EP1963202A1

EP1963202A1 - Peel-off films for closing a sterilizable container

Info

Publication number: EP1963202A1
Application number: EP06841837A
Authority: EP
Inventors: Alain Grayer; Sandrine Cabioch; Guy Boiron
Original assignee: Alcan Packaging Selestat
Current assignee: Amcor Flexibles Selestat SAS
Priority date: 2005-12-01
Filing date: 2006-12-01
Publication date: 2008-09-03
Anticipated expiration: 2026-12-01
Also published as: WO2007063226A1; ATE481335T1; EP1963202B1; DE602006016987D1; FR2894231A1; FR2894231B1

Abstract

The film (10) of multilayer material comprises a tear-off tab (12) and a sealing area (11), said multilayer material comprising an outer layer (14) and, coated with a sealing agent (20), an inner layer (16); said film (10) being designed to be sealed, by a peripheral sealing border (13), to a rim (30) of a container that is to be closed, said film being characterized in that: a) the inner layer (16) has a first line of weakness formed along a peripheral line (22), said peripheral line (22) being identified and intended to be placed against said rim (30), b) said outer layer (14) and said inner layer (16) are held together by an intermediate layer (18), the type and thickness of which are chosen to allow said sealed peripheral border to be broken. Advantages: excellent sterilization resistance and easy opening by pulling the tab manually.

Description

PEELABLE OPERATORS FOR SEPARATING A STERILIZABLE CONTAINER

FIELD OF THE INVENTION

The invention relates to the field of peelable closure lids for sealing containers. These covers form a closure membrane, typically provided with a manual gripping tab, to be sealed on the rim of a container.

STATE OF THE ART

It is known to close containers with a film-forming membrane seal, said film comprising an inner sealing layer. Such lids are sealed directly on the edge surrounding the opening of the container, for example in plastic or glass containers. With aluminum or tinplate containers, the seal is usually sealed to the edge of a lid ring.

To facilitate the opening of the container by peeling the seal from the edge of the opening, simply pull on said tab. For peeling to be possible without undue effort, the lid should not be sealed too tightly on the edge of the container. PROBLEMS POSED

In the case where the containers with a closure by a lid must be sterilized, and especially in the case where they must be sterilized without back pressure, or without a perfectly regulated back pressure, the adhesion force between the edge of the container and the seal sealed thereon must be large enough so that the seal does not come off the edge of the container under the action of the pressure produced inside the container during the sterilization operation. However, in the closure systems known today, the adhesive force of the lid on the edge of the container must be chosen so large that, at the opening of the container, the force required for the peel of the operculum is excessively high.

The aim of the invention is to develop a seal forming a seal capable of being sealed on a rim of an opening of a container intended to be sterilized, after filling with a content, typically a food product to be sterilized, and closure by sealing said seal, this seal allowing:

on the one hand, to preserve the integrity of said closure by sealing during the entire sterilization stage, even when said sterilization is carried out without back pressure, or with a slightly stabilized or poorly regulated back pressure,

- On the other hand, to be able to subsequently open the sterilized container closed by said lid, by pulling on said tongue with a moderate effort.

DESCRIPTION OF THE INVENTION

According to the invention, the closing cap, made of a multilayer flexible material, comprises a tear-off tab and a shut-off pad, said multilayer material comprising an outer layer and an inner layer coated with a sealing agent, said cap being intended to be sealed, by a sealing peripheral edge, on a rim of a container to be sealed, a manual pull exerted on said tongue of said seal sealed on said rim of said container by means of a sealed peripheral rim, resulting in peeling of said lid and an opening of said container.

This seal is characterized in that: a) the inner layer has a first line of weakness formed along a peripheral line, said peripheral line being marked and intended to be opposite said rim, on its inner part, when said peripheral edge of said lid is sealed to said flange, b) said outer layer and said inner layer are joined to each other by means of an intermediate layer solidarisant said outer and inner layers, said intermediate layer being chosen in nature and thickness so as to allow a rupture of said a peripheral edge sealed in its thickness between said outer layer and said inner layer, so that said manual traction exerted on said tongue causes a central portion of said inner layer delimited by said peripheral line, so as to form a central opening, a peripheral portion of said inner layer remaining sealed to said flange.

The Applicant has observed that this combination of means solves the problems posed.

