EP1243523A1 - Multilayered packaging sheet with a tear strip - Google Patents

Abstract

The laminated packaging sheet has a first film (20), a second film (22) and an adhesive (24) between them. An opening strip (18) defines a line of weakness (27) and is defined laterally on one side and on the other by a lateral border (25). Each border separates an exterior area of the opening strip where the films are glued together.

Description

The invention relates to a laminated packaging sheet, of the type comprising a first film, a second film and an adhesive interposed between the two films, the sheet having an opening strip formed along its surface, which strip defines a priority propagation path for a break in the sheet, the opening strip comprising a mechanical weakening treatment.

We know of laminated packaging sheets for making bags with easy opening, especially for wrapping chocolate bars.

To allow easy opening by tearing of the packaging sheet, an opening strip is formed on the surface of the sheet. This strip defines a priority propagation path for the rupture of the sheet. This opening strip comprises for example a mechanical treatment weakening formed over the width of the opening strip, this treatment weakening being carried out in a first film of the sheet.

Such an opening strip effectively facilitates tearing and propagation of the rupture along the course of the strip.

However, if the strip has a curved outline, the tear may propagate outside the opening strip, away from the strip layout. Furthermore, if the traction exerted on the two parts of the sheet is not perfectly transverse to the band, the tear can spread outside of the opening strip.

The object of the invention is to propose a laminated packaging sheet. allowing a precise propagation of the rupture of the sheet during its opening, this propagation taking place along the route of an opening strip, even if this line is curved.

To this end, the subject of the invention is a laminated packaging sheet of the aforementioned type, characterized in that the opening strip is delimited laterally on both sides by a lateral border, each border separating an area outside the opening strip where the two films are held glued to each other at least along the lateral border and a lateral area of the opening band bordering the lateral border and free of adhesive between the two films, and in that the mechanical treatment is exactly confined between the two borders outside the areas outside the strip where the two films are bonded.

• le traitement mécanique d'affaiblissement comporte un ensemble de perforations traversant le premier film de part en part ;
• le traitement mécanique d'affaiblissement comporte des irrégularités de surface non débouchantes ménagées sur la surface externe du premier film ;
• le traitement mécanique d'affaiblissement comporte des irrégularités de surface non débouchantes ménagées sur la surface interne du premier film ;
• ladite bande d'ouverture comporte une plage centrale dans laquelle de l'adhésif est disposé, au moins localement entre les deux films, les deux plages latérales de la bande d'ouverture bordant les frontières constituant deux raies exemptes d'adhésif ;
• le traitement mécanique d'affaiblissement s'étend sur toute la surface de la plage centrale, d'une raie exempte d'adhésif à l'autre.
• le traitement mécanique d'affaiblissement se prolonge au-delà de la plage centrale et s'étend au moins partiellement dans la région des raies exemptes d'adhésif ;
• le traitement mécanique d'affaiblissement s'étend seulement dans la région médiane de la plage centrale à l'écart des raies exemptes d'adhésif, des marges dépourvues de traitement mécanique d'affaiblissement étant définies dans la plage centrale le long des raies exemptes d'adhésif ;
• de l'adhésif est déposé entre les deux films suivant toute la surface de la plage centrale ;
• la plage centrale comporte transversalement, suivant toute sa longueur, une alternance de lignes comportant de l'adhésif et de lignes exemptes d'adhésif, les lignes s'étendant suivant la longueur de la bande d'ouverture ;
• les lignes comportant de l'adhésif et les lignes exemptes d'adhésif sont plus étroites dans la région médiane de la plage centrale que dans les régions de bord de la plage centrale ;
• la plage centrale présente, le long des raies exemptes d'adhésif, deux lignes d'adhésif parallèles séparées par une région dépourvue d'adhésif, et le traitement mécanique d'affaiblissement est ménagé sur le premier film seulement dans la région dépourvue d'adhésif ;
• chaque raie exempte d'adhésif a une largeur comprise entre 0,3 mm et 10 mm ; et
• les deux plages latérales de la bande exemptes d'adhésif se rejoignent pour former sur toute la largeur de la bande d'ouverture une unique raie continue exempte d'adhésif.

