WO2007113783A1

WO2007113783A1 - Package formed by a butt-sealed multilayer film

Info

Publication number: WO2007113783A1
Application number: PCT/IB2007/051250
Authority: WO
Inventors: Jacques Thomasset; Stéphane MATHIEU
Original assignee: Aisapack Holding S.A.
Priority date: 2006-04-06
Filing date: 2007-04-06
Publication date: 2007-10-11
Also published as: KR101419695B1; KR20080108296A; EP2007568A1

Abstract

The invention concerns a plastic tubular package comprising a head assembled on a tubular body (1) consisting of a laminate (2) the ends of which are mutually sealed and covered with a strip (7), said laminate (2) consisting at least of one sealing layer (3, 5) and one non-sealing layer (4). The invention is characterized in that the strip (7) comprises a bi-oriented polymer (9) and a layer (8) enabling the strip (7) to be fixed on the laminate (2), the tensile rigidity of the strip (7) being further not less than the rigidity of the non-sealing layer (4).

Description

PACKAGING OF MULTI-LAYER FILM SOLDERING END-TO-END

Field of the invention

The invention lies in the field of flexible tubes formed by means of plastic films. It relates more specifically to a flexible tube whose ends are welded end to end.

State of the art

Many flexible tubes are made by welding the ends of a laminate containing at least one layer of plastic.

The most common welding method consists of forming an overlap of the ends of the laminate and assembling the inner face on the upper face of the laminate. This assembly has many advantages because it allows in particular to obtain a high resistance of the welded zone, to ensure the hygiene properties vis-à-vis the packaged product and ensure good barrier and sealing properties. However, this assembly may be insufficient for the packaging of aggressive products that migrate into the welded zone and lead to the delamination of the laminate. This assembly does not allow a decoration of the tube on its entire periphery. It finally has the disadvantage of forming an extra thickness in the welded zone.

The patent application EP0187541 (Figure 1) proposes the use of a band welded inside the tube to protect the welded zone from the migration of aggressive products. Figure 1 illustrates assembly 1 described in EP0187541 for packaging products containing cyanoacrylates. According to the preferred embodiment of the invention, the laminate 2 comprises a first layer 5 of high density polyethylene (HDPE) in contact with the packaged product, an aluminum layer 4 and a second layer 3 of HDPE on the outer surface. The laminate 2 also comprises a layer of polyethylene imine (PEI) and a layer of ethylene acrylic acid copolymer (EAA) between the layers 5 and 4 and a layer of EAA between the layers 4 and 3 to ensure good adhesion between the layers 3, 4 and 5. The ends of the laminate 2 form an overlap in the welded zone 6. The HDPE strip 7 is welded to the inner face of assembly 1 and is inside the tube. The band 7 makes it possible to slow the diffusion of the cyanoacrylates in the welded zone and avoids the problems of delamination.

US Pat. No. 4,733,800 (FIG. 2) proposes the use of a band welded inside a plastic tube in order to suppress the elastic return effect of the package when it is compressed in order to extract the product. This elastic return also called "dead fold" by the skilled person brings air into the package as it empties, resulting in accelerated oxidation of the packaged product. To overcome this drawback, patent US4733800 proposes the use of a band welded inside the tube and comprising a metal layer. Figure 2 illustrates the invention described in US4733800. The tube is formed by the assembly 1 of a laminate 2 welded end to end. Said laminate 2 comprises at least one metal layer 4 with a thickness of between 5 and 40 microns and a welding layer 5. The strip 7 welded on the inner face of the assembly 1 is superimposed on the ends of the laminate 2 at the butt welding zone 6. The strip 7 located inside the tube comprises at least one metal layer of thickness of between 40 and 200 microns and two welding layers 8 and 10. Said strip 7 prevents the elastic return of the tube during the extraction of the product, and reinforces the welded zone due to the thickness of the layer However, the invention described in patent US4733800 has several major disadvantages. A first disadvantage lies in the fact that the metal layer 9 is in direct contact with the packaged product which creates problems when the product is food. A second disadvantage is related to the large thickness of the strip which makes it difficult or impossible to assemble the tube head on the tubular body.

