MULTI-LAYER FILM

Abstract

The present invention relates to a multilayer film. The multilayer film is characterized by a combination of desirable properties, such as excellent thermoformability, good optical properties, excellent sealing, puncture resistance and recyclability.

Description

Title of the invention: MULTILAYER FILM

[0001] The present invention relates to a multilayer film characterized by a combination of desirable properties, such as excellent thermoformability, good optical properties, excellent sealing, puncture resistance and recyclability. The invention further relates to a method for producing said film. The invention further relates to the use of said film for packaging applications, in particular for food products, and to the use of said film for deep-drawing packaging applications. The invention further relates to a deep-drawing package comprising said film.

[0002] In general, the packaging of food articles by means of a thermoforming machine comprises the following steps:

[0003] 1. thermoforming a suitable film (often called “lower” or “lower” film) deep drawing”) using temperature, vacuum and / or pressure or a plug;

[0004] 2. placing the product to be packaged in the “pockets” formed in step 1;

[0005] 3. vacuuming the final package at a different station (sealing) and the sealing the thermoformed material on a “top” lidding film.

[0006] The critical physical properties that are considered important by those skilled in the art for films of such application are as follows:

[0007] 1. for deep drawing film, it is important to be able to achieve efficient thermoforming under the conditions of different thermoforming machines;

[0008] 2. excellent optical properties are also important for a beautiful presentation of packages in supermarkets and other display windows;

[0009] 3. mechanical protection properties and puncture resistance are also important to minimize the percentage of rejects during the shelf life of the product;

[0010] 4. oxygen shielding properties are important to minimize oxygen penetration which affects the shelf life of foods that are often thermoformed, for example fresh meat, processed meat, cheese and other foods.

[0011] In some cases, when food is stored in frozen conditions for example, it is possible to use a non-gaseous protective film. The other characteristics remain the same.

[0012] Packaging films with the above-mentioned properties are well known in the art.

[0013] A typical patent application representing films that are often used in the prior art is CA 2 122 283 A1.

[0014] In general, the films used in the prior art comprise polymers such as polyamides, which are considered a very good solution since they combine excellent properties of thermoformability, puncture resistance, mechanical protection and visual presentation.

[0015] Although prior art films provide a suitable combination of such properties, they are not considered optimal due to new trends requiring ease of recycling. Recycling platforms, such as on-pack recycling label (OPRL) platforms, do not accept such films into their recycling streams.

[0016] An object of the present invention is to provide a multilayer film having properties at least as good as those of the aforementioned traditional films, in particular visual presentation, thermoforming, mechanical protection and oxygen protection properties, and additionally having improved recycling capacity and ease of recycling compared to known films, which in particular allows it to be recycled in a polypropylene (PP) recycling stream. Summary of the invention

[0017] In a first aspect, the present invention relates to a multilayer film comprising an outer layer, an oxygen barrier layer and an inner sealant layer, wherein the oxygen barrier layer is located between the outer layer and the inner sealant layer, wherein the oxygen barrier layer comprises an ethylene vinyl ester copolymer (EVOH).

[0018] The multilayer film comprises at least 90% by weight of polypropylene or polybutene polymers or copolymers, not more than 8% by weight of EVOH, and at least 25% by weight of random propylene-ethylene copolymer having a melting point in the range of 135°C to 148°C, based on the total weight of the film. In addition, the multilayer film does not comprise polyamide, polyester, polyvinyl chloride (PVC), or polyvinylidene chloride (PVDC).

[0019] In a second aspect, the multilayer film according to the first aspect comprises a polypropylene homopolymer, preferably wherein the multilayer film comprises a polypropylene homopolymer in the outer layer.

[0020] In a third aspect, the polypropylene homopolymer in the multilayer film according to the second aspect is a polypropylene homopolymer produced by Ziegler Natta or metallocene catalysts and having a melting point of at least less than 150°C, more preferably the polypropylene homopolymer has a melting point in the range of 150°C to 170°C and even more preferably a finage index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

[0021] In a fourth aspect, the multilayer film according to one of the preceding aspects comprises, in the outer layer, a random propylene-ethylene copolymer, preferably the random propylene-ethylene copolymer has a melting point in the range of 135°C to 148°C and more preferably a finage index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

[0022] In a fifth aspect, the multilayer film according to one of the preceding aspects comprises, in the outer layer, a propylene-ethylene copolymer with less than 10% by weight of ethylene and a melting point of less than 130°C, more preferably less than 125°C, even more preferably less than 120°C.

