EP1606367A2

EP1606367A2 - Multilayer metallised film

Info

Publication number: EP1606367A2
Application number: EP04708790A
Authority: EP
Inventors: Siaw Teck Sang; Yves Ledu; Patrice Robert
Original assignee: Arkema SA
Current assignee: Arkema France SA
Priority date: 2003-02-07
Filing date: 2004-02-06
Publication date: 2005-12-21
Also published as: SG115614A1; TW200426024A; CN1532248A; JP2004263171A; FR2850975A1; AU2004200499B2; JP2006299258A; IL160279A0; KR100629668B1; CA2456668C; KR20040072470A; CN100523108C; BRPI0401000A; NZ531048A; MY140678A; IL160279A; NO20040574L; AU2004200499A1; MXPA04001232A; US20080131672A1

Abstract

The invention relates to a metallised film, produced by means of a multilayer structure with a binder layer comprising 5 to 50 wt. % of a mixture (A) with: 5 to 100 % of a mixture of co-grafted polymers (C1) and (C2) comprising 90 to 20 wt. % of a polyethylene metallocene (C1) with a density of between 0.865 and 0.915, 10 to 80 wt. % of a polymer (C2) which is either a non-metallocene LLDPE or a homo- or co-polymerised polypropylene and 95 to 0 wt. % of a polyethylene (D) selected from the homo- or co-polymerised polyethylenes and the elastomers. The mixture (A) is such that the content of graft monomer grafted is between 30 and 105 ppm, the MFI or flow index in the molten state (standard ASTM D 1238, at 190 °C with 2.16kg) is between 0.1 and 30g/10min and 50 to 95 wt. % of a polypropylene (B) homo- or co-polymer.

Description

DESCRIPTION

METALLIC MULTILAYER FILM

The present invention relates to the field of packaging using in particular multilayer films, bi-oriented or not, metallized and laminated with a film of polypropylene bi-oriented (abbreviated BOPP) or polyethylene terephthalate bi-oriented (abbreviated BOPET) or not, having very good adhesion of the layers to each other even when the films are weakened by welding. The invention applies, inter alia, to packaging of the sachets, bags, pockets or packages type made from these welded films, the composition of which generates good manual opening of the packaging. Mention may be made, without limitation, for example, of packets of crisps, cookies, candies, meat.

Document WO01 / 34389 describes a packaging using a multilayer film having barrier properties to oxygen and to water vapor, but this packaging has the disadvantage when one wants to open it of not opening properly . Indeed, there is a delamination between the metal layer and the polypropylene layer on which the metal layer is deposited.

It is important in the field of packaging to have packaging which opens cleanly and neatly with moderate force, so that it can be opened by both an adult and a child. In addition, the films constituting the packaging must have oxygen and water vapor barrier properties in order to preserve the foodstuffs, solid or liquid, food or the like, which are inside the packaging. .

The Applicant has now found a film having a strong adhesion between a metallic layer and a layer having a composition based (i) mainly on polypropylene, (ii) on the minority of a mixture of either co-grafted polyethylenes (abbreviated PEg), or polyethylene and cografted polypropylene and (iii) optionally polyethylene or ungrafted elastomer. This film allows inter alia the manufacture of packages closed by a sealing strip of said film, the opening taking place at the same strip. Unlike the prior art, there is no delamination or peeling preferably between the metal and PP layers to the detriment of the opening of the packaging at the level of the weld strip. Indeed, the packaging according to the invention opens cleanly at the weld strip without damage to the multilayer structure otherwise.

The subject of the invention is a binder comprising: - 5 to 50% by weight of a mixture (A), said mixture (A) comprising:

- 5 to 100% by weight of a mixture of polymers (C1) and (C2) consisting of 90 to 20% by weight of a metallocene polyethylene (C1) with a density between 0.865 and 0.915 and from 10 to 80% by weight of a polymer (C2) which is either a non-metallocene LLDPE or a homo- or copolymerized polypropylene, the mixture of polymers (C1) and

(C2) being co-grafted with an unsaturated carboxylic acid or a functional derivative of this acid as grafting monomer, and

- 95 to 0% by weight of a polyethylene (D) chosen from homo or copolymer polyethylenes and elastomers; the mixture (A) being such that:

© the content of grafted grafting monomer is between 30 and 10 ⁵ ppm; o the MFI or melt flow index (ASTM D 1238 standard, at 190 ° C under 2.16 kg) is between 0, 1 and 30g / 10min - 50 to 95% by weight of a polypropylene ( B) homo or copolymer.