The patent application JP06166107 (FIG. 3) proposes the use of a welded strip inside the tube in order to overcome the drawbacks of butt welding. end of the laminate ends. The patent application JP06166107 proposes in particular to avoid the contact of the barrier layers with the packaged product by positioning the ends of the laminate end to end and by welding a strip which connects said ends. A tube is formed of the assembly 1 of a laminate 2 whose ends are positioned end to end. The ends 6 are not welded together; they are connected via the strip 7 welded to the underside of the laminate. According to the patent application JP06166107, the strip may comprise several layers and the welded layer is identical in nature to the lower layer 5 of the laminate. The invention described in the patent application JP06166107 is useful for associating non-welding laminates end to end. However, it has several disadvantages. A first disadvantage is of aesthetic order because the outer surface of the tube has a break at the level of the end-to-end assembly zone 6. A second disadvantage is related to the extra thickness created by the inner band which makes it difficult to assemble the tube head on the tubular body. In addition, the information included in this patent does not make it possible to effectively reinforce the resistance of the welded zone. As a result, the teaching of the aforementioned patent application can be applied only very restrictively to reinforce the welded zone.

Problem to solve

During their use, the tubes undergo many stresses, especially in the welded zones. Among these stresses, there may be mentioned those which are repeated in flexion - traction of the welded zone during the extraction of the product; the bending stresses created by the formation of folds during the welding of the end of the tube and during the extraction of the product. The bending strength of the welded zone is particularly critical and difficult to achieve with butt welding. The welded zone is also subjected to traction shock during an impact corresponding, for example, to the fall of the tube from a height of 1 m. It has been observed that a tube formed by butt welding the ends of the laminate has a lower weld zone resistance than the laminate. In particular, a loss of elongation properties is observed in the welded zone, which leads to a brittle fracture during tensile stress. It is also observed a very poor flexural strength of the welded zone which results in the rupture of the welded zone during folding. It was finally observed that during a fall, the tube bursts at the welded zone, which illustrates the low resistance of the welded zone.

The addition of a band that solidifies the welded zone can overcome these disadvantages. However, contrary to what is described in the prior art, this addition of a band causes many difficulties. It is proposed in the prior art to add a band inside the tube to avoid contact of the ends of the laminate with the packaged product. The addition of an inner band according to the description of the prior art makes it difficult to assemble the component due to the extra thickness created by said strip and creates leakage in the thickness. Conversely, the addition of a strip to the outside of the tube according to the description of the prior art is detrimental to the aesthetics of the packaging and makes this tube unfit for consumption. There is therefore a problem related to the properties of the band and its geometry.

Making plastic tubes by butt welding the ends of a laminate and reinforcing the welded zone by a band connecting the welded ends has many advantages; However, these tubes can not be produced today because of the difficulty of finding a reinforcing strip which jointly withstands the mechanical stresses during the lifetime of the package, does not damage the aesthetics of the package, and allows making said packaging at a high rate of production.

It has been tested for example polyethylene strips welding on the ends of the laminate. In this case, it has been observed that the package obtained does not have sufficient strength when the thickness of the strip is less than a quarter of the thickness of the laminate. But when the strip has a thickness greater than a quarter of the thickness of the laminate, the aesthetics of the tube is not not acceptable if the strip is welded to the outside of the package, and if the strip is welded to the inside of the package, the tube leaks at the assembly of the tubular body and the head.

The welding of a strip whose structure is identical to the structure of the laminate has also been tested and makes it possible to obtain a welded zone of high strength.

However the aesthetics of the tube is not acceptable when the strip is welded to the outer face of the package. Indeed, to obtain a suitable resistance, it is necessary to use a relatively thick band. A problem also arises when the strip is welded to the inner face of the package, difficulties are encountered when welding the tube head on the tubular body.

Definition of the terms used in the disclosure of the invention

In the disclosure of the invention the following terms and abbreviations are used:

Laminated: multilayer film resulting from the complexing of several films

BOPET: bi-oriented polyethylene terephthalate

BOPP: bi-oriented polypropylene BOPA: bi-oriented polyamide

PE: polyethylene

LDPE: low density polyethylene

LLDPE: linear low density polyethylene

HDPE: high density polyethylene EVOH: ethylene vinyl alcohol

Adhesive: glue used when making laminates to combine several films

Glue: adhesive product used to glue the strip to the laminate

Welding: the welding operation amounts to assembling by melting two materials of the same nature or miscible in the molten state, said miscibility being manifested by the diffusion and interpenetration of the chains Molecular and then cooling said materials to freeze the state of molecular interpenetration.

Bonding: As opposed to welding, bonding is defined as an assembly operation of two materials that are not of the same kind or immiscible in the molten state. Bonding can involve chemical mechanisms (reaction of chain ends, crosslinking), physical mechanisms (Van der Waal forces, evaporation). Bonding is an assembly operation that can be performed at room temperature or by heating the materials.