[0023] In a sixth aspect, the multilayer film according to one of the preceding aspects comprises at least one polypropylene polymer, preferably a mixture of different polypropylene polymers, in the inner heat-sealing layer, preferably the melting point of the polypropylene material in the inner heat-sealing layer is at least 10°C lower than the melting point of any polypropylene material used in any other layer of the multilayer film.

[0024] In a seventh aspect, the multilayer film according to the sixth aspect comprises a propylene-ethylene copolymer in the inner heat-sealing layer, preferably the propylene-ethylene copolymer has a melting point of less than 135°C, preferably less than 130°C, more preferably a melting point of less than 125°C, even more preferably a melting point of less than 120°C.

[0025] In an eighth aspect, the multilayer film according to the sixth or seventh aspect comprises at least 10% propylene-ethylene copolymer based on the total weight of the multilayer film.

[0026] In a ninth aspect, the multilayer film according to one of the preceding aspects comprises the inner sealing layer which (further) comprises a propylene-butene copolymer, preferably said copolymer has a melting point of less than 135°C, preferably less than 130°C, more preferably a melting point of less than 125°C, even more preferably a melting point of less than 120°C.

[0027] In a tenth aspect, the multilayer film according to one of the preceding aspects comprises the inner sealing layer which (further) comprises a propylene-ethylene-butene copolymer, preferably the sum of the ethylene content and the butene content in the propylene-ethylene-butene copolymer is less than 10% by weight based on the total weight of the copolymer.

[0028] In an eleventh aspect, the multilayer film according to one of the preceding aspects comprises at least one intermediate layer between the outer layer and the oxygen protection layer and / or between the oxygen protection layer and the inner heat-sealing layer, preferably the multilayer film comprises the following layer structure: outer layer / intermediate layer 1 / protective layer / intermediate layer 2 / inner sealing layer.

[0029] In a twelfth aspect, the multilayer film according to one of the first aspect to the tenth aspect comprises the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / intermediate layer 3 / protective layer / intermediate layer 4 / intermediate layer 5 / intermediate layer 6 / inner sealing layer, or the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / protective layer / intermediate layer 3 / intermediate layer 4 / inner sealing layer.

[0030] In a thirteenth aspect, the multilayer film according to one of the preceding aspects has a haze of less than 10%, as measured according to ASTM D 1003.

[0031] In a fourteenth aspect, the multilayer film according to one of the preceding aspects has a gloss of at least 100GU (45° angle), as measured according to ASTM D2457.

[0032] In a fifteenth aspect, the present invention relates to a use of the multilayer film according to one of the preceding aspects for packaging applications, in particular food packaging.

[0033] In a sixteenth aspect, the present invention relates to a use of the multilayer film according to one of the first aspect to the fourteenth aspect as a top film and / or bottom film in a deep-drawn package.

[0034] In a seventeenth aspect, the present invention relates to a deep-drawn package comprising, as an upper film and / or a lower film, a multi-layer film according to one of the first aspect to the fourteenth aspect.

[0035] Definitions

[0036] In the present application, the following definitions are used.

[0037] The term "film" means a flexible flat or tubular structure of thermoplastic material.

[0038] The term "heat shrinkable" means a film that shrinks at least 10% in at least one of the longitudinal direction and the transverse direction when heated at 90°C for 4 seconds. The shrinkage capacity is measured according to ASTM 2732.

[0039] The term "longitudinal direction" or "machine direction", hereinafter abbreviated as "MD", means a direction in the direction of the length of the film.

[0040] The term "outer layer" means the film layer that comes into immediate contact with the external environment (the atmosphere).

[0041] The term "inner layer" means the film layer that comes into direct contact with the packaged product. This is also called the "sealing layer" since this layer must be hermetically sealed to protect the product from any air penetration.