According to particular embodiments, the packaging sheet includes one or more of the following characteristics:

• the mechanical weakening treatment comprises a set of perforations passing right through the first film;
• the mechanical weakening treatment comprises non-emerging surface irregularities formed on the external surface of the first film;
• the mechanical weakening treatment comprises non-emerging surface irregularities formed on the internal surface of the first film;
• said opening strip comprises a central area in which adhesive is disposed, at least locally between the two films, the two lateral areas of the opening strip bordering the borders constituting two lines free of adhesive;
• the mechanical weakening treatment extends over the entire surface of the central area, from one line free of adhesive to the other.
• the mechanical weakening treatment extends beyond the central range and extends at least partially in the region of the lines free of adhesive;
• the mechanical weakening treatment extends only in the middle region of the central range away from the lines free of adhesive, margins devoid of mechanical weakening treatment being defined in the central range along the free lines d 'adhesive;
• adhesive is deposited between the two films along the entire surface of the central area;
• the central area comprises transversely, along its entire length, an alternation of lines comprising adhesive and lines free of adhesive, the lines extending along the length of the opening strip;
• the lines with adhesive and the lines without adhesive are narrower in the middle region of the central area than in the edge regions of the central area;
• the central area has, along the lines free of adhesive, two parallel lines of adhesive separated by a region devoid of adhesive, and the mechanical weakening treatment is provided on the first film only in the region devoid of adhesive ;
• each line free of adhesive has a width of between 0.3 mm and 10 mm; and
• the two lateral areas of the strip free of adhesive meet to form over the entire width of the opening strip a single continuous strip free of adhesive.

The invention further relates to a packaging comprising at least a sheet as defined above.

• la figure 1 est une vue en élévation d'un sachet d'emballage selon l'invention ;
• la figure 2 est une vue de face schématique de la feuille d'emballage de la figure 1, dans la région de la bande d'ouverture ;
• la figure 3 est une vue en coupe transversale suivant la ligne III-III de la feuille de la figure 2 ;
• les figures 4 et 5 sont des vues analogues à celle de la figure 3 illustrant deux variantes de réalisation de la feuille ;
• la figure 6 est une vue analogue à celle de la figure 2 illustrant une variante de réalisation des feuilles des figures 2 à 5 ;
• la figure 7 est une vue de face schématique d'une variante de réalisation d'une feuille d'emballage pouvant être utilisée pour le sachet de la figure 1, dans la région de la bande d'ouverture ;
• la figure 8 est une vue en coupe transversale suivant la ligne VIII-VIII de la feuille de la figure 7 ;
• les figures 9 et 10 sont des vues analogues à celle de la figure 8 illustrant deux variantes de réalisation de la feuille ;
• les figures 11 et 12 sont deux vues analogues à celle de la figure 7 illustrant deux variantes de réalisation des feuilles des figures 7 à 10 ;
• les figures 13 et 14 sont des vues analogues à celle de la figure 3 illustrant deux variantes d'un autre mode de réalisation d'une feuille selon l'invention ;
• les figures 15 et 16 sont des vues analogues à celle de la figure 3 illustrant deux variantes d'un autre mode de réalisation d'une feuille selon l'invention ;
• les figures 17 et 18 sont des vues analogues à celle de la figure 3 illustrant deux variantes d'un autre mode de réalisation d'une feuille selon l'invention; et
• la figure 19 est une vue en élévation d'une variante de réalisation d'un sachet selon l'invention.

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

• Figure 1 is an elevational view of a packaging bag according to the invention;
• Figure 2 is a schematic front view of the packaging sheet of Figure 1, in the region of the opening strip;
• Figure 3 is a cross-sectional view along line III-III of the sheet of Figure 2;
• Figures 4 and 5 are views similar to that of Figure 3 illustrating two alternative embodiments of the sheet;
• Figure 6 is a view similar to that of Figure 2 illustrating an alternative embodiment of the sheets of Figures 2 to 5;
• Figure 7 is a schematic front view of an alternative embodiment of a packaging sheet which can be used for the bag of Figure 1, in the region of the opening strip;
• Figure 8 is a cross-sectional view along line VIII-VIII of the sheet of Figure 7;
• Figures 9 and 10 are views similar to that of Figure 8 illustrating two alternative embodiments of the sheet;
• Figures 11 and 12 are two views similar to that of Figure 7 illustrating two alternative embodiments of the sheets of Figures 7 to 10;
• Figures 13 and 14 are views similar to that of Figure 3 illustrating two variants of another embodiment of a sheet according to the invention;
• Figures 15 and 16 are views similar to that of Figure 3 illustrating two variants of another embodiment of a sheet according to the invention;
• Figures 17 and 18 are views similar to that of Figure 3 illustrating two variants of another embodiment of a sheet according to the invention; and
• Figure 19 is an elevational view of an alternative embodiment of a bag according to the invention.

