Coextruded multilayer film

Abstract

The invention discloses a heat sealable multilayer polyester based film that form hermetic and peelable seals onto polyester containers and their use in food packaging.

Claims

1. A heat sealable, coextruded multilayer film which is non heat shrinkable or is heat shrinkable and has a percentage of free shrink at 120° C. lower than 10% in longitudinal and/or transverse direction, measured in oil according to ASTM D 2732 and/or is biaxially oriented, with an orientation ratio between 2:1 and 5:1 in both longitudinal and transverse direction, the film comprising at least the following layers: 1) an outer heat sealable layer comprising at least 90 wt % of a composition consisting of: a) between 20 and 100 wt % of one or more propylene copolymers and one or more antiblock agents and/or slip agents; b) between 0 and 80 wt % of one or more ethylene alpha olefin copolymers; 2) an inner layer comprising at least 95 wt % of one or more polymers selected from ethylene (meth)acrylate or ethylene (meth)acrylic acid copolymers, anhydride modified ethylene (meth)acrylate or anhydride modified ethylene (meth)acrylic acid copolymers, anhydride modified ethylene alpha olefin copolymers and mixtures thereof, 3) a polyester based layer; wherein layer 2) adheres to layer 1) and to layer 3).

2. A heat sealable film according to claim 1, having between 3 and 10 lavers and/or having a total thickness between 3 and 150 microns and/or wherein the heat sealable layer 1) has a thickness comprised between 1 and 15 microns and/or layer 2) has a thickness comprised between 1 and 20 microns and/or layer 3) has a thickness comprised between 5 and 60 microns.

3. A heat sealable film according to claim 1, wherein said composition of layer 1) consists of one or more propylene copolymers and one or more antiblock agents and/or slip agents.

4. A heat sealable film according to claim 1, wherein said composition of layer 1) comprises an amount of between 25 and 99 wt % of one or more propylene copolymers and one or more antiblock agents and/or slip agents, and an amount between 1 and 80 wt % of one or more ethylene alpha olefin copolymers.

5. A heat sealable film according to claim 1, wherein said propylene copolymers of said composition of layer 1) are selected from copolymers of propylene with ethylene and/or butene, propylene/ethylene/butene copolymers and propylene/ethylene copolymers and mixtures thereof.

6. A heat sealable film according to claim 1, wherein layer 1) comprises one or more antiblock agents and one or more slip agents.

7. A heat sealable, coextruded multilayer film comprising at least the following layers: 1) an outer heat sealable layer comprising at least 90 wt % of a composition consisting of: c) between 20 and 100 wt % of one or more propylene copolymers and one or more antiblock agents, wherein the antiblock agents are natural or synthetic silica and/or are present in layer 1) in an amount of at least 0.07 wt % with the respect to the total amount of propylene copolymers and/or slip agents, wherein the slip agent are oleamide and erucamide and/or are present in layer 1) in an amount between 0.1 wt % and 10 wt % with the respect to the total amount of propylene copolymers; d) between 0 and 80 wt% of one or more ethylene alpha olefin copolymers; 2) an inner layer comprising at least 95 wt % of one or more polymers selected from ethylene (meth)acrylate or ethylene (meth)acrylic acid copolymers, anhydride modified ethylene (meth)acrylate or anhydride modified ethylene (meth)acrylic acid copolymers, anhydride modified ethylene alpha olefin copolymers and mixtures thereof, 3) a polyester based layer, wherein layer 2) adheres to layer 1) and to layer 3).

8. A heat sealable film according to claim 1, wherein said ethylene alpha olefin copolymers of the composition of layer 1) are ethylene (C.sub.4-C.sub.10) alpha olefin copolymers, ethylene octene copolymers and/or are selected from very low density polyethylene or linear low density polyethylene and mixtures thereof, or a mixture between very low density polyethylene and linear low density polyethylene in weight ratio among them comprised between 1.5:1 and 1:1.