The invention also relates to a multilayer structure comprising a binder layer as defined above.

According to one embodiment, the multilayer structure comprises a metal layer bonded to the binder layer.

According to one embodiment, the structure is characterized in that the metal layer is a layer of Al, Fe, Cu, Sn, Ni, Ag, Cr, Au or an alloy containing minus one of these metals mainly.

According to one embodiment, the multilayer structure is characterized in that it comprises a layer of polypropylene homopolymer or copolymer, the layer of binder being sandwiched between the metal layer and said layer of polypropylene.

According to one embodiment, the multilayer structure is characterized in that it comprises a layer suitable for thermocell comprising either an Ethylene / Propylene / Butylene terpolymer, or an Ethylene / Propylene copolymer or a metallocene PE or their mixtures in this case said mixture includes at least two of the previously listed compounds, the polypropylene being sandwiched between the binder layer and said layer suitable for thermocell

The invention further relates to a film comprising a multilayer structure as defined above. According to one embodiment, the film is characterized in that it comprises a layer of bi-oriented polypropylene (BOPP) or of bi-oriented polyethylene terephthalate. (BOPET) printed, on which is applied with an adhesive a metallized multilayer film comprising a structure described above, said film being bi-oriented or not and the metal layer of said metallized multilayer film being directly bonded by adhesive to the printed BOPP or BOPET layer

The invention also relates to the use of the binder to manufacture a multilayer structure defined above.

The invention relates to an object comprising a multilayer structure as described above

According to one embodiment, the object is manufactured with a film as previously described

According to one embodiment, the object is a packaging

FIG. 1 represents an embodiment of a film according to the invention, said metallized cast polypropylene film (abbreviated MCPP) comprising a structure with layers from 1 to A succeeding one another in the following order 'a layer (1) of metal, a layer (2) of mixture of co-grafted PE and LLDPE, of LLDPE and of homo or copolymer PP, a layer (3) of homopolymer or copolymer PP and a layer (A) of polymer suitable for thermocell.

Figure 2 shows in cross section a bag (6) closed by a weld strip (5a), according to the prior art cited above, after a failed opening attempt, said bag being made with a film comprising the following structure a layer (1 1) of metal, a layer (12) of a mixture of syndiotactic PP and butylene / propylene copolymer or of a mixture of syndiotactic PP and homo PP or graft copolymer, a layer (13) of homo PP or copolymer, a layer (14) of ethylene / propylene / butylene terpolymer or of ethylene / propylene copolymer or of metallocene PE. FIG. 3 represents in cross section a bag according to the invention after opening at the level of the weld strip, the opening being delimited by the edges (5b) and the bag (6) being produced with the film having a multilayer structure (layers 1 -4) shown in Figure 1 We will now describe the invention in more detail. The packaging, objects of the invention, includes a metallized cast PP film (abbreviated as MCPP). This film can enter into a structure of the type: BOPP or BOPET layer / ink layer / adhesive layer / MCPP film.

The MCPP film comprises a multilayer structure shown in FIG. 1 and having the following form: layer (1) / layer (2) / layer (3) / layer (4), the composition of which will be given below.

We then have in a MCPP film the following successive layers in order: BOPP or BOPET layer / ink layer / adhesive layer / layer (1) / layer (2) / layer (3) / layer ( 4).

The layer (1) is a metallic layer applied to a layer (2). It can for example be a sheet or a film of a metal such as Ai, Fe, Cu, Sn, Ni, Ag, Cr, Au or an alloy containing at least one of these metals mainly.

The layer (3) is a layer of PP. The polypropylene of layer (3) can be a homopolymer or a copolymer. As a comonomer, we can cite:

»Alpha olefins, advantageously those having from 2 to 30 carbon atoms such as ethylene, 1 -butene, 1 -pentene, 3-methyl-1 -butene, 1 -hexene, 4-methyl- 1 -pentene, 3-methyl-1 -pentene, 1-octene, 1 - decene, 1 -dodecene, 1 -tetradecene, 1 -hexadecene, 1 -octadecene, 1 - eicocene, 1 -dococene, 1 -tetracocene, 1 -hexacocene, 1 -octacocene and 1 triacontene. These alpha olefins can be used alone or as a mixture of two or more than two. "The dienes. The polypropylene can also be a polypropylene block copolymer. Advantageously, the layer (3) comprises a mixture of several polymers in which there is at least one polypropylene comprising at least 50% by moles and preferably at least 75% of propylene. By way of example, the polypropylene of the layer (3) can be a mixture of polypropylene and EPDM or EPR. As homopolymer PP, mention may be made of isotactic PP between 80 and

