Polyethylene-based laminate film, use in packaging applications and packages obtained therefrom

Abstract

The present invention relates to a polyethylene laminate film which comprises a first, oriented and cross-linked polyethylene-based outer film, and a second, non-cross-linked polyethylene-based sealant film, having a gel content of at least 10%, measured with the method disclosed in the present application. The invention also relates to flexible containers and packages comprising such laminate film and to the use of such laminate for packaging products, especially food products.

Description

[0001] TITLE

[0002] “Polyethylene-based laminate film, use in packaging applications and packages obtained therefrom”

[0003] DESCRIPTION

[0004] Technical Field

[0005] The present invention relates to polyethylene-based laminate films and their use as lidding films and in the manufacture of flexible containers for packaging goods, particularly for the packaging of food. The laminate films of the present invention have high thermal resistance, which allows their use in several packaging applications. The invention also relates to packages manufactured with the laminate films herein disclosed.

[0006] Background Art

[0007] Laminate films have long been used as packaging materials, also for food packaging, thanks to their versatility. The main advantages of traditional laminates are thermal resistance and excellent mechanical properties such as stiffness, abuse resistance, puncture resistance etc. Laminate films are generally “multi material” structures, where different types of polymers are used in order to confer them the above stated properties. Typically, laminates have a polyester or polyamide outermost layer, which offers mechanical resistance, printing quality and heat resistance. Often, polyester and / or polyamide layers are also used as inner layers of the laminate films. In food packaging, the laminates generally also comprise one or more layers acting as a barrier to gases, especially oxygen, which causes food spoilage and / or to moisture. Furthermore, laminate films often also comprise a glue layer which adheres the two or more films which make up the whole structure.

[0008] Because of the presence of many different polymers, traditional laminate films are currently not considered recyclable.

[0009] However, nowadays there is a strong push towards the development of sustainable and ready-to- recycle packaging materials. One solution is the development of so called “mono-material” packaging films, which are made up of a percentage of a certain polymer high enough to allow recycling the film in that specific polymer recycling stream. For example, mono-PET films can be recycled in the polyester waste recycling stream, mono-PP films can be recycled in the polypropylene waste recycling stream, mono-PE films can be recycled in the polyethylene waste recycling stream, etc. Monopolyolefin films are particularly attractive, due to their ease of recyclability.

[0010] For this reason, in the latest years many efforts have been made to develop and effectively employ mono-material films in general, and even mono-material laminate films. Recyclability of glue laminate films is particularly challenging because the presence of a glue layer between the films already accounts for a certain percentage of a non-recyclable resin into the structure. Accordingly, the content of a same polymer must be maximized in the films making up the laminate, in order to obtain a “mono-material” laminate film.

[0011] As already said, mono-polyolefin films and laminate films are particularly advantageous. However, polyethylene (PE) films have poor heat resistance and mechanical properties that, for many packaging applications, are insufficient. To improve the mechanical properties of the films, PE films are typically oriented, either in a single direction (typically the “machine” or “longitudinal” direction) or in both directions (the “longitudinal” direction and the “transverse” direction).

[0012] As regards the heat resistance, the melting temperatures of the various polyethylene polymers range within a narrow interval. The consequence is that, even in multilayer films where a PE with a higher melting temperature is used as the outer skin layer and a PE with a lower melting temperature is used as the sealant layer, at the temperature needed to melt the PE of the sealing layer also the PE of the outer layer starts to melt, or at least softens. As a consequence, when the film is used to manufacture packages, the softened outer layer will stick to the sealing means, causing on one side the need to frequently stop the packaging machine and clean the sealing means (with in turn results in loss of time and additional costs) and on the other side the manufacture of defective, bad sealed packages which may be rejected due to leakages.

[0013] The problems connected with the scarce heat resistance of PE films are particularly evident with high- throughput machines such as horizontal form fill seal (HFFS) machines, vertical form fill seal (VFFS) machines, thermoform-lidding equipment or tray-lidding equipment, because of the high speed at which they work, which constantly requires operability of the sealing means. HFFS machines are particularly demanding because the longitudinal sealing bars are constantly working to form the continuous longitudinal seal of the package.

[0014] The low heat resistance of PE-based films can be improved through irradiation, (e.g. through an electron beam device). Irradiation provokes cross-linking of the polyethylene polymeric chains and thus increases heat resistance. While irradiation is a proper solution for films as such, it cannot be applied to laminate films.

[0015] WO 2023 / 249605 in the name of Amcor Flexibles North America Inc. discloses recyclable, polyethylene-based laminate films with a total gel content of less than 3% measured according to ASTM D2765-01. Such laminate films comprise an oriented coextruded film, which comprises a first region and a second region comprising antioxidants, and a third region, laminated to the second region and comprising a sealing film. The presence of antioxidants results in cross-linking being localized at the first region and the total gel content being particularly low, thus favoring recyclability. The Examples of this application do not show the process of manufacturing packages from the laminates of the invention and do not demonstrate that those laminates can actually and efficiently run on packaging machines - even less on the more demanding ones such as the high-throughput HFFS and VFFS machines - without incurring the above-mentioned drawbacks due to heat resistance.

[0016] US 2020 / 0324513 A1 in the name of Bemis Company, Inc. discloses polyethylene-based, oriented and cross-linked recyclable films with improved heat resistance properties. The films are coextruded and can be used for manufacturing flexible packages. The films of US 2020 / 0324513 A1 are not coupled to another film to form an adhesive laminate to be used for packaging applications.

[0017] US 2021 / 0291503 in the name of Bemis Company, Inc. is directed to a film comprising an oriented, annealed and irradiatively crosslinked base film comprising polyethylene, and a sealant film. Nothing is stated about the crosslinking level of the film as a whole, nor about the gel content thereof.

[0018] US 2024 / 0165940 in the name of Energy Science Inc. discloses a flexible packaging material comprising a polyethylene substrate layer and a polyethylene sealant layer adhered by an adhesive, wherein at least a portion of the substrate layer is crosslinked through electron-beam. US 2024 / 0165940 focuses on the minimum thickness of the substrate film to be irradiated, in order to reduce formation of gels. It does not teach that the material as a whole must have a certain minimum gel content percentage.

[0019] Therefore, there still remains the need for a polyethylene-based laminate film endowed with an increased heat resistance which can be effectively used for manufacturing packages, even on high- throughput machines such as HFFS, VFFS, tray-lidding machines, overcoming the issues of traditional laminates. Advantageously, the laminate film should be easy to recycle.

[0020] Summary of the Invention

[0021] When facing with the above-mentioned problems of low heat resistance of polyethylene films on packaging machines, the Applicant has surprisingly found out that an oriented, cross-linked polyethylene based outer film can be laminated to a non-cross-linked polyethylene based sealant film, thus obtaining a polyethylene based laminate film with increased heat resistance. Thanks to its heat resistance, the laminate film of the present invention can effectively be used in packaging application, even on high-throughput machines such as tray lidding, thermoform-lidding, HFFS, VFFS machines, without experiencing any sticking to the sealing means during package manufacturing. The laminate film of the invention is advantageously recyclable-ready, given its high percentage by weight of polyethylene (“mono-material laminate”).

[0022] Therefore, an object of the present invention is a recyclable-ready, polyethylene based laminate film, comprising:

[0023] - a first, oriented and cross-linked polyethylene-based outer film, and - a second, non-cross-linked polyethylene-based sealant film, wherein the polyethylene based laminate film has a gel content of at least 10%, measured with the method disclosed in the present application.

[0024] Another object of the present invention is a process for manufacturing the laminate film according to the present invention.

[0025] Another object of the present invention is a flexible container obtainable by heat-sealing the laminate according to the invention on itself, or by heat-sealing a portion of a laminate according to the invention to a portion of another film or laminate. A flexible container may be in the form of a bag or a pouch.

[0026] Another object of the present invention is a package, comprising the laminate film or the flexible container according to the invention, and a product packaged therein. The package can be a lidded package comprising a support, a product placed onto the support, and a lid made of the laminate of the present invention or a flexible package comprising the flexible container according to the invention that encloses a product.

[0027] A further object of the present invention is the use of the laminate film of the present invention for packaging products, preferably food products, preferably in lidding or flowpack (HFFS or VFFS) applications.