[0042] The term "intermediate layer" means any layer of the film that is not the outer layer or the inner layer. A film may comprise several intermediate layers.

[0043] As used herein, the term "homopolymer" means a polymer resulting from the polymerization of a single monomer.

[0044] As used herein, the term "copolymer" means a polymer resulting from the polymerization of at least two different polymers.

[0045] As used herein, the term "polymer" includes both of the aforementioned types.

[0046] As used herein, the term "polyethylene" identifies polymers consisting substantially of the ethylene repeating unit. Those having a specific gravity greater than 0.940 are referred to as high-density polyethylene (HDPE) and those having a specific gravity less than 0.940 are referred to as low-density polyethylene (LDPE).

[0047] As used herein, the term "ethylene alpha-olefin copolymer" means polymers such as linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), very low density polyethylene (VLDPE), ultra-low density polyethylene (ULDPE), metallocene-catalyzed polymers, and polyethylene plastomers and elastomers.

[0048] In these cases, the alpha-olefin may be propene, butene, hexene, octene, etc., as is known in the art.

[0049] As used herein, the term "homogeneous ethylene-alpha-olefin copolymers" means ethylene-alpha-olefin copolymers having a molecular weight distribution of less than 2.7 as measured by GPC. Typical examples of such polymers are AFFINITY from DOW or Exact from Exxon.

[0050] As used herein, the term "styrene polymers" means a styrene homopolymer such as polystyrene and styrene copolymers such as styrene-butadiene copolymers, styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers, styrene-ethylene-butadiene-styrene copolymers, ethylene-styrene copolymers, and the like.

[0051] As used herein, the term "ethylene-methacrylate copolymers" means copolymers of ethylene and methacrylate monomer. The monomer content is less than 40%.

[0052] As used herein, the term "ethylene-vinyl acetate copolymer" means copolymers of ethylene and vinyl acetate, EVA being the usual abbreviation for copolymers of ethylene and vinyl acetate.

[0053] As used herein, the term "EVOH" means saponified products of ethylene and vinyl ester copolymers. The ethylene content is generally in the range of 25 to 50%.

[0054] As used herein, the term "PVDC" means a vinylidene chloride copolymer, wherein a major amount of the copolymer comprises vinylidene chloride and a minor amount of the copolymer comprises one or more monomers such as vinyl chloride and / or alkyl acrylates and methacrylates.

[0055] As used herein, the term "polyamide" means homopolymers and copolymers.

[0056] As used herein, the term "ionomer" means copolymers of acid and ethylene that have been neutralized with metals such as sodium, zinc, lithium, or the like.

[0057] The acid used is generally methacrylic or acrylic acid.

[0058] As used herein, the term "polybutylene" means homopolymers and copolymers of butene-1. Useful copolymers include ethylene mer units. An ethylene content should generally be less than 50%.

[0059] As used herein, the term "glycol-modified polyester" encompasses polyesters such as PETG, PCTG, spiroglycol-modified polyethylene terephthalate, and the like.

[0060] As used herein, the term "polypropylene" means homopolymers, copolymers, and terpolymers of propylene.

[0061] A suitable material for the invention is a PP homopolymer.

[0062] A new, more advanced category of PP homopolymer is one produced by the use of metallocene catalysts, such as Total Petrochemicals' Lumicene MR2002.

[0063] A random copolymer of propylene and ethylene is a polymer in which the ethylene content is often in the range of 0.5 to 10%, most often 1 to 5%. The ethylene α-mers are randomly distributed among the propylene α-mers.

[0064] Another category of polypropylene copolymers are propylene-ethylene-butene "terpolymers". Such polymers well known in the art are Adsyl from Lyondell Vasell.

[0065] Another category of polypropylene polymers useful for the invention are copolymers of propylene and butene.

[0066] Another category of polymers useful for the invention are copolymers of propylene and ethylene with melting points below 130°C, more preferably below 125°C, even more preferably below 120°C. Such materials are Vistamaxx from Exxon and Versify from Dow.