General presentation of the invention

The invention consists of a plastic tubular package comprising a tube head assembled on a tubular body formed of a laminate whose ends are welded to one another and covered by a strip, said laminate being composed of at least a welding layer and a non-welding layer, characterized in that the strip comprises a layer of bi-oriented polymer and a layer for fixing the strip on the laminate, the tensile rigidity of the strip being also greater than or equal to the rigidity of the non-welding layer.

Due to the presence of a bi-oriented polymer layer, the thickness of the strip can be significantly reduced.

The invention is particularly applicable to the butt welding of a laminate composed of several layers including at least one functional layer (eg barrier) and a welding layer, said functional layer being at best partially welded.

The invention allows the production of high strength tubes and improved aesthetics. In particular, the invention makes it possible to obtain a tube whose butt welded zone is at least as strong as the laminate. Jointly, the aesthetics of the tube is improved because the tube has an extra thickness negligible in the welded zone and has the possibility to be decorated on its entire circumference without interruption in the welded zone.

Together, because of the properties of the band, the invention improves the welding of the tube head to the tubular body.

According to a first embodiment of the invention the strip is welded or glued to the upper surface of the laminate.

According to a preferred embodiment of the invention, the band is transparent.

The thickness of the strip is between 12 microns and 80 microns and preferably between 12 and 50 microns.

The width of the strip is between 3 and 15 mm; preferably between 4 and 6 mm when the strip is welded; and preferably between 6 and 15 mm when the tape is glued.

The invention will be better understood with the aid of the description of embodiments thereof and the following figures in which:

Figures 1 to 3 describe the main uses of a welding strip known in the prior art for connecting the welded ends of a laminate.

Figure 1 illustrates the use of a band to limit the migration of aggressive components contained in the package.

Figure 2 illustrates the use of a band for the elastic return effect of the tube when compressed to extract the product.

FIG. 3 illustrates the use of a band welded inside the tube in order to overcome the drawbacks of the welding by covering the ends of the laminate. Figures 4 and 5 illustrate band structures according to the invention and their use for making tubes.

Figure 4 shows a first embodiment of the invention to use a strip having a bi-oriented layer and bonded to the outer surface of the package.

FIG. 5 shows a second embodiment of the invention of using a strip comprising a bi-oriented layer and bonded to the inner surface of the package.

Detailed exposition of the invention

It has been found that a web containing at least one bi-oriented polymer layer has a great advantage. Surprisingly, it has been observed that a strip consisting solely of a bi-oriented PET film of 12 microns, a polyethylene film of 20 microns and a layer of adhesive of 2 microns connecting the two films, confers the butt welded tube has sufficient strength while the thickness of said strip is about 5 to 10 times less than that of the laminate. Said strip is welded to the outer face of the package and connects the ends welded end to end of the laminate. Said strip was welded to the butt welded ends of a 275 micron thick laminate and containing a 20 micron aluminum layer trapped between the polyethylene layers. The butt welding zone of the laminate has a double weakness; the former being related to the discontinuity of the aluminum layer and the second to the weak resistance of the PE layers welded end to end. The welding on the outer face of the tube of the aforementioned strip comprising a bi-oriented PET layer gives unexpected resistance to the welded zone while the thickness of the strip is 8 times lower than that of the laminate. When using the tube, no breakage or weakness is observed in the welded zone. Subject to a pressurization test, bursting of the tube is observed by rupture of the laminate outside the welded zone. The thin strip has a high transparency and is hardly visible on the surface external of the packaging. The aesthetics of the packaging is not penalized by the presence of the band on the outer surface.

FIG. 4 illustrates a first embodiment of the invention which consists in adding a strip 7 to the outer surface of a package 1 formed of a laminate 2 welded end to end. The strip 7 comprises at least one bi-oriented polymer layer 9 and a second layer 8 for bonding said strip 7 to the ends of the laminate. When the strip 7 is applied by welding, the layer 8 is identical in nature to the layer 3 of the laminate. Preferably, the layer 8 is based on polyolefin to allow high speed welding production. The laminate 1 has several layers, generally at least one does not weld end to end because of its properties or because of its small thickness. Layers with barrier properties such as, for example, aluminum layers, ethylene vinyl alcohol (EVOH); or the bi-oriented thin layers such as the BOPP and BOPET layers, or the layers having a melting point 20 ^° C higher than the melting temperature of the welding layer do not weld end to end. This results in a discontinuity of the mechanical properties of the package at the weld. FIG. 4 shows a laminate 2 comprising a non-sealing layer 4 trapped between layers 3 and 5. The strip 7 has a stiffness and a resistance greater than or equal to the rigidity and the strength of the non-sealing layer 4. At least the layer 5 is butt welding to ensure continuity of the inner wall of the package at the welded area, and to ensure packaging hygiene properties vis-à-vis the packaged product. The ends of the upper layer 3 of the laminate are connected by welding layer 8 of the strip.