[0028] Definitions

[0029] The term “laminate” or “laminate film”, as used herein refers to a thermoplastic structure comprising a first film and a second film, laminated to one another by any suitable lamination technique. Lamination techniques are well known in the art and include, but are not limited to, glue lamination, thermal (or hot) lamination, extrusion-lamination, use of lamination additives.

[0030] The expression “polyethylene film” or “polyethylene-based film” as used herein relates to films comprising at least 90%, preferably at least 95% by weight of the film of polyethylene polymers.

[0031] The expression “polyethylene laminate film” or “polyethylene-based laminate film” as used herein relates to laminate films comprising at least 85%, preferably at least 90% by weight of the laminate film of polyethylene polymers.

[0032] The term “polyethylene(s)” or “polyethylene polymer(s)” as used herein refers to homopolymers or copolymers of ethylene, in which the ethylene monomer predominates. Polyethylene polymers can be linear, branched, cyclic, substituted or unsubstituted, and possibly modified.

[0033] Polyethylene homopolymers include high density polyethylene (HDPE) and low density polyethylene (LDPE). HDPE homopolymer is generally considered to have a density of greater than or equal to 0.955 g / cc and a relatively low degree of branching. LDPE is a branched homopolymer and is generally considered to have a density between 0.915 g / cc and 0.930 g / cc. Polyethylene copolymers include for example ethylene-alpha olefin copolymers and copolymers of ethylene with a comonomer which is not an olefin such as ethylene-vinyl acetate copolymers (EVA), ethylene-(meth)acrylic acid copolymers, ethylene-alkyl (meth)acrylate copolymers.

[0034] The phrase "ethylene-alpha-olefin copolymer" as used herein, refers to heterogeneous and to homogeneous polymers such as linear low density polyethylene (LLDPE) with a density usually in the range from about 0.900 g / cc to about 0.930 g / cc, linear medium density polyethylene (LMDPE) with a density usually in the range from about 0.930 g / cc to about 0.945 g / cc, and very low and ultra-low density polyethylene (VLDPE and ULDPE) with a density lower than about 0.915 g / cc, typically in the range from 0.868 to 0.915 g / cc, and such as Maleic Anhydride-Modified Ethylene / Butene Copolymer BYNELTMresins obtainable from DuPont, metallocene-catalyzed EXACTTMand EXCEEDTMhomogeneous resins obtainable from Exxon, single-site AFFINITY™ resins obtainable from Dow, and TAFMER ™ homogeneous ethylene- alpha -olefin copolymer resins obtainable from Mitsui. Ethylene- alpha-olefin copolymers may also include HDPE: HDPE copolymers generally have a density between 0.941 g / cc and 0.954 g / cc. Ethylene-alpha-olefin copolymers also encompass polyolefin plastomers (POP) which is a range of ethylene copolymers with butene or octene comonomers, manufactured with metallocene catalysts, having a density typically in the range of 0.886 to 0.912 g / cc. All these materials generally include copolymers of ethylene with one or more comonomers selected from (C4- Ci o)-alp ha-olefi n such as butene-1 , hexene-1 , octene-1 , etc., in which the molecules of the copolymers comprise long chains with relatively few side chain branches or cross-linked structures.

[0035] Polyethylene copolymers also include modified polymers, where the term "modified" is intended to refer to such polymers having an anhydride functionality grafted thereon and / or copolymerized therewith and / or blended therewith. Preferably, such modified polymers have the anhydride functionality grafted on or polymerized therewith, as opposed to merely blended therewith. As used herein, the term “modified” refers to a chemical derivative, e.g. one having any form of anhydride or carboxylic acid functionalities, such as anhydride of maleic acid, cratonic acid, citraconic acid, itaconic acid, fumaric acid, etc., whether grafted onto a polymer, copolymerized with a polymer, or blended with one or more polymers, and is also inclusive of derivatives of such functionalities, such as acids, esters, and metal salts derived therefrom.

[0036] As used herein, the term "adhered" refers to films or to layers having a principal surface directly or indirectly (via one or more additional layers between them) in contact with one another via coextrusion, extrusion coating, or lamination, e.g. via adhesive.

[0037] As used herein, films or layers which are “directly adhered” have a principal surface in direct contact with one another, without an adhesive or other layer between them. As used herein, the phrases "corona treatment" and "corona discharge treatment" refer to subjecting the outer surfaces of the film to a corona discharge treatment, i.e., the ionization of a gas such as air in close proximity to a film surface, the ionization initiated by a high voltage passed through a nearby electrode, and causing oxidation and other changes to the film surface, such as surface roughness. Corona treatment of polymeric materials is disclosed in e.g. US-A-4, 120,716.

[0038] As used herein, the phrases “longitudinal direction” and "machine direction", herein abbreviated “LD” and “MD”, respectively, refer to a direction "along the length" of the film, i.e., in the direction of the film as the film is formed during coextrusion.

[0039] As used herein, the phrase "transverse direction" or “crosswise direction”, herein abbreviated "TD", refers to a direction across the film, perpendicular to the machine or longitudinal direction.

[0040] As used herein, the term "extrusion" is used with reference to the process of forming continuous shapes by forcing a molten plastic material through a die, followed by cooling or chemical hardening. Immediately prior to extrusion through the die, the relatively high-viscosity polymeric material is fed into a rotating screw of variable pitch, i.e., an extruder, which forces the polymeric material through the die.

[0041] As used herein, the term "coextrusion" refers to the process of extruding two or more materials through a single die with two or more orifices arranged so that the extrudates merge and weld together into a laminar structure before chilling, i.e., quenching.

[0042] As used herein, the term “orientation” refers to “solid state orientation” namely to the process of stretching of the film carried out at a temperature higher than the Tg (glass transition temperatures) of all the resins making up the layers of the structure and lower than the temperature at which all the layers of the structure are in the molten state. The solid-state orientation may be mono-axial, transverse or, preferably, longitudinal, or bi-axial. As used herein, the acronym “BOPE” refers to biaxially oriented polyethylene. As used herein, the acronym “MDO-PE” refers to monoaxially oriented polyethylene, where orientation occurred in the machine direction.

[0043] As used herein the term “annealing” or “heat-setting” refers to a heat-treatment process aiming at the partial or complete removal of strains and stresses set up in the material during its forming and fabricating operations. Annealing can be typically carried out to remove or reduce the strains introduced in the material because of orientation, and is performed after the orientation step.

[0044] As used herein, the phrases "orientation ratio in the machine or longitudinal direction” and "orientation ratio in the transverse direction” refer to the number of times the film has been oriented (i.e. stretched) in that direction in relation to its original size. For example, if a film has been oriented to three times its original size in the longitudinal direction, the orientation ratio in longitudinal direction is 3:1 . The phrase "orientation ratio" refers to the multiplication product of the extent to which the film material has been oriented in the two directions. Thus, if a film has been oriented to three times its original size in the longitudinal direction (3:1) and three times its original size in the transverse direction (3:1), then the overall film has an orientation ratio of 3x3 or 9:1 .

[0045] As used herein the phrases “heat-shrinkable,” “heat-shrink,” and the like, refer to the tendency of the solid-state oriented film to shrink upon the application of heat, i.e., to contract upon being heated, such that the size of the film decreases while the film is in an unrestrained state. The heat shrink behavior of an unrestrained film, is herein referred to as “free shrink”. Free shrink is measured in accordance to ASTM D 2732.

[0046] As used herein, the term “tray lidding” refers to a packaging application in which a lid is sealed onto or around a container (e.g. a tray) which hosts a product, generally onto a circumferential flange, thus air tightly enclosing the product and the inner atmosphere. As used herein, the term “lidding (laminate) film” or “lidding laminate” refers to a laminate that closes the opening of a container and / or encloses a product contained in a container.

[0047] As used herein the term “flexible container” refers to a container obtainable by heat-sealing a single piece of laminate film in the form of e.g. an envelope, a bag, a pouch, a wrapped package, or by heat sealing a laminate to another, identical or different laminate or to a film. Bags or pouches include, for example lay flat pouches made by heat sealing two flat (laminate) films to one another, the pouch having an open top, a first side seal, a second side seal and a bottom seal. Flexible containers encompass the wrapped packages that can be made on form-fill-seal machines such as a Horizontal Form-Fill-Seal (HFFS) or Vertical Form-Fill-Seal (VFFS) machines.