[0067] Another category of polymers useful for the invention are heterophasic impact copolymers, such as Inspire 137.02 from Braskem. Such materials are homopolymers modified with PP elastomers and exhibit much greater impact resistance under freezing conditions compared to unmodified homopolymers.

[0068] Other materials useful for the present invention are syndiotactic and / or atactic PPs.

[0069] Polybutene polymers can also be used, as they are very compatible with PP and can be recycled in PP recycling streams. Such materials can be a polybutene homopolymer and / or copolymers of butene and ethylene or butene and propylene.

[0070] All measurement methods mentioned herein are readily available to those skilled in the art. For example, they may be obtained from the American National Standards Institute at: www.webstore.ansi.org.

[0071] All percentages used are percentages by weight unless otherwise indicated. Detailed description of the invention

[0072] In a first aspect, the present invention relates to a multilayer film comprising an outer layer, an oxygen barrier layer, and an inner sealant layer, wherein the oxygen barrier layer is located between the outer layer and the inner sealant layer, wherein the oxygen barrier layer comprises an ethylene vinyl ester copolymer (EVOH).

[0073] The multilayer film comprises at least 90% by weight of polypropylene or polybutene polymers or copolymers, not more than 8% by weight of EVOH, and at least 25% by weight of random propylene-ethylene copolymer having a melting point in the range of 135°C to 148°C, based on the total weight of the film. In addition, the multilayer film does not include polyamide, polyester, polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC).

[0074] In one embodiment, the multilayer film comprises at least one intermediate layer between the outer layer and the oxygen shielding layer and / or between the oxygen shielding layer and the inner heat seal layer.

[0075] In another embodiment, the multilayer film comprises the following layer structure: outer layer / intermediate layer 1 / protective layer / intermediate layer 2 / inner sealing layer.

[0076] In another embodiment, the multilayer film comprises the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / intermediate layer 3 / protective layer / intermediate layer 4 / intermediate layer 5 / intermediate layer 6 / inner sealing layer.

[0077] In another embodiment, the multilayer film comprises the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / protective layer / intermediate layer 3 / intermediate layer 4 / inner sealing layer.

[0078] Outer layer

[0079] The outer layer of the film is the layer that is in contact with the atmosphere.

[0080] According to a first embodiment of the invention, the outer layer comprises a polypropylene (PP) homopolymer. Preferably, the polypropylene homopolymer has a melting point of at least 150°C, more preferably, the polypropylene homopolymer has a melting point in the range of 150°C to 170°C and even more preferably a finage index in the range of 0.2 to 20 grams as measured by ASTM DI238 (at 230°C for 10 minutes). Preferably, the polypropylene homopolymer is produced by Ziegler Nata or metallocene catalysts.

[0081] According to a second embodiment of the invention, the outer layer comprises a random propylene-ethylene copolymer. Preferably, the random propylene-ethylene copolymer has a melting point in the range of 135°C to 148°C and more preferably a fining index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

[0082] According to a third embodiment of the invention, the outer layer comprises a propylene-ethylene copolymer with less than 10% by weight of ethylene and a melting point below 130°C, more preferably below 125°C, even more preferably below 120°C.

[0083] According to another embodiment of the invention, the outer layer comprises a mixture of at least two polymers of the first, second or third embodiment mentioned above.

[0084] According to another embodiment of the invention, the outer layer comprises a mixture of polymers of the first, second and third embodiments mentioned above.

[0085] Inner layer

[0086] In the film according to the present invention, the inner heat-sealing layer may comprise a single polypropylene polymer or a mixture of different polypropylene polymers.

[0087] Preferably, the melting point of the polypropylene material in the inner heat seal layer is at least 10°C, preferably at least 20°C lower than the melting point of any polypropylene material used in any other layer of the film.

[0088] In a first preferred embodiment, the inner heat-sealing layer comprises a propylene-ethylene-butene copolymer, preferably the sum of the ethylene content and the butene content in the propylene-ethylene-butene copolymer is less than 10% by weight based on the total weight of the copolymer.

[0089] In a second preferred embodiment, the inner heat-sealing layer comprises a copolymer of propylene and butene, preferably the melting point of such a copolymer is less than 135°C, more preferably less than 130°C.