The bag 10 shown in Figure 1 is intended, for example, to the packaging of a chocolate bar. It has a sheet 12 folded over itself whose two opposite longitudinal edges are linked to each other by a longitudinal weld 14. At each end, the sheet folded over itself and forming a tube is closed by transverse welds 16.

In addition, the sheet 12 has an opening strip 18 extending transversely across the width of the sheet. The opening strip 18 extends parallel to an end weld 16. The opening strip has a width between 5 mm and 3 cm.

This opening strip, formed on the surface of the sheet, defines a priority propagation plot for leaf rupture after initiation a tear. In the embodiment illustrated in FIG. 1, the strip opening 18 defines a straight line.

The opening band extends mainly outside the regions welded from the packaging, except for the longitudinal weld 14 which it crosses.

The laminated packaging sheet according to the invention comprises, as illustrated in FIGS. 2 and 3, an exterior film 20 and an interior film 22.

The outer film 20 is for example a bi-oriented plastic film such than polyethylene terephthalate, bi-oriented polypropylene, polyamide bi-oriented, polyvinyl chloride or cellulosic film.

The inner film 22 has a thickness greater than the outer film 20. It preferably constitutes a welding film allowing the sheet to be welded packaging by heat sealing on itself or on a tray.

The inner film 22 is for example a bi-oriented film of polyamide type bi-oriented or polyester, a non-oriented film of polyethylene type or cast polypropylene, a layer of varnished aluminum or a layer of paper covered with a sealable coating.

The two films 20 and 22 are laminated to each other by a layer discontinuous adhesive 24.

In Figure 2, the regions of the sheet where the adhesive is present between films 22 and 24 are hatched with broken lines. On the other hand, adhesive-free areas are left white.

Apart from the opening strip 18, the two films 20 and 22 are glued to each other by the adhesive 24 at least along the lateral borders 25 delimiting the opening strip 18. Advantageously, films 22 and 24 are glued over their entire surface, outside the opening strip 18.

According to the invention, the opening strip 18 has on either side a lateral area 26 bordering each lateral border 25, these lateral areas being free of adhesive between the two films.

In addition, according to the invention, the opening strip 18 includes a treatment mechanical weakening 27, this mechanical treatment being confined exactly between the two borders 25 outside the areas outside the opening strip 18 where the films are glued.

In the embodiment illustrated in FIG. 3, the two ranges side 26 of the tape free of adhesive connect to each other to form a single line free of glue extending from one border 25 to the other.

In the embodiment of Figures 2 and 3, the mechanical treatment weakening 27 consists of a set of perforations 28 passing through right through the outer film 20. In this embodiment, the mechanical weakening treatment is carried out away from the borders 25 thus leaving untreated margins on both sides of the treated region 29.

With a packaging as illustrated in FIGS. 1 to 3, it can be seen that, during the initiation of a rupture of the packaging in the opening strip 18, the rupture of the sheet spreads along the path of the opening strip 18, even if the traction exerted on the two parts of the packaging is not strictly transverse to the opening strip.

An explanation hypothesis concerning a satisfactory propagation of the break along the route of the opening strip 18 is that the two lateral areas 26 free of adhesive bordering the areas stuck outside the opening strip 18 across borders 25 act as walls of reference on which the rupture rebounds during its propagation, ensuring thus confining the rupture line in the opening strip 18.

The presence of mechanical weakening treatment promotes tearing of the sheet and propagation of the rupture thus initiated.

In Figures 4 and 5 are shown two alternative embodiments from the sheet of figure 1.

In these two variants, the mechanical weakening treatment 27 is produced not by a set of through perforations 28 but by non-emerging surface irregularities formed on the surface of the outer film 20.

In particular, in the embodiment of Figure 4, the irregularities of non-emerging surface denoted 32 are provided on the surface exterior of the exterior film 20. On the other hand, in the embodiment of FIG. 4, the surface irregularities noted 34 are formed on the surface interior of exterior film 20.

