ES2240030T3 - STRATIFIED PACKING SHEET THAT ALLOWS THE CLOSURE AND PACKING THAT BEHAVES IT. - Google Patents

Abstract

The packaging film for food containers has a support layer (24) and a weldable layer (26) connected by a layer (28) of permanent adhesive. In corresponding areas (22A) of the layers, the weldable layer has a line of weakness defining an area for connective welding of the layers. The line of weakness aids tearing of the package along them.

Description

Stratified packing sheet that allows again the closure and packaging that involve it.

The present invention relates to a sheet of stratified packaging, of the type that involves a primary layer associated with a weldable layer between which it is interposed, at less in a designated area, a layer of a permanent adhesive.

The object of the invention is also a packaging which involves an external wall that defines a housing provided of an access step to said accommodation that includes said sheet of packaging.

Currently used packaging that involves a packing sheet that allows easy opening and that can close again, for example, to condition products food The structure of these sheets is described in particular in the patent application FR-A-95-14117.

In this patent, the laminated sheet used to allow opening and again closing the packaging involves two layers of polymer between which a layer of permanent adhesive. One of the layers, called "welding layer or weldable "is intended to be oriented inside the packaging. It is adapted to be welded on the peripheral edge of a container in the form of a wafer. The other layer, called "layer support ", is intended to form the outer face of the packaging, This layer can be printed.

At the time of opening the wafer described in the cited patent, the weld layer is torn by both parts of the welded region. After opening the wafer, a residual welded bead remains on the contour of it, constituted by the welded part of the welding layer.

Upon obtaining the opening of the wafer by rupture of the welding layer, it is convenient to choose said layer so that present breakage characteristics compatible with the conditions of use of the packaging.

In particular, it is convenient that the welding layer can be torn manually without the need to exercise pulling force too important on the packing sheet. Thus, the welding layers used have a thickness rather reduced.

However, it should also be that the layer welder present good characteristics in relation to the welding, in order to ensure reliable bonding of the sheet packing in the wafer. In addition, it is necessary that the welding layer is compatible with the permanent adhesive interposed between the two leaf layers. To satisfy this condition, it is convenient to choose a rather thick layer.

Thus, it is conceived that the choice of the layer Soldering iron is relatively delicate due to numerous limitations to which you must satisfy. This choice is in particular dictated by the possibility that the layer is torn manually. Without However, this feature is hardly reconcilable with the other necessary properties for the layer.

On the other hand, US Patent 5,002,223 describes a stratified packaging sheet of another type that involves locally a line of weakening of its welding layer.

The object of the invention is to propose a sheet of packaging that allows the opening and reopening of a package, whose welding layer can be chosen from a wide range.

For this purpose, the invention aims at a stratified packing sheet, as defined in the claim 1.

According to particular embodiments, the Packing sheet involves one or more of the features defined in the dependent claims.

The object of the invention is also a packaging which involves an external wall that defines a housing provided of an access passage to said accommodation, characterized in that said step is sealed by a laminated sheet according to any one of the preceding claims, said sheet being welded on said external wall to the periphery of the passage according to its weldable layer in a region essentially delimited between the lines of weakening

The invention will be better understood with reading of the description that follows, given only by way of example and made with reference to the drawings, in which:

Figure 1 is a partial perspective view and in section of a packing vessel whose access passage is sealed by a laminated sheet according to the invention;

Figure 2 is a plan view of the nozzle of figure 1, the sealing blade being extended by both parts of the wafer;

Figure 3 is a view analogous to that of the Figure 1, after opening the packaging;

Figure 4 is a plan view of a variant embodiment of the packaging of figures 1 to 3;

Figure 5 is a cross-sectional view. of the welded area of a variant embodiment of a sheet according to the invention applied to the flange of a wafer of packaging;

Figure 6 is a perspective view and in section of a packing bag consisting of a sheet of packaging according to the invention, before opening it; Y

Figure 7 is a view analogous to that of the Figure 6, after opening the bag.

The packaging 10, shown in Figure 1, is consisting of a rectangular 12-hole and an operculum flexible shutter 14 of an access passage 16 inside the nacelle.

The nozzle 12 is constituted for example by an outer support layer of an appropriate material, for example polyvinyl chloride coated on its inner surface of a weldable layer, for example, polyethylene.

The nozzle defines a receptacle 18 bordered in all its contour by a flange 20 that delimits a surface welding plane of operculum 14, according to a rectilinear welding 22

The operculum 14 is stratified, that is made with several overlapping layers. For clarity, in the figures has been exaggeratedly increased the thickness of the layers.

The operculum 14 is essentially constituted by a support layer 24 and a weldable layer 26 with a layer of permanent adhesive 28 interposed flat between them throughout the surface.

The support layer 24 advantageously behaves some impressions on his outer face. It can behave equally a transparent layer that carries said counterbalanced prints on the outer surface of the support layer by means of a glue layer applied on your printed face.