[0048] As used herein the term “cross-linking” refers to the chemical reaction resulting in the formation of bonds between polymer chains, typically but not exclusively, carbon-carbon bonds. Cross-linking may be obtained through chemical agents such as peroxides or silanes (chemical crosslinking) or through ionizing radiation such as high-energy electron beam, gamma rays, beta particles (physical crosslinking).

[0049] As used herein, the term "gel content" refers to the content of gel material in a thermoplastic film or laminate formed because of cross-linking within the polymeric material. Gel content is expressed as a relative percent (by weight) of the polymer which - having formed insoluble carbon-carbon bonds between polymer chains due to cross-linking - is in a gel form. Gel content may be determined by ASTM D-2765-01 Test Method, which is incorporated herein by reference in its entirety or by the method described in the experimental section of the present application.

[0050] As used herein the phrases “recyclable”, “suitable for recycling”, “recycle-ready” and similar refer to the capability of a material to be processed in a recycling process that accepts “mono-PE” materials. ASTM International has developed a Resin Identification Coding System (RIC), which assigns a numerical code to plastic items, identifying which type of plastic polymers it is made of. The numerical code is generally marked on the plastic item, inside a triangle. For example, code "1" stands for polyethylene terephthalate (PET) made articles, code "4" stands for low-density polyethylene (LDPE) made articles, code "5" stands for polypropylene (PP) made articles, and so on. Articles which are substantially mono-materials (most commonly PET articles such as water and soft drinks bottles, trays, containers, PE articles such as shopping bags and various containers, PP articles such as disposable dishware), can be easily recycled in dedicated recycle streams, namely the RIC 1 stream, the RIC 4 stream, the RIC 5 stream. The total composition by weight of materials defines the recyclability of the packaging materials. Typically, recycling processes for a certain polymer may accept low percentages by weight of contaminant polymers (i.e. polymers other from the polymerto which the recycling process is dedicated). The recyclability standards for plastic materials are defined by either regional or international associations, e.g. APS (Association of Plastic Recycling), CEFLEX (Circular Economy for FLEXible packaging) or RecyClass.

[0051] As used herein, the phrase "inner layer" in connection with a multilayer film or laminate refers to a layer having both its principal surfaces directly adhered to other layers of the film or laminate.

[0052] As used herein, the phrase "outer layer" in connection with a multilayer film or laminate refers to a layer having only one of its principal surfaces directly adhered to another layer of the film or laminate. As used herein the phrase “outer film”, in connection with a laminate, refers to the film that, in the final package made with the laminate, will be in contact with the environment.

[0053] As used herein the phrase “inner film” or “sealant film”, in connection with a laminate, refers to the film that, in the final package made with the laminate, will be in contact with or face the packaged product, and is sealed to itself or onto a container.

[0054] As used herein, the term "tie layer" refers to any inner layer of a multilayer film having the primary function of adhering two layers to one another.

[0055] As used herein, the term “bulk layer” or "structural layer” refers to a layer of a multilayer film generally used to improve the abuse or puncture resistance of a film or just to provide the desired thickness.

[0056] As used herein, the term “barrier” or “gas barrier” when referred to a layer, to a resin contained in said layer, or to a film, refers to the property of the layer, resin or film to limit to a certain extent the passage of gases, preferably of oxygen, through itself. A barrier layer typically results in an Oxygen Transmission Rate through the barrier film (evaluated at 23°C and 0 % R.H. according to ASTM D- 3985) of less than 500 cc / sqm.day.atm.

[0057] Thermoplastic materials that provide gas-barrier properties are, e.g., polyvinylidene chloride (PVDC), polyamides, ethylene vinyl alcohol (EVOH), polyesters, and blends thereof. EVOH is generally preferred for sustainability reasons. EVOH includes saponified or hydrolyzed ethylene-vinyl acetate copolymers, and refers to vinyl alcohol copolymers having an ethylene comonomer content preferably comprised from about 25 to about 48 mole%, more preferably, from about 32 to about 44 mole% ethylene, and even more preferably, from about 38 to about 44 mole% ethylene, and a saponification degree of at least 85%, preferably at least 90%.

[0058] Detailed description of invention

[0059] In one aspect, the present invention is directed to a polyethylene-based laminate film comprising a first, oriented and cross-linked, polyethylene-based film, laminated to a second, non-cross-linked, polyethylene-based film, wherein the polyethylene based laminate film has a gel content of at least 10%, measured with the method disclosed in the present application.

[0060] The first oriented and cross-linked film of the laminate (“first film”) is the outer film of the laminate, i.e. the film that, in the final package, will be in contact with the environment. Accordingly, it is also called “outer film”.

[0061] The second, non-cross-linked film of the laminate (“second film”) is the inner (or sealant) film of the laminate, i.e. the film that, in the final package, will be in contact with or face the product, and that is sealed to itself or onto a container to form a package. Accordingly, it is also called “sealant film”. FIRST FILM

[0062] The first, outer, oriented and cross-linked polyethylene film comprises at least one polyethylene layer. The first polyethylene film may have any desired number of layers, typically from 1 to 10 layers, from 1 to 8 layers, from 1 to 5 layers, from 1 to 3 layers.

[0063] The total thickness of the first polyethylene film may vary within wide limits. It is preferably from 5 to 80 micron, preferably from 8 to 60 micron, more preferably from 15 to 40 micron, even more preferably from 20 to 35 micron. In some embodiments, the total thickness of the first polyethylene film can be lower than 40 micron, than 35 micron, than 30 micron. In some preferred embodiments, the total thickness of the first polyethylene film can be at least 5, at least 10, at least 15 micron.

[0064] The total thickness of the first polyethylene film is preferably between 30% and 70% of the total thickness of the laminate film, preferably between 35% and 65%, more preferably between 40% and 60%.

[0065] The first polyethylene film comprises at least 90%, more preferably at least 95% by weight in respect of the total weight of the first film of one or more polyethylene polymers. In some embodiments, the first polyethylene film may comprise at least 98% by weight in respect of the total weight of the first film of one or more polyethylene polymers. The first polyethylene film may also consist of polyethylene polymers.

[0066] For sustainability issues, said one or more polyethylene polymers are suitably selected among polyethylene homopolymers, ethylene-alpha olefin copolymers, blends and combinations thereof. While a “blend” is meant as a mixture of polymers in the same layer, a “combination” may refer to the presence of said one or more polyethylene polymers in different layers of a multilayer film.

[0067] Polyethylene copolymers other than ethylene-alpha olefin copolymers (i.e. copolymers such as EVA, ethylene-(meth)acrylic acid copolymers, ethylene-alkyl (meth)acrylate copolymers, etc.) should preferably be present in the first film in a total amount lower than 5 wt% in respect to the weight of the first film, preferably lower than 2 wt%.

[0068] For example, the first polyethylene film may comprise at least 90%, at least 95%, or at least 98% by weight in respect of the total weight of the first film of at least one polyethylene homopolymer, preferably HDPE or LDPE.

[0069] In other embodiments, the first polyethylene film may comprise at least 90%, at least 95% or at least 98% by weight in respect of the total weight of the first film of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0070] Also, the first polyethylene film may comprise at least 90%, at least 95% or at least 98% by weight in respect of the total weight of the first film of blends of combinations of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE

[0071] In embodiments, the first polyethylene film can be a monolayer film.

[0072] In other embodiments, the first polyethylene film can be a multilayer film.

[0073] The first polyethylene film can be a barrier film. In some embodiments, the multilayer first polyethylene film comprises a barrier layer (barrier multilayer first film). In other embodiment, the multilayer first polyethylene film does not comprise a barrier layer (non-barrier multilayer first film).

[0074] When the first polyethylene film is a monolayer film, or a non-barrier multilayer film, it can typically comprise at least 95%, preferably at least 98% by weight in respect of the total weight of the first film of one or more polyethylene polymers, as described above. In embodiments, such monolayer film or such non-barrier multilayer film can consist of one or more polyethylene polymers as described above. In embodiments, said one or more polyethylene polymers can be polyethylene homopolymers, preferably HDPE or LDPE. Said one or more polyethylene polymers can also be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE.

