FR2855453A1 - METHOD AND MACHINE FOR MANUFACTURING A PACKAGING POUCH AND POUCH OBTAINED THEREBY - Google Patents

Abstract

In this method, there are one above the other two polyolefin sheets (22, 24), there is between these sheets at least one folded strip (26) in polyolefin, interposed between the folds of this strip a body (44) thermally conductive and non-stick, and the two sheets are welded to one another, on the one hand, and the strip folded to each of these sheets, on the other hand. obtained thus comprises at least one bellows capable of opening over substantially its entire length.

Description

The present invention relates to a method of

  manufacture of a bellows packaging pouch, in '- single-layer plastic material, in particular in polyolefin.

  The invention also relates to a machine for manufacturing such a packaging pouch and to a polyolefin pouch thus produced.

  In the field of flexible plastic film bags or sachets, plastics capable of being assembled by welding fall into two categories.

  On the one hand, materials with a polar molecular structure, such as polyvinyl chloride (PVC), have been used for several years, generally being welded by high frequency welding processes. The welding of these materials provides reliable, aesthetic and open field welds to the most complex assemblies, in particular with a view to manufacturing bags with bellows or with multiple pockets. On the other hand, materials with a non-polar molecular structure are also used, such as polyolefins including polyethylene and polypropylene, which, because of their structure, do not allow high frequency welding but support processes of heat input welding, such as thermal, ultrasonic, pulse welding, etc. These welds remain difficult to shape, however, and are not very attractive in appearance.

  Furthermore, PVC has the drawback of releasing emissions harmful to the environment during its elimination. This environmental constraint has prompted the plastic packaging manufacturers to offer alternative solutions, in particular based on polyolefin, the recycling of which is easier and less polluting.

  For this purpose, there are currently bellows bags, made of polyethylene, which consist of a single sheet of monolayer plastic, folded back on itself so as to form at its fold a bellows. The two ends of the bellows, along its length, are pinched by lateral welds so that the bellows cannot extend over its entire length.

  The bags obtained have an unattractive appearance due, on the one hand, to unattractive side welds and, on the other hand, excessive stresses of the plastic material at the pinches of the ends of the bellows.

  This last drawback is sometimes circumvented by using multilayer plastic films which allow the bellows to be released over its entire length. This solution has the drawback, however, of being expensive and of making it difficult to recycle the sachets due to the joint use of materials of different natures.

  The aim of the present invention is to propose a method for manufacturing a polyolefin single-layer plastic bellows packaging pouch which, while using an easily recyclable material, guarantees obtaining an aesthetic pouch in order to enhance the content of this pocket.

  To this end, the subject of the invention is a method of manufacturing a packaging pouch, in which two polyolefin sheets are placed one above the other and these two sheets are welded together to each other on at least one weld line, characterized in that, before welding the two sheets to one another, at least 30 sheets are arranged between these sheets, in a direction transverse to the weld line a folded polyolefin strip, in that a thermally conductive and non-stick body is interposed between the folds of said strip, and in that the folded strip is welded to the sheets.

  The method according to the invention makes it possible to quickly obtain packaging or polyolefin pouches provided with one or more bellows which open over their entire length and thus have a more attractive appearance. The process is easily industrializable and does not require any costly adjustment compared to existing processes. In addition, it is reliable and uses only materials whose elimination is not polluting or which are easily recyclable.

  According to other characteristics of this process, taken in isolation or in all technically possible combinations: - the heat-conducting and non-stick body is made of polyester and / or polyimide; - the thickness of the thermally conductive and non-stick body is less than 25 im; the steps of welding the two sheets to one another and of welding the folded strip to these sheets are substantially concomitant; - The two sheets are pre-cut in a width so that, after the steps of welding the two sheets together and welding the folded strip to these 25 sheets, allow the pouch obtained to be detached from the rest width; - During the steps of welding the two sheets to each other and welding the folded strip to these sheets, the weld (s) is marked with a decorative pattern; - After the steps of welding the two sheets to each other and welding the folded strip to these sheets, the thermally conductive and non-stick body is released from the folds of the strip to be recovered.