The support layer 24 is, for example, a layer of 36 µm thick polyethylene.

Permanent adhesive layer 28 is made by coating with the help of an adhesive mass initially in solution, in particular in aqueous dispersion. It can also be hot applied, in particular by extrusion.

A permanent adhesive, commonly designated under the name "hot melt" it suits this perfectly application. It is possible in particular to use Plastoflex 87.18 marketed by the Paramelt company in the Netherlands.

The thickness of the adhesive layer 28 is advantageously between 10 and 30 µm and particularly it is equal to about 20 µm.

Weldable layer 26 is for example a layer of polyethylene or polypropylene whose thickness is between 20 and 60 µm and is in particular advantageously equal to 40 µm. Be make this layer in a material that allows welding with the layer in front of the nozzle 12.

As shown in Figure 2, the cord of peripheral welding 22 extends on all four sides of the flange 20 of the rectangular wafer. This ensures a tight seal. from the boat. For reasons of clarity, peripheral welding 22 has been indicated in gray in figure 2.

Weldable layer 26 has two lines 30A, 30B of weakening, which extend parallel to each other. A zone 22A welded rectilinear of peripheral welding extending according to the length of a flange 20 of the wafer is bordered by these two lines 30A, 30B.

The weakening lines 30A, 30B are each consisting of a pre-cut line formed by a continuous groove or notch leading to the face of the layer weldable that is oriented towards the nozzle, as represented in figure 2.

The groove depth is included between 25 and 100% of the thickness of the weldable layer 26. From Preference is substantially equal to 50% of the thickness of the layer weldable

The welded zone 22A extends advantageously in the entire width indicated by i of the band delimited by the weakening lines 30A and 30B. However, the width i is such that the weakening lines are outside the welded region 22A.

As shown in Figure 2, the lines of weakening 30A and 30B are advantageously performed in the layer weldable when the packing sheets are still assembled to form a continuous band of adjacent packing sheets. The weakening lines 30A, 30B are arranged according to the direction of the machine, that is the direction of movement of the band formed by adjacent leaves. These lines therefore extend parallel to the longitudinal edge of the band.

Weakening lines 30A, 30B are made consisting of continuous grooves before placing the blade which forms the operculum in the wafer. They are done for example by continuous cutting with the help of a laser beam on the occasion of the passage from the band. In a variant, the lines of weakening by cutting them with a knife. In this last solution, on the occasion of the circulation of the band, rotating organs Shears are brought in contact with the free surface of the weldable layer 26, in order to practice the notch in it with a certain depth corresponding to the desired depth for slots 30A, 30B.

Peripheral welding 22 is obtained by heat welded On the occasion of welding, the inner layer weldable of the wafer and weldable layer 26 of the packing sheet are melt together, allowing to obtain, after cooling, a weld very reliable

As illustrated in Figure 3, on the occasion of the traction packing opening at the edge of operculum 14 located near welded area 22A, weldable layer 26 breaks easily along the lines of weakening 30A, 30B.

Only a residual band from the layer weldable 26 is present on flange 20. She forms a cord soldier, indicated with numerical reference 40. The latter is bounded laterally by both sides by the flanks of the weakening lines practiced 30A and 30B.

As is known, the presence of the adhesive permanent 28 on a welded bead and / or the surface opposite the support layer 24 allows the subsequent closure of the packaging to the put operculum 14 back in its place.

It is conceived that the presence of the lines of weakening 30A, 30B favors the opening of the wafer by traction at operculum 14. In particular, whatever the thickness and The tear resistance Initials of the weldable layer 26, is possible to determine the depth of the grooves that form the weakening lines so that they allow tearing Manual weldable layer 26 by simple traction on the operculum 14.

Thus, the characteristics of weldable layer 26 depending on the limitations linked to the welding, to compatibility with permanent adhesive or to any other limitations linked to product protection packed, without it being necessary to take into account tear characteristics necessary for opening the packaging. Indeed, the tear-off ability of weldable layer 26 is determined by the nature of the weakening lines.

A variant of embodiment of a wafer according to the invention.

In this embodiment, the lines of weakening 30A and 30B are separated by an interval i higher to the width, indicated by i, of the welds 42 performed according to the other three sides of the boat. The fourth is done welding, indicated 44, of the operculum on the wafer following all the delimited extension between the weakening lines 30A and 30B. Thus, the weld 44 has a greater width and particularly advantageous between double and quadruple of the thickness of the other welds 42.

It is understood that the widening of the weld 44 allow to increase the surface of the permanent adhesive discovered after the opening of the operculum. So when you come back to Close the packaging, improve the reliability of closure.