100%, preferably 95%. The polypropylene homopolymer preferably has an MFI (melt flow index) of between 1, 2 and 30 g / 10 min, preferably between 3 and 8 g / 10 min measured according to ASTM D1 38. The layer (4) is a layer suitable for thermocell. It may for example comprise an Ethylene / Propylene / Butylene terpolymer, an Ethylene / Propylene copolymer, a metallocene PE or their mixtures (mixture of at least two of the compounds previously listed). Advantageously, the layer (4) comprises a terpolymer mainly comprising propylene as a comonomer.

The layer (2) is produced with a mixture comprising: - 5% to 50%, preferably 20 to 40% by weight of a mixture (A) and

50 to 95%, preferably 60 to 80% by weight of a polymer (B).

As regards the mixture (A) defined by a mixture (C) optionally mixed with a polymer (D), it comprises: - 5 to 100% by weight (relative to the mixture (A)) of the mixture (C), - even consisting of a mixture of 80 to 20% by weight (relative to the mixture (C)) of a metallocene polyethylene (C1) with a density between 0.865 and 0.915 and from 20 to 80% by weight (relative to to the mixture (C)) of a non-metallocene LLDPE (C2), the mixture of (C1) and (C2) being co-grafted with an unsaturated carboxylic acid or a functional derivative of this acid as grafting monomer, and

95 to 0% by weight (relative to the mixture (A)) of a polyethylene (D) chosen from homo or copolymer polyethylenes and elastomers; the mixture (A) being such that: the content of grafted grafting monomer is between 30 and 10 ⁵ ppm; the MFI or melt flow index (ASTM D 1238 standard, at 190 ° C under 2.16 kg) is between 0.1 and 30g / 10min.

With regard to the polymer (C1), the term “metallocene polyethylene” denotes the polymers obtained by copolymerization of ethylene and alpha olefin such as, for example, propylene, butene, hexene or octene in the presence of a monosite catalyst generally consisting of a atom of a metal which may for example be zirconium or titanium and two cyclic alkyl molecules linked to the metal. More specifically, metallocene catalysts are usually composed of two cyclopentadienic rings linked to the metal. These catalysts are frequently used with aluminoxanes as cocatalysts or activators, preferably methylaluminoxane (MAO). Hafnium can also be used as the metal to which cyclopentadiene is attached. Other metallocenes may include transition metals from groups IVA, VA and VIA. Metals from the lanthanide series can also be used.

These metallocene polyethylenes can also be characterized by their Mw / Mn ratio <3 and preferably <2 in which Mw and Mn denote respectively the average molar mass by weight and the average molar mass by number. Also designated by metallocene polyethylene are those having an MFR (Melt Flow Ratio) <6.53 and an Mw / Mn ratio> (MFR-4.63). MFR designates the ratio of MFI ₁₀ (MFI under a load of 10 kg) to MFI ₂ (MFI under a load of 2.16 kg). Other metallocene polyethylenes are defined by an MFR = or> 6.13 and an Mw / Mn ratio <or = (MFR-4.63).

Advantageously, the density of (C1) is between 0.870 and 0.900.

As regards the polymer (C2), it is either a copolymer of ethylene and of an alpha-olefin of the LLDPE type (linear low density polyethylene) which is not of metallocene origin is a homo- or polyptopylene. copolymer with as conrionυmères for example alpha-olefins or dienes. The polymer (C2) can also be a polypropylene block copolymer.

The alpha-olefins advantageously have from 3 to 30 carbon atoms. Examples of alpha-olefins having 3 to 30 carbon atoms include ethylene (only PP comonomer), propylene (only PE comonomer), 1-butene, 1 -pentene, 3-methyl-1 - butene, 1-hexene, 4-methyl-1 -pentene, 3-methyl-1 -pentene, 1-octene, 1-decene, 1-dodecene, 1 -tetradecene, 1 -hexadecene , 1-octadecene, 1-eicocene, 1 -dococene, 1 -tetracocene, I hexacocene, 1 -octacocene and 1 -triacontene. These alpha olefins can be used alone or as a mixture of two or more than two.

The density of (C2) is advantageously between 0.900 and 0.950. The MFI of (C2) is between 0.1 and βg / 10 min (at 190 ° C under 2.1 6 kg).

