EP2361843B1 - Zipper-like closure strip for a bag and bag including it - Google Patents

Description

The invention relates to the field of bags or bags comprising a closure assembly adapted to allow successive openings and closures at will of the user.

More specifically, the invention relates to closure strips disposed at the mouth of the bags.

Such closure strips are conventionally formed of support webs, provided on their inner surface opposite and at a distance from their lateral edges, from at least one longitudinal closure assembly consisting of two complementary closure profiles.

Nowadays, there is a strong demand to have an opening witness for such bags, allowing the user to ensure that no one has yet access to its contents of the bag.

On the market, such opening indicators are in particular made in the form of a U-shaped web disposed on the inside of the closure profiles and connecting the two inner walls of the bag. Alternatively, the web may be disposed on the outside of the support webs, and connecting the two outer walls of the bag.

The U-shaped web is then arranged on the bag so as to be broken during the first opening and allow the user a normal and repeated access to its contents, as described for example in the document FR 2 546 481 .

The document EP 0 945 359 proposes a closure band comprising an upper part, comprising complementary closure means, and a lower part, comprising a peelable seal formed of a sealing layer made of an easily melting material and a layer of peeling composed of ribs.

However, when the user tries to break the U-shaped veil to open the bag, it happens that it is not the veil but one of the walls of the bag that tears, especially when the U-shaped veil extends to the outside. outside of the bag.

Moreover, the manufacture of tamper-proof closure strips comprising an internal opening indicator is made difficult by the presence of the U-shaped web between the support webs or on top of them. The U-shaped veil creates an extra thickness at the closure that can interfere with the running of tapes in traditional forming machines. Moreover, in the case where the closure bands are When applied to the bag, the U-shaped walls of the veil may be welded together by the jaws of the machine when the strips are welded to the mouth of the bag.

The present invention therefore aims to improve the closure strips and existing bags.

• une première desdites parties, dite partie supérieure, s'étendant longitudinalement dans une partie supérieure du voile support 21, et
• une deuxième partie, dite partie inférieure, s'étendant longitudinalement dans une partie inférieure du voile support, de manière sous-jacente à la partie supérieure,

dans laquelle, pour au moins l'un des voiles 21, les faces des parties supérieure et inférieure qui sont en regard, dites faces internes, sont réalisées dans des matériaux ayant des températures de fusion différentes, la température de fusion du matériau constitutif de la face interne de la partie supérieure étant inférieure à la température de fusion du matériau constitutif de la face interne de la partie inférieure.For this, the invention proposes a bag closure strip, comprising two support webs provided, on their internal surfaces opposite and at a distance from their longitudinal edges, of at least one longitudinal closure assembly, each support veil comprising two parts. ,

• a first of said parts, said upper part, extending longitudinally in an upper part of the support veil 21, and
• a second part, called the lower part, extending longitudinally in a lower part of the support web, underlying the upper part,

in which, for at least one of the webs 21, the faces of the upper and lower parts which are opposite said internal faces, are made of materials having different melting temperatures, the melting temperature of the constituent material of the internal face of the upper part being lower than the melting temperature of the constituent material of the inner face of the lower part.