Indeed, on the one hand, the tests carried out with both a laboratory sterilizer and an industrial sterilizer, have shown that the invention made it possible to preserve the integrity of said closure by sealing during the entire sterilization stage, even when said sterilization is carried out without back pressure, or even in cases, where, deliberately, the sterilization was carried out with a little stabilized or poorly regulated back pressure, so as to reproduce the hazards encountered in industrial production. On the other hand, it has been observed that it was possible to subsequently open the sterilized container closed by said lid, by pulling on said tongue with a moderate effort.

DESCRIPTION OF THE FIGURES

Figure 1 is a plan view of the sealing face of a lid.

Figure 2 shows a section through the seal of Figure 1 welded to a container edge along its line I-I.

Figures 3 and 4 illustrate the seal of Figure 2 welded to the edge of a container at different stages of the opening. Figure 5 is an enlarged representation of a portion of Figure 3. DETAILED DESCRIPTION OF THE INVENTION

According to the invention, and as illustrated in FIGS. 1 to 6, said inner layer (16) may comprise a second line of weakness (26) formed along a line (26 ') forming a junction between said tongue of tear (12) and said shutter area (11), said line (26 ') being located and intended to be opposite said flange

(30), on its outer part, so as to facilitate said rupture.

Said second line of weakness (26) may extend for at least 50% of the length of said marked line (26 ') which is typically curvilinear. On the example of the lid shown in FIG. 1, said second line of weakening

(26) extends about 75% of the length of said marked line (26 '), which has been shown in dashed lines in Figure 1 for its two end portions which do not include a line of weakness.

Typically, said first line of weakness (22) and said second line of weakness (26) may be formed by an incision formed in said inner layer (16) coated with said sealant (20), at least half-flesh on a fraction at least 50% of the thickness of said inner layer (16) coated with said sealant (20). Said incision may be formed over the entire thickness of said inner layer (16) coated with said sealant (20) and typically over a portion of the thickness of said intermediate layer (18), such that an adhesive break between said inner layer (16) and said intermediate layer (18) allows said operculum (10) to be peeled off by forming said central opening.

According to the invention, said outer layer (14) may comprise an aluminum film having a thickness ranging from 20 μm to 80 μm, and typically having a thickness ranging from 45 μm to 65 μm. Said aluminum film may comprise an impression on its outer surface, said printing being typically covered with a protective varnish called overprinting. Said inner layer (16) may comprise a thermoplastic film of traction modulus at least equal to 800 MPa, and of thickness ranging from 20 μm to 80 μm, and typically of a thickness ranging from 40 μm to 60 μm.

Said thermoplastic film may be a polyolefin film, preferably PP, typically an unoriented PP, or polyester.

According to another embodiment of the invention, said inner layer (16) may comprise a second aluminum film having a thickness ranging from 20 μm to 80 μm, and typically having a thickness ranging from 45 μm to 65 μm.

As illustrated in FIG. 5, said outer (14) and intermediate (18) layers may be secured by an adhesive layer (19) with a grammage ranging from 1 to 6 g / m ² .

Advantageously, said intermediate layer (18) may be a polyolefin-based thermoplastic extrusion monolayer or a polyolefin-based thermoplastic coextrusion multilayer, said monolayer or said multilayer having a basis weight of 30 g / m 2. m ² at 80 g / m ² and typically 40 g / m ² to 60 g / m ² .

Said monolayer or said multilayer may be chosen so as to fasten said inner layer (16) to said outer layer (14) or possibly to said adhesive layer (19) and to allow said rupture.

According to the invention, said sealing agent (20) may be formed by an extruded or coextruded sealing layer (20 ') of plastics material having a basis weight ranging from 30 g / m ² to 80 g / m ² and typically 40 g / m ² at 60 g / m ² .

Said sealing layer (20 ') may be chosen to adhere to any material constituting said flange (30), typically chosen from: glass, aluminum, iron or tinplate, a plastic material.

According to the practical embodiment of the seal, said rupture, when said manual traction is exerted on said tab of said seal (10) sealed on said rim (30) of said container, may be either a cohesive rupture of said intermediate layer (18), or an adhesive break between said inner layer (16) and said intermediate layer (18).

Generally, said shutter range (11) has a shape and an outer contour corresponding to the outer contour of said rim (30), said shutter range (11) being of typically round or oval or polygonal, rectangular or square shape, said shutter range (11) having an area ranging from 10 cm ² to 400 cm ² .

Another object of the invention is constituted by a method of manufacturing lids according to the invention.