9. A heat sealable, coextruded multilayer film comprising at least the following layers: 4) an outer heat sealable layer comprising at least 90 wt % of a composition consisting of: e) between 20 and 100 wt % of one or more propylene copolymers and one or more antiblock agents and/or slip agents; f) between 0 and 80 wt % of one or more ethylene alpha olefin copolymers; 5) an inner layer comprising at least 95 wt % of one or more polymers selected from ethylene (meth)acrylate or ethylene (meth)acrylic acid copolymers. anhydride modified ethylene (meth)acrylate or anhydride modified ethylene (meth)acrylic acid copolymers, anhydride modified ethylene alpha olefin copolymers and mixtures thereof, 6) a polyester based layer; wherein layer 2) adheres to layer 1) and to layer 3), and wherein said ethylene (meth)acrylate copolymers of layer 2) are copolymers of ethylene with methyl acrylate containing between 15 and 30 wt % of methyl acrylate comonomer and/or said anhydride modified ethylene alpha olefin copolymers of layer 2) are anhydride modified ethylene (C.sub.4-C.sub.10) alpha olefin copolymers, anhydride modified ethylene octene copolymers and/or anhydride modified linear low density polyethylenesand/or are maleic anhydride modified ethylene alpha olefin copolymers and/or, maleic anhydride modified linear low density polyethylenes.

10. A heat sealable film according to claim 1, wherein the outer layer of the film, opposite to the heat sealable layer 1), comprises at least 90 wt % of polyesters, the latter preferably comprising (semi)crystalline polyesters in an amount between 90 wt % and 100 wt between 1 and 5 wt %, of amorphous polyesters and/or said polyesters are copolyesters, poly(ethylene terephthalate) copolymers.

11. A heat sealable film according to claim 1, wherein the film has more than 3 layers, comprises at least 90 wt % of one or more polyesters consisting of an amount between 50 wt % and 100 wt % if (semi)crystalline polyesters and an amount between 0 and 50 wt % of amorphous polyesters and/or said polyesters are copolyesters, or poly(ethylene terephthalate) copolymers.

12. A heat sealable film according to claim 1, comprising an antifog agent coated onto at least the surface of the heat sealable layer 1) of the film.

Description

DETAILED DESCRIPTION OF INVENTION

(1) A first object of the present invention is a heat sealable, coextruded multilayer film comprising at least the following layers: 1) an outer heat sealable layer comprising at least 90 wt %, preferably at least 95 wt %, more preferably at least 98 wt %, more preferably at least 99 wt %, even more preferably 100 wt % of a composition consisting of: a) between 20 and 100 wt % of one or more propylene copolymers and one or more antiblock agents and/or slip agents; b) between 0 and 80 wt % of one or more ethylene alpha olefin copolymers; 2) an inner layer comprising at least 95 wt %, preferably at least 98 wt %, more preferably at least 99 wt %, even more preferably 100 wt % of one or more polymers selected from ethylene (meth)acrylate or ethylene (meth)acrylic acid copolymers, anhydride modified ethylene (meth)acrylate or anhydride modified ethylene (meth)acrylic acid copolymers , anhydride modified ethylene alpha olefin copolymers and mixtures thereof, 3) a polyester based layer;

(2) wherein layer 2) adheres to layer 1) and to layer 3).

(3) The film of the invention may have 3 or more layers, preferably between 3 and 10, more preferably between 3 and 6, even more preferably 4.

(4) The total thickness of the film of the invention may vary within wide limits. It is preferably between 3 and 150 microns, preferably between 10 and 100 microns, more preferably between 20 and 70 microns, more preferably between 30 and 60 microns, even more preferably of 40 microns.

(5) Preferably, the heat sealable layer 1) has a thickness comprised between 1 and 15 microns, preferably between 3 and 12 microns, more preferably between 4 and 8 microns.

(6) Preferably, layer 2) has a thickness comprised between 1 and 20 microns, preferably between 2 and 15 microns, more preferably between 3 and 10 microns, even more preferably between 3 and 8 microns.

(7) Preferably, layer 3) has a thickness comprised between 5 and 60 microns, more preferably between 10 and 40 microns, even more preferably between 15 and 30 microns.

(8) The film according to the invention may be heat shrinkable or not. Preferably the film is non heat shrinkable.

(9) Preferably, when the film is heat shrinkable, it has a percentage of free shrink at 120° C. lower than 10%, preferably lower than 7%, more preferably lower than 5%, more preferably lower than 2%, even more preferably lower than 1% in longitudinal and/or transverse direction, measured in oil according to ASTM D 2732.