• l'écart entre les températures de fusion des matériaux constitutifs des faces internes des parties supérieure et inférieure respectivement est au moins égal à 20 degrés ;
• l'ensemble de fermeture s'étend dans les parties inférieures des voiles support ;
• les faces internes des parties supérieures des voiles support sont soudées entre elles ;
• la bande comprend en outre une ligne de faiblesse qui s'étend longitudinalement dans une zone intermédiaire de chaque voile s'étendant entre les parties supérieures et l'ensemble de fermeture ;
• la ligne de faiblesse est réalisée par découpe discontinue des voiles support et/ou par réduction locale de l'épaisseur des voiles dans chaque zone intermédiaire ;
• les zones intermédiaires sont réalisées dans un troisième matériau de sorte que lesdites zones présentent une résistance à la traction plus faible que les parties supérieure et inférieure ;
• les autres faces des parties inférieures, dites faces externes, et les faces internes desdites parties inférieures sont réalisées dans des matériaux ayant des températures de fusion différentes entre elles ;
• la température de fusion du matériau constitutif des faces externes des parties inférieures est inférieure à celle du matériau constitutif des faces internes desdites parties inférieures ;
• la face interne de la partie supérieure de l'au moins un voile et les faces externes des parties inférieures sont réalisées dans un même matériau ;
• la bande comporte en outre un onglet formé dans l'un de ses bords latéraux, dans une zone intermédiaire s'étendant entre les parties supérieures et l'ensemble de fermeture ; et
• l'ensemble de fermeture est constitué par l'un des éléments du groupe suivant : profilés de fermeture complémentaires, bandes de velours-crochet, bande autocollante.

Some preferred but non-limiting aspects of the closure strip according to the invention are the following:

• the difference between the melting temperatures of the constituent materials of the internal faces of the upper and lower parts respectively is at least equal to 20 degrees;
• the closure assembly extends into the lower portions of the support webs;
• the inner faces of the upper portions of the support webs are welded together;
• the strip further comprises a line of weakness extending longitudinally in an intermediate zone of each web extending between the upper portions and the closure assembly;
• the line of weakness is produced by discontinuous cutting of the support webs and / or by local reduction of the thickness of the webs in each intermediate zone;
• the intermediate zones are made of a third material so that said zones have a lower tensile strength than the upper and lower parts;
• the other faces of the lower parts, said outer faces, and the inner faces of said lower parts are made of materials having different melting temperatures therebetween;
• the melting temperature of the constituent material of the outer faces of the lower parts is less than that of the constituent material of the inner faces of said lower parts;
• the inner face of the upper part of the at least one web and the outer faces of the lower parts are made of the same material;
• the strip further comprises a tab formed in one of its lateral edges, in an intermediate zone extending between the upper parts and the closure assembly; and
• the closure assembly is constituted by one of the elements of the following group: complementary closure profiles, velvet-hook strips, adhesive tape.

According to a second aspect, the invention proposes a bag comprising a mouthpiece, a bottom generally parallel to the mouth and opposite thereto, and two generally parallel side walls interconnected on three of their sides so as to form side edges, the bottom and the mouth, a closure band according to the invention extending from its mouth.

According to a preferred but non-limiting aspect of the bag according to the invention, the closing band is integral on the walls of the bag or attached to said walls.

• La figure 1a est une vue en plan d'un sachet selon l'invention ;
• La figure 1b est une vue en plan du sachet de la figure 1a comportant en outre une ligne de faiblesse et un onglet ;
• La figure 2 est une coupe transversale d'un premier mode de réalisation d'un sachet selon l'invention, dans lequel les bandes de fermeture sont rapportées sur les voiles support ;
• La figure 3 est une coupe transversale d'un deuxième mode de réalisation d'un sachet selon l'invention, comprenant une ligne de faiblesse, et dans lequel les bandes de fermeture sont venues de matière sur les voiles support;
• La figure 4 est une coupe transversale d'un mode de réalisation d'un sachet selon l'invention après ouverture ; et
• La figure 5 est une coupe transversale d'une variante du mode de réalisation de la figure 3 ;
• La figure 6 est une coupe transversale d'une variante de réalisation d'une bande de fermeture selon l'invention.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting examples and in which:

• The figure 1a is a plan view of a bag according to the invention;
• The figure 1b is a plan view of the bag of the figure 1a further comprising a line of weakness and a tab;
• The figure 2 is a cross section of a first embodiment of a bag according to the invention, wherein the closure strips are attached to the support webs;
• The figure 3 is a cross section of a second embodiment of a bag according to the invention, comprising a line of weakness, and wherein the closure strips are integral on the support webs;
• The figure 4 is a cross section of an embodiment of a bag according to the invention after opening; and
• The figure 5 is a cross-section of a variant of the embodiment of the figure 3 ;
• The figure 6 is a cross section of an alternative embodiment of a closure strip according to the invention.