  - The sheets, the strip and the thermally conductive and non-stick body are driven sequentially and the two sheets are welded together and the strip folded over to these sheets intermittently; - Once the thermally conductive and non-stick body released from the folds of the strip, this body is returned between the folds of a part of the strip to be welded for a new use.

  The invention further relates to a machine for manufacturing a packaging pouch allowing the implementation of the process mentioned above and comprising first means for sequentially driving two polyolefin sheets, and first means for welding two sheets to each other, characterized in that it further comprises: - second means for sequentially driving a polyolefin strip, associated with first shaping means suitable for folding said strip, - second means for welding the strip folded to the two sheets and - third means for sequentially driving a thermally conductive and non-stick body, associated with second means for shaping said body, adapted for input second welding means, interpose the body 25 between the folds of the strip.

  According to other characteristics of this machine, taken in isolation or according to any technically possible combination: the first and second welding means are carried by common welding equipment; - The second shaping means are adapted to offset the driving direction of the thermally conductive and non-stick body in a direction transverse to the driving direction of the folded strip; - It includes means for recovering the thermally conductive and non-stick body at the outlet of the second welding means; - Said recovery means comprise means for returning said body to the input of the second shaping means.

  The invention also relates to a pocket 10 obtained by the method or the machine defined above, comprising two front walls welded to one another on at least one of their sides and at least one bellows connecting the two walls on the other hand, the walls and the bellows being made of polyolefin, characterized in that the bellows is welded to the two walls so as to open over substantially its entire length.

  The pouch according to the invention thus has one or more bellows which extend over their entire length, allowing for example the pouch to stand upright. The welding of only two layers of polyolefin material around the entire periphery of the pouch allows the formation of larger welds and avoids the formation of residual stresses of the plastic material, both at the bellows and at the side walls.

  According to other characteristics of this pouch, taken individually or in any technically possible combination: - the walls and the bellows are made of polypropylene; - On one side of the walls at which said walls are neither welded to one another, nor connected by the bellows, it comprises closing means chosen from a flap and / or a reinforcing element; - on at least one of the sides at which the walls are welded to each other, it is provided with a perforated strip to allow the pocket to be stored in a filing cabinet.

  The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings, in which: - Figure 1 is a perspective view of a pocket of packaging according to the invention; - Figure 2 is a schematic perspective view of a machine according to the invention used to manufacture the pouch of the figure,; Figure 3 is a perspective view of a detail of a folded polyolefin strip used in the machine of Figure 2; - Figure 4 is a perspective view on a larger scale of a detail of the machine of Figure 2; - Figure 5 is a schematic section taken along the plane V in Figure 2; - Figures 6 and 7 are views similar to Figure 1, of cover pouches according to the invention; and - Figure 8 is an elevational view of another variant of a pouch according to the invention.

  In Figure 1 is shown a pouch 1 of polypropylene. This pocket has two front walls, namely a front wall 2 (the wall facing the reader in FIG. 1) and a rear wall 4. The pocket 1 also has a bottom wall in the form of a foldable bellows 6 connecting walls 2 and 4 at one of their side. More precisely, the bellows 6 is fixed on the one hand to the front wall 2 by a weld 8 and, on the other hand, to the rear wall 4 by a weld 10.

  When the bellows 6 is deployed or open, the pocket 1 is able to stand on a flat surface on which the bellows 6 rests.

  The walls 2 and 4 are also directly connected 5 to each other by two lateral welds 12 which extend at two opposite sides of these walls, from the junction points 14 of the welds 8 and 10. At the Unlike the polyolefin bags of the prior art, the bellows 6 is not, at its ends along its length, pinched by welds extending the lateral welds 12 in a straight line. On the contrary, these ends of the bellows 6 are connected to the front 2 and rear 4 walls by respective parts of the welds 8 and 10 distinct from the welds 12, which allows the bellows 15 to be deployed over its entire length.

  The walls 2 and 4 and the bellows 6 consist of a single layer of polypropylene, for example with a thickness of approximately 120 mt.

  The rear wall 4 is advantageously provided with a closing flap 16 adapted to cover the side of the front wall 2 opposite the bellows 6. Optionally, the face of this flap intended to come to press against the front wall 2 is coated with an adhesive material, possibly adapted to allow the flap 16 to be opened and closed at will.