In addition, whatever the embodiment, with occasion of the opening of the wafer, the absence of line weakening along welds arranged at the edges parallel adjacent to the edge of welded area 22A or 42 delimited by these weakening lines does not influence the ease of opening Indeed, if applied traction is exerted in the operculum from the welded zone 22A or 42, after the rupture of the layer 26 according to lines 30A and 30B, subsequent traction is performed parallel to the direction of welding. It causes then the rupture of adjacent welds by propagation of an area tear according to the length of these welds. The tear without excessive difficulties whatever the nature of the weldable layer because at one point all tensions are applied at the same point of the layer and not distributed according to all The length of the weld.

A variant of realization of a packing sheet according to the invention welded on the flange of a boat, designated 52.

In this embodiment, the weldable layer 26 two lines of welding on both sides of the weld 22 weakening 56 A, 56 B and 58 A, 58 B.

These lines extend parallel to each other and parallel to welding 54.

In this embodiment, the lines of weakening are made up of continuous grooves that they flow into the permanent adhesive layer 28.

The presence, on both sides of the weld 22, two lines of weakening ensures that, even in presence of slight welding deviations 22 due to the inaccuracy of the procedure implemented, at least one of the weakening lines are located outside the welding, thus allowing an easy opening of the operculum, as He has explained above.

The packaging represented in figures 6 and 7 Form a packing bag. This consists of a sheet of packaging according to the invention folded on itself welded laterally on both sides and whose two extremities are joined each other by welding, with coating. More specifically, it weld 100 between the free surface of the sheet support 24 and the free surface in front of the weldable layer 26. The Bag closure is "leather over meat" type.

According to the invention, and as above, Weld between two weakening lines 30A, 30B initially practiced on the sheet to both parts of the area destined to be welded.

Advantageously, the lines of weakening following the direction of the machine, that is the direction of unwinding of the belt in the manufacturing machine the bags. This sense of unwinding corresponds equally to the direction of passage of the band on the occasion of the manufacture of the bags Thus, weakening can be easily performed in continuous.

It is understood, as illustrated in Figure 7, that, at the time of traction at the free end of the blade, the weldable layer 26 is broken along the lines of weakening 30A, 30B to both parts of the welded area.

Therefore, weldable layer 26 can be chosen with characteristics appropriate to the type of packaging desired, regardless of its breaking characteristics. Indeed, the presence of some weakening lines allows, which are which be the characteristics of the layer, make sure that it can be manually torn along the weakening lines.

In the embodiments described in the In this application, the permanent adhesive extends over the entire surface of the weldable layer. However, the permanent adhesive may be arranged between the support layer 24 and the weldable layer 26 only in designated areas, then performing the sealing sealing of the packaging in at least one of these zones indicated that present the permanent adhesive between some lines of previously practiced weakening.

In all embodiments, the sheet can be manufactured by laminate and plywood. It can also be manufactured by coextension of the superimposed layers.

Claims (10)

1. Stratified packing sheet, of the type that involves a primary layer (24) associated with a weldable layer (26) between which a layer (28) of a permanent adhesive is interposed, at least in a designated area, characterized in that , in a designated area (22A) of the sheet where the permanent adhesive is present, the weldable layer (26) comprises, on both sides of an area (22A) intended to be welded, at least one line of weakening (30A, 30B ) of the weldable layer (26) that favors its rupture along said lines. 2. Packing sheet according to claim 1, characterized in that at least one weakening line (30A, 30B) has a pre-cut line. 3. Packing sheet according to claim 2, characterized in that the pre-cutting line has a continuous groove leading to the weld face of the weldable layer (26). 4. Packing sheet according to claim 2, characterized in that the pre-cutting line has a continuous groove leading to the face of the weldable layer (26) in contact with the permanent adhesive layer (28) (28). 5. Packaging sheet according to any one of the preceding claims, characterized in that the weldable layer (62) has, on each side of the area (22A) intended to be welded, at least two weakening lines (56A, 56B; 58A, 58B) that extend substantially parallel. 6. Packaging sheet according to any one of the preceding claims, characterized in that the weakening line (30A, 30B) of the welding layer (26) is made with the aid of a laser beam. 7. Packing sheet according to claim 6, characterized in that the weakening line (30A, 30B) is made by continuous cutting when the belt passes. 8. Packaging comprising an external wall that delimits a housing (20) provided with an access passage (16) to said housing, characterized in that said passage (16) is sealed by a laminated sheet (14) according to any one of the claims above, said sheet (14) being welded to said outer wall at the periphery of the passage (16) following its weldable layer (26) in an area (22A) essentially delimited between the weakening lines (30A, 30B). 9. Packaging according to claim 8, characterized in that the width of the weld (22) made between the weakening lines (30A, 30B) is greater than the current width of the weld made at the periphery of said passage (16). 10. Bag with a packing sheet stratified according to any one of claims 1 to 7, whose blade is folded on itself and welded laterally by both parts, the two extremities being welded with coating following the weldable layer (26) in an area (100) essentially delimited between the weakening lines (30A, 30B).