[0090] In a third preferred embodiment, the heat-sealing layer inner wall comprises a copolymer of propylene and ethylene, preferably the melting point of such a copolymer is less than 135°C, preferably less than 130°C, more preferably less than 125°C, even more preferably less than 120°C.

[0091] According to another preferred embodiment of the invention, the inner heat-sealing layer comprises a mixture of at least two polymers of the first, second or third embodiment mentioned above.

[0092] In a preferred version of the invention, the sealing layer may be a "peelable" layer, for example specially designed to facilitate opening. In this case, materials such as Borpeel™ or Steripeel™ from Borealis or special blends of PP and PE are used as known in the art.

[0093] Oxygen protection layer

[0094] The multilayer film comprises an oxygen shielding layer comprising EVOH.

[0095] The oxygen barrier layer is located in an intermediate layer of the film between the outer layer and the inner heat seal layer.

[0096] In general, EVOH with an ethylene content of between 48 and 24% by mole, more preferably 27 to 44% by mole, even more preferably 38 to 44% by mole is preferred.

[0097] Other intermediate layers

[0098] Between the sealing layer and the oxygen shielding layer, tie layers may be used. Preferred materials for the tie layer may be grades of maleic anhydride-modified PP, such as Bynel™ 50E109 from Dow or Admer™ 541E from Mitsui Chemicals, which are materials well known in the art.

[0099] Other intermediate layers may be used as resistive layers.

[0100] According to a preferred embodiment of the invention, an intermediate resistant layer comprises a polypropylene homopolymer, having a melting point in the range of 150°C to 170°C and a fining index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

[0101] According to another preferred embodiment of the invention, the intermediate resistant layer comprises a random polypropylene-ethylene copolymer, having a melting point of 135°C to 148°C and a fining index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

[0102] According to another preferred version of the invention, the intermediate resistant layer comprises a propylene-ethylene copolymer with less than 10% by weight of ethylene and preferably a melting point below 130°C, more preferably below 125°C, even more preferably below 120°C.

[0103] Other film features

[0104] Any of the aforementioned layers may also include additives well known in the art, such as anti-slip agents, anti-blocking agents, polymer processing aids, anti-static agents, anti-fog agents, acid scavengers, odor scavengers, nucleating agents, hydrocarbon resins and the like. Those skilled in the art can select suitable additives according to particular needs.

[0105] The thickness of the film is preferably in the range of 10 to 300 microns, more preferably 20 to 250 microns. The thickness of the outer layer is 1 to 50 microns, more preferably 3 to 25 microns. The thickness of the inner layer is 5 to 100 microns, more preferably 10 to 60 microns.

[0106] In another aspect of the invention, the film is irradiated or certain layers of the film are irradiated.

[0107] A preferable method is an electron beam, ultraviolet radiation, or gamma radiation. Other methods are also known in the art. Irradiation using an electron beam is preferred.

[0108] For the production of the film of the invention, the film hot blowing process is suitable, either by air cooling or by "quick quenching", for example water cooling or any other means more efficient than air cooling. The quick quenching process is preferred. A casting process is also suitable.

[0109] The multilayer film of the present invention preferably has a haze of less than 10% measured according to ASTM D 1003 and a gloss of at least 100GU (at an angle of 45°) measured according to ASTM D2457.

[0110] The present invention will be described below according to the following examples. Examples [YES] Example 1

[0112] A 9-layer film was produced in a hot-blowing film line operating with a highly efficient rapid tempering process. The multi-layer film comprises the following structure:

[0113] outer layer, masterbatch of 99% PPH1 + 1% anti-slip and anti-blocking agents, thickness of 25 microns

[0114] intermediate layer 1, 100% PPR1, 10 micron thickness

[0115] intermediate layer 2, 100% PPR1, 8 micron thickness

[0116] intermediate layer 3, 100% TIE1, 5 micron thickness

[0117] protective layer, 100% EVOHl, 4 micron thickness

[0118] intermediate layer 4, 100% TIE1, 5 micron thickness

[0119] intermediate layer 5, 100% PPPE1, 10 micron thickness

[0120] intermediate layer 6, 100% PPR1, 10 micron thickness

[0121] sealing layer, masterbatch of 70% PPB1 + 29% PPPE1 + 1% anti-slip and anti-blocking agents, thickness of 13 microns.