[0075] The first monolayer film or the first non-barrier multilayer film may also comprise at least 95% preferably at least 98% by weight in respect of the total weight of the first film of a blend or a combination of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. In embodiments, the first monolayer film or the first non-barrier multilayer film can consist of a blend or a combination of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. For example, a monolayer first film can suitably consist of a blend of LDPE and LLDPE and / or VLDPE.

[0076] The first non-barrier multilayer film can comprise more than one layer, typically 2, or 3 layers, wherein each layer independently comprises or consists of one or more polyethylene polymers as described above. The layer that in the package made with the final laminate will face the environment is indicated as the outer layer, the layer that will be laminated to the second, sealant film to form the final laminate is indicated as internal layer.

[0077] Each layer of the first non-barrier multilayer film can independently comprise or consist of at least one polyethylene homopolymer, preferably HDPE or LDPE, or at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer. Preferably, such blend can comprise or consist of LDPE and LLDPE and / or VLDPE.

[0078] BOPE films (biaxially oriented polyethylene films) or MDO-PE films (oriented in MD only) are commercially available on the market and can be used as the PE first film in the laminate of the invention. An example is the film marketed by Kraus Folie under the tradename MDOPE 100UEX, which consists of LLDPE and LDPE. MDOPE 10OUEX is oriented in the machine direction only.

[0079] It is noted that bi-oriented PE films and mono-oriented PE films (including MDOPE 100UEX) are generally marketed as non-cross-linked film, therefore they need to undergo cross-linking, preferably by irradiation, as described in detail below, before they can be used as the first outer film in the laminate of the invention.

[0080] When the first polyethylene film is a barrier multilayer first film which comprises a barrier layer, it can typically comprise at least 90%, preferably at least 95% by weight in respect of the total weight of the first film of one or more polyethylene polymers, as described above.

[0081] Typically, a barrier multilayer first film may have a number of layers comprised between 3 and 9. Generally a barrier multilayer first film may comprise a polyethylene outer layer, a barrier layer, and a polyethylene internal layer. The outer layer is the one that, in the final laminate, will be in contact with the environment. The internal layer is the one that is laminated to the second, sealant film to form the final laminate. In some embodiments, one or more bulk (structural) layers can be positioned between the outer layer and the barrier layer and / or between the barrier layer and the internal layer. Typically, to improve adhesion of the barrier layer to the adjacent layers, tie layers can be positioned between the barrier layer and the outer layer (or, if present, a bulk layer) and between the barrier layer and the internal layer (or, if present, a bulk layer).

[0082] The barrier multilayer first film generally comprises at least a barrier layer. Typically, barrier layers can comprise one or more polymers such as polyvinylidene chloride (PVDC), polyamides, ethylene vinyl alcohol (EVOH), polyesters, and blends thereof, which are capable of reducing the film permeability to gases. PVDC and polyesters are presently less preferred because of recyclability issues. EVOH and polyamides, in particular polyamide 6 and polyamide 6,6, are generally preferred for sustainability issues. In particular, EVOH is the most preferred polymer and, preferably, it is used as the only component of the barrier layer.

[0083] Examples of suitable resins for the barrier layer of the barrier multilayer first film are SOARNOL AT4403, or SOARNOL ET3803 or SOARNOL GH3804B (Nippon Gohsei), Eval E171 B, (EVALCA / Kuraray), EVAL F101 B (EVALCA / Kuraray), ET3803RB (Mitsubishi Chemical Corporation). The at least one barrier layer may have a thickness in a range from 0.5 micron to 15 micron. In some embodiments, the at least one barrier layer may have a thickness in a range from 1 micron to 10 microns. In further embodiments, the at least one barrier layer may have a thickness in a range from 1.5 micron to 8 microns. In some embodiments, the barrier multilayer first film may have one only barrier layer.

[0084] The total thickness of the barrier layer(s) in relative percentage vs. the thickness of the whole barrier multilayer first film can range from 5 to 12%, preferably from 6% to 10%, more preferably about 8%. The barrier layer comprises barrier polymer(s), preferably EVOH, in a total amount not higher than 10 wt% in respect of the total weight of the barrier multilayer first film, preferably not higher than 8 wt%, more preferably not higher than 5 wt%.

[0085] The barrier multilayer first film also comprises a polyethylene outer layer.

[0086] The polyethylene outer layer may comprise at least 90%, preferably at least 95%, more preferably at least 98% by weight in respect of the total weight of the outer layer of polyethylene polymers, as described previously. In a preferred embodiment, such polyethylene polymers can be polyethylene homopolymers, preferably HDPE or LDPE. In another preferred embodiment, such polyethylene polymers can be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE. In another preferred embodiment, such polyethylene polymers can be a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. In embodiments, the polyethylene outer layer can consist of a polyethylene homopolymer, preferably HDPE or LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0087] Examples of suitable resins for the outer layer of the barrier multilayer first film are Eltex PF6220AA (INEOS Olefins & polymers Europe), Exceed 2018MA (ExxonMobil), AF5841 LL (Tosaf), DOWLEX 2045.04 or DOWLEX 2037 (both by Dow), EF437AA (Westlake Chemical). The polyethylene outer layer may have a thickness in a range from 2 micron to 20 micron. In some embodiments, the outer layer may have a thickness in a range from 3 micron to 10 micron. In further embodiments, the outer layer may have a thickness of about 5 micron.

[0088] The thickness of the outer layer in relative percentage vs. the thickness of the whole barrier multilayer first film can range from 10 to 35%, preferably from 18% to 28%, more preferably from 22% to 26%. The barrier multilayer first film also comprises a polyethylene internal layer. The polyethylene internal layer of the first film is an outer layer of the barrier multilayer first film, as in such film it has only one of its principal surfaces directly adhered to another layer of said film, but it is an inner layer when considering the final laminate of the invention, being the one which is laminated to the second sealant film to form the final laminate film.

[0089] The resin composition of the polyethylene internal layer may be the same as the polyethylene outer layer, or may be different. In embodiments, the polyethylene internal layer may have the same composition as the polyethylene outer layer.

[0090] The polyethylene internal layer may comprise at least 90%, preferably at least 95%, more preferably at least 98% by weight in respect of the total weight of the internal layer of polyethylene polymers. In a preferred embodiment, such polyethylene polymers can be polyethylene homopolymers, preferably HDPE or LDPE. In another preferred embodiment, such polyethylene polymers can be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE. In another preferred embodiment, such polyethylene polymers can be a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. In embodiments, the polyethylene internal layer can consist of a polyethylene homopolymer, preferably HDPE or LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0091] Examples of suitable resins for the internal layer of the barrier multilayer first film are Eltex PF6220AA (INEOS Olefins & polymers Europe), Exceed 2018MA (ExxonMobil), AF5841 LL (Tosaf), DOWLEX 2045.04 or DOWLEX 2037 (both by Dow), EF437AA (Westlake Chemical).

[0092] The polyethylene internal layer may have a thickness in a range from 2 micron to 20 micron. In some embodiments, the internal layer may have a thickness in a range from 3 micron to 10 micron. In further embodiments, the internal layer may have a thickness of about 5 micron.

[0093] The thickness of the internal layer in relative percentage vs. the thickness of the whole barrier multilayer first film can range from 10 to 35%, preferably from 18% to 28%, more preferably from 22% to 26%.

[0094] Optionally, one or more bulk (or structural) layers may be present in the barrier multilayer first film. The main role of bulk layers is to improve the mechanical resistance of the film (e.g. abuse or puncture resistance) and / or to provide the desired thickness thereof.

[0095] The resin composition of the bulk layer may be the same as the polyethylene outer layer and / or of the polyethylene internal layer, or may be different.

[0096] Each bulk layer may independently comprise at least 90%, preferably at least 95% more preferably at least 98% by weight in respect of the total weight of the internal layer of polyethylene polymers, as described above. In a preferred embodiment, such polyethylene polymers can be polyethylene homopolymers, preferably HDPE or LDPE. In another preferred embodiment, such polyethylene polymers can be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE. In another preferred embodiment, such polyethylene polymers can be a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0097] Preferably, each bulk layer can independently consist of a polyethylene homopolymer, preferably HDPE or LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0098] Examples of suitable resins for the bulk layer of the barrier multilayer first film are Eltex PF6220AA (INEOS Olefins & polymers Europe), Exceed 2018MA (ExxonMobil), DOWLEX 2045.04 or DOWLEX 2037 (both by Dow), EF437AA (Westlake Chemical).