According to a variant of the invention, the strip 7 can be applied by gluing on the outer layer 3 of the laminate 2. According to this variant, the layer 8 of said strip 7 is an adhesive. An adhesive tape is particularly advantageous when the tape is applied directly to a printed surface having inks or varnishes. The width of the glued strip is preferably greater than or equal to 6 mm so that the adhesive force is sufficiently high to withstand the tensile and flexural stresses generated by the use of the tube and avoid delamination. According to this variant, the upper layer of the laminate is not necessarily welding, which allows a large choice of resins. The upper layer 3 may be for example PET, PA or PP. An upper layer 3 of PET, PP or PA has great advantages when used as a printing medium. Indeed, because of its high melting temperature relative to the welding layers, the layer 3 is not damaged during the welding operation. This results in improved decoration and optical properties of the packaging in the welding zone.

Transparent bands make it possible to obtain decorated tubes around the circumference.

The first embodiment of the invention makes it possible to obtain packaging whose visual quality is improved. Tapes containing a layer of BOPET or BOPP are particularly advantageous because they have a high transparency. It is advantageous to use a bonded or welded band of thin thickness and transparent so that the assembly area is invisible. The invention allows the manufacture of tubes having an uninterrupted decoration at the assembly area. When the strip is welded to the outer surface of the laminate, the decoration is preferably trapped between the layers of the laminate; while when the tape is glued the decoration can be indifferently surface or imprisoned.

The invention illustrated in FIG. 4 makes it possible to obtain tubes having an excess thickness at the welded zone of less than 25% and preferably less than or equal to 20%.

According to the second embodiment of the invention illustrated in Figure 5, the strip 7 is connected to the lower surface of the laminate 2 forming the inner surface of the package. The strip 7 comprises at least one bi-oriented layer 9 trapped between two welding layers 8 and 10. The welding layers 8 and 10 are generally of the same nature as the layer 5 forming the inner layer packaging; and the sealing layers 8 and 10 are preferably polyolefin layers. PE solder layers 8 and 10 are particularly advantageous because they allow high speed welding of production. The thickness of the strip 7 illustrated in FIG. 5 is advantageously less than a quarter of the thickness of the laminate 2, which makes it possible to avoid leaks in the welding of the tube head on the tubular body. For example, the strip 7 is composed of a layer 9 made of BOPET with a thickness of 12 microns and layers 8 and 10 made of LDPE with a thickness of 20 microns. The layers 8, 9 and 10 are bonded together by 2 micron adhesive layers. The total thickness of the strip is less than 60 microns. The strip 7 is welded to the ends of the inner layer 5 of the laminate 2. The laminate 2 comprises an inner layer 5 of LDPE with a thickness of 240 microns and a layer 6 of bi-oriented polypropylene (BOPP) with a thickness of 10 microns. Layer 6 is not welded end to end.

It has been observed that a stiffness and strength band greater than or equal to the rigidity and strength of the non-welded layers makes it possible to reinforce the welded zone sufficiently and to prevent a rupture of the tube at the level of the welded zone during its use.

The invention illustrated by FIGS. 4 and 5 is particularly advantageous for assembling a laminate consisting of a functional layer and a welding layer end-to-end, said functional layer being at best partially welded; the strip connecting the ends of the laminate to compensate for the loss of resistance at the welded zone. The strength of the band is such that it compensates for the fragility of the butt welded area. Surprisingly, the tube obtained according to the invention illustrated by FIGS. 5 and 6 has a resistance at the weld zone greater than or equal to the strength of the laminate. It is observed for example a rupture of the tube next to the welded zone during a burst test, an excellent resistance of the welded zone during a repeated stressing in flexural tension, a very good resistance to bending of the welded zone. welded zone during the formation of fold, and a rupture of the package next to the welded zone during an impact. The invention illustrated in FIGS. 4 and 5 is advantageous for end-to-end connection of laminates comprising layers whose melting temperature difference is greater than 20 ^° C. The assembly of these films according to the preferred embodiment consists in heating said laminated at a temperature close to the melting temperature of the welding layer, and reinforcing the ends of said laminate by means of a strip comprising at least one bi-oriented polymer layer.