  The various welds 8, 10 and 12 thus connect only two layers of plastic material, which makes it possible to easily obtain welds with a width of up to a few millimeters and advantageously having decorative patterns, such as imitation stitching. .

  To obtain the pouch 1, in particular the various welds 8, 10 and 12, a manufacturing machine 20 is used, shown schematically in FIG. 2. This machine is adapted to be fed by a single-layer sheet of polypropylene 22 known as upper (shown in the upper part of FIG. 2) intended to constitute the front wall 2 of the pocket 1, a single-layer sheet 5 of so-called lower polypropylene 24 intended to constitute the rear wall 4 of this pocket, and a single-layer strip of polypropylene 26 intended to form the bellows 6.

  For this purpose, the machine 20 comprises means 10 for sequentially driving the sheets 22 and 24 and the strip 26, which move the sheets and the strip according to the arrows F. These means, known per se, are not shown on the Figure 2. By way of example, an air cushion, drive rollers 15 or a KAPTON (registered trademark) fabric can be used. These drive means are associated with deflection rollers 34 so as to position the sheets 22 and 24 one above the other, while shaping means 36 are capable of folding the strip 26 on itself as 20 shown in FIG. 3, and directing the strip thus folded between the sheets 22 and 24.

  To make the welds 8, 10 and 12, the machine 20 is equipped with welding means 38 comprising an upper assembly 40 and a lower assembly 42 between which the sheets 22 and 24 and the strip 26 are intended to be positioned. More specifically, the facing faces of these equipments 40 and 42 carry complementary welding jaws which, when they enclose two layers of polyolefin between them, cause their localized melting and thus their welding. Various welding techniques can be envisaged in these jaws, in particular thermal welding techniques or ultrasonic welding. Advantageously, these jaws are coated with a non-stick product vis-à-vis the polyclines.

  In addition, these jaws carry complementary reliefs adapted to form decorations on the surfaces of the welds obtained.

  These welding jaws are also provided with elements for pre-cutting the sheets 22 and 24, suitable for, during the application of these jaws, cutting the plastic material at the outer periphery of the welds 10 produced.

  To allow the simultaneous formation of welds 8 and 10 substantially aligned along the direction of application of the welding jaws, provision is made to supply the manufacturing machine 20 with a strip 44 15 made of a thermally conductive material, flexible and non-stick with respect to polyolefins, in particular with respect to polypropylene. For example, the strip 44 is formed from a single layer of polyester or polyimide, of thickness less than 25 μm.

  As a variant, the strip 44 could also be made of any other material having thermal conduction characteristics allowing the assembly of the sheets 22 and 26, on the one hand, 24 and 26, on the other hand, as well as an incompatibility with the welding and / or bonding with polypropylene at the temperatures used.

  The machine 20 is equipped for this purpose with means 46 for shaping the strip 44, adapted to insert this strip between the folds 26a and 26b of the strip 26. These means 30 for shaping 46 are partly detailed in FIG. 4 and include a rigid plate 48. More precisely, this plate defines a path C of generally Z-shaped conformation shown in phantom in FIG. 4, along which the thermally conductive strip 44 passes, at the input of the plate, from a position outside the folds of the strip 26, at the outlet from this plate, a position in which the strip 44 is interposed between the folds 26a and 26b of the strip 26. For this purpose, the path of conformation C extends at the inlet and at the outlet of the plate 48 in respective parallel directions and offset along a perpendicular to the direction of drive of the strip 26.

  The shaping means 46 are associated with means 50 for recovering the strip 44, arranged downstream of the welding means 38 and comprising a shaping plate 52 substantially similar to the plate 48 adapted to release the strip 44 towards the outside. in a direction transverse to the direction of movement F. 15 Advantageously, these recovery means 50 further comprise a series of deflection rollers 54 capable of returning the strip 44 to the inlet of the plate 48 in order to rotate the strip in closed cycle . In a variant not shown, the strip 44 is intended to be stored, for example by winding, at the outlet of the release plate 52. Once the reel is full, it can be mounted near the plate 48 to supply the means 16.

