EP1481912A1 - Packaging bag and its method and device of manufacture - Google Patents

Abstract

Between folds (26a, 26b), a thermally-conducting body (44) is interposed. With respect to polypropylene, this is anti-adherent. Each weld (12) is made transversely with respect to a folded web (26) between the sheets (22, 24) and its direction of deposition. An independent claim is included for a corresponding machine to make the packaging.

Description

The present invention relates to a method of manufacture of a bellows packaging pouch, single-layer polypropylene. The invention also relates to a machine for manufacturing such a packaging pouch and a polypropylene pouch thus produced.

In the field of packaging bags or sachets in flexible plastic film, plastics capable of being welded joints fall into two categories. On the one hand, materials with a polar molecular structure, such as polyvinyl chloride (PVC), are used for several years, being generally welded by high frequency welding processes. Welding these materials provide reliable, aesthetic and opening the way to the most complex assemblies, in particular for the production of bellows or multiple pockets. On the other hand, we also use non-polar molecular materials, such as polyolefins including polyethylene and polypropylene, which, due to their structure, do not allow high frequency welding but support processes heat input welding, such as thermal welding, ultrasonic, pulse, etc. These welds remain however difficult to shape and are aesthetically pleasing not very attractive.

Furthermore, PVC has the disadvantage of emit harmful emissions for its disposal the environment. This environmental constraint prompted plastic packaging manufacturers in propose alternative solutions, in particular based on polyolefin whose recycling is easier and less pollutant.

For this purpose, there are currently sachets with bellows, made of polyethylene, which are made a single sheet of single-layer plastic, folded over itself so as to form at the level of its fold a bellows. The two ends of the bellows, according to its length, are clamped by side welds so that the bellows cannot extend over its entire length. The sachets obtained have a not very attractive appearance in reason, on the one hand, for unsightly side welds and, on the other hand, excessive tensions of the material plastic at the pinches of the ends of the bellows.

This last drawback is sometimes overcome by using multilayer plastic films which allow to release the bellows over its entire length. This solution has the disadvantage of being expensive and make it difficult to recycle sachets due to the joint use of natural materials different.

US-B-6,425,847 proposes to produce a pocket, possibly in polypropylene or from multi-layer films, three of whose sides are each provided with a bellows, the fourth side being left free yawning. Welding the folds of these bellows to the walls front cover is not described in this document and a priori only requires the application of matrices of overlapping welding, which suggests that the pocket mentioned above can only be made by using complex multi-layer films with only one single weldable face.

The purpose of the present invention is to provide a method of manufacturing a packaging pouch bellows and single-layer polypropylene, which, while using an easily recyclable material, guarantees obtaining an aesthetic pouch to enhance the contents of this pocket.

To this end, the subject of the invention is a method of manufacture of a packaging pouch, as defined in claim 1.

The method according to the invention makes it possible to obtain quickly polypropylene packaging pouches provided with one or more bellows which open onto their entire length and thus more attractive aesthetic. The process is easily industrializable and does not require no costly layout compared to processes existing. In addition, it is reliable and uses only materials whose elimination is not polluting or which are easily recyclable.

Other characteristics of this process, taken individually or in any combination technically possible, are set out in dependent claims 2 to 9.

The invention further relates to a machine for manufacture of a packaging pouch, allowing implementing the method mentioned above, as defined to claim 10.

Other characteristics of this machine, taken individually or in any combination technically possible, are set out in dependent claims 11 to 15.

The invention also relates to a pocket obtained by the process or the machine defined above, as defined in claim 16.

The pouch according to the invention thus has one or more several bellows which deploy over their entire length, allowing for example the pouch to hold standing. The welding of only two layers of material in polypropylene all around the pouch allows formation of larger welds and prevents the formation of residual stresses of the plastic, both at bellows level as side walls.

Other characteristics of this pouch, taken individually or in any combination technically possible, are set out in dependent claims 17 and 18.