[0099] Each bulk layer may independently have a thickness in a range from 0.5 micron to 20 micron. In some embodiments, such thickness may be in a range from 1 micron to 10 micron. In further embodiments, such thickness may be in a range from 1 .5 micron to 6 micron.

[0100] The thickness of each bulk layer in relative percentage vs. the thickness of the whole barrier multilayer first film can range from 4 to 30%, preferably from 6% to 20%, more preferably from 8% to 15%. Furthermore, the barrier multilayer first film may comprise one or more tie layer, whose purpose is to improve the adhesion between adjacent layers. The one or more tie layers may comprise adhesive polymers that are employed to better adhere one layer to another in the overall structure of the barrier multilayer first film.

[0101] Typically, tie layers are used to improve the adhesion of the barrier layer to the layers adjacent to it, either the polyethylene outer layer and the polyethylene internal layer, or the bulk layers.

[0102] In particular, a tie layer may directly adhere to one or, preferably, both sides of the barrier layer and to the outer layer (or, if present, to a bulk layer), and / or to the internal layer (or, if present, to a bulk layer). Additional tie layers may also be positioned between the bulk layer(s), if present, and the adjacent polyethylene outer layer and / or the adjacent polyethylene internal layer. In preferred embodiments, the first film may have two tie layers, each one directly adhered to a side of the barrier layer and to a bulk layer, thus resulting in the following preferred structure for the barrier multilayer first film: PE outer layer / bulk / tie / barrier / tie / bulk / PE internal layer.

[0103] Tie layers may include polyethylene polymers having grafted polar groups which are capable of covalently bonding to polar polymers such as EVOH. Suitable polymers for tie layers include ethylene- unsaturated acid copolymers, ethylene-unsaturated ester copolymers, anhydride-modified polyethylenes, and mixtures thereof. Examples of ethylene-unsaturated acid copolymers include ethylene-(meth)acrylic acid copolymers. Examples of ethylene-unsaturated ester copolymers include ethylene-vinyl acetate copolymers with high vinyl acetate content (e.g. 18- 28 wt% or even more). Examples of anhydride-modified polyethylenes include ethylene homopolymers or co-polymers, modified with anhydride or carboxylic acid functionalities. For sustainability reasons, preferred polymers for tie layers include ethylene homo-polymers or ethylene alpha olefin copolymers modified with anhydride or carboxylic acid functionalities and blends thereof.

[0104] Examples of suitable tie resins are ADMER™ NF358E ADMER™ SF730E, ADMER™ NF927E and ADMER™ NF518E (Mitsui Chemical), OREVAC 18303 and OREVAC 18300 (Arkema).

[0105] Tie layers are typically of a sufficient thickness to provide the adherence function, as is known in the art. Each tie layer may be of a substantially similar or of a different composition and / or thickness.

[0106] Each of the one or more tie layers may have a thickness in the range from 1 micron to 20 micron. In some embodiments, each tie layer may have a thickness in the range from 1 .5 micron to 10 micron. In other embodiments, each tie layer may have a thickness in the range from 2 micron to 6 micron. Exemplary layer structures for the barrier multilayer first film are the following:

[0107] - PE outer layer / barrier / PE internal layer

[0108] - PE outer layer / tie / barrier / tie / PE internal layer

[0109] - PE outer layer / bulk / barrier / bulk / PE internal layer

[0110] - PE outer layer / bulk / tie / barrier / tie / bulk / PE internal layer

[0111] - PE outer layer / tie / bulk / tie / barrier / tie / bulk / tie / PE internal layer

[0112] - PE outer layer / bulk / bulk / tie / barrier / tie / bulk / bulk / PE internal layer

[0113] - PE outer layer / tie / bulk / bulk / tie / barrier / tie / bulk / bulk / tie / PE internal layer

[0114] Suitable barrier multilayer films for use as first film in the laminate of the invention are for example those marketed by Cryovac as BDF®S10, BDF®20M, BDF®28M.

[0115] The monolayer first film, or one or more of the layers of the multilayer first film may include appropriate amounts of additives typically included in thermoplastic films for food packaging for the desired effect, as it is known to the person skilled in the packaging art. For instance, a layer may include additives such as slip agents, anti-blocking agents, antioxidants, fillers, dyes and pigments, oxygen scavengers, antistatic agents, and the like agents. In particular, as the laminate of the invention is particularly conceived for use on high-speed packaging equipment, in order to improve the machinability and the processing, slip and / or anti-blocking additives may be added into the monolayer first film or into the outer layer of the multilayer first film and optionally also into the internal layer. These additives may advantageously be added in the form of a concentrate in a polyethylene carrier resin, thus forming a masterbatch. The total amount of additives is typically in the order of 0.2 to 5% by weight of the total weight of the layer in which they are comprised.

[0116] The polyethylene first film of the laminate of the invention is typically oriented. Orientation is a process by which the film is heated at a temperature higher than the Tg (glass transition temperatures) of all the resins making up the layers of the structure and lower than the temperature at which all the layers of the structure are in the molten state, and stretched.

[0117] Orientation provides the film with increased mechanical properties. It may be carried out by means known in the art, after extrusion of the film. In particular, if the film is manufactured by flat co-extrusion, mono- or bi-orientation may be performed by flat, sequential or simultaneous tenterframe orientation. If the film is manufactured by round coextrusion, e.g. on double or triple bubble lines, mono- or biorientation may be performed by trapped bubble orientation or, alternatively, mono-orientation in the machine direction may be performed by a standard MDO unit, wherein the film is stretched longitudinally passing through a series of stretching rolls.

[0118] In some embodiments, the polyethylene outer first film is oriented in both the longitudinal and the transverse directions (bi-axial orientation). In some embodiments, the polyethylene first film is oriented in one direction only (mono-axial orientation), preferably in the longitudinal (or machine) direction.

[0119] Typical orientation ratios for the polyethylene outer first film of the laminate of the invention in the longitudinal direction can be higher than 2:1 , preferably higher than 3:1. Typical orientation ratios in the transverse direction can be higher than 2:1 , preferably higher than 3:1. When the outer first film is oriented in the machine direction only, the orientation ratio may be higher than 4:1 , and typically it is of 5:1.

[0120] It is well known in the art that upon orientation, thermoplastic films become shrinkable, i.e. they acquire the capability to recover the (smaller) size they originally had before being stretched, upon the application of heat, in a process known as thermoretraction, or shrinking.

[0121] In the present invention, the oriented first film is part of a laminated film, which also includes a typically non-oriented film and, in certain embodiments, a glue layer. Therefore, shrinking of the oriented first film is not desirable.

[0122] One approach to reduce or remove the tendency of an oriented film to shrink is to anneal (or heat-set) the film. Annealing is a controlled heating-cooling treatment, that is aimed at modulating the shrink properties of the resulting film and at having a better control on the low temperature dimensional stability of the film by removing its internal tensions.

[0123] Therefore, in some embodiments the oriented first film is annealed. Annealing may be carried out by means known in the art, after extrusion and orientation of the film. For example, if the film is manufactured by flat co-extrusion and machine-directionally oriented by flat orientation (e.g. a MDO film), annealing may be performed through a series of so-called annealing rolls, positioned within the MDO unit just after the stretching rolls and typically heated at temperatures comprised between 70 and 130°C. The contact of the mono-oriented film with such annealing rolls removes most of the tendency of the film to shrink. If the film is manufactured by flat co-extrusion and bi-directionally oriented by flat orientation (e.g. a BOPE film), annealing may be performed typically through a simultaneous or sequential tenterframe process. If the film is manufactured by round coextrusion and oriented by trapped bubble orientation in a double bubble process, annealing may be performed passing the film onto a series of annealing rolls, typically heated at temperatures comprised between 65 and 80°C. If the film is manufactured by round coextrusion and oriented by trapped bubble orientation in a triple bubble process, annealing occurs in the so-called third bubble. The annealing step can be carried out by heating the film at temperatures comprised e.g. between 90 and 140°C. The skilled person can easily determine the conditions of the annealing process necessary to reduce the internal tensions in the oriented first film to such a level that no shrink occurs when the laminate is used on packaging equipment. Typically, commercially available BOPE or MDO-PE films are annealed.