(10) The non heat shrinkable film or the heat shrinkable film according to the above preferred embodiment has the advantage that it can be advantageously used both in inside or outside cut packaging methods.

(11) When the film of the invention is oriented, it is preferably biaxially oriented, with an orientation ratio preferably comprised between 2:1 and 5:1, more preferably between 2:1 and about 4:1, even more preferably of 3.8:1 in in both longitudinal and transverse direction.

(12) According to one preferred embodiment, said composition of layer 1) consists of only one or more propylene copolymers and one or more antiblock agents and/or slip agents (component a) above).

(13) The films according to this embodiment are suitable to be sealed to containers made of polypropylene homopolymers and copolymers or on containers having a heat sealable area made of polypropylene homopolymers and copolymers.

(14) According to an alternative preferred embodiment, said composition of layer 1) consists of an amount between 25 and 99 wt %, more preferably between 30 and 50 wt %, more preferably between 30 and 40 wt %, even more preferably of 35 wt % of one or more propylene copolymers and one or more antiblock agents and/or slip agents (component a) above), and an amount between 1 and 80 wt %, preferably between 20 and 70 wt %, more preferably between 60 and 70 wt %, even more preferably of 60 wt % of one or more ethylene alpha olefin copolymers (component b) above).

(15) The films according to this second embodiment are suitable to be used for tray lidding applications on polypropylene or polyethylene containers or on containers having a heat sealable area of polypropylene or polyethylene.

(16) Said propylene copolymers of component a) of said composition of layer 1) are preferably selected from copolymers of propylene with ethylene and/or butene, preferably propylene/ethylene/butene copolymers and propylene/ethylene copolymers and mixtures thereof. More preferably, said propylene copolymers are propylene/ethylene/butene copolymers.

(17) Preferably, component a) of said composition of layer 1) comprises one or more antiblock agents. The antiblock agents are preferably present in layer 1) in an amount of at least 0.07 wt %, more preferably between 0.07 wt % and 10 wt %, more preferably between 0.07 and 2 wt %, even more preferably between 0.07 and 0.5 wt % with respect to the total amount of propylene copolymers. Preferably, the antiblock agents are natural or synthetic silica.

(18) Preferably, component a) of said composition of layer 1) comprises one or more slip agents. The slip agents are preferably present in an amount of at least 0.1 wt % preferably between 0.1 wt % and 10 wt %, more preferably between 0.1 and 2%, even more preferably between 0.1 and 0.5 wt % with the respect to the total amount of propylene copolymers. Preferably, the slip agent are oleamide and erucamide.

(19) Preferably, component a) of said composition of layer 1) comprises both antiblock agents and slip agents.

(20) Said ethylene alpha olefin copolymers of said composition of layer 1) are preferably ethylene (C.sub.4-C.sub.10) alpha olefin copolymers, more preferably ethylene octene copolymers and/or are selected from very low density polyethylene (VLDPE) or linear low density polyethylene (LLDPE) and mixtures thereof. Preferably, said ethylene alpha olefin copolymers are a mixture between very low density polyethylene and linear low density polyethylene, preferably in weight ratio among them comprised between 1.5:1 and 1:1.

(21) A suitable VLDPE to be used in the present invention has a density preferably between 0.900 g/cc and 0.920 g/cc, more preferably of about 0.910 g/cc, such as for example the product commercialised under the tradename AFFINITY PL 1845G by Dow. A suitable LLDPE to be used in the present invention has a density preferably between 0.910 g/cc and 0.930 g/cc, more preferably of about 0.920 g/cc, such as for example the product commercialised under the tradename DOWLEX 2045S by Dow.

(22) A suitable composition a) to be used in layer 1) of the film of the present invention is the product commercialized under the tradename ELTEX KS350 by Ineos.

(23) Preferably, said layer 2) comprises at least 95 wt %, preferably at least 98wt %, more preferably at least 99 wt %, even more preferably 100 wt % of ethylene (meth)acrylate copolymers or anhydride modified ethylene alpha olefin copolymers.

(24) Preferably, said ethylene (meth)acrylate copolymers of layer 2) are copolymers of ethylene with methyl acrylate, preferably containing between 15 and 30 wt %, more preferably 20 wt % or 24 wt % of methyl acrylate comonomer. A suitable ethylene methylacrylate copolymer to be used in the inner layer 2) of the film of the invention is for example the product commercialized under the tradename Elvaloy AC 12024S or Elvaloy 1820 AC by Du Pont or Lotryl Bestpeel 2012 by Arkema.