  The operation of the machine 20 is as follows: The machine 20 is supplied with both the sheets 22 and 24 and the strips 26 and 44, these different elements being driven sequentially.

  The shaping means 36 and 46 bring the strips 26 and 44 respectively between the sheets 22 and 24 so as to form, at the input of the welding means 38, the structure of FIG. 5. More precisely, the free edge of the fold 26a of the strip 26 is placed just below the sheet 22 at a weld area 56, the free edge of the fold 26b is placed just below the lower sheet 24 at a weld area 58 11 and the strip 44 is interposed between these folds 26a and 26b and these areas to be welded 56 and 58.

  This structure is then clamped by the aforementioned welding jaws. The thermally conductive strip 44 ensures the conduction of heat at the level of the zones to be welded 56 and 58, with a view to producing the welds 8 and 10 of the pocket 1. The strip 44 being made of a non-stick screw material -with respect to polypropylene, the welds 8 and 10 do not adhere to the strip 44. In addition, the material 10 constituting this strip is sufficiently flexible to allow the transfer of the marking forces by the reliefs of the jaws, in order to forming along the welds 8 and 10 the aforementioned decorative imitations.

  Simultaneously, the welding jaws cause the formation of the lateral welds 12 and pre-cut the sheets 22 and 24 all around the welds produced.

  At the outlet from the welding means 38, the recovery means 50 release the strip 44 and return it to the inlet of the shaping means 46, as shown by the arrows F ′, the path of the strip 44 between these arrows being omitted for the clarity of the drawing.

  The pouch 1 thus obtained only has to be torn from the rest of the sheets 22 and 24, this operation being facilitated by the pre-cuts made during the application of the welding jaws.

  The manufacturing machine 20 thus makes it possible to quickly obtain the polypropylene pouch 1 of FIG. 1, the welding means 38 simultaneously forming the welds 8, 10 and 12. Compared to machines for manufacturing 30 known polypropylene sachets, the modifications to be made are inexpensive and essentially concern the shaping means 36 and 46 and the welding means 38.

  Furthermore, the welding jaws advantageously have a stepped profile so that they homogeneously weld zones with two thicknesses of polypropylene sheet to form the welds 12 and 5 of the zones with four thicknesses of sheet / strip in polypropylene and with a strip thickness 44 to form the welds 8 and 10. The height separating the welding faces from the pre-cutting edges is correspondingly modified.

  In Figures 6 to 8 are shown variants of polypropylene pouches according to the invention. In FIG. 6 is shown a pocket 1 similar to that of FIG. 1 except in its part opposite to the bellows 6.

  More specifically, the closing flap 16 is replaced by a reinforcing pediment 16 ′ welded directly to the front 2 and rear 4 walls of the pocket so as to close them one over the other. Advantageously, this pediment 16 ′ is provided with a perforation in order to suspend the pocket 1, in particular during its marketing.

  The pocket 1 of FIG. 7 combines the closing flap 16 of the pocket of FIG. 1 and the reinforcement pediment 16 ′ of the pocket of FIG. 6.

  FIG. 8 shows a polypropylene pocket 1 more particularly intended for filing documents. Although the geometry and dimensions are slightly different from those of the pouch of FIG. 1, the pouch of FIG. 8 has the same structural elements as the pouch of FIG. 1, referenced by the same numbers, and is further provided, 30 at one of its lateral welds 12, a reinforcing strip 18. This strip is provided with a series of perforations 19 intended to receive the rings of a filing cabinet.

  Various arrangements and variants of the pockets, machines and methods described above can also be envisaged. In particular, the material constituting the walls 2 and 4, as well as the bellows 6 of the pouch, 5 can be chosen from all the polyolefins, for example polyethylene. Furthermore, unlike the pouches of Figures 1 and 6 to 8, the pouch according to the invention does not necessarily have only one bellows. On the contrary, it is conceivable to provide two lateral bellows 10 opposite and that the front and rear walls, on at least one of the remaining sides, are connected directly to each other by a weld similar to the welds 12.