[0124] In some embodiments, the oriented first film can also be non-annealed. Preferably, this can be the case if the percentage ratio between the thickness of the first oriented film and the total thickness of the laminate is lower than 60%, preferably lower than 55%, more preferably lower than 50% or of 45%. With such thickness ratio, the oriented first film is sufficiently thin in respect to the whole laminate that it does not tend to shrink when the laminate is used on packaging equipment.

[0125] The polyethylene outer first film of the laminate of the invention is cross-linked.

[0126] In the present invention, preferably the polyethylene first film is crosslinked after orientation.

[0127] As used herein, the term cross-linked means that at least a part of the polyethylene first film is crosslinked. In embodiments, the polyethylene first film is irradiated through all its layers, and all layers of the films are cross-linked. In other embodiments, only some layers of the polyethylene first film are irradiated; in this case, the outer layer of the first outer film is irradiated.

[0128] Preferably, the polyethylene first film is crosslinked after orientation and is irradiated through all its layers.

[0129] Cross-linking may be imparted chemically or physically as described herein after. Cross-linking of one or more layers or of the polyethylene first film may be assessed by measuring the gel content as explained in the present application.

[0130] The polyethylene first film is cross-linked to such a level that the whole first film - if before cross-linking all the polymers making the first film are toluene-soluble - or at least the part of the film made of polymers which before cross-linking are toluene-soluble, has a gel content of not less than 20%, measured in accordance with the internal test method described in the Experimental Part. In embodiments, such gel content can be not less than 25%, not less than 30% or not less than 40%, For sustainability reasons, the gel content should be not higher than 60%, preferably not higher than 50%.

[0131] The above indicated levels of cross-linking for the first polyethylene film result in a gel content for the whole laminate film of at least 10%.

[0132] As used herein, the term “soluble in toluene” or “toluene-soluble” refers to a solubility of at least 1 .25 g / l at the boiling temperature of toluene (about 110°C, at standard pressure of 1 atm, measured after boiling the sample in toluene for 30 minutes).

[0133] The polyethylene first film can be crosslinked by any chemical or low or high radiation method or combination thereof.

[0134] The preferred method of crosslinking is by electron-beam irradiation, which is well known in the art. One skilled in the art can readily determine the radiation exposure level suitable for obtaining a gel content level in the above-disclosed ranges. Generally, radiation dosages of up to about 120 kGy can be applied. For favoring recyclability of the final laminate, radiation dosages can preferably be lower than 100 kGy, lower than 80 kGy, lower than 70 kGy. In some embodiments, radiation dosages can be comprised between 40 and 80 kGy, preferably between 45 and 70 kGy.

[0135] SECOND FILM

[0136] The laminate film of the present invention comprises a second, non-cross-linked polyethylene film (“second film”), which is laminated to the first, oriented and cross-linked outer film and, in the final package, will be in contact with or face the packaged product. For this reason, being on the inner, sealing side of the laminate, the second polyethylene film will also be indicated as “sealant film”.

[0137] The second polyethylene film comprises at least one polyethylene layer. The second polyethylene film may have any desired number of layers, typically from 1 to 10 layers, from 1 to 8 layers, from 1 to 5 layers, from 1 to 3 layers.

[0138] The total thickness of the second polyethylene film may vary within wide limits. It is preferably from 5 to 80 micron, preferably from 8 to 60 micron, more preferably from 15 to 40 micron, even more preferably from 20 to 35 micron. In some embodiments, the total thickness of the second polyethylene film can be lower than 40 micron, than 35 micron, than 30 micron. In some preferred embodiments, the total thickness of the second polyethylene film can be at least 5, at least 10, at least 15 micron. The total thickness of the second polyethylene film is preferably between 30% and 70% of the total thickness of the laminate film, preferably between 35% and 65%, more preferably between 40% and 60%.

[0139] The second polyethylene film comprises at least 90%, preferably at least 95% by weight in respect of the total weight of the second film of one or more polyethylene polymers. In some embodiments, the second polyethylene film may comprise at least 98% by weight in respect of the total weight of the second film of one or more polyethylene polymers, or it may also consist of polyethylene polymers. For sustainability issues, said one or more polyethylene polymers are suitably selected among polyethylene homopolymers, ethylene-alpha olefin copolymers, blends and combinations thereof. While a “blend” is meant as a mixture of polymers in the same layer, a “combination” may refer to the presence of said one or more polyethylene polymers in different layers of a multilayer film. Polyethylene copolymers other than ethylene-alpha olefin (such as EVA, ethylene-(meth)acrylic acid copolymers, ethylene-alkyl (meth)acrylate copolymers), should preferably be present in the second film in a total amount lower than 5 wt% in respect to the weight of the second film, preferably lower than 2 wt%.

[0140] For example, the second polyethylene film may comprise at least 90%, at least 95%, or at least 98% by weight in respect of the total weight of the second film of at least one polyethylene homopolymer, preferably LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of blends or combinations of at least one polyethylene homopolymer, preferably LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0141] In embodiments, the second polyethylene film can be a monolayer film.

[0142] In other embodiments, the second polyethylene film can be a multilayer film.

[0143] The second polyethylene film can be a barrier film. The multilayer second polyethylene film can comprise a barrier layer (barrier multilayer second film). Alternatively, the multilayer second polyethylene film does not comprise a barrier layer (non-barrier multilayer second film).

[0144] Preferably, the second polyethylene film can advantageously comprise one or more antifog agents, so that a final laminate endowed with antifog properties is obtained.

[0145] Antifog packaging materials are particularly useful for packaging moisture producing or respiring food products. In the presence of the antifog agent, the moisture coming from the packaged products condensates on the surface of the film facing the product and forms a uniform layer or few very large uniform areas. Therefore, no fog appears on the surface of the film, resulting in good see-through properties and in the possibility to visually inspect the packaged product. In embodiments, the antifog agent(s) can be applied to the external surface of the second polyethylene film (i.e. the surface that is not laminated to the first, outer film) in the form of a coating. Antifog coatings are well known in the art and can be applied in various ways (spraying, rotogravure, etc) with or without previously treating the surface by corona treatment.

[0146] In another, preferred, embodiment, the antifog agent(s) is coextruded in the (only) layer of the second polyethylene film, when the second polyethylene film is a monolayer film, or at least in the heat sealant layer of the second polyethylene film when the second polyethylene film is a multilayer film. In a multilayer second polyethylene film, the heat sealant layer is the one that is in contact with or faces the product in the package made with the final laminate film, and is opposite the layer that is laminated to the first, outer film. In some embodiments, when the second film is a multilayer film, also the layer directly adhered to the sealant layer can comprise antifog agent(s).

[0147] The total amount of antifog agent(s) is typically comprised between 0.1 wt% and 10 wt% with respect to the weight of the layer in they are comprised, preferably between 0.2 wt% and 6 wt%, more preferably between 0.3% and 4 wt%.

[0148] Antifog agents are known in the art and mainly fall into classes such as: esters of aliphatic alcohols, polyethers, polyhydric alcohols, esters of polyhydric aliphatic alcohols, poly-ethoxylated aromatic alcohols, polyhydric alcohol fatty acid esters, hydrophilic fatty acid esters, polyethoxylated aromatic alcohols, nonionic ethoxylates, 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. Examples of antifog agents are polyoxyethylene, sorbitan monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene monopalmitate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitantrioleate, poly(oxypropylene), polyethoxylated fatty alcohols, polyoxyethylated 4-nonylphenol, polyhydric alcohol, propylene diol, propylene triol, ethylene diol, monoglyceride esters of vegetable oil or animal fat, mono- and / or diglycerides such as glycerol mono- and dioleate, glyceryl stearate, monophenyl polyethoxylated, sorbitan monolaurate, and the like.

[0149] Other examples of antifog agents are ethoxylated sorbitan derivatives with higher fatty acids such as those marketed under the trade name of Tweens or polysorbates, preferably with fatty acids from C14 to C24, for example Atmer 116 commercialized by Croda.

[0150] The antifog agent(s) can be mixed with (a) polyethylene polymer(s) to form a masterbatch to be supplied to the extruder, the polyethylene polymer(s) working as the carrier resin for the antifog agent(s).