As shown in the accompanying figures, a bag 10 according to the present invention comprises a mouthpiece 11, a bottom 12 generally parallel to the mouth 11 and opposite thereto, and two generally parallel side walls 13, 14. The side walls 13, 14 are interconnected on three of their sides so as to form lateral edges 15, the bottom 12 and the mouth 11 of the bag 10.

Preferably, the side walls 13 and 14 are generally parallel to the mouth 11 and the bottom 12, and connect them.

The walls 13, 14 of the bag may be made from a plastic film, in sheets of complex material such as sheets of paper covered with aluminum, or in any other material conventionally used in the manufacture of bags.

The bottom 12 and / or the lateral edges 15 connecting the walls 13, 14 may comprise a bellows, thus allowing the bag 10 to stand upright.

A closure strip 20 extends longitudinally along the mouth 11 of the bag 10.

The closure strip 20 comprises in particular support webs 21 which are either integral with the walls 13 and 14 constituting the bag 10 (as illustrated in FIGS. Figures 3 or 5 ), are attached and fixed thereto by any appropriate means, such as by gluing 20a ( figure 2 ) or welding.

Each support web 21 has a first longitudinal portion 211, said upper portion, and a second longitudinal portion 212, said lower portion, extending below the upper portion 211. Here, the upper portion 211 is the furthest from the center of the bag 10 while the lower part 212 is the closest.

According to a first variant embodiment, the upper part 211 is made of a first material having a first melting temperature, while the lower part 212 is made of a second material having a second melting temperature, different from the first melting temperature. .

Here, the first melting temperature is lower than the second melting temperature.

The difference between the respective melting temperatures of the first and second materials may be at least 20 ° C.

For example, the first material may be low-density, medium-density or high-density polyethylene (melting temperature of the order of 120 ° C.), while the second material may be metallocene, a low-pressure polyethylene copolymer. melting or a mixture of both (melting temperature of the order of 80 ° C to 100 ° C)

The closing sails 21 are provided on their inner surfaces 211a, 212a opposite and at a distance from the mouth 11 of at least one longitudinal closure assembly 22.

This may include complementary closure profiles, velvet-hook strips, a self-adhesive tape, or any equivalent means.

The closure assembly 22 extends below the upper portion of the webs 211, preferably in the lower portion 212, away from the upper portion 211.

According to a first embodiment, each web 21 of the closure strips 20 is formed by continuous and simultaneous coextrusion of the two materials forming the upper portions 211 and lower 212. The interface between the two parts 211 and 212 of the sails 21 is then a strip made of a material formed of a mixture between the first material and the second material.

According to a second embodiment, the upper part 211 1 and the lower part 212 are formed separately and then fastened together by welding, gluing, or any other conventional fastening means. The interface between the upper portion 211 and the lower portion 212 thus forms a discontinuity between the two materials.

Such support webs 21 then make it easy to form the opening indicator of a tamper-evident closure band 20.

It suffices to weld the support webs 21 together at a temperature, a pressure and for a predetermined time, for example by superimposing the support webs 21 and applying, on at least the upper part of the webs 21, welding jaws.

The duration, the pressure and the welding temperature are chosen so that only the upper portion 211 of the closure strips 20 on which the jaws are applied is welded. Indeed, at equal thicknesses, the melting temperature of the second material being higher by at least twenty degrees, the thermal diffusion through the second material layer of the lower portion 212 is slower than through the layer. of first material of the upper part 211. This diffusion can also be accelerated by reducing the layer of first material relative to the second material layer. It is therefore not necessary to implement complex devices to avoid applying the welding jaws on all of the sails 21, since the choice of materials of the upper 211 and lower 212 and the conditions of welding imply that the lower part 212 can not be welded with the rest of the support webs 21.