[0122] See table 1.

[0123] The film of Example 1 has a weight percentage of random propylene-ethylene copolymer of 30.8%, a weight percentage of EVOH of 5.71% and a weight percentage of low melting point (less than 130°C) propylene ethylene of 15%.

[0124] Example 2

[0125] A 9-layer film was produced in a hot-blowing film line operating with a highly efficient rapid tempering process. The multi-layer film comprises the following structure:

[0126] outer layer, masterbatch of 99% PPR1 + 1% anti-slip and anti-blocking agents, thickness of 45 microns

[0127] intermediate layer 1, 100% PPR1, 20 micron thickness

[0128] intermediate layer 2, 100% PPR1, 12 micron thickness

[0129] intermediate layer 3, 100% TIE1, 7 micron thickness

[0130] protective layer, 100% EVOHl, 5.5 micron thickness

[0131] intermediate layer 4, 100% TIE1, 7 micron thickness

[0132] intermediate layer 5, 100% PPPE1, 15 micron thickness

[0133] intermediate layer 6, 100% PPR1, thickness 15 microns

[0134] sealing layer, masterbatch of 70% PPB1 + 29% PPPE1 + 1% anti-slip and anti-blocking agents, thickness of 25 microns.

[0135] The film of Example 2 has a weight percentage of random propylene-ethylene copolymer of 30.8%, a weight percentage of EVOH of 4.7% and a weight percentage of low melting point (less than 130°C) propylene-ethylene of 14.5%.

[0136] Table 1 Type Description Description Manufacturer Finishing Index g / 10 min (230 °C for all resins) Density g / cm3 Melting Point °C PPH 1 Medium Molecular Weight Polypropylene Homopolymer TIPPLEN® H 659 F MOL Petrochemicals Co. L TD 1.7 0.9 Approx. 160 °C EVO H1 38 mol% Ethylene-Vinyl Alcohol Copolymer EVAL™ H 1 71B EVAL, Kurar ay 1 1.17 172 °C PPR 1 Propylene-Polypropylene Copolymer PPR 3221 TotalEnergies 1.8 0.902 142 °C random ethylene ppp El Propylene-ethylene copolymer DOW 2.2 0.885 Less than 120 °C TIE1 Maleic anhydride modified PP Bynel™ 50 E 109 DOW 3.1 0.908 125 °C PPB 1 Propylene-olefinic butene copolymer 5 0.895 131 °C

[0137] Comparative examples

[0138] A conventional upper film and a conventional lower film were produced according to the prior art.

[0139] Comparative example 1

[0140] A 9-layer film was produced in a hot-blowing film line operating with a highly efficient rapid tempering process. The multi-layer film comprises the following structure:

[0141] outer layer, masterbatch of 99% PA1 + 1% anti-slip and anti-blocking agents, thickness of 25 microns

[0142] intermediate layer 1, 100% TIE2, 10 micron thickness

[0143] intermediate layer 2, 70% PE1 + 30% PE2, thickness of 8 microns

[0144] intermediate layer 3, next layer, 100% TIE1, 5 micron thickness

[0145] protective layer, 100% EVOHl, 4 micron thickness

[0146] intermediate layer 4, 100% PA1, 5 micron thickness

[0147] intermediate layer 5, 100% TIE2, 10 micron thickness

[0148] intermediate layer 6, 70% PE1 + 30% PE2, thickness of 10 microns

[0149] sealing layer, masterbatch of 70% PE 1 + 29% PE2 + 1% agents non-slip and anti-blocking, 23 micron thickness.

[0150] See table 2.