Claims (18)

  1. Packaging pouch, comprising two front walls 5 (2, 4) welded to each other on at least one of their sides and at least one bellows (6) connecting the two walls on another on their side , the walls (2, 4) and the bellows (6) being made of polyolefin, characterized in that the bellows (6) is welded to the two walls (2, 4) 10 so as to open over substantially its entire length .   2. Sleeve according to claim 1, characterized in that the walls (2, 4) and the bellows (6) are made of polypropylene.   3. Sleeve according to one of claims 1 or 2, 15 characterized in that, on one side of the walls (2, 4) at which said walls are neither welded to each other, nor connected by the bellows (6), it comprises closing means chosen from a flap (16) and / or a reinforcing element (16 ').   4. Sleeve according to any one of claims 1 to 3, characterized in that, on at least one of the sides at which the walls (2, 4) are welded to each other, it is provided with a perforated strip (18) to allow the pocket to be stored in a filing cabinet.   5. Method for manufacturing a packaging pouch (1) according to any one of claims 1 to 4, in which there are arranged one above the other two polyolefin sheets (22, 24) and these two sheets are welded to each other on at least one weld line (12), characterized in that, before welding the two sheets (22, 24) to one another, has between these sheets, in a direction transverse to the weld line (12), at least one folded strip (26) of polyolefin, in that there is interposed between the folds (26a, 26b) of said strip a body (44 ) thermally conductive and non-stick, and in that the folded strip (26) is welded to the sheets (22, 24).   6. Method according to claim 5, characterized in that the thermally conductive and non-stick body (44) consists of polyester and / or polyimide.   7. Method according to one of claims 5 or 6, characterized in that the thickness of the thermo-conductive and non-stick body (44) is less than 25 µm.   8. Method according to any one of claims to 7, characterized in that the steps of welding the two sheets (22, 24) to each other and welding the folded strip (26) to said sheets are substantially 15 concomitant.   9. Method according to any one of claims to 8, characterized in that the two sheets are pre-cut (22, 24) in a width so that, after the steps of welding the two sheets one to the other. 'other and 20 welding the folded strip (26) to said sheets, allow to detach the pocket obtained (1) from the rest of the width.   10. Method according to any one of claims 5 to 9, characterized in that, during the 25 steps of welding the two sheets (22, 24) to each other and of welding the folded strip (26) to said sheets, the weld (s) (8, 10, 12) of a decorative pattern are marked.   11. Method according to any one of claims 5 to 10, characterized in that, after the steps of welding the two sheets (22, 24) to each other and welding the folded strip (26) to said sheets, the thermally conductive and non-stick body (44) is released from the folds (26a, 26b) of the strip (26) to be recovered.   12. Method according to any one of claims 5 to 11, characterized in that it drives the 5 sheets (22, 24), the strip (26) and the thermally conductive and non-stick body (44) sequentially and on welds the two sheets to each other and the folded strip to said sheets intermittently.   13. Method according to claims 11 and 12 taken 10 sets, characterized in that, once the thermally conductive and non-stick body (44) released, this body is returned between the folds (26a, 26b) of a part of the strip to weld (26).   14. Machine for manufacturing a packaging pouch 15 (1) for implementing a method according to any one of claims 5 to 13, comprising first means for sequentially driving two sheets (22 , 24) in polyolefin, and first means (38) for welding the two sheets to one another, characterized in that it further comprises: - second means for sequentially driving a strip ( 26) in polyolefin, associated with first shaping means (36) adapted to fold said strip, - second means (38) for welding the folded strip (26) to the two sheets (22, 24) and - third means sequential drive of a thermally conductive and non-stick body (44), associated with second means (46) for shaping said body, adapted for, at the input of the second welding means, interposing the body between the plies (26a, 26b) of the strip (26).   15. Machine according to claim 14, characterized in that the first and second welding means (38) are carried by common welding equipment.   16. Machine according to one of claims 14 or 15, 5 characterized in that the second shaping means (46) are adapted to shift the driving direction of the thermally conductive and non-stick body (44) in a direction transverse to the direction (F) for driving the folded strip (26).   17. Machine according to any one of claims 14 to 16, characterized in that it comprises means (50) for recovering the thermally conductive and non-stick body (44) at the outlet of the second welding means (38) .   18. Machine according to claim 17, characterized in that said recovery means comprise means (54) for returning said body (44) to the input of the second shaping means (46).