In this process: a) supplying: al) said outer layer (14) comprising said aluminum film, said aluminum film optionally comprising on its outer face, an impression, preferably covered by an overprint varnish and optionally on its inside, said adhesive layer (19), a2) said inner layer (16) comprising said thermoplastic film or said second aluminum film, b) said outer layers (14) are assembled and interior (16) extruding or coextruding said intermediate layer (18), c) depositing said sealant (20) on said inner layer (16) by extruding or coextruding on said inner layer (16) a layer extruded or coextruded sealing (20 '), so as to obtain a strip of multilayer material, d) forming a plurality of lids: dl) either by first cutting the lids in said strip, and then incising the operculas for forming said first and second weakening lines, d2) either by first incising said strip to form an incised strip comprising said first and second lines of weakness, and then cutting the covers in said incised strip, said caps thus cut and incised are then arranged in stacks. Another object of the invention is constituted by a container with a container rim (30) delimiting a filling and sampling aperture (32) closed by a lid (10) according to the invention, said lid (10) having been sealed to said flange (30) after loading a product, typically a food product, said container thus loaded being sterilized or intended to be sterilized.

In this container, at least said flange (30), and possibly said container, may be formed of a material selected from: glass, aluminum, iron or tinplate, plastic. In this container, said rim (30) may be an outer rim or an inner rim.

EXAMPLE OF REALIZATION

Figures 1 to 5 illustrate an embodiment of a closure cap (10). Round lids (10) of diameter, typically ranging from 40 mm to 120 mm, have thus been manufactured and intended to seal metal cans to be sterilized. In this example:

the outer layer (14) is an aluminum film 30 μm thick, the intermediate layer (18) is a 40 μm thick PE extrusion layer,

the inner layer (16) is a non-oriented PP film (PPN) of 50 μm in thickness.

- The sealing agent (20) consists of an extruded sealing layer (20 ') of 50 microns thick.

- A layer of adhesive (19) of 3 microns thick was used to secure the aluminum film (14) to the intermediate layer (18).

A layer of multilayer material having a structure symbolically represented by: 14/19/18/16/20 was first formed by assembling layers.

In some tests, the outer layer (14) was a layer externally coated with an impression typically constituted by a plurality of patterns, each seal having said pattern. The strip of multilayer material is then incised to form an incised strip comprising said first (22) and second (26) lines of weakness. In the case where the outer layer (14) was a layer externally coated with an impression comprising a plurality of patterns, said strip of multilayer material was incised in a marked manner, so that the printing pattern is correctly centered especially relative to at said first line of weakness (22). For this, the inner layer (16) has been incised partially or completely along the peripheral line (22 ') so as to form said first line of weakness (22). In the region of the tear tongue (12), the inner layer (16) has been incised totally or partially along a marked line (26 ') disposed transversely to the pull direction of the tear tongue (12) to form said second line of weakness (26) over a curvilinear distance substantially equal to 75% of the length of said curvilinear line (26 '). The lids (10) were then cut in a marked manner in said incised strip.

FIG. 2 represents the closing cap (10) during the sealing operation of the lid (10) on the edge (30) of a container not shown in the drawing. Sealing between the sealing layer (20 ') and the sealing rim (30) of the container has been performed by means of a sealing jaw (28), which presses the closure cap (10) against the rim ( 30) of the container under a pressure sufficient to seal and at a predetermined sealing temperature by the combination of the facing materials. The higher temperature during sealing has led to an increased adhesive force between the layers of the seal (10) in its sealed peripheral edge (13 ').

The containers thus closed by lids (10) according to the invention, and previously filled with a food product to be packaged, could be sterilized in an autoclave without back pressure, and this, without it being observed on the containers thus sterilized any alteration of the sealing range or any separation of the seal from the container. To open the container, as illustrated in Figures 2 to 4, the lid (IQ) is grasped by the tear tab (12) which is then pulled over the portion of the lid (10) sealed and remaining to remove.

It has been observed that the manual effort to exert on the tongue (12) remains within the usual stress range, typically ranging from 0.1 daN to 0.6 daN.

During this opening operation of the container, and as illustrated in FIG. 5, a tear extending from the tip of said second weakening line (26) propagates firstly between the outer layer (14) and the peripheral portion (16 ") of the inner layer (16) transversely to the sealed peripheral edge (13 '), and joins, at the exit of this border (13'), said first line of weakness (22) along said line peripheral (22 '). By continuing the peeling of the closing cap (10), the central portion (16') is separated from said inner layer (16), said peripheral portion (16 ") from said inner layer (16). ) remaining welded on said edge (30) of the container, so as to provide access to the opening (32) for filling and sampling said container.