The mixture (C1) and (C2) is grafted with a grafting monomer taken from the group of unsaturated carboxylic acids or their functional derivatives. Examples of unsaturated carboxylic acids are those having 2 to 20 carbon atoms such as acrylic, methacrylic, maleic, fumaric and itaconic acids. The functional derivatives of these acids include, for example, anhydrides, ester derivatives, amide derivatives, imide derivatives and metal salts (such as alkali metal salts) of unsaturated carboxylic acids. The unsaturated dicarboxylic acids having 4 to 10 carbon atoms and their functional derivatives, particularly their anhydrides, are particularly preferred grafting monomers.

These grafting monomers include, for example, maleic, fumaric, itaconic, citraconic, allylsuccinic, cyclohex-4-ene-1, 2-dicarboxylic, 4-methylcyclohex-4-ene-1, 2-dicarboxylic, bicyc! O (2 , 2,1) -hept-5-ene-2,3-dicarboxylic, x-methylbicyclo (2,2,1) hept-5-ene-2,2-dicarboxylic, maleic, itaconic, citraconic, allylsuccinic anhydrides , cyclohex-4-ene-1, 2-dicarboxylic, 4-methylenecyclohex-4-ene-1, 2-dicarboxylic, bicyclo (2,2,1) hept-5-ene-2,3-dicarboxylic and x-methylbicyclo (2,2,1) hept-5-ene-2,2-dicarboxylic.

Examples of other grafting monomers include:

"C1 to C8 alkyl esters or glycidyl ester derivatives of unsaturated carboxylic acids such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate, monomethyl itaconate and diethyl itaconafe;

»Amide derivatives of unsaturated carboxylic acids such as acrylamide, methacrylamide, maleic monoamide, maleic diamide, maleic N-monoethylamide, maleic N, N-diethylamide, maleic N-monobutylamide, N, N- maleic dibutylamide, fumaric monoamide, fumaric diamide, fumaric N-monoethylamide, N, fumaric N-diethylamide, fumaric N-monobutylamide and fumaric N, N-dibutylamide; o imide derivatives of unsaturated carboxylic acids such as mayeimide, N-butylmaleimide and N-phenylmaleimide; and o metal salts of unsaturated carboxylic acids such as sodium acrylate, sodium methacrylate, potassium acrylate and potassium methacrylate.

Maleic anhydride is preferred.

Various known methods can be used to graft a grafting monomer to the mixture of (C1) and (C2). The amount of grafting monomer is chosen appropriately and is between 0.01 to 10%, preferably between

600 and 5000 ppm relative to the total weight of mixture of (C1) and (C2) grafted. The amount of the grafted monomer is determined by assaying the functions succinics by IRTF spectroscopy. The MFI of (C), that is to say of (C1) and (C2) co-grafted is advantageously 0.1 to 10 g / 10 min.

As regards Polyethylene (D), it is a polyethylene homopolymer or a copolymer of ethylene with as comonomer a monomer chosen from the alphaolefins defined above for (C2), esters of unsaturated carboxylic acids or vinyl esters saturated carboxylic acids. The esters of unsaturated carboxylic acids are, for example, alkyl (meth) acrylates, the alkyl of which has from 1 to 24 carbon atoms. Examples of alkyl acrylate or methacrylate are in particular methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate. The vinyl esters of saturated carboxylic acids are, for example, vinyl acetate or propionate.

The polyethylene (D) can be a high density PE (HDPE), a low density PE (LDPE), a linear low density PE (LLDPE), a very low density PE (VLDPE) or a metallocene PE.

Polyethylene (D) can also be an elastomeric polymer, that is to say it can be (i) an elastomer within the meaning of ASTM D412, which means a material which can be stretched at room temperature twice its length, thus maintained for 5 minutes then return to less than 10% near its initial length after being released or (ii) a polymer not having exactly the preceding characteristics but which can be stretched and return substantially to its initial length. As examples, we can cite:

- EPR (ethylene propylene rubber) and EPDM (ethylene propylene diene);

- styrene elastomers such as SBR (styrene butadiene rubber), SBS block copolymers (styrene butadiene styrene), SEBS block copolymers (styrene ethylene butadiene styrene) and SIS block copolymers (styrene isoprene styrene).

Advantageously, the polyethylene (D) is an LLDPE of density between 0.900 and 0.935 or else a HDPE of density between 0.935 and 0.950.