(25) Preferably, in the composition of layer 2), said anhydride modified ethylene (meth)acrylate or anhydride modified (meth)acrylic acid copolymers are maleic anhydride modified ethylene (meth)acrylate or anhydride modified (meth)acrylic acid copolymers.

(26) Preferably, said anhydride modified ethylene alpha olefin copolymers are anhydride modified ethylene (C.sub.4-C.sub.10) alpha olefin copolymers, more preferably anhydride modified ethylene octene copolymers and/or are anhydride modified linear low density polyethylenes. Preferably, said anhydride modified ethylene alpha olefin copolymers are maleic anhydride modified ethylene alpha olefin copolymers. More preferably, said anhydride modified ethylene alpha olefin copolymers are maleic anhydride modified linear low density polyethylenes.

(27) A suitable maleic anhydride modified linear low density polyethylene for use in layer 2) of the film of the invention is for example the product commercialized under the tradename ADMER NF911E by Mitsui Chemical.

(28) Preferably, in the film according to the invention, the outer layer of the film, opposite to the heat sealable layer 1), comprises at least 90 wt %, preferably at least 95 wt %, more preferably at least 98 wt %, even more preferably 100 wt % of polyesters.

(29) Preferably, said polyesters are polyesters of aromatic dicarboxylic acids, more preferably of terephtalic acid.

(30) Preferably said polyesters comprise at least 80 wt % of (semi)crystalline polyesters, preferably consist of an amount between 90 wt % and 100 wt %, preferably between 95 wt % and 99 wt %, even more preferably 98 wt % of (semi)crystalline polyesters and an amount between 0 and 10 wt %, more preferably between 1 and 5 wt %, even more preferably 2 wt % of amorphous polyesters.

(31) Preferably, said polyesters are copolyesters, more preferably poly(ethylene terephthalate) copolymers.

(32) Preferably, in order to improve the processing of the film in a high speed packaging equipment, slip and/or anti-blocking additives may be added to above said outer layer of the film. These additives may be added in the form of a concentrate in a polyester carrier resin. The amount of carrier is typically in the order of 0.1-5% of the total weight of the layer.

(33) According to one preferred embodiment of the present invention, the film has only three layers and layer 3) of the film is an outer layer of the film (outer layer 3), preferably having the preferred composition described above. According to an alternative preferred embodiment of the present invention, the film has more than 3 layers, preferably 4, layer 3 is an inner layer of the film (inner layer 3) and the outer layer of the film, opposite to the heat sealable layer, is a further polyester based layer of the film, in addition to layer 3), preferably having the preferred composition described above.

(34) In a film according to this embodiment, layer 3) preferably comprises at least 90 wt %, preferably at least 95 wt %, more preferably at least 98 wt %, even more preferably 100 wt % of one or more polyesters. Preferably, said polyesters are polyesters of aromatic dicarboxylic acids, more preferably of terephtalic acid.

(35) Preferably, said polyesters consist of an amount between 50 wt % and 100 wt % if (semi)crystalline polyesters and an amount between 0 and 50 wt % of amorphous polyesters.

(36) Preferably, said polyesters are copolyesters, more preferably poly(ethylene terephthalate) copolymers.

(37) According to a particularly preferred embodiment, layer 3) comprises an amount of at least 50 wt %, more preferably between 50 and 80 wt %, even more preferably between 55 wt % and 70 wt %, even more preferably about 60 wt % of (semi)crystalline polyesters and an amount between 20 and 50 wt %, more preferably between 30 and 45 wt %, even more preferably of about 40 wt % of amorphous polyesters.

(38) A suitable amorphous copolyester for use in the inner layer 3) of the invention for example the product commercialized under the tradename GN001 by Eastman Chemical.

(39) A suitable amorphous copolyester for use in the above outer layer of the film of the invention is for example the product commercialized under the tradename Sukano G dc S503 or TDC S497 by Sukano.