• la figure 1 est une vue en perspective d'une pochette d'emballage selon l'invention ;
• la figure 2 est une vue schématique en perspective d'une machine selon l'invention utilisée pour fabriquer la pochette de la figure 1 ;
• la figure 3 est une vue en perspective d'un détail d'une bande pliée en polypropylène utilisée dans la machine de la figure 2 ;
• la figure 4 est une vue en perspective et à plus grande échelle d'un détail de la machine de la figure 2 ;
• la figure 5 est une coupe schématique prise selon le plan V sur la figure 2 ;
• les figures 6 et 7 sont des vues analogues à la figure 1, de variantes de pochette selon l'invention ; et
• la figure 8 est une vue en élévation d'une autre variante de pochette selon l'invention.

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 packaging pouch according to the invention;
• Figure 2 is a schematic perspective view of a machine according to the invention used to manufacture the pouch of Figure 1;
• Figure 3 is a perspective view of a detail of a folded polypropylene 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 plane V in Figure 2;
• Figures 6 and 7 are views similar to Figure 1, of pouch variants 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 pocket 1 in polypropylene. This pocket has two walls front, namely a front wall 2 (the wall turned towards the reader in FIG. 1) and a rear wall 4. The pocket 1 also has a bottom wall in the form a foldable bellows 6 connecting the walls 2 and 4 at the level from one side. More specifically, 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 opened, the pocket 1 is able to stand on a flat surface on which rests the bellows 6.

Walls 2 and 4 are also directly connected 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 difference from the polyolefin sachets of the prior art, the bellows 6 is not, at its ends according to its length, pinched by welds extending so rectilinear the lateral welds 12. On the contrary, these bellows ends 6 are connected to the front walls 2 and rear 4 by respective parts of the welds 8 and 10 separate from the welds 12, allowing the bellows to be deployed over its entire length.

The walls 2 and 4 and the bellows 6 are formed a single layer of polypropylene, for example thick about 120 µm.

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. So optional, the face of this flap intended to come is press against the front wall 2 is coated with a material adhesive, possibly adapted to allow opening and to close the flap 16 at will.

The different welds 8, 10 and 12 thus connect only two layers of plastic, which allows easily obtain welds with a width that can reach a few millimeters and presenting advantageously decoration patterns, such as imitations of stitching.

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

The machine 20 for this purpose comprises means sequential drive 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 in Figure 2. As an example, can be used an air cushion, drive rollers or a KAPTON canvas (registered trademark). These means drives are associated with deflection rollers 34 so as to position the sheets 22 and 24 one above on the other, while means 36 of conformation are able to fold the band 26 back on itself as shown in Figure 3, and direct the tape as well folded between sheets 22 and 24.

To make the welds 8, 10 and 12, the machine 20 is equipped with welding means 38 comprising a crew upper 40 and lower crew 42 between which the sheets 22 and 24 and strip 26 are intended to be positioned. More specifically, the facing faces of these crews 40 and 42 carry welding jaws complementary which, when they enclose each other two layers of polyolefin, cause their fusion localized and thus their welding. Various techniques of welding are possible at these jaws, including thermal welding or welding techniques by ultrasound. Advantageously, these jaws are coated with a non-stick product vis-à-vis polyolefins.

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

These welding jaws are also provided elements for pre-cutting sheets 22 and 24, adapted for, when applying these jaws, cut the plastic material on the outer periphery of the welds performed.

It is thus understood that the outline of the jaws of welding, i.e. the areas of the jaws intended for enclose and melt the sheets 22 and 24 and the strip 26, conditions the course of the welds and therefore the shape outside of the pocket. Different pouch shapes can therefore be considered by changing only the welding footprint of the jaws.

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

Alternatively, the strip 44 could also be made of any other material with 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 incompatibility in welding and / or when bonding with polypropylene at temperatures used.