Advantageously, the proportions in the mixture (A) of polymers (C) and (D) are respectively 10 to 30% by weight of (C) for 90 to 70% by weight of (D). As regards the polymer (B) in which the mixture (A) is diluted, it is a PP copolymer or terpolymer Propylene / Ethylene / Butylene. As a comonomer, we can cite:

• alpha olefins, advantageously those having from 2 to 30 carbon atoms such as ethylene, 1 -butene, 1 -pentene, 3-methyl-1 -butene, 1 -hexene, 4-methyl- 1 -pentene, 3-methyl-1 -pentene, 1-octene, 1 - decene, 1 -dodecene, 1 -tetradecene, 1 -hexadecene, 1 -octadecene, 1 - eicocene, 1 -dococene, 1 -tetracocene, 1 -hexacocene, 1-octacocene and 1 triacontene. These alpha olefins can be used alone or as a mixture of two or more than two.

• The dienes.

The polypropylene can also be a polypropylene block copolymer.

Advantageously, the polymer (B) comprises a mixture of several polymers in which there is at least one polypropylene comprising at least 50% by moles and preferably at least 75% of propylene. For example, the polymer (B) can be a mixture of polypropylene and EPDM or EPR.

The layers (1), (2), (3) and (4) can have a thickness between 50 and 500 angstroms for the layer (1), between 2 and 6 μm for the layer (2), between 5 and 30 μm for the layer (3) and between 2 and 10 μm for the layer (4).

The layers (2), (3) and (4) can be laminated together by a coextrusion process before the application of the metal layer (1). The layer (1) can be applied by vapor deposition using a technique well known to those skilled in the art, preferably it is deposited under vacuum.

The metal layer (1) constitutes a good barrier to oxygen and water vapor.

The compositions of layers (2), (3) and (4) can contain the additives usually used during the processing of polyolefins at contents of between 10 ppm and 5% such as antioxidants based on substituted phenolic molecules, UV protective agents, processing agents such as fatty amides, stearic acid and its salts, fluoropolymers known as agents for preventing extrusion defects, anti-fogging agents based on amines , anti-blocking agents such as silica or talc, masterbatches with dyes and nucleating agents. Figs. 2 and 3 allow the result of the invention to be clearly seen in relation to the prior art. The bags represented in these figures are similar to packets of chips comprising firstly a pocket delimited by a multilayer structure (1 1, 12, 13, 14) in the case of Fig. 2 and a multilayer structure (1 , 2, 3, 4) in the case of Fig.3, the metal layer (1) or (1 1) being in contact with the outside of the pocket while the layer (4) or (14) is in contact with the inside of the pocket. The two bags or packages are closed by a weld strip (5a) of the multilayer film which constitutes them, the layer (4) or (14) of each weld edge (5b) delimiting the opening of the bags (6) being welded on herself. These two packages are then exerted with an identical force (f) on either side of the region adjoining the weld strips (5a) in order to open said packages. We note that by exerting the same force (f) on both sides of the packages in the directions indicated in the figures, we do not get the same result depending on whether we have a package made with a film according to the prior art and a package made with a film according to the invention.

In the case of the bag or package of Fig. 2, it can be seen that there is delamination, that is to say separation, of the metallized layer (1 1) of the layers (12), (13) and (14) which they remain united with each other. We can therefore say that the delamination force of the layer (1 1) is less than the force necessary to break the weld strip (5a). It follows that the bag in this case is difficult to open, the metallized layer (1 1) dissociating first.

In the case of Fig. 3, there is no separation of the layers (1), (2), (3) and (4), but a rupture at the level of the weld strip of the bag which leads to the opening of the package materialized by the edges (5b). The adhesive force of the metal layer (1 1) is much greater than the force necessary to break the weld strip (5a) causing the opening of the bag.

Film samples from 1 to 8 are produced (see TABLE 1 below) comprising a multilayer structure of the BOPP type (substantially 20 μm) / ink layer / liquid adhesive layer / MCPP film (substantially 25 μm).

The MCPP film is a 4-layer structure, as shown in Fig. 1, respectively:

* layer (1) of AI thick 250 angstroms;

»Layer (2) 3 μm thick comprising:> X% by weight of a mixture (A) itself comprising 25% by weight of metallocene PE (C1) with density d = 0.870 with 1-octene as comonomer and LLDPE (C2) of density d = 0.920 with 1 -butene as comonomer, the mixture (C1) and (C2) being grafted with anhydride maleic with a grafting rate of 0.8% and 75% by weight of LLDPE (D) with 1-butene as comonomer and of d = 0.910; > Y% by weight of PP homopolymer (B) having an MFI = 7 and a d = 0.900; > The value of X being indicated in the second column of the

TABLE 1 and the value of Y being equal to 100-X.