(40) A suitable (semi)crystalline polyester for use in inner layers 3) or in the above outer layer of the film or in the inner layer 3) of the invention of the invention is for example the product commercialized under the tradename Ramapet N180 by Eastman Chemical or Poliprotect APB by Mossi & Ghisolfi.

(41) The film according to the first object of the present invention may be manufactured according to processes well known in the art such as flat co-extrusion, optionally followed by mono- or bi-orientation, performed by flat, sequential or simultaneous tenterframe orientation.

(42) Preferably, coextrusion is carried out by means well known in the art, for example using a flat or a circular film die that allows shaping the polymer melt into a flat tape or a film tubing, wherein each of the blends of the different layers of the film are extruded simultaneously through the extrusion die.

(43) Optionally, the film of the present invention, co-extruded as described above, is then oriented through a flat film orientation process that produces a monoaxially, preferably biaxially oriented film by heating the tape to its softening temperature but below its melt temperature and by stretching in the solid state with a simultaneous or a sequential tenterframe process. The film is then rapidly cooled to somehow freeze the molecules of the film in their oriented state and wound. Preferably, orientation is carried out with a ratio comprised between about 2:1 and about 5:1, more preferably between 2:1 and about 4:1, even more preferably of 3.8:1 in each direction,

(44) Furthermore, it may be desirable to submit the oriented structure to a controlled heating-cooling treatment, so-called annealing, that is aimed at having a better control on low temperature dimensional stability of the film.

(45) The film according to the present invention can also optionally comprise an antifog agent coated onto at least the surface of the heat sealable layer 1) of the film, which is directly facing the product in the container, so as to obtain an antifogging surface. Antifog agents for this application method are well known in the art. For example, they can be selected from non-ionic surfactants such as polyhydric alcohol fatty acid esters, higher fatty acid amines, higher fatty acid amides, polyoxyethylene ethers of higher fatty alcohols and ethylene oxide adducts of higher fatty acid amines or amides and the like.

(46) The application of the antifogging agent to the film of the invention may be carried out either by in-line method involving application during the manufacture or by off-line method involving the application after the manufacture of the film. The antifogging agent may be added in an amount of from about 30 mg/sqm to 70 mg/sqm, preferably from about 40 mg/sqm to 60 mg/sqm, more preferably of 50 mg/sqm.

(47) Preferably, the heat sealable layer surface of the film is corona treated before applying the coating.

(48) The coating composition may be applied to the film by any suitable conventional technique, well known in the art, such as for example digital printing, roller printing, flexography, slot die, rotogravure, vapour deposition, or by blade, brush or scraper, or by spraying or pouring.

(49) As will be demonstrated in the experimental section, films according to this embodiment when sealed onto polypropylene or polyethylene containers show very good hermeticity, antifog properties and are easily opened from the container. Furthermore, films according to this embodiment show particularly good optical properties. A second object of the present invention is a package comprising a container, preferably a tray, a product placed onto/into the container, and a lid made of the film according to the first object of the present invention hermetically sealed onto said container, thus enclosing the product, wherein the heat sealable layer of the film is in contact with or faces the product.

(50) Examples of suitable supports for the package of the invention are container made of propylene or polyethylene or having a sealing area made of polypropylene or polyethylene, respectively.

(51) The package is produced by techniques well known to those skilled in the art. The film of the invention is particularly suitable for use in inside-cut packaging methods. The film can also be used in outside cut packaging methods.

(52) For example, once the food to be packaged has been placed in the container, the film according to the second object of the invention is sealed to the container, e.g. a tray, by means of temperature using conventional techniques and equipment.

(53) In particular, the container with the product loaded therein is brought into a lid sealing station, which comprises a lower chamber and an upper chamber, and a web of the film of the invention is provided over the top of the container. The lower chamber and the upper chamber are then closed together, the air in-between the container and the lidding film is replaced by the suitable gas or gas admixture, with or without prior air evacuation, and then the lidding film of the invention is sealed to the rim or the peripheral lip of the container by means of the combination of a heated frame or platen above the lidding film and a similarly framed anvil supporting the container rim or peripheral lip, that are pressed together. In outside-cut packaging methods, the lidding film is cut almost at the same time as the lid is sealed. In case of shrinkable lids, shrinkage of the lid in the package typically occurs at the same time as the heat of the sealing elements in the lidding station is sufficient to get the desired shrinkage.