In the embodiment of FIGS. 2 to 5, the mechanical treatment weakening extends away from the borders 25.

On the other hand, in the variant embodiment of FIG. 6, the processing mechanical attenuation 27 extends over the entire strip surface opening 18, that is to say over the entire line free of glue. The treatment does not, however, extend over the bonded regions outside the strip Opening 18.

In the embodiment of Figures 7 and 8, the opening strip 18 comprises transversely, along its entire length, a central area 35 in which adhesive 24 is disposed at least locally between the two films. On either side of the central area 35, the opening strip 18 has two lines 36 free of adhesive laterally bordering the surface central 35.

The two lines 36 free of adhesive have a width of between 0.5 mm and 3 mm.

Furthermore, according to the invention, the mechanical weakening treatment 27 formed in the opening strip is formed, at least in the central area 35. This mechanical weakening treatment is carried out in the outer film 20.

This mechanical weakening treatment consists, for example, a set of perforations 28, as illustrated in FIG. 8, or else by irregularities 32 formed on the outer surface of the outer film 20, as illustrated in FIG. 9, or by irregularities 34 formed on its inner surface, as illustrated in figure 10.

In the embodiment of FIGS. 7 to 10, the mechanical treatment attenuation extends exactly over the entire surface of the beach central 35, the adhesive extending itself over the entire surface of this area Central.

In contrast, in the embodiment of Figure 11, the processing mechanical weakening extends on both sides beyond the central beach 35 and partially extends in the region of the lines 36 free of adhesive. However, mechanical weakening treatment extends away from the borders 25 laterally delimiting the opening strip. Thus, margins 29 devoid of processing are formed along borders 35.

According to an embodiment not shown, the mechanical treatment weakening extends to the borders 25 bordering the opening strip. However, mechanical weakening treatment is maintained in the opening strip between the two borders, without overflowing beyond borders on the bonded regions outside the opening strip.

In the variant illustrated in FIG. 12, the mechanical treatment weakening 27 extends only in the middle region of the range central 35, away from the lateral stripes 36 free of adhesive. Margins 37 without mechanical weakening treatment are thus defined in the central area 35, along the lines free of adhesive 36.

In the embodiment of FIG. 13, the central area 35 has, along the lines 36 free of adhesive, two parallel lines of adhesive 38 separated by a region 40 without adhesive.

This region 40 constitutes the middle region of the central area 35.

A mechanical weakening treatment 27 is provided on the film outside 20 only and exactly on the surface of region 40 without adhesive. The expression "exactly" means over the entire surface of the region considered, however taking into account manufacturing tolerances which are of the order of 0.2 mm.

In FIG. 13, the mechanical weakening treatment 27 consists of in a set of surface irregularities 42 not emerging on the outer surface of the outer film 20.

In contrast, in the embodiment of Figure 14, the irregularities surface area not marked 44 are provided on the surface interior of exterior film 20.

Alternatively, uneven surface irregularities are replaced by a set of through perforations.

The sheets illustrated in Figures 15 and 16 are variants of production, respectively, of the sheets of FIGS. 13 and 14. In these embodiments, an intermediate film 50 is interposed between the adhesive 24 applied discontinuously and the inner film 22. The intermediate film 50 is for example a bi-oriented film such as polyethylene terephthalate, bi-oriented polypropylene, bi-oriented polyamide, polychloride vinyl or cellulosic film.

Between the intermediate film 50 and the inner film 22 is interposed a layer 52 of an adhesive. This layer 52 extends along the entire surface of the intermediate film 50.

Such an intermediate film can be used between the inner film and the adhesive in all the embodiments described in the previous figures and following.

The sheet illustrated in FIG. 17 includes, as before, an outer film 20, an inner film 22, between which an adhesive is interposed 24. The central area 35 is bordered by two lines 36 free of adhesive.

In this embodiment, the central area 35 comprises, transversely along its entire length, an alternation of lines 56 comprising of adhesive and lines 58 free of adhesive, the lines extending parallel to each other along the entire length of the strip opening. Lines 56 with adhesive extend along the glue-free lines 36. Thus, for n lines 56, there are (n-1) lines 58.

Lines 56 and 58 each have a width of between 0.5 mm and 2 mm and preferably substantially equal to 1 mm.

Advantageously, lines 56 and 58 have variable widths depending on the width of the central area. Preferably, the lines placed in the middle region are narrower than the lines placed on the edges.