For example, for strips made of low density polyethylene (melt temperature of about 120 ° C.) and metallocene (melt temperature of about 80 ° C.), the solder jaws are temperature of the order of 140 ° C.

The welding of the upper portions 212 of the support webs 21 also makes it possible to stiffen the upper part of the closure band that is accessible to the user, and thus to facilitate its handling.

The user can therefore easily open the bag 10 by holding the bag 10 with one hand, for example at the closure assembly 22, and by pulling the other hand on the upper part of the closure band 20 By the least resistance of the intermediate zone 213 of the webs 21 situated between the upper part of the web (stiffened by the weld) and its lower part (stiffened by the closure assembly), the support webs 21 have a tendency to tear longitudinally between the upper part and the closure assembly, and more particularly at the interface line between the part stiffened upper and the intermediate zone, leaving the walls 13, 14 intact.

Once the opening indicator has been removed, a bag 10 having visibly been opened once and the closure assembly 22 is easily accessible.

If a malicious third party tried to open the bag 10 and access its contents, it would be impossible for it to do so without tearing the stiffened upper part of the tamper-proof closure band 20 and visibly and permanently signaling it. prior opening of the bag 10.

According to a second variant embodiment, illustrated on the figure 6 , the upper parts 211 and / or the lower parts 212 are bimaterial, that is to say that they themselves are made of two different materials: their inner faces 211a, 212a, which are opposite when they are fixed on the bag 10, and / or their external faces, which are directed towards the outside of the bag 10, are made of different materials.

The closure strip 20 is then composed of a bimaterial upper portion 211, having an inner face 211a made in the first material (having a lower melting temperature) and an outer face 211b made in the second material (having a higher melting temperature) and a homogeneous lower portion 212, whose internal faces 212a and outer 212b are both made in the second material.

The closure strip 20 may also be composed of a homogeneous upper portion 211, whose inner faces 211a and outer 211b are both made of the first material, and a lower portion 212 having two bimaterials, having an internal surface 212a. made in the second material and an outer face 211b made in the first material.

According to another form, the upper part 211 and the lower part 212 may both be bimaterial: the upper part 211 then comprises an inner face 211a made in the first material and an outer face 211b made in the second material, while the lower portion 212 comprises an inner face 212a made in the second material and an outer face 212b made in the first material.

Advantageously, these three alternative embodiments make it possible to obtain a closure strip having a more aesthetic and clean finish than in the first embodiment, where the upper parts 211 and lower 212 are homogeneous and formed respectively of the first material and the second material.

Thus, when the welding jaws are applied to the webs 21, only the inner faces 211a of the upper portions 211 are welded, since the melting temperature of the second material (constituting the internal faces 212a of the lower part 212) is more high.

It is of course possible to play on the respective thicknesses of the first and second material layers forming the internal faces 211a, 212a and external 211b, 212b of the upper portions 211 and lower 212 to adjust the thermal diffusion through these and therefore the welding conditions.

Furthermore, the production of the outer face 211b of the lower part 211 in a material having a melting temperature lower than the melting temperature of its internal face 212a makes it possible to improve the quality of the welding of the sails 21 on the mouthpiece 11 of the bag 10 and modulate the height on which the sails 21 are fixed on the mouth 11 of the bag 10.

Indeed, when applying welding jaws on the webs 21 in order firstly to fix the band 20 on the mouth 11 of the bag 10 and secondly to weld together the upper parts 211. 21, the outer faces 212b of the lower portions 212 are found fixed on the walls 13, 14 of the bag 10 while their internal faces 212a, whose melting temperature is higher, remain separate and do not weld one to the other.

Furthermore, it is possible to modulate the height of the sails 21 fixed on the mouth 11 of the bag 10 by applying the welding jaws on all or part of the lower part 212 of the sails.