[0151] Comparative example 2

[0152] A 9-layer film was produced in a hot-blowing film line operating with a highly efficient rapid tempering process. The multi-layer film comprises the following structure:

[0153] outer layer, masterbatch of 99% PA1 + 1% anti-slip and anti-blocking agents, thickness of 45 microns

[0154] intermediate layer 1, 100% TIE2, 20 micron thickness

[0155] intermediate layer 2, 70% PE1 + 30% PE2, thickness of 12 microns

[0156] intermediate layer 3, 100% TIE2, 7 micron thickness

[0157] protective layer, 100% EVOHl, 4 micron thickness

[0158] intermediate layer 4, 100% PA1, 7 micron thickness

[0159] intermediate layer 5, 100% TIE2, 15 micron thickness

[0160] intermediate layer 6, 70% PE1 + 30% PE2, thickness 15 microns

[0161] sealing layer, masterbatch of 70% PE 1 + 29% PE2 + 1% agents non-slip and anti-blocking, 25 micron thickness.

[0162] Table 2 Type Description Description Manufacturer Fineness index g / 10 min Density g / cm3 Melting point °C PA1 Polyamide category 6 Ultramid® B 4 0LN BASF 01.13 218 °C EVO H1 38 mol % of ethylene-vinyl alcohol copolymer EVAL™ H 17 IB EVAL, K uraray 1 1.17 172 °C TIE2 Maleic anhydri-grafted LLDPE-based bonding resin ADMER™ N F358E Mitsui Ch emicals 1.6 0.91 122 °C PE1 ETHYLENE-HEXENE COPOLYMER METAL OCENES Marlex® D13 9 CHEVRO N PHILIP S CHEMI CALS 1 0.918 Approximately 1 20 °C PE2 Low Density Polyethylene Resin DOW™ LDP E310E DOW 0.7 0.923 110 °C

[0163] Evaluation test

[0164] The following evaluation test was carried out on the films of the invention and comparative examples.

[0165] Disturbance measurement

[0166] The haze measurement is carried out according to ASTM D 1003.

[0167] Gloss measurement

[0168] Gloss measurement is performed according to ASTM D2457.

[0169] Puncture resistance

[0170] Puncture resistance is measured using a MECMESIN instrument comprising a VERSA TEST vertical stand, an AFG 100N load cell, which is mounted on the stand, and a MITUTOYO SDV 60B digital height gauge. A cylindrical shaft terminating at a conical indenter is attached to the load cell. The indenter has a 60° angle and a 0.5 mm diameter tip.

[0171] The film is conditioned at 23°C and a relative humidity of about 50% for at least 24 hours prior to measurement. Square samples of 8.5 cm by 8.5 cm are prepared and clamped onto a circular base of 5 cm diameter. The indenter moves perpendicular to the film and a force is measured as the indenter contacts the film and punctures it. The speed of the indenter is set at 25 mm / min. The maximum force required to puncture the film is recorded. The puncture force of a material is determined by calculating the average of the values ​​obtained for at least 5 samples of the material under test.

[0172] Thermoformability test

[0173] The test was carried out on a VC999 thermoforming machine.

[0174] The films of Example 1 and Comparative Example 1 were used as upper films, and respectively the films of Example 2 and Comparative Example 2 were used as lower films.

[0175] The characteristics examined were thickness uniformity of the thermoformed pouches, the ability to thermoform in a relatively wide processing window, and the ability to have sufficient heat resistance to allow effective sealing in the sealing station without "burning" the pulled film.

[0176] The combination of the top film example 1 and the bottom film example 2 was as good as the combination of the comparative films and both received a score of A.

[0177] A = good thermoformability

[0178] B = average thermoformability

[0179] C = poor thermoformability

[0180] Table 3 TROUBLE BRILLIANCE PERFORMANCE Evaluation of PUNCTURE RESISTANCE THERMOFORM AGE Example 1 6 120 A 22 Newtons Example 2 9 112 A 37 Newtons Comparative example 1 6.7 110 A 24 Newtons Comparative example 2 9.2 120 A 35 Newtons

Claims

Claims

1. A multilayer film comprising an outer layer, an oxygen shielding layer, and an inner sealing layer, wherein the oxygen shielding layer is located between the outer layer and the inner sealing layer, wherein the oxygen shielding layer comprises an ethylene vinyl ester copolymer (EVOH), and wherein the multilayer film comprises at least 90% by weight of polypropylene or polybutene polymers or copolymers, not more than 8% by weight of EVOH, and at least 25% by weight of random propylene-ethylene copolymer having a melting point in the range of 135°C to 148°C, based on the total weight of the multilayer film, and wherein the multilayer film does not comprise polyamide, polyester, polyvinyl chloride (PVC), or polyvinylidene chloride (PVDC).