[0151] For example, AF5841 LL 1 .5 Percent Sylobloc 47 As AB from Tosaf, wherein the carrier resin is LLDPE, may be used as a suitable antifog masterbatch. When the second polyethylene film is a monolayer film, or a non-barrier multilayer film, it can typically comprise at least 95%, preferably at least 98% by weight in respect of the total weight of the second film of one or more polyethylene polymers as described above. In embodiments, such monolayer film or such non-barrier multilayer film can consist of one or more polyethylene polymers as described above.

[0152] Said one or more polyethylene polymers can be polyethylene homopolymers, preferably LDPE. The one or more polyethylene polymers can also be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE.

[0153] The monolayer second film or the non-barrier multilayer second film may also comprise at least 95%, preferably at least 98% by weight in respect of the total weight of the second film of a blend or a combination of at least one polyethylene homopolymer, preferably LDPE and at least one ethylenealpha olefin copolymer, preferably LLDPE or VLDPE. In embodiments, the second monolayer film or the second non-barrier multilayer film can consist of a blend or a combination of at least one polyethylene homopolymer, preferably LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. A monolayer second film can consist of a blend of LDPE and LLDPE and / or VLDPE.

[0154] Preferably, the monolayer second film can comprise one or more antifog agent(s) as described above. The second non-barrier multilayer film can comprise more than one layer, typically 2, or 3 layers, wherein each layer independently comprises or consists of one or more polyethylene polymers as described above. In such embodiments, the layer that will be laminated to the first, outer film is indicated as the internal layer, and the layer that in the package made with the final laminate will face or contact the product is indicated as the heat sealant layer.

[0155] For example, each layer of the second non-barrier multilayer film can independently comprise or consist of: at least one polyethylene homopolymer, preferably LDPE, or at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or a blend of at least one polyethylene homopolymer, and at least one ethylene-alpha olefin copolymer. Preferably, such blend can comprise, or consist of LDPE and LLDPE and / or VLDPE.

[0156] Preferably, the heat sealant layer of the non-barrier multilayer second film can comprise one or more antifog agent(s) as described above.

[0157] An example of a commercially available polyethylene film which can be used as the polyethylene second film in the laminate of the invention is the one marketed by Kraus Folie under the tradename Lamilen LT+ AF XL, which is a multilayer LLDPE film. Lamilen LT+ AF XL contains an antifog agent. When the second polyethylene film is a barrier multilayer second film which comprises a barrier layer, it can typically comprise at least 90%, preferably at least 95% by weight in respect of the total weight of the first film of one or more polyethylene polymers, as described above.

[0158] A barrier multilayer second film may have a number of layers generally comprised between 3 and 9. The layers structure and composition of the barrier multilayer second film may be as described above with reference to the barrier multilayer first film. It may generally comprise a polyethylene heat sealant layer, a barrier layer, and a polyethylene internal layer. The sealant layer is the one that, in the package made with the final laminate, will face or contact the packaged product. The internal layer is the one that is laminated to the first outer film.

[0159] The polyethylene sealant layer of the second film may comprise at least 90%, preferably at least 95% more preferably at least 98% by weight in respect of the total weight of the sealant layer of polyethylene polymers, as described above. In a preferred embodiment, such polyethylene polymers can be polyethylene homopolymers, preferably LDPE. In another preferred embodiment, such polyethylene polymers can be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE. In another preferred embodiment, such polyethylene polymers can be a blend of at least one polyethylene homopolymer, preferably LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0160] The polyethylene sealant layer may also consist of a polyethylene homopolymer, preferably LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of a blend of at least one polyethylene homopolymer, preferably LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0161] Preferably, the heat sealant layer of the barrier multilayer second film can comprise one or more antifog agent(s) as described above.

[0162] Examples of suitable resins for the heat sealant layer of the barrier multilayer second film are AF5841 LL (Tosaf), AFFINITY PL 1880G (DOW), DOWLEX SC 2108G (DOW).

[0163] The polyethylene sealant layer may have a thickness in a range from 2 micron to 20 micron. In some embodiments, the sealant layer may have a thickness in a range from 3 micron to 10 micron.

[0164] The thickness of the sealant layer in relative percentage vs. the thickness of the whole barrier multilayer second film can range from 10 to 45%, preferably from 18% to 40%.

[0165] Polyethylenes with a low melting point are preferred for a monolayer second film or for the heat-sealant layer of a multilayer (either barrier or non-barrier) second film. For example, polyethylenes with a melting point below 115°C, preferably below 105°C or below 100°C can advantageously be employed. Examples of such polymers can be Affinity PL1880G, Affinity PL1280G, Exact 4011 .

[0166] The presence of polyethylenes with a low melting point in the sealant layer allows the final laminate to start sealing at a lower temperature than using standard polyethylenes. This is an appreciated feature, as it results in energy and costs savings. In addition, when the laminate is used as a lid to be sealed onto a tray or a thermoformed container, considering that lighter and less resistant trays and containers are being introduced in the market, lower sealing temperatures minimise distortion of the tray or container after packaging. Furthermore, the use of polyethylenes with a low melting point in the sealant layer indirectly increases the heat resistance of the first film of the laminate, as a lower temperature for sealing, as well as a higher sealing speed, can be employed.

[0167] The polyethylene internal layer of the second film is an outer layer of the barrier multilayer second film, as in such film it has only one of its principal surfaces directly adhered to another layer of said film, but it is an inner layer when considering the final laminate of the invention, being the one which is laminated to the first, outer film.

[0168] The composition of the polyethylene internal layer of the second film may be the same as the polyethylene sealant layer of the second film, or may be different. In embodiments, the polyethylene internal layer may have the same composition as the polyethylene sealant layer.

[0169] The polyethylene internal layer may comprise at least 90%, preferably at least 95% more preferably at least 98% by weight in respect of the total weight of the internal layer of polyethylene polymers as described above. In a preferred embodiment, such polyethylene polymers can be polyethylene homopolymers, preferably HDPE or LDPE. In another preferred embodiment, such polyethylene polymers can be ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE. In another preferred embodiment, such polyethylene polymers can be a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE. In embodiments, the polyethylene internal layer can consist of a polyethylene homopolymer, preferably HDPE or LDPE, or of at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE, or of a blend of at least one polyethylene homopolymer, preferably HDPE or LDPE and at least one ethylene-alpha olefin copolymer, preferably LLDPE or VLDPE.

[0170] Examples of suitable resins for the internal layer of the barrier multilayer first film are 2201 HO or 2201 H1 (Sabie).

[0171] The polyethylene internal layer of the second film may have a thickness in a range from 2 micron to 20 micron. In some embodiments, the internal layer may have a thickness in a range from 3 micron to 10 micron.

[0172] The thickness of the internal layer in relative percentage vs. the thickness of the whole barrier multilayer first film can range from 10 to 35%, preferably from 18% to 28%.

[0173] The barrier multilayer second film may comprise at least a barrier layer, as described above with reference to the first multilayer barrier film. The barrier multilayer second film may optionally comprise one or more bulk (or structural) layers, as described above with reference to the first multilayer barrier film. The one or more bulk layers can be positioned between the sealant layer and the barrier layer and / or between the barrier layer and the internal layer. Also, one or more tie layers, as described above with reference to the first multilayer barrier film, may be present in the barrier multilayer second film. Typically, they can be positioned directly adhered to one or preferably both sides of the barrier layer and to one or both the adjacent bulk layers, if present, or to the polyethylene heat sealant layer and the polyethylene internal layer. Additional tie layers may also be positioned between the bulk layer(s), if present, and the adjacent polyethylene internal layer and polyethylene heat sealant layer.

[0174] In a preferred embodiment, the barrier multilayer second film may have two tie layers directly adhered to both sides of the barrier layer, thus resulting in the preferred layers structure: PE internal layer / tie / barrier / tie / PE heat sealant layer.

[0175] In another preferred embodiment, the barrier multilayer second film may have two bulk layers and two tie layers, thus resulting in the preferred layers structure: PE internal layer / bulk / tie / barrier / tie / bulk / PE heat sealant layer.

[0176] Exemplary layers structures for the barrier multilayer second film are the following:

[0177] - PE internal layer / barrier / PE sealant layer

[0178] - PE internal layer / tie / barrier / tie / PE sealant layer

[0179] - PE internal layer / bulk / barrier / bulk / PE sealant layer

[0180] - PE internal layer / bulk / tie / barrier / tie / bulk / PE sealant layer

[0181] - PE internal layer / tie / bulk / tie / barrier / tie / bulk / tie / PE sealant layer

[0182] - PE internal layer / bulk / bulk / tie / barrier / tie / bulk / bulk / PE sealant layer

[0183] - PE internal layer / tie / bulk / bulk / tie / barrier / tie / bulk / bulk / tie / PE sealant layer.

