FR2807015A1 - LAMINATE PACKAGING SHEET AND RECLOSABLE PACKAGE COMPRISING SAME - Google Patents

Abstract

Resealable packaging sheet with a weldable sheet comprising a welding film and a gas barrier film which is e.g. a copolyester. Laminated packaging sheet (14) which is resealable and comprises a support film (24) next to a welded film (26) between which is interposed in at least one of the zones, a layer (28) of a permanent adhesive attached to the film support (24) and the welded film (26), characterized in that the welded film (26) has a welding layer (36) and at least one gas barrier layer (37), where at least one of the barrier layers is a composition selected from vinyl alcohol/ethylene copolymer, polyvinylidene chloride, polyvinyl alcohol, silica, aluminum oxide, polyester and copolyester. An INDEPENDENT claim is included for packaging (10) especially a sachet type, with an external wall (16) defining an opening (15) characterised in that the opening is closed by laminated sheet (14) such that it welds to the external wall (16) at the periphery of the opening (15) by means of the weldable film (26) in a part of the sheet which is filled with a permanent adhesive (28).

Description

The present invention relates to a laminated packaging sheet of the type

  comprising a support film associated with a welding film between which is

  interposed, at least in identified areas, a layer of adhesive

  manent, linked to the support film and the welding film.

  It further relates to a packaging comprising such a sheet, this packaging possibly being a sachet or a tray closed by such a sheet. Packages comprising a packaging sheet allowing easy opening and reclosing are currently used for example for packaging food products. The structure of such a sheet

  is described in particular in French patent application FR-95 14117.

  In this document, the laminated sheet used to allow the opening

  ture and the resealing of the packaging has two polymer films between

  which a layer of permanent adhesive is interposed.

  One of the films, called "welding film" is intended to be oriented towards

  inside the package. It is suitable for being welded to the peripheral flange.

  risk of a tray. The other film, called "support film", is intended to form the

  outer side of the package. The welding film consists of a single layer

  che of the same polymer or a mixture of polymers.

  It can be seen that, when such packaging is used for the condition-

  food, the taste and smell of that food can

  be altered. In particular, the smell and taste of the products may be

  pleasant for the user, the user perceiving that the foodstuffs

  vées in the package have a "plastic" or "scent" smell or taste

trole ".

  The object of the invention is to provide a solution to the degradation of taste.

  ive and olfactory of the food preserved in packaging putting in

  works at least one packaging sheet allowing reclosure.

  To this end, the invention relates to a laminated packaging sheet of the

  aforementioned type, characterized in that it comprises means forming bar-

  due to gases and molecular migrations, integrated in the welding film.

  According to particular embodiments, the packaging sheet comprises one or more of the following characteristics - the welding film comprises a welding layer and at least one layer forming a barrier to gases and to molecular migrations; the or each layer forming a barrier to gases and to molecular migrations comprises a copolymer of ethylene and of vinyl alcohol; - the or each layer forming a barrier to gases and migration

  molecules contains at least one compound chosen from the group consisting of

  both polyamide, polyvinylidene chloride, polyester terephthalate, polyvinyl alcohol, silica oxide and aluminum oxide; - the or each layer forming a barrier to gases and migration

  molecular has a thickness between 2 and 15 microns and preferably

  substantially equal to 3 microns;

  - the welding film has a total thickness of between 20 and 60 mi-

  crons and preferably substantially equal to 35 microns; - The or each layer forming a barrier to gases and to molecular migrations is arranged with respect to the weldable layer on the side of the layer of permanent adhesive; - Said welding film further comprises a bonding layer disposed on the side of the permanent adhesive layer, the layer forming a barrier to gases and to molecular migrations being disposed between the welding layer and the bonding layer; - the welding layer and the bonding layer are made of the same material; - it is obtained by coextrusion; and

  - the welding film is obtained by co-extrusion.

  The invention further relates to a packaging comprising a wall

  external delimiting a housing provided with an access passage to said housing

  ment, characterized in that said passage is closed by a laminated sheet

  as defined above, which sheet is welded to said wall ex-

  dull at the periphery of said passage, following its film weldable in a

  area of the sheet which is provided with permanent adhesive.

