinal level of the half-sleeve 14b and respectively at the same distance from the two edges 12. Des toothed crowns (not shown) can thus cut into a same operation the two walls of a half-sheath superimposed edge to edge.

Then, as visible in FIG. 7, a strand made of a plastic tape 8 is placed along each longitudinal edge 12 inside each half-sheath (of which only one 14 a is shown), at right of the innermost semi-circular portion of each aforementioned circular cut 16. The longitudinal edges 12 of the half-sheath are then folded inwards along a longitudinal axis B substantially diametrical relative to the circular cutouts 16, to form a fold around each strand 8, so that each strand 8 remains accessible in a recess 18 of semi-circular shape.

In a second embodiment of the method, the steps of Figures 6 and 7 above are replaced by the two steps following:

The two longitudinal edges 12 of each half-sheath are first folded inwards over a distance d substantially greater than the radius of the abovementioned circular cutouts, to form a fold along each edge 12, as can be seen in FIG. 5 where only 14a is shown. Then portions in semicircles 116 are cut at regular intervals corresponding to twice the width ℓ of a bag. The portions 116 are cut in pairs at the same longitudinal level of the half-sheath 14 a with their diameter substantially coinciding with the two edges 12. When the two edges 12 are superimposed, toothed rings (not shown) can cut the two double walls superimposed by a half sheath in one operation.

Then, as visible in FIG. 7, a strand made of a plastic tape 8 is introduced into each fold along each longitudinal edge 12 through the interior of each half-sheath (of which only one 14 a is shown) . At the location of the cut portions 116, the recesses 18 of semi-circular shape leave the strands 8 visible and accessible.

The rest of the process is the same in the two modes of production :

As shown in FIG. 8, the free edges of the abovementioned folds are welded inside each half-sheath (of which only one 14a is shown), along line 10, to form a sheath 7 on each of the edges 12 of the film. The sheath 7 is formed by a double wall of the film, the recesses 18 of semi-circular shape are superimposed. The bottom 3 of the bags is the side of the half sleeve 14 opposed to the ducts 7.

As shown in Figure 9, we then carry out regular intervals corresponding to the width t of a bag, a plurality of pairs 19 and 20 of adjacent transverse heat seals. The pairs 19 transverse heat seals are carried out midway between two recesses 18 and correspond to the lateral sides 4 of a chain 13 of adjacent bags. 20 pairs of heat seals transverse, alternating with pairs 19, are made in line with each recess 18 and correspond to the lateral sides 5 of the bags of the chain 13. Each pair 19 and each pair 20 of heat seals adjacent so that the individual bags can then be separated 1 by transverse cutting, between the heat seals of each pair. The strands of the link 8 are fixed in the sheath 7 by the pairs of heat seals 19, while the strands of the link 8 are connected together, at level of semicircular recesses 18, by pairs of heat seals 11 which are in the transverse extension of the pairs of heat seals 20. It is therefore understood that by the same operation welding, we can weld the sides 5 and the links 8, independently of the each other.

Then, as shown in Figure 10, we perform a precut between the two heat seals of each pair 19 and of each pair 20, to facilitate subsequent separation of each bag 1 individual chain 13 obtained. Pre-cutting consists of making a line of least resistance throughout the thickness of the bag, by example a line of perforations crossing the two faces of the half-sheath. The line of perforations between each pair 19 of thermowelds also passes through the sheaths 7 of each face and the plastic tapes 8 which are arranged therein. The line of perforations between each pair 20 of heat seals extends also at the level of the pair of heat seals 11 of the two tapes 8 visible in the recess 18. Finally, a label 21 is affixed on one face of each bag of the chain 13, that is to say at intervals of length equal to the width ℓ of a bag on the chain 13.

In the method described above, the sheath 14 having a constant running speed, pairs of heat seals 19 and 20 are produced by the same machine, operating at a double rate compared to the machine cutting the portions into discs 16 or in half-discs 116.

Figure 2 shows the chain 13 of bags completed, formed of bags 1a, 1b, 1c, 1d, the assembled by their adjacent lateral sides 4, 4a; 5a, 5b; 4b, 4c; 5c, 5d; 4th. Each precut made between a pair 20 of heat seals corresponds to a transverse axis of symmetry of the recess 18 at the bottom of which it ends. It follows that each recess 18 in a semicircle straddles two adjacent bags and is able to be divided into a recess 9 in the form of a quarter circle on each of the two bags. Therefore, the bags 1 a - e of the chain 13 are presented alternately with their recess 9 at the right end or at the left end of their respective opening edges 6 a - e . The finished chain 13 is detached from the production line when it has the desired number of bags and it can be rolled up for storage. The chain 13 can also be used to manufacture individual bags 1 by separating the two edges on each side of the precuts.

Of course, the abductions could have a form any, for example elliptical. So that the bags all have the same form of abutment, it is better that the film portions cut from the continuous film sheath each have an axis transverse of symmetry, and, in the first embodiment of the method, a longitudinal axis of symmetry.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not there in no way limited and that it includes all the technical equivalents of means described as well as their combinations if these fall within the part of the invention.