Indeed, conventional welding machines generally comprise welding jaws formed of U or two-part welding bars and adapted to weld the sails 21 on either side of the closure assembly 22 so as not to deteriorate. this last.

Thus, if the outer face 211a of the lower portions 211 is made of the first material (having a lower melting temperature), it is possible to selectively apply the solder bars to the entire lower portion (211), thus fixing the entirety of the lower part 211 on the webs 21, or on only a fraction of the lower parts 211, for example on the underlying part of the closure assembly 22, so that only the underlying part of the closure assembly is fixed on the bag 10, while avoiding welding the inner faces 211b between them.

By producing a closure band having a lower portion 211 of large size with respect to the upper portion 212, as shown in FIG. figure 6 it is therefore easy to fix the closure strip 20 at a greater or lesser distance from the mouthpiece 11 by applying the solder bars over a larger or smaller area of the lower portions 211.

The same closure band 20 thus makes it possible to modulate the height of the sails 21 which is fixed on the mouth 11 of the bag during the automatic manufacture of the bags 10.

In order to simplify the description, we have described the embodiment in which the closure strip 20 is made in two different materials. Nevertheless, this is in no way limiting: the internal portions 211a, 212a and external 212a, 212b can be made in four different materials, as long as the melting temperature of the material constituting the inner face 211 of the upper portion 211 is smaller at the melting temperature of the constituent material of the inner face 212a of the lower portion 212. Optionally, the constituent material of the outer face 212b of the lower portion 212 may also be chosen so that its melting temperature is lower than that of the constituent material of the inner face 212a.

Furthermore, it is also possible that only one of the webs 21 of the closure strip is provided with an inner face 211a made of a material having a melting point lower than the melting temperature of the constituent material of the face. internal 212 of the lower portion 212, the other web then comprising inner faces 211a, 212a made of the same material or a material having a similar melting temperature.

It has already been seen that the intermediate zone 213 situated between the upper part 211 of the support webs 21 and the closure assembly 22 has a lower tear resistance in comparison with the zones which are adjacent thereto.

In order to further facilitate the first opening of the bag 10, the support webs 21 may further comprise a longitudinal line of weakness 24 in the zone 213, line along which the tear resistance is further reduced compared with that of the zone 213. .

For example, the line of weakness 24 may be a discontinuous cut of the zone 213 of the sails 21 ( figure 5 ) and / or is produced by locally reducing the thickness of all or part of the zone 213.

Alternatively (illustrated on the figure 3 ), the intermediate zone 213 of the support webs 21 is made of a third material distinct from the first and second materials, so that its tensile strength (and therefore tearing) is lower at the same time as those of the upper part of the band 20 and the lower parts of the sails 21.

Preferably, the melting temperature of the constituent material of the intermediate zone 213 is also greater than that of the constituent material of the inner face 211 at the upper part 211, in order to guarantee direct access to the closure assembly 22 during the first opening of the sachet 10.

Nevertheless, the intermediate zone 213 may, alternatively, be made of a material having a melting temperature substantially equal to or less than that of the inner face 211a of the upper portion 211, as long as the breaking strength obtained after welding of the walls of the web 21 remains lower than that of the upper and lower portions of the web 20.

For example, the first material constituting the inner face 211 of the upper portion 211 and the outer face 212b of the webs 21 may be low density polyethylene. The second constituent material of the inner face 212a of the lower portion 212 and the outer face 211b may then be metallocene, while the third constituent material of the intermediate zone 213 may be polypropylene or a high density polyethylene.

Alternatively, the entire upper portion 211 may be made of low density polyethylene, the entire lower portion 212 may be made of metallocene and the intermediate zone may be made of polypropylene.

Finally, to further facilitate the opening of the bag 10, the closure strips 30 may further comprise a tab 23. It may be for example a V cut or dihedral support webs opening on one lateral edges of the strip 20.