  The invention will be better understood on reading the description which will

  follow, given only as an example and made with reference to the

  sins, on which - FIG. 1 is a partial perspective view in section of a packaging tray, the access passage of which is closed by a laminated sheet according to the invention, and

  - Figure 2 is a view similar to that of Figure 1, after opening-

packaging.

  The package 10 shown in Figure 1 consists of a bar-

  rectangular quette 12 and a flexible cover 14 for closing a passage

  access 15 inside the tray.

  The tray 12 consists of a support layer 16 of suitable material, for example polyvinyl chloride or amorphous polyester (APET, CPET), covered on its inner surface with a weldable film 18,

for example polyethylene.

  The tray defines a receptacle 20 bordered over its entire periphery with a rim 22 delimiting a planar surface for welding the flexible seal 14

following a straight weld 23.

  The cover 14 consists essentially of a support film 24 and of a multilayer film welding 26 with a layer of permanent adhesive 28 interposed in flat between them over the entire surface. As a variant, the permanent adhesive 28 can be placed only in zones marked with the cover, these areas being intended to form the welding regions of the cover. A transparent film 30 carrying impressions 32 is secured to the support film 24 by means of a layer of adhesive 34 applied to its

printed side.

  As a variant, the prints 32 are produced on the film 30 and / or 24

front and / or back.

  The multilayer sealing film 26 comprises a sealing layer 36 adapted to form the interior surface of the package. It is intended for

  be welded by heat sealing on the weldable film 18 of the tray 12.

  According to the invention, the welding film 26 further comprises at least one layer 37 forming a barrier to gases and to molecular migrations. This layer 37

  is able to block the movement of small molecules or oli-

gomeres.

  In the example given, the welding film 26 has a single layer

che forming barrier.

  As a variant, the prints 32 are produced on the film 30 and / or 24

front and / or back.

  Advantageously, the welding film 26 comprises a bonding layer

  38 disposed in contact with the layer of permanent adhesive 28. Thus, the layer

  che forming a barrier to migration and gases is interposed between the layer

  welding 36 and the bonding layer 38.

  The sealing film 26 can be obtained by bubble type or cast type coextrusion or by extrusion of each of the

  layers, coating and layers thereof.

  The longitudinal weld 23 is obtained by heat sealing. During welding, the welding film 18 and the welding layer 36 melt together,

  allowing to obtain after cooling a very reliable weld. In part-

  the tensile strength of the weld 23 is greater than the resistance

  tear strength of the sealing film 26, tensile strength of the interfaces between the layer of permanent adhesive and films in contact 24 and

  26, as well as the tensile strength of the core of the adhesive layer 28.

  For example, the different layers and films of the cover 14 have

the following features.

  The support film 24 is a polyester film 36 microns thick.

  The layer of permanent adhesive 28 is produced by coating using

  a liquid or solid adhesive mass.

  The layer of permanent adhesive can still be applied hot,

especially by extrusion.

  A permanent adhesive commonly referred to as "hot melt" is ideal for this application. It is possible in particular to use PLASTOFLEX 8718 sold by the company PARAMELT

in Holland.

  The thickness of the adhesive layer 28 is advantageously included

  between 10 and 30 microns and preferably between 15 and 20 microns.

  The transparent film 30 is for example a polyester film of a

  thickness of 12 microns. This film may have functional characteristics

  particular properties, in particular visually

  certain gases. To this end, it is treated according to known techniques

adapted, such as coating.

  The adhesive used to ensure the connection between the film 30 and the support film

  port 24 is of any type adapted according to the nature of the films to be bound.

  The following characteristics relate to the welding film 26.

  This can, of course, be implemented with a layer 28 of adhesive

  permanent sif of any kind as well as a support film 24 of any kind

  appropriate size, layers 30 and 32 being optional.

  Preferably, the barrier layer 37 comprises a resin of

  copolymer of ethylene and vinyl alcohol (EVOH) while the two

  ches 36 and 38 between which it is interposed are layers of poly-

  ethylene which can be linked to the EVOH layer by a binding layer

of compatibilization.

  Preferably, the welding film 26 is obtained by co-extrusion of the

  layer of EVOH during the extrusion of the two layers of polymer between the

which it is enclosed.

  The copolymer of ethylene and vinyl alcohol is for example that

  marketed under the reference EVAL LCH 101BD by the company KU-

  RARAY, the ethylene content being 38%.