In FIG. 5, the path of a tear (34) is plotted from the tip (27) of said second line of weakness (26) to the incision of the inner layer (16) forming said first line weakening (22). In the illustrated example, the tear (34) progresses in a cohesive rupture inside the intermediate layer (18). This tear path (34) occurs when the cohesive forces within the intermediate layer (18) are greater than the adhesion forces between the intermediate layer (18) and the outer layer (14) or the inner layer (16). Depending on the composition of the intermediate layer (8) and the outer (14) and inner (16) layers, the tear (34) in the sealed peripheral edge (13 ') forming the sealing region may also propagate in the boundary layer between the intermediate layer (18) and the outer (14) or inner (16) layers, or optionally between the intermediate layer (18) and the adhesive layer (19).

ADVANTAGES OF THE INVENTION The invention has great advantages.

Indeed, on the one hand, it is adapted to a wide field, that relating to the packages that are the subject of sterilization, these packaging can be of all types, and mainly metal, glass. This is generally the field of vegetable preserves, but many other products may require sterilization.

On the other hand, it constitutes an advantageous alternative to the means traditionally used, at the same time:

- by the substitution of materials operated: replacement of traditional lids by lids,

- By the closing technique: a heat seal is easier to implement than a lid crimping,

- By the ease of opening: indeed, the said metal lids easy opening are not always really easy to open given the need to have incisions in the metal point too deep,

- finally, by renewing the image brought by the use of operculas in place of traditional lids, which can encourage consumer buying and thus constitute a great commercial advantage.

LIST OF REFERENCES

Closing gate 10

Shutter range 11

Stripping tab 12 Peripheral sealing edge 13

Sealed peripheral edge on 30 13 '

Outer layer 14

Inner layer 16

Central part of 16 16 'Peripheral part of 16 16 "

Intermediate layer 18 Adhesive layer. 19

Sealing agent 20

Extruded or coextruded sealing layer 20 '

First line of weakness 22 Peripheral line 22 22 '

Second line of weakness 26

Line marked 26 26 '

26 27 point

Closure of the container to be closed 30 Filling and sampling opening 32

Tear 34

Claims

A closure cap (10) of a multilayer flexible material comprising a tear tab (12) and a shutter pad (11), said multilayer material comprising an outer layer (14) and an inner layer (16). coated with a sealing agent (20), said lid (10) being intended to be sealed, by a peripheral sealing edge (13), on a rim (30) of a container to be closed, a manual pull exerted on said tab of said seal (10) sealed to said rim (30) of said container by a sealed peripheral rim (13 '), causing a peel of said seal (10) and an opening of said container, characterized in that: a) the diaper interior (16) has a first line of weakness (22) formed along a peripheral line (22 '), said peripheral line (22') being marked and intended to be opposite said rim (30), on its inner portion, when said peripheral border said cover (10) is sealed to said flange (30), b) said outer layer (14) and said inner layer (16) are joined to each other by means of an intermediate layer (18). ) solidarisant said outer (14) and inner (16) layers, said intermediate layer (18) being selected in nature and thickness so as to allow a rupture of said sealed peripheral edge (13 ') in its thickness between said outer layer ( 14) and said inner layer (16), so that said manual pull exerted on said tongue (12) drives a central portion (16 ¹ ) of said inner layer (16) delimited by said peripheral line (22 '), so as to forming a central opening, a peripheral portion (16 ") of said inner layer (16) remaining sealed to said flange (30).

The cap of claim 1 wherein said inner layer (16) comprises a second line of weakness (26) formed along a marked line (26 ') forming a junction between said tear tab (12) and said shutter range (11), said marked line (26 ¹ ) being intended to be opposite said rim (30), on its outer part, so as to facilitate said rupture.

The cap of claim 2 wherein said second line of weakness (26) extends at least 50% of the length of said typically curvilinear line (26 ').

A seal according to any one of claims 1 to 3 wherein said first line of weakness (22) and said second line of weakness (26) are formed by an incision formed in said inner layer (16) coated with said sealant At least half of the thickness of said inner layer (16) coated with said sealant (20).