A strip comprising a bi-oriented polymer layer is particularly advantageous because the bi-oriented layer retains its properties even if it is heated and cooled in the tube-making process.

The strip may be welded or glued to the top or bottom surface of the laminate. Many glues and bonding methods can be considered. As an example, a first method consists in reporting a strip on which the glue has been previously applied. A first variant of this method is the adhesive tape applicable at room temperature, a second variant is an adhesive tape that is glued on heating. The use of an adhesive tape leads to a process that is easy to control and easily indestructible. Another method is to apply the glue on the tape or on the film at the time of assembly. The use of two-component reactive glues provides high levels of adhesion. Generally the bonding operation does not require special treatment of the surface of the assembled area, however it is possible to make surface treatments before bonding (corona treatment for example).

When the strip is stuck to the surface of the laminate, it is sometimes advantageous to interrupt the strip before the end of the tubular body. The band therefore extends over only a portion of the length of the tubular body. When assembling the end of the tubular body and the tube head; it is often preferable that the band be absent from the assembly area. Another embodiment of the invention consists of a strip having high oxygen or aroma barrier properties and containing at least one bi-oriented polymer layer. By way of example, the barrier properties can be provided by an additional layer of barrier polymer such as ethylene vinyl alcohol (EVOH) or by a plasma-deposited coating on the bi-oriented layer (Siox coating for example).

According to the invention, the thickness and the choice of the bi-oriented polymer layer in the strip depends on the non-welded end-to-end layers of the laminate. It has been found that the bi-oriented layer of the strip should have a tensile strength and rigidity at least equal to that of the non-welded end-to-end laminate layers.

Examples

The layers are listed from the outer surface of the package to the inner surface of the package.

Examples of strips welded to the outer surface of the tube

Band 1

BOPET / adhesive / LLDPE diapers

Thickness (microns) 12/3/20

Band2 BOPP / adhesive / LDPE layers

Thickness (microns) 20/3/20

Band 3

BOPET SiOx / adhesive / LLDPE layers Thickness (microns) 12/3/20

Band 4 BOPP / adhesive / PP layers - EVOH - PP

Thickness (microns) 20/3/45

Strip 5 BOPA / adhesive / LLDPE layers Thickness (microns) 20/3/30

Examples of tape stuck on the outer surface of the tube

BOPET 6-ply tape metallized / hot melt (Bostik TLH 2013)

Thickness (microns) 12/5 Band 7 Layers PET / adhesive (Bostik Vitel 1912) Thickness (microns) 40/5

Examples of strips welded to the inner surface of the tube

8 LLDPE Tape / Adhesive / BOPET / Adhesive / LLDPE

Thickness (microns) 20/3/12/3/20

Claims

claims

1. Plastic tubular package comprising a tube head assembled on a tubular body (1) formed of a laminate (2) whose ends are welded to one another and covered by a strip (7), said laminate ( 2) being composed of at least one welding layer (3,5) and a non-welding layer (4), characterized in that the strip (7) comprises a bi-oriented polymer layer (9) and a layer ( 8) for fixing the strip (7) on the laminate (2), the tensile rigidity of the strip (7) being also greater than or equal to the rigidity of the non-welding layer (4).

2. Package according to claim 1 wherein the strip (7) is bonded to the laminate (2).

3. Packaging according to claim 1 wherein the strip (7) is welded to the laminate (2).

4. Packaging according to any one of the preceding claims wherein the strip (7) is disposed on the outer face of the laminate (2).

5. Packaging according to any one of claims 1 to 3 wherein the strip (7) is disposed on the inner face of the laminate (2).

6. Package according to any one of the preceding claims comprising a strip disposed on the outer face of the laminate (2) and a strip disposed on the inner face of the laminate (2).

7. Packaging according to any one of the preceding claims wherein the ends are welded to each other by overlap.

8. Package according to any one of claims 1 to 6 wherein the ends are welded end to end.

9. Package according to any one of the preceding claims wherein the thickness of the strip (7) is between 12 microns and 80 microns.

10. Package according to the preceding claim wherein the thickness of the strip (7) is between 12 and 50 microns.

11. Package according to any one of the preceding claims wherein the width of the strip (7) is between 3 and 15 mm.

12. Package according to any one of claims 1 or 3 to 11 wherein the strip (7) is welded and whose width is between 4 and 6 mm.

13. Package according to any one of claims 1, 2 or 4 to 11 wherein the strip (7) is bonded and whose width is between 6 and 15 mm.