Advantageously, the tab is made in the intermediate zone 213.

Finally, in the case where the strips 20 already comprise a line of weakness 24, the tab 12 is preferably made in alignment with the line 24.

Claims (14)

1. A closure strip (20) for a bag (10), comprising two supporting webs (21) provided, on their internal surfaces facing each other and at a distance from their longitudinal edges, with at least one longitudinal closure assembly (22), each supporting web (21) comprising two portions,

   - a first (211) of said portions, a so-called upper portion, extending longitudinally in an upper portion of the supporting web (21), and

   - a second portion (212), a so-called lower portion, extending longitudinally in a lower portion of the supporting web (21), underlying the upper portion (211),

   wherein, for at least one of the webs (21), the faces (211a, 212a) of the upper and lower portions (211, 212) which are facing each other, so-called internal faces, are made in materials having different melting temperatures,
   characterized in that the melting temperature of the constitutive material of the internal face (211a) of the upper portion (211) is inferior to the melting temperature of the constitutive material of the internal face (212a) of the lower portion (212), such that the upper portion is capable of forming an opening indicator by permanent welding of its internal faces (211a, 212a).
2. The closure strip (20) according to claim 1, characterized in that the difference between the melting temperatures of the constitutive materials of the internal faces (211a, 212a) of the upper (211) and lower (212) portions respectively is at least equal to 20 degrees.
3. The closure strip (20) according to one of the precedingclaims, characterized in that the closure assembly (22) extends in the lower portions (212) of the supporting webs (21).
4. The closure strip (20) according to one of the foregoing claims, characterized in that the internal faces (211a, 212a) of the upper portions of the supporting webs (21) are welded together.
5. The closure strip (20) according to one of the preceding claims, characterized in that it further comprises a line of weakening (24) which extends longitudinally in an intermediate area (213) of each web (21) extending between the upper portions (211) and the closure assembly (22).
6. The closure strip (20) according to the preceding claim, characterized in that the line of weakening (24) is made by discontinuous cutting of the supporting webs (21) and/or by local reduction in the thickness of the webs (21) in each intermediate area (213).
7. The closure strip (20) according to one of claims 5 or 6, characterized in that the intermediate areas (213) are made in a third material so that said areas (213) have a lower tensile strength than the upper (211) and lower (212) portions.
8. The closure strip (20) according to one of the preceding claims, characterized in that the other faces (212b) of the lower portions (211), so-called external faces, and the internal faces (212a) of said lower portions (212) are made in materials having melting temperatures different from each other.
9. The closure strip (20) according to the preceding claim, characterized in that the melting temperature of the constitutive material of the external faces (212b) of the lower portions (212) is inferior to the melting temperature of the constitutive material of the internal faces (211b) of said lower portions (211).
10. The closure strip (20) according to claim 8, characterized in that the internal face (211a) of the upper portion (211) of said at least one web (21) and the external faces (212b) of the lower portions (212) are made in a same material.
11. The closure strip (20) according to one of the preceding claims, characterized in that it further includes a tab (23) formed in one of its side edges, in an intermediate area (213) extending between the upper portions (211) and the closure assembly (22).
12. The closure strip (20) according to one of the preceding claims, characterized in that the closure assembly (22) is formed by one of the elements from the following group: complementary closure profiles, hook and loop strips, self-adhesive tape.
13. A bag (10) comprising a mouth (11), a bottom (12) globally parallel to the mouth (11) and opposite the latter, and two side walls (13, 14) generally parallel and connected together on three of their sides so as to form side edges (15), the bottom (12) and the mouth (11), characterized in that it comprises a closure strip (20) extending from its mouth (11) according to one of the preceding claims.
14. The bag (10) according to the preceding claim, characterized in that the closure strip (20) is integral with the walls (13, 14) of the bag, or added onto said walls (13, 14).

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