(54) In inside-cut methods, the film is cut before application and sealing on the container.

(55) Lidding machines that can be suitable for the lidding process include for instance Multivac 400 and Multivac T550 by Multivac Sep. GmbH, Mondini Trave, E380, E390 or E590 by Mondini S.p.A., Ross A20 or Ross S45 by Ross-Reiser, Meca-2002 or Meca-2003 by Mecaplastic, the tray lidding machines of Sealpac and the like machines.

(56) As it will be demonstrated in the experimental section, the films of the present invention have the advantage that sealing at relatively low temperatures. In particular, the temperature necessary for hermetic sealing of the film to the support are generally between 130° C. and 150° C. and sealing times in the order of 0.5 to 1 second, preferably 0.5 to 1.0 second.

(57) A third object of the present invention is the use of the film according to the first object of the invention for packaging food, preferably ready meals for cooking applications (either in microwave oven or in conventional oven), or moist or respiring products, such as fruits and vegetables or for packaging medical equipment.

EXAMPLES

(58) The present invention can be further understood by reference to the following examples that are merely illustrative and are not to be interpreted as a limitation to the scope of the claims.

Example 1

Preparation of Films

(59) In the following films, the polymers and compositions indicated in Table 1 below were used

(60) TABLE-US-00001 TABLE 1 Polymers and compositions TRADENAME SUPPLIER ACRONYM RAMAPET N180 Indorama PET1 GN001 Eastman Chemical PETG1 SUKANO G Dc S503 Sukano PETG2 TDC S 497 Sukano PETG3 ELTEX P KS350 Ineos EPC1 AFFINITY PL 1845G DOW VLDPE1 Elvaloy AC 12024S DuPont EMA1 Lotryl Bestpeel 2012 Arkema EMA2 Elvaloy 1820 AC DuPont EMA3 ADMER NF911E Mitsui Chemical LLDPE-md1 DOWLEX 2045S DOW LLDPE1 Poliprotect APB Mossi & Ghisolfi Polyester PET1: Copolymer of terephtalic acid, isophtalic acid and mono ethylene glycol-Bulk (Apparent) Density 0.830 g/cc, Density 1.4 g/cc, Glass Transition 78° C., Melting point 245° C., Viscosity Solution 0.80 mPa .Math. sec; PETG1: Polyethylene Terephthalate/Glycol-Density 1.27 g/cc, Glass Transition 78° C., Viscosity Intrinsic 0.75 dl/g; PETG2: Polyethylene Terephthalate/Glycol with amorphous silica and ester wax-Additives(SiO2) 10%, Additives(Wax) 6%, Bulk (Apparent) Density 0.74 g/cc, Density 1.4 g/cc, Vicat softening point 82° C.; PETG3: Polyethylene Terephthalate/Glycol-Bulk (Apparent) Density 0.74 g/cc, Density 1.4 g/cc; EPC1: Polypropylene copolymer, Propylene/Ethylene/Butene copolymer with anti-block and slip additives, Density 0.895 g/cc, Melt Flow Rate (230° C./02.16 kg) 5 g/10 min, Melting point 131° C., Vicat softening point 105° C.; VLDPE1: Polyethylene, Very low density ethylene/octane copolymer-Density 0.91 g/cc, Melt Flow Rate (190° C./2.16 kg) 3.5 g/10 min, Melting point 103° C., Vicat softening point 95° C.; EMA1: Copolymer of ethylene and methyl acrylate, 24% by weight methyl acrylate comonomer content, density 0.944 g/cc, Melt Flow Rate (190° C./2.16 kg) 20 g/10 min, Melting point 88° C.; EMA2: Copolymer of ethylene and methyl acrylate, 20% by weight methyl acrylate comonomer content, Melt Flow Rate (190° C./2.16 kg) 11 g/10 min, Melting point 79° C.; EMA3: Copolymer of ethylene and methyl acrylate with 20% methyl acrylate comonomer content. Density 0.942 g/cc, Melt Flow Rate (190° C./02.16 kg) 8 g/10 min, Melting Point 92° C., Vicat Softening Point 54° C.; LLDPE-md1: Maleic anhydride modified polyethylene, Linear Low Density-Density 0.900 g/cc, Melt Flow Rate (190° C./2.16 kg) 2.5 g/10 min, Vicat softening point 74° C.; LLDPE1: Polyethylene, Linear Low Density Ethylene/Octene Copolymer (linear, Ziegler/Natta)-Density 0.92 g/cc, Melt Flow Rate (190° C./02.16 kg).1.00 g/10 min, Melting point 124.0° C., Vicat softening point 103° C.; Polyester: Polyethylene terephthalate copolymer with PA-Density 1.3 g/cc, Melting point 250° C., Viscosity Intrisic 0.85 dl/g;

(61) Films 1-5 having the structure and composition set out in Table 2 were prepared.