Claims (9)

Chain of a plurality of bags (1 a - e ) assembled by adjacent lateral sides (4, 4 a ; 5 a , 5 b ; 4 b , 4 c ; 5 c , 5 d ; 4 d , 4 e ), each bag (1) of said chain (13) having two faces interconnected over their entire periphery, except for a longitudinal edge (12) of said chain, each bag of said chain having an opening (6,6 a - d ) opening onto said longitudinal edge (12), each face of each bag (1) having a sheath (7) bordering said opening (6), a sliding link (8) being disposed in each sheath (7), each link (8) being fixed in said sheath at one (4) on the two lateral sides of said bag and grippable from the outside by a recess (9) formed in said sheath (7) at the other lateral side (5) of said bag, characterized in that the recesses (18) of the bags of said chain (13) are cut along said longitudinal edge (12) at regular intervals corresponding spondant to the width of two bags, the bags of said chain being precut transversely between their lateral edges adjacent to the right of each recess (18) and halfway between two successive recesses to be able to be separated. Chain according to claim 1, characterized in that said transverse precut at each recess (18) is carried out substantially on a transverse axis of symmetry of said recess, so that said recess (18) is able to separate into two recesses (9 a - b ) of substantially symmetrical shapes and specific to each bag (1 a - b ) respectively after separation of the bags from the two sides of said precut. Chain according to claim 1 or 2, characterized in that the link (8) disposed in each sheath (7) of a bag (1) consists of two strands connected together at said recess (18). Chain according to one of claims 1 to 3, said chain comprising at least three consecutive bags (1 a - c ), characterized in that the median bag (1 b ) among said three bags has a first lateral side (5 b ) adjacent to the opposite lateral side (5 a ) of a second bag (1 a ) among said three bags, the two adjacent lateral sides (5 a , 5 b ) of the median bag and of the second bag ending at said longitudinal edge ( 12) in the bottom of a recess (18), said recess (18) being astride said median bag (1 b ) and said second bag (1 a ); the second lateral side (4 b ) of the median bag being adjacent to the opposite lateral side (4 c ) of the third bag (1 c ) among said three bags, the two adjacent lateral sides (4 b , 4 c ) of the median bag and the third bag not communicating with any recess of said chain. Chain according to one of claims 1 to 4, characterized in that it is in the form of a winding around a substantially transverse direction. Method for manufacturing a chain of bags according to one of claims 1 to 5, characterized in that it consists in: a) cutting a continuous sheath (14) made of a plastic film, for example of polyethylene, substantially along two transversely opposite longitudinal axes of said sheath, to obtain two separate half-sheaths (14 a , 14 b ), b) move the two half-sleeves apart from one another, c) cutting portions (16) of film in the vicinity of the two longitudinal edges (12) of each half-sheath (14 a , 14 b ), at regular intervals corresponding to twice the width (t) of a bag the along each longitudinal edge (12), said cut portions being substantially matched in the transverse direction of said half-sheath, d) placing inside each half-sheath two strands (8) each consisting of a plastic tape, said strands (8) being arranged along each of the two longitudinal edges (12) of said half-sheath, in line with said cut portions (16), e) fold inwards each longitudinal edge (12) of each half-sheath (14 a , 14 b ) around the corresponding strand (8), substantially along a longitudinal axis (B) passing over said portions (16 ) cut, so that each strand remains accessible from the outside by a recess (9 a , 9 b , 9 c , 9 d ) resulting from the folding on itself of the location of each portion (16) of cut film supra, f) heat-sealing the folded edges, parallel to the longitudinal direction (10) of said half-sheath, to form on each edge (12) of the film a sheath (7) in which is housed a strand of link, g) carry out, at regular intervals corresponding to the width (ℓ) of a bag, a plurality of pairs (19, 20) of adjacent transverse heat seals, corresponding to the lateral sides (4, 4 a ; 5 a , 5 b ; 4 b , 4 c ; 5 c , 5 d ; 4 d , 4 e ) of a plurality of adjacent bags (1, 1 a - e ) forming a chain (13), each pair of heat seals (19,20) being formed alternatively to the right of a kiss (18), and halfway between two successive kiss, h) precut the bags between the heat seals of each pair (19,20) of the aforementioned heat seals. Method according to claim 6, characterized in that it consists, in step c) above, of cutting substantially circular portions, so as to obtain in step h) above, bags (1, 1 a - e ) each having a single recess (9.9 a - d ) substantially in the shape of a quarter circle. Method for manufacturing a chain of bags according to one of claims 1 to 5, characterized in that it consists in: a) cut longitudinally a continuous sheath (14) consisting of a plastic film, for example of polyethylene, substantially in the middle to obtain two separate half-sheaths (14 a , 14 b ), b) move the two half-sleeves apart from one another, c) fold inwards each longitudinal edge (12) of each half-sleeve, d) cutting along the two folded longitudinal edges (12) of each half-sheath (14 a , 14 b ), at regular intervals corresponding to the width of two bags, portions (116) of film, e) introduce inside each folded edge of the half-sheath, a strand (8) made of a plastic tape, so that each strand is accessible from the outside by the recess (18) resulting from each portion (116) of cut film, f) heat-sealing the folded edges, parallel to the longitudinal direction (10) of said half-sheath, to form a sheath (7) on each edge (12) of the film, in which is housed a strand of link (8), g) carry out, at regular intervals corresponding to the width (ℓ) of a bag, a plurality of pairs (19, 20) of adjacent transverse heat seals, corresponding to the lateral sides (4, 4 a ; 5 a , 5 b ; 4 b , 4 c ; 5 c , 5 d ; 4 d , 4 e ) of a plurality of adjacent bags (1, 1 a - e ) forming a chain (13), each pair (19,20) of heat seals being formed alternatively to the right of a kiss (18), and halfway between two successive kiss, h) precut the bags between the heat seals of each pair (19,20) of the aforementioned heat seals. Method according to claim 8, characterized in that it consists, in the aforementioned step d), of cutting substantially semi-circular portions (116), so as to obtain, in the aforementioned step h), bags (1 , 1 a - e ) each having a single recess (9, 9 a - d ) substantially in the form of a quarter circle.

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