The machine 20 is equipped for this purpose with means 46 of conformation of the strip 44, adapted to insert this strip between the folds 26a and 26b of the strip 26. These means of conformation 46 are partially detailed in FIG. 4 and comprise a rigid plate 48. More specifically, this plate defines a path C of conformation generally in Z shape shown in phantom in Figure 4, following which the thermally conductive strip 44 passes, at the input of the plate, from an external position to the folds of the strip 26, at the exit of this plate, a position in which the strip 44 is interposed between the folds 26a and 26b of strip 26. For this purpose, the trajectory of conformation C extends at the inlet and outlet of the plate 48 in respective parallel directions and offset perpendicular to the direction band drive 26.

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

The operation of the machine 20 is as follows: On feeds machine 20 with both sheets 22 and 24 and bands 26 and 44, these various elements being trained sequentially.

The conformation means 36 and 46 bring the strips 26 and 44 respectively between the sheets 22 and 24 so as to form at the input welding means 38, the structure of Figure 5. More specifically, the slice free of the fold 26a of the strip 26 is arranged just at the vertical alignment of the sheet 22 at a weld zone 56, the free edge of the fold 26b is arranged just below the lower sheet 24 at a weld zone 58 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 jaws welding aforementioned. The thermally conductive strip 44 ensures heat conduction at the areas to be welded 56 and 58, with a view to carrying out the welds 8 and 10 of the pocket 1. The strip 44 being made of a material non-stick vis-à-vis polypropylene, welds 8 and 10 do not adhere to the strip 44. In addition, the material constituting this strip is flexible enough to allow the transfer of marking efforts by reliefs of the jaws, in order to form along the welds 8 and 10 the aforementioned decorative imitations. At the same time, the welding jaws cause the formation of the lateral welds 12 and pre-cut the sheets 22 and 24 all around the welds made.

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

The pouch 1 thus obtained only has to be torn from the rest of 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 obtain quickly the polypropylene pouch 1 of FIG. 1, the welding means 38 simultaneously forming the welds 8, 10 and 12. Compared to machines for manufacturing known polypropylene sachets, bring are inexpensive and relate mainly to shaping means 36 and 46 and the welding means 38.

In addition, the welding jaws have advantageously a stepped profile so that they homogeneously weld areas with two thicknesses of polypropylene sheet to form the welds 12 and areas with four sheet / strip thicknesses in polypropylene and a strip thickness 44 to form welds 8 and 10. The height separating the faces of welding of the precut edges is modified by corresponding way.

In Figures 6 to 8 are shown variants of polypropylene pouches according to the invention. On the Figure 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 reinforcement pediment 16 'welded directly to the walls front 2 and rear 4 of the pocket so as to close these one on top of the other. Advantageously, this pediment 16 'is provided with a perforation in order to suspend the pocket 1, especially during its marketing.

The pocket 1 of FIG. 7 combines the flap of closure 16 of the pocket of FIG. 1 and the pediment of reinforcement 16 'of the pouch of FIG. 6.

In Figure 8 is shown a pocket in polypropylene 1 more particularly intended for filing documents. Although of geometry and slightly different dimensions than the pouch of Figure 1, the pocket of Figure 8 includes the same structural elements as the cover of the figure 1, referenced by the same numbers, and is further provided, at one of its lateral welds 12, a strip reinforcement 18. This strip is provided with a series of perforations 19 intended to receive the rings of a workbook.

Various layouts and variants in the pockets, machines and processes described above are further conceivable. In particular, unlike the pockets Figures 1 and 6 to 8, the pouch according to the invention does not not necessarily have only one bellows. At on the contrary, it is possible to envisage two bellows facing each other 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 welds 12.