(62) TABLE-US-00002 TABLE 2 Examples Film Layer Total thickness n. Layer Layer composition thickness (μ) film (μ) 1 1 EPC1 35.00% 6 40 VLDPE1 35.00% LLDPE1 30.00% 2 LLDPE-md1 100.00% 4 3 PET1 60.00% 24 PETG1 40.00% 4 PET1 98.00% 6 PETG2 2.00% 2 1 EPC1 35.00% 6 40 VLDPE1 35.00% LLDPE1 30.00% 2 EMA2 100.00% 4 3 PET1 60.00% 24 PETG1 40.00% 4 PET1 98.00% 6 PETG2 2.00% 3 1 EPC1 35.00% 6 40 VLDPE1 35.00% LLDPE1 30.00% 2 EMA1 100.00% 4 3 PET1 60.00% 24 PETG1 40.00% 4 PET1 98.00% 6 PETG2 2.00% 4 1 EPC1 35.00% 6 33 VLDPE1 35.00% LLDPE1 30.00% 2 EMA3 100.00% 4 3 Polyester 60.00% 19 PETG1 40.00% 4 Polyester 98.00% 4 PETG2 2.00% 5 1 EPC1 100.00% 6 33 2 EMA3 100.00% 4 3 Polyester 60.00% 19 PETG1 40.00% 4 Polyester 98.00% 4 PETG3 2.00%

(63) All the above films were manufactured through a flat coextrusion process followed by in line simultaneous Teneterframe orientation using the following operative conditions:

(64) MD ratio: 3.8:1

(65) TD ratio: 3.8:1

(66) Pre-heating temperature: 98° C.

(67) Stretching temperature: 98° C.

(68) Heat setting temperature: 158° C.

(69) The film so obtained were cooled down first by an air flow at 30° C. and then by passing them onto a cooling roll that was cooled with water and kept at 20° C.

Example 2

Characterization of Films

(70) Clarity and Haze

(71) Haze of films 1 to 5 has been evaluated according to the standard test method ASTM D1003. The results of the test are reported in Table 3 below.

(72) TABLE-US-00003 TABLE 3 Haze Film N. Haze (%) Film 1 3 Film 2 3 Film 3 3 Film 4 3 Film 5 3

(73) As can be seen from the data above, all films according to the invention show excellent optical properties.

Example 3

Characterization of Films in Sealed Trays

(74) The films prepared above were sealed at different sealing conditions reported in Tables 4 and 5 below onto EsPlastic mono PP black trays 1826-50, 450 micron thick, using a Sealpac A7 machine in cold room with either a 1826 OC (Outside Cut) tool with 2 different sealing bar profiles (flat 4 mm and convex 4 mm) or a 1826 IC (Inside Cut) tool with a flatbar profile. V/G setting was 300 mbar vacuum and 925 mbar gas.

(75) The seals were clean, i.e. the films were sealed onto the tray keeping the tray flange under clean (i.e. non contaminated) conditions and no product was packaged.

(76) As will be described in the examples below, hermeticity of the packages obtained and manual opening of packages were evaluated according to the test methods described below.

(77) a. Hermeticity Test

(78) The packages obtained were put in a closed water tank. Vacuum was created in the headspace of the water tank and recording was taken of the value of the pressure (in bars) inside the tank when bubbles start to escape from the closed packages. A number of packages were tested for each sealing.

(79) The packages were considered to provide a hermetic seal fit for use when they had a Dopack value higher than 0.4. Packages with a Dopack value equal or lower to 0.4 were considered as not providing a hermetic seal.