• layer (3) of thickness 17 μm of PP homopolymer having an MFI = 7 and a d = 0.900;

* 5 μm thick layer (4) of PP propylene / Ethylene / Butylene terpolymer with majority propylene MFI = 7, d = 0.900 and the flexural modulus = 1000 mPa.

"[D expressed in g / cm ³ and measured according to standard ASTM D790 at 1900 mPa and MFI or melt flow index expressed in g / 10 min according to standard ASTM D 1238 at 230 ° C];

The layers (1), (3) and (4) are the same for samples 1 to 8. Only the layer (2) differs by the proportions X and Y expressed in% by weight. We then make sealed sachets and then measure the peel strength in g / 15mm. It is noted that for the compositions comprising 5 to 50% of mixture

(A), there is a rupture in the layer (2) as shown in Fig. 3, the AI layer being strongly linked to the layer (2) whereas in the cases indicated by a (*), we have a rupture at the interface of the AI layer and the layer (2) as illustrated in FIG. 2, the AI layer being more weakly bonded to the layer (2). Films comprising a layer (2) with a mixing ratio (A) of between 5 and 50% are therefore suitable for the manufacture of bags, sachets, bags, packages according to the invention.

TABLE 1

* peeling of the AI film.

Tests carried out with the other metals mentioned above have led to the same observations.

Claims

REVENPICATIQNS

1. Binder including:

- 5 to 50% by weight of a mixture (A), said mixture (A) comprising: - 5 to 100% by weight of a mixture of polymers (C1) and (C2) consisting of 90 to 20% by weight a metallocene polyethylene (C1) with a density between 0.865 and 0.915 and from 1 0 to 80% by weight of a polymer (C2) which is either a non-metallocene LDPE L or a homo- or copolymeric polyptopyieno, the mixture polymers (C1) and (C2) being co-grafted with an unsaturated carboxylic acid or a functional derivative of this acid as grafting monomer, and

95 to 0% by weight of a polyethylene (D) chosen from homo or copolymer polyethylenes and elastomers; the mixture (A) being such that: the content of grafted grafting monomer is between 30 and 10 ⁵ ppm; "The MFI or melt flow index (standard ASTM D 1238, at 1 90 ° C under 2, 16kg) is between 0.1 and 30g / 10min - 50 to 95% by weight of a polypropylene (B) homo or copolymer.

2. Multilayer structure comprising a layer (2) of binder according to claim 1.

3. Multilayer structure according to claim 2, characterized in that it comprises a metal layer (1) bonded to the layer (2) of binder.

4. Structure according to claim 3, characterized in that the metallic layer is a layer of AI, Fe, Cu, Sn, Ni, Ag, Cr, Au or an alloy containing at least one of these metals mainly.

5. Multilayer structure according to claim 4, characterized in that it comprises a layer (3) of polypropylene homopolymer or copolymer, the binder layer (2) being sandwiched between the metal layer (1) and said layer (3 ) of polypropylene.

6. Multilayer structure according to claim 5, characterized in that it comprises a layer (4) such that the layer (3) of polypropylene is sandwiched between the layer (2) of binder and said layer (4), this the latter being suitable for thermocell and comprising either an Ethylene / Propylene / Butylene terpolymer, or an Ethylene / Propylene copolymer or a metallocene PE or their mixtures in this case said mixture comprises at least two of the compounds previously listed.

7. Film comprising a multilayer structure according to one of claims 2 to 6.

8. Film characterized in that it comprises a layer of bi-oriented polypropylene (BOPP) or of bi-oriented polyethylene terephthalate (BOPET) printed on which is applied with an adhesive a metallized multilayer film comprising a structure according to one of claims 3 to 6, said film being bi-oriented or not and the metal layer (1) of said metallized multilayer film being directly bonded by the adhesive to the printed BOPP or BOPET layer.

9. Use of the binder according to claim 1 for manufacturing a multilayer structure according to one of claims 2 to 6.

10. Object comprising a multilayer structure according to one of claims 2 to 6. o 5

11. Object manufactured with a film according to one of claims 7 to 8.

12. Object according to claim 1 1, characterized in that this object is a package.

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