Claims (18)

Method for manufacturing a packaging pouch (1), in which two polypropylene sheets (22, 24) are placed one above the other and at least one folded strip (26) is placed between these sheets ) made of polypropylene, characterized in that there is interposed, between the folds (26 a , 26 b ) of said strip, a body (44) thermally conductive and non-stick with respect to polypropylene and in that it is welded , on the one hand, the two sheets to one another on at least one weld line (12) transverse to the direction in which the folded strip is arranged between the sheets and, on the other hand, the folded strip (26) leaves (22, 24). Method according to claim 1, characterized in that the thermally conductive and non-stick body (44) consists of polyester and / or polyimide. Method according to one of claims 1 or 2, characterized in that the thickness of the thermally conductive and non-stick body (44) is less than 25 µm. Method according to any one of the preceding claims, characterized in that the steps of welding the two sheets (22, 24) to each other and of welding the folded strip (26) to the said sheets are substantially concomitant. Method according to any one of the preceding claims, characterized in that , during the steps of welding the two sheets (22, 24) to each other and welding the folded strip (26) to the said sheets, -cut the two sheets on the outer periphery of the bores so as to allow the pouch obtained (1) to be detached from the rest of the sheets. Method according to any one of the preceding claims, characterized in that , during the steps of welding the two sheets (22, 24) to each other and welding the folded strip (26) to the said sheets, the weld (s) (8, 10, 12) of a decorative pattern. Method according to any one of the preceding claims, characterized in that , after the steps of welding the two sheets (22, 24) to each other and welding the folded strip (26) to the said sheets, the body thermally conductive and non-stick (44) is released from the folds (26a, 26b) of the strip (26) to be recovered. Method according to any one of the preceding claims, characterized in that the sheets (22, 24), the strip (26) and the thermally conductive and non-stick body (44) are driven sequentially and the two are welded sheets to each other and the strip folded to said sheets intermittently. Method according to Claims 7 and 8 taken together, characterized in that , once the heat-conducting and non-stick body (44) is released, this body is returned between the folds (26a, 26b) of a part of the strip to be welded (26). Machine for manufacturing a packaging pouch (1) for implementing a method according to any one of the preceding claims, comprising first means for sequentially driving two sheets (22, 24) of polypropylene and second means for sequentially driving a strip (26) of polypropylene, associated with first shaping means (36) adapted to fold said strip, characterized in that it further comprises: first means (38) for welding the two sheets to one another, second means (38) for welding the folded strip (26) to the two sheets (22, 24) and third means for sequentially driving a body (44) thermally conductive and non-stick vis-à-vis polypropylene, associated with second means (46) for shaping said body, adapted for entering the second means welding, interpose the body between the folds (26 a , 26 b ) of the strip (26). Machine according to claim 10, characterized in that the first and second welding means (38) are carried by common welding equipment. Machine according to one of claims 10 or 11, characterized in that the first and second welding means (38) carry complementary welding jaws adapted to locally weld the two sheets (22, 24) one to the other. other and the folded strip (26) to said two sheets. Machine according to one of claims 10 to 12, characterized in that the second shaping means (46) are adapted to offset the direction of drive of the heat-conducting and non-stick body (44) in a direction transverse to the direction (F) for driving the folded strip (26). Machine according to any one of Claims 10 to 13, characterized in that it includes means (50) for recovering the heat-conducting and non-stick body (44) at the outlet from the second welding means (38). Machine according to claim 14, characterized in that said recovery means comprise means (54) for returning said body (44) to the input of the second shaping means (46). Packaging pouch obtained by the process according to any one of Claims 1 to 9,
characterized in that it comprises, on the one hand, two front walls (2, 4) of polypropylene welded to each other on at least one of their sides and consisting of respective parts of the two sheets (22, 24 ) and, on the other hand, at least one bellows (6) made of polypropylene connecting the two walls on another on their side and consisting of a part of the folded strip (26) welded to said parts of the two sheets so as to s '' open over substantially its entire length. Sleeve according to claim 16, characterized in that , on one side of the walls (2, 4) at the level of which said walls are neither welded to one another, nor connected by the bellows (6), it comprises closing means chosen from a flap (16) and / or a reinforcing element (16 '). Pouch according to one of claims 16 or 17, 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.

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