(80) Table 4 reports the results obtained in the test, wherein the Dopack value corresponds to the average pressure measured in mbars for each set of packages and the Dopack range indicates the lowest and highest pressure value measured in mbars obtained for each set of packages

(81) TABLE-US-00004 TABLE 4 Hermeticity Packs Film Sealing conditions Seal bar tested Dopack average Dopack range 1 120° C. for 0.8 sec Flat OC 12 NA-Weak seal NA-Weak seal Convex OC 12 NA-Weak seal NA-Weak seal 130° C. for 0.8 sec Flat OC 12 0.41 0.40-0.44 Convex OC 12 0.42 0.41-0.45 140° C. for 0.5 sec Flat OC 12 0.48 0.44-0.52 Convex OC 12 0.48 0.45-0.52 2 120° C. for 0.8 sec Flat OC 12 NA-Weak seal NA-Weak seal Convex OC 12 NA-Weak seal NA-Weak seal 130° C. for 0.8 sec Flat OC 12 0.44 0.41-0.46 Convex OC 12 0.44 0.42-0.46 140° C. for 0.5 sec Flat OC 12 0.47 0.46-0.48 Convex OC 12 0.48 0.46-0.50 3 120° C. for 0.8 sec Flat OC 12 NA-Weak seal NA-Weak seal Convex OC 12 NA-Weak seal NA-Weak seal 130° C. for 0.8 sec Flat OC 12 NA-Weak seal NA-Weak seal Convex OC 12 0.39 0.36-0.41 140° C. for 0.5 sec Flat OC 12 0.47 0.42-0.52 Convex OC 12 0.49 0.43-0.53 160° C. for 0.5 sec Flat OC 12 0.50 0.47-0.52 Convex OC 12 0.50 0.48-0.52 4 130° C. for 0.8 sec Flat IC 10 0.33 0.29-0.38 140° C. for 0.8 sec Flat IC 10 0.45 0.39-0.50 140° C. for 0.5 sec Flat OC 10 0.28 0.22-0.33 Convex OC 10 0.38 0.36-0.40 160° C. for 0.5 sec Flat IC 10 0.5 0.39-0.54 180° C. for 0.5 sec Flat IC 10 0.48 0.47-0.49 Convex OC 10 0.48 0.45-0.50 5 130° C. for 0.8 sec Flat IC 10 NA-No seal NA-No seal 140° C. for 0.8 sec Flat IC 10 0.42 0.40-0.45 160° C. for 0.5 sec Flat IC 10 0.41 0.38-0.45 180° C. for 0.5 sec Flat IC 10 0.43 0.42-0.45 NA: Not available

(82) b. Opening of the Packages

(83) The quality of the opening of the packages obtained at the different sealing conditions indicated in Table 5 was manually tested by 2 panelists, opening at least 15 packs for each set of films.

(84) The quality of the opening of the packages was recorded and the average outcome of the test classified according to the following parameters:

(85) Peel:

(86) Poor: −

(87) Acceptable: +

(88) Good: ++

(89) Residue on Tray:

(90) Present: +

(91) Not present: −

(92) TABLE-US-00005 TABLE 5 Opening of packages Sealing Opening of packages Film conditions Seal bar Peel Residue on tray 1 130° C. for 0.8 Flat OC + − sec Convex OC + − 140° C. for 0.5 Flat OC + NA sec Convex OC + NA 160° C. for 0.5 Flat OC − NA sec Convex OC − NA 2 130° C. for 0.8 Flat OC + − sec Convex OC + − 140° C. for 0.5 Flat OC + NA sec Convex OC + NA 160° C. for 0.5 Flat OC + − sec Convex OC + − 3 130° C. for 0.8 Flat OC + − sec Convex OC + − 140° C. for 0.5 Flat OC + − sec Convex OC + − 160° C. for 0.5 Flat OC ++ NA sec Convex OC ++ NA 4 130° C. for 0.8 Flat OC Weak seal-NA Weak seal-NA sec 140° C. for 0.8 Flat IC ++ − sec 160° C. for 0.5 Flat IC ++ − sec 5 140° C. for 0.8 Flat IC ++ − sec 160° C. for 0.5 Flat IC ++ − sec NA: not available

(93) As can be seen from the results above, in both inside cut and outside cut packaging, all the films of the invention show a good sealability and high hermeticity at low sealing temperatures combined with acceptable or good peelability, with no tearing.