  Advantageously, the thickness of the barrier layer 37 is

  between 2 and 15 microns, that being preferably equal to sensitive-

3 microns.

  As a variant, the layer or layers forming a barrier to gases and to migra-

  molecular tions are formed for example of polyamide, PVDC (polychlo-

  vinylidene rure), PETP (polyester terephthalate), PVOH (polyvinyl alcohol-

  que), SIOX (silica oxide) or A1203 (aluminum oxide).

  The total thickness of the sealing film 26, consisting of the three layers

  above, is between 20 and 60 microns and is preferably sensitive to

roughly equal to 35 microns.

  The thicknesses of the welding layer 36 and of the bonding layer 38 are preferably substantially equal, each of them being included

  between 10 and 20 microns, and preferably substantially equal to 15 microns.

  They are preferably made of the same polymer and in particular of polyethylene.

  As a variant, layers 36 and 38 are formed from LDPE (polyethylene

  low density lene), LLDPE (linear polyethylene), MDPE (medium density polyethylene) or an ionomer (for example commercially available "SURLYN"

  by Dupont de Nemours), a mixture of these products, or

  polypropylene core (homo or copolymer).

  In the embodiment shown in the figures, the welding film 26 has three layers. However, as a variant, the bonding layer 38 is

  removed and layer 28 of permanent adhesive is then applied directly

  ment on the layer forming a barrier to gases and to molecular migrations 37. The bonding layer 38 can also undergo an appropriate treatment.

  giving it barrier properties to gases and molecular migrations

  res. This treatment is for example a vacuum deposition of aluminum oxide,

  of silica or metal oxide at different levels of purity.

  In addition, the layer 38 can be made of a barrier material, of a different nature from that forming the layer 37. Thus the layer

  38 can for example be made of polyamide or polyester.

  According to another embodiment, the welding film 26 comprises at least two distinct layers forming a barrier to gases and to migrations

  molecular, these two layers being separated from each other by a layer

intermediate che.

  In such an alternative embodiment, the welding film comprises by

  example five layers consisting of two layers forming barriers for

  before being of the same or different nature and of equal or different thickness and consisting for example of EVOH, of an intermediate layer interposed between the two layers forming barriers, of a welding layer forming the inner surface of the packaging and of a bonding layer on which is

  applied the layer of permanent adhesive.

  The welding film 26 comprising at least two layers forming a bar-

  This is advantageously obtained by coextrusion.

  As shown in FIG. 2, during a traction exerted on the cover 14 for opening the packaging by lifting the cover,

  the welding film 26 breaks on either side of the welded zone. In particular

  bonding, the welding layer 26, the barrier layer 37 and the bonding layer 38 rupture. Thus, the lid 14 is separated from the tray 12, following at least

  part of the length of the rim 22. It forms a welded bead denoted 40.

  Under the action of traction, the layer of permanent adhesive 28 breaks in its intermediate part or delaminates at its interface with the

film 24 or film 26.

  For example, a part, denoted 42, of the layer of permanent adhesive remains on the welded bead 40, while the complementary part, denoted 44, remains on the support film 24. The two complementary parts 42, 44 each have a thickness substantially equal to half the thickness

total of layer 28.

  Thus, when replacing the cover 14, the two parts of the adhesive layer 28 are brought back into contact ensuring the reclosure of the packaging. It can be seen that with a packaging sheet as described here and

  comprising a layer forming a barrier to gases and to molecular migrations

  interposed between the layer of permanent adhesive and a sealed layer

  lante clean to ensure welding with the complementary part of the package

  food, the food contained in the packaging has no

  degraded taste and / or olfactory properties.

  In the example described above, the cover is obtained by association

  of films extruded separately, these being linked to each other in particular

  by gluing. As a variant, the cover is formed by coextrusion of the different

  annents films, the layers constituting the welding film then being coextruded

  simultaneously with the other films of the cover.

  In a variant not shown, the laminated sheet comprises a layer of permanent adhesive only in the regions intended to be welded to the edge of the tray. In this case, the support film and the weldable film

  are linked to each other by a layer of glue of any suitable type.

  The sheet according to the invention is described here applied to the obturation of a

  tray. However, this could be used to form a sachet

  closable. In the latter case, the permanent adhesive may also be available.

  placed only in the sealing areas of the bag.