The outer film also has a mechanical weakening treatment 27 made up of non-emerging surface irregularities on its outer surface.

As a variant, and as illustrated in FIG. 18, the treatment is spared on its internal surface.

In the embodiments of FIGS. 15 to 18, the irregularities of non-opening surface can be replaced by perforations therethrough.

In Figure 19 is illustrated a bag substantially similar to that of Figure 1 showing two opening strips 118 and 218.

The opening strip 118 is straight and extends from a longitudinal edge from the packaging to its end seal 16. This strip 118 allows you to remove a corner of the packaging to cause opening.

The opening strip 218 also connects a longitudinal edge of the packaging at its transverse weld 16. However, the strip layout opening 218 is curved, thus defining, after removal of the defined corner through the opening strip, a profile opening spout suitable for dispensing items contained in the bag.

Claims (15)

Laminated packaging sheet (10) comprising a first film (20), a second film (22) and an adhesive (24) interposed between the two films (20, 22), the sheet having an opening strip (18; 118; 218) formed along its surface, which strip (18; 118; 218) defines a priority propagation path for a rupture of the sheet, the opening strip comprising a mechanical weakening treatment (27), characterized in that the opening strip (18; 118; 218) is delimited laterally on either side by a lateral border (25), each border (25) separating an area external to the opening strip (18; 118 ; 218) where the two films (20, 22) are held glued to each other by an adhesive (24) at least along the lateral border (25) and a lateral region (26) of the strip d opening (18) bordering the lateral border (25) and free of adhesive between the two films, and in that the mechanical treatment of weakening nt (27) is exactly confined between the two borders (25) outside the areas outside the strip where the two films (20, 22) are glued. Sheet according to claim 1, characterized in that the mechanical weakening treatment (27) comprises a set of perforations (30) passing through the first film (20) right through. Packaging sheet according to claim 1, characterized in that the mechanical weakening treatment (27) comprises non-emerging surface irregularities (32; 42) formed on the external surface of the first film (20). Packaging sheet according to claim 1, characterized in that the mechanical weakening treatment (27) comprises non-emerging surface irregularities (34; 44) formed on the internal surface of the first film (20). Sheet according to any one of the preceding claims, characterized in that said opening strip (18) has a central area (35) in which adhesive (24) is placed at least locally between the two films (20, 22), the two lateral areas of the opening strip (18) bordering the borders (25) constituting two lines (28) free of adhesive. Packaging sheet according to claim 5, characterized in that the mechanical weakening treatment (27) extends over the entire surface of the central area (35), from a strip (36) free of adhesive to the 'other. Packaging sheet according to claim 5, characterized in that the mechanical weakening treatment (27) extends beyond the central region (35) and extends at least partially in the region of the free lines (36) adhesive. Packaging sheet according to claim 5, characterized in that the mechanical weakening treatment (27) extends only in the middle region of the central area (35) away from the lines (36) free of adhesive. , margins (37) devoid of mechanical weakening treatment (27) being defined in the central region (35) along the lines (36) free of adhesive. Packaging sheet according to any one of claims 5 to 8, characterized in that adhesive is deposited between the two films (20, 22) along the entire surface of the central area (35). Packaging sheet according to any one of claims 5 to 8, characterized in that the central area (35) comprises transversely, along its entire length, an alternation of lines (56) comprising adhesive and lines (58 ) free of adhesive, the lines (50, 52) extending along the length of the opening strip (18). Packaging sheet according to claim 10, characterized in that the lines (56) comprising adhesive and the lines (58) free of adhesive are narrower in the central region of the central area (35) than in the regions bordering the central beach (35). Packaging sheet according to any one of Claims 5 to 8, characterized in that the central area (35) has, along the lines (36) free of adhesive, two parallel lines of adhesive (38) separated by an adhesive-free region (40) and in that the mechanical weakening treatment (27) is provided on the first film (20) only in the adhesive-free region (40). Packaging sheet according to any one of claims 5 to 12, characterized in that each stripe (36) free of adhesive has a width of between 0.3 mm and 10 mm. Sheet according to any one of Claims 1 to 4, characterized in that the two lateral areas of the strip free of adhesive meet to form over the entire width of the opening strip (18) a single continuous strip free of 'adhesive. Packaging comprising at least one packaging sheet according to any of the preceding claims.

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