The cap of claim 4 wherein said incision is formed over the entire thickness of said inner layer (16) coated with said sealant (20) and typically over a portion of the thickness of said intermediate layer (18). ), so that an adhesive break between said inner layer (16) and said intermediate layer (18) allows to peel said seal (10) forming said central opening.

6. Seal according to any one of claims 1 to 5 wherein said outer layer (14) comprises an aluminum film with a thickness ranging from 20 microns to 80 microns, and typically with a thickness ranging from 45 microns to 65 microns. .

7. The cap according to claim 6 wherein said aluminum film comprises a print on its outer surface, said printing being typically covered with a protective varnish called overprinting.

8. The seal according to any one of claims 1 to 7 wherein said inner layer (16) comprises a thermoplastic film of tensile modulus of at least 800 MPa, and thickness of 20 microns to 80 microns, and typically with a thickness ranging from 40 μm to 60 μm.

9. The cap according to claim 8 wherein said film of thermoplastic material is a polyolefin film, preferably PP, typically an unoriented PP, or polyester.

10. Seal according to any one of claims 1 to 7 wherein said inner layer (16) comprises a second aluminum film having a thickness of 20 microns to 80 microns, and typically of a thickness ranging from 45 microns to 65 microns. .mu.m.

11. Operacle according to any one of claims 1 to 10 wherein said outer layers (14) and intermediate (18) are secured by a layer of adhesive

(19) with a basis weight ranging from 1 to 6 g / m ² .

12. Seal according to any one of claims 1 to 11 wherein said intermediate layer (18) is a polyolefin-based thermoplastic extrusion monolayer or a polyolefin-based thermoplastic coextrusion multilayer, said monolayer or said multilayer having a basis weight ranging from 30 g / m ² to 80 g / m ² and typically from 40 g / m ² to 60 g / m ² .

13. The dispenser according to claim 12 wherein said monolayer or said multilayer are selected so as to secure said inner layer (16) to said outer layer (14) or possibly to said adhesive layer (19) and to allow said rupture.

A seal according to any one of claims 1 to 13 wherein said sealant (20) is formed by an extruded or coextruded seal layer (20 ') of plastic having a basis weight of from 30 g / m ² to 80 g / m ² and typically 40 g / m ² to 60 g / m ² .

The cap according to claim 14 wherein said sealing layer (20 ') is chosen to adhere to any material constituting said flange (30), typically selected from: glass, aluminum, iron or tinplate, a plastic material.

The cap according to any one of claims 1 to 15 wherein said rupture, when said manual pull is exerted on said tongue of said seal (10) sealed on said rim (30) of said container, is either a cohesive rupture of said intermediate layer ( 18), an adhesive break between said inner layer (16) and said intermediate layer (18).

17. The dispenser according to any one of claims 1 to 16 wherein said shutter pad (11) has a shape and an outer contour corresponding to the outer contour of said flange, said shutter pad (11) being of typically round or oval shape. or polygonal, rectangular or square, said shutter range (11) having an area ranging from 10 cm ² to 400 cm ² .

18. A method of manufacturing caps according to any one of claims 1 to 17 wherein: a) supplying: al) said outer layer (14) comprising said aluminum film, said aluminum film optionally comprising on its outer face an impression, preferably coated with an overprint varnish, and optionally on its inner side, said adhesive layer (19), a2) said inner layer (16) comprising said thermoplastic film or said second film of aluminum, b) assembling said outer (14) and inner (16) layers by extruding or coextruding said intermediate layer (18), c) depositing said sealant (20) on said inner layer (16) by extruding or co-extruding on said inner layer (16) an extruded or coextruded sealing layer (20 '), so as to obtain a strip of multilayer material, d) forming a plurality of lids: dl) either by cutting first the lids in said strip, and then incising the lids to form said first and second lines of weakness, d2) or by first incising said strip to form an incised strip comprising said first and second lines of weakness, and then cutting the covers in said incised strip, said caps thus cut and incised then being arranged in stacks.

Container with a container rim (30) delimiting a filling and sampling aperture (32) closed by a cover (10) according to any one of claims 1 to 17, said seal (10) having been sealed to said rim (30). ) after loading a product, typically a food product, said container thus loaded being sterilized or intended to be sterilized.

20. Container according to claim 19 wherein at least said flange (30), and possibly said container, is formed of a material selected from: glass, aluminum, iron or tinplate, a plastics material.

The container of any one of claims 19 to 20 wherein said rim (30) is an outer rim or an inner rim.