2. The multilayer film of claim 1, wherein the multilayer film comprises a polypropylene homopolymer, preferably wherein the multilayer film comprises a polypropylene homopolymer in the outer layer.

3. A multilayer film according to claim 2, wherein the polypropylene homopolymer is a polypropylene homopolymer produced by Ziegler Natta or metallocene catalysts and having a melting point of at least 150°C, more preferably the polypropylene homopolymer has a melting point in the range of 150°C to 170°C and even more preferably a finage index in the range of 0.2 to 20 grams as measured by ASTM D1238 (at 230°C for 10 minutes).

4. A multilayer film according to any preceding claim, wherein the multilayer film comprises, in the outer layer, a random propylene-ethylene copolymer, preferably the random propylene-ethylene copolymer has a melting point in the range of 135°C to 148°C and more preferably a finage index in the range of 0.2 to 20 grams as measured by ASTM DI238 (at 230°C for 10 minutes).

5. A multilayer film according to any preceding claim, wherein the multilayer film comprises, in the outer layer, a propylene-ethylene copolymer with less than 10% by weight of ethylene and a melting point of less than 130°C, more preferably less than 125°C, even more preferably less than 120°C.

6. A multilayer film according to any preceding claim, wherein the multilayer film comprises at least one polypropylene polymer, preferably a blend of different polypropylene polymers, in the inner heat-sealing layer, preferably the melting point of the polypropylene material in the inner heat-sealing layer is at least 10°C lower than the melting point of any polypropylene material used in any other layer of the multilayer film.

7. A multilayer film according to claim 6, wherein the multilayer film comprises a propylene-ethylene copolymer in the inner heat-sealing layer, preferably the propylene-ethylene copolymer has a melting point below 135°C, preferably below 130°C, more preferably a melting point below 125°C, even more preferably a melting point below 120°C.

8. A multilayer film according to claim 6 or 7, wherein the multilayer film comprises at least 10% propylene-ethylene copolymer based on the total weight of the multilayer film.

9. Multilayer film according to one of the preceding claims, wherein the inner sealing layer (further) comprises a propylene-butene copolymer, preferably said copolymer has a melting point below 135°C, preferably below 130°C, more preferably a melting point below 125°C, even more preferably a melting point below 120°C.

10. A multilayer film according to any preceding claim, wherein the inner sealing layer (further) comprises a propylene-ethylene-butene copolymer, preferably the sum of the ethylene content and the butene content in the propylene-ethylene-butene copolymer is less than 10% by weight based on the total weight of the copolymer.

11. Multilayer film according to one of the preceding claims, comprising at least one intermediate layer between the outer layer and the oxygen protection layer and / or between the oxygen protection layer and the inner heat sealing layer, preferably the multilayer film comprises the following layer structure: outer layer / intermediate layer 1 / protective layer / intermediate layer 2 / inner sealing layer.

12. A multilayer film according to one of claims 1 to 10, comprising the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / intermediate layer 3 / protective layer / intermediate layer 4 / intermediate layer 5 / intermediate layer 6 / inner sealing layer, or the following layer structure: outer layer / intermediate layer 1 / intermediate layer 2 / protective layer / intermediate layer 3 / intermediate layer 4 / inner sealing layer.

13. A multilayer film according to any preceding claim, wherein the multilayer film has a haze of less than 10%, as measured according to ASTM D 1003.

14. A multilayer film according to any preceding claim, wherein the multilayer film has a gloss of at least 100GU (45° angle), as measured according to ASTM D2457.

15. Use of the multilayer film according to one of the preceding claims for packaging applications, in particular food packaging.

16. Use of the multilayer film according to one of claims 1 to 14 as top film and / or bottom film in deep-drawn packaging.

17. Deep-drawn packaging comprising, as top film and / or bottom film, a multi-layer film according to one of claims 1 to 14.