  Furthermore, it can be seen that the presence of a barrier layer integrated into the weldable film also provides a solution to the problem of the ineffectiveness of a possible barrier layer when it is placed, as is the case. in the state of the art, on the film side

  base relative to the layer of permanent adhesive.

  Indeed, it is known, in order to avoid the circulation of gases, and in particular oxygen and / or carbon dioxide between the interior and the exterior of the packaging, to have the same side of the permanent adhesive as the film of

  base, a layer forming a barrier to gases and molecular migratins.

  It can be seen that due to the welding of the weldable film, the seal is

  found mechanically held at its periphery along one of its faces.

  On the contrary, the other side of the film is left free, there is thus the risk of a delamination phenomenon at one or the other of the interfaces.

  of the permanent adhesive layer with the base film or the weldable film.

  This phenomenon is known as "tunnel effect" or "chimney effect".

  The air can then circulate through the delaminated areas and thus exchange ga-

  They can take place through the welding layer.

  When the layer forming a barrier to gases and molar migrations

  is arranged on the inner side of the package in relation to the

  che permanent adhesive, even in case of delamination of this layer, the

  layer forming barrier to gases and molecular migrations remains main-

  held over the entire surface of the packaging opening since this

  che forming a barrier to gases and molecular migrations is integrated

in the welding film.

  Thus, even if outside air is introduced into possible delaminated regions of the layer of permanent adhesive, that a gaseous exchange cannot occur between the interior of the package and this region, due to the

  presence of the layer forming a barrier to gases and to molecular migrations

res.

Claims (12)

  1.- Laminated packaging sheet (14), of the type comprising a support film (24) associated with a welding film (26) between which is interposed, at least in marked areas, a layer (28) of an adhesive permanent linked to the support film (24) and to the welding film (26), characterized in that it comprises   carries means (37) forming a barrier to gases and to molecular migrations   res, integrated in the welding film (26).   2. A laminated packaging sheet according to claim 1, characterized in that the welding film (26) comprises a welding layer (36) and at least one layer forming a barrier to gases and to molecular migrations (37). 3.- packaging sheet according to claim 2, characterized in that   that the or each layer forming a barrier to gases and molar migrations   eyelets (37) comprises a copolymer of ethylene and vinyl alcohol.   4.- packaging sheet according to claim 2, characterized in that   that the or each layer forming a barrier to gases and molar migrations   eyelets (37) comprises at least one compound chosen from the group consisting of   both in polyamide, polyvinylidene chloride, polyester terephthalate,   polyvinyl alcohol, silica oxide and aluminum oxide.   5.- packaging sheet according to any one of claims 2 to   4, characterized in that the or each layer (37) forming a gas barrier   and at molecular migrations between 2 and 15 m thick   crons and preferably substantially equal to 3 microns.   6.- packaging sheet according to any one of claims 2 to   5, characterized in that the welding film (26) has a total thickness including   taken between 20 and 60 microns and preferably substantially equal to 35 mi- crons.   7.- packaging sheet according to any one of claims 2 to   6, characterized in that the or each layer forming a gas barrier and   molecular migration (37) is arranged in relation to the subsoil   dante (36) on the side of the permanent adhesive layer (28).   8.- packaging sheet according to claim 7, characterized in that   that said sealing film (26) further comprises a bonding layer (38) which   laid on the side of the permanent adhesive layer (28), the layer forming a barrier to gases and to molecular migrations (37) being disposed between the   welding layer (36) and the bonding layer (38).   9. A packaging sheet according to claim 8, characterized in that the welding layer (36) and the bonding layer (38) are produced in the same material.   10.- packaging sheet according to any one of claims   above, characterized in that it is obtained by coextrusion.   11.- packaging sheet according to any one of claims   above, characterized in that the welding film (26) is obtained by co-   extrusion. 12.- Package (10), in particular sachet or tray, comprising an external wall (16) delimiting a housing (20) provided with an access passage (15) to said housing, characterized in that said passage (15) is closed by   a laminated sheet (14) according to any one of the preceding claims   teeth, which sheet is welded to said outer wall (16) at the periphery   laughing of said passage (15), following its weldable film (26) in an area of the   sheet which is provided with permanent adhesive (28).