[0184] Suitable barrier multilayer films for use as second films in the laminate of the invention may be as described for the barrier multilayer first films, provided they are not crosslinked and, preferably, not oriented.

[0185] The monolayer second film, or one or more of the layers of the multilayer second film may include appropriate amounts of additives typically included in thermoplastic films for food packaging for the desired effect, as it is known to the person skilled in the packaging art. For instance, a layer may include additives such as slip agents, anti-blocking agents, antioxidants, fillers, dyes and pigments, oxygen scavengers, antistatic agents, and the like agents. Preferably, slip and / or anti-blocking additives may be added into the internal layer of the second film and / or into the sealant layer. Additives may advantageously be added as a masterbatch, i.e. in the form of a concentrate in a polyethylene carrier resin. The total amount of additives is typically in the order of 0.2 to 5% by weight of the total weight of the layer in which they are comprised.

[0186] The second polyethylene film of the laminate of the invention can be oriented, either bi-axially or mono- axially or not oriented. Preferably, the second polyethylene film is not oriented. The presence in the laminate film of the invention of an outer, oriented (and cross-linked) first film and of a non-oriented sealant second film increases the difference in the melting temperatures of the first and second film, increasing accordingly the heat resistance of the outer first film.

[0187] The second polyethylene film of the laminate of the invention is not cross-linked.

[0188] LAMINATE

[0189] The laminate film of the present invention comprises a first, mono- or multilayer polyethylene outer film laminated to a second, mono- or multilayer polyethylene sealant film. Any suitable lamination technique may be employed to adhere the first, outer film to the second, sealant film. Lamination techniques are well known in the art and commonly used in the field of polymeric packaging films.

[0190] For ease of reference, in some passages describing lamination, one film is indicated as “support film”, the other film is indicated as “laminating film”. Either the first outer film or the sealant second film may correspond to the support film. Either the first outer film or the sealant second film may correspond to the laminating film.

[0191] In a first, preferred embodiment, the first outer film and the second sealant film may be adhered to one another through glue lamination. In glue lamination (or “adhesive lamination”), a glue layer (or “adhesive layer”) directly adheres to both the first film and the second film.

[0192] The glue layer may be formed, for example, by providing a coating of a dry lamination adhesive, followed by curing the dry lamination adhesive. For instance, as a dry lamination adhesive for serving as a base material of the adhesive layer, an adhesive derived from a base resin and a curing agent as principal components may be used. In this case, the dry lamination adhesive may contain a resin compound having a plurality of hydroxyl groups in a molecule and a polyisocyanate compound. Polyisocyanates can be either aliphatic polyisocyanates or aromatic polyisocyanates. Materials that may be used for the resin compound include, but are not limited to, polyester polyols, polyurethane polyols, polycarbonate polyols, acrylic polyols, polyether polyols, polyolefin polyols, and the like. As the curing agent configuring the dry lamination adhesive, materials containing a polyisocyanate compound having two or more isocyanate groups in one molecule may be used, for example.

[0193] Preferably, the glue layer can comprise a polyurethane adhesive. For example, the glue layer can be made of a polyurethane adhesive derived from a base resin, selected from the group consisting of polyester polyols, polyurethane polyols, polycarbonate polyols, acrylic polyols, polyether polyols and polyolefin polyols, and a curing agent, selected from the group consisting of polyisocyanate compounds having two or more isocyanate groups in one molecule.

[0194] Typically, the glue layer thickness is comprised between 0.5 and 5 microns, preferably between 1 and 3 microns.

[0195] The glue lamination of the first polyethylene film with the second polyethylene film is made using conventional techniques. Glue lamination could be solvent-less or solvent based as well known in the art. Some exemplary and non-limiting techniques for glue application are gravure (either direct or reverse), solventless cart, flexo, semiflexo, all of which are well known in the art.

[0196] The glue layer can be applied either to the first, oriented and cross-linked polyethylene film or to the second, non-cross-linked polyethylene film. In preferred embodiments, the glue layer is applied to the first, oriented and cross-linked film.

[0197] Preferably, the material for serving as a base material of the glue layer is a polyurethane adhesive derived from a base resin and a curing agent as principal components. Materials that can be used for the resin compound include, but are not limited to, polyester polyols, polyurethane polyols, polycarbonate polyols, acrylic polyols, polyether polyols, polyolefin polyols, and the like. The curing agent can be materials containing a polyisocyanate compound having two or more isocyanate groups in one molecule.

[0198] An example of a suitable solvent-less polyurethane adhesive may include SF10M A and SF10M B (both marketed by Bostik) as the polyisocyanate component and the polyether polyol component, respectively.

[0199] An example of a suitable solvent polyurethane adhesive may include Novacote CA 101 and Novacote NC 560 A (both marketed by Coim SpA) as the polyisocyanate component and the polyether polyol component, respectively, and ethyl acetate as the solvent.

[0200] In another embodiment, lamination of the two polyethylene films is glueless.

[0201] An example of glueless lamination may be for example thermal (or “hot”) lamination. In thermal lamination, the laminating film (which is typically the second, sealant film) comprises polyethylene polymer(s) with a low melting point, for example with a melting point below 115°C, below 110°C, below 105°C, or below 100°C. For example, such polyethylene polymers may be ethylene-vinyl acetate copolymers. In the case of a multilayer film, the internal layer of the multilayer film should comprise such polyethylene polymer(s) with a low melting point.

[0202] Lamination occurs by heating the laminating film by passing it on a series of heated rolls and pressing it against the support film (which is typically the first, outer film). The combination of heat and pressure results in the two films getting directly adhered to one another. Another type of glueless lamination is extrusion lamination. In extrusion lamination, the laminating film (typically the second, sealant film) is (co-)extruded directly onto the support film (typically the first, outer film). The (co-)extruded laminating film is laid out onto the support film immediately after it exits the extrusion die, before it is cooled. The heat of the film exiting the extrusion die results in its direct adhesion to the support film.

[0203] Also, glueless lamination may be carried out by incorporating into the laminating film (typically into the second, sealant film) specific additives which, upon surface treatment of that film e.g. by corona treatment, become activated and allow the film to adhere to the support film (typically the first, outer film). In the case of a multilayer laminating film, the internal layer of the multilayer film should comprise such additives. Typically, such additives can be anhydride-modified polyethylene polymers, preferably selected from ethylene homo-polymers, ethylene alpha olefin copolymers and blends thereof. Preferably, the polyethylene polymers are modified with a maleic anhydride functionality.

[0204] In embodiments, the laminate film of the present invention may comprise a first, mono- or multilayer non-barrier film and a second, mono- or multilayer non-barrier film, and is intended for use in packaging products which do not require an oxygen barrier.

[0205] In other, preferred embodiments, the laminate film of the invention may comprise at least one barrier film, which can be the first film and / or the second film. Preferably, the laminate comprises only one barrier film.

[0206] In embodiments, the laminate may comprise a first, outer barrier film and a second, sealant non-barrier film. In these embodiments, the first, outer barrier film may typically be a multilayer film and the second, sealant non-barrier film may be either a monolayer film or a multilayer film.

[0207] In other, preferred, embodiments, the laminate may comprise a first, outer non-barrier film and a second, sealant barrier film. In these embodiments, the outer non-barrier film may be either a monolayer film or a multilayer film and the sealant barrier film may typically be a multilayer film.

[0208] The embodiments where the second, sealant film is a barrier film are particularly advantageous when a glue laminate with antifog properties is desired. In this case, the sealant, second film comprises, in at least its heat-sealant layer, one or more antifog agents as described above. It is well known in the art that the antifog agents show a tendency to migrate from the layer where they are contained towards the glue layer of the laminate, which “absorbs” them into its polymeric matrix. This results in a reduction of the amount of antifog agent(s) which actually reaches the surface of the sealant layer directed towards the packaged product, where they have to “bloom” to exert their function, and, consequently, in a decreased antifog effect.

[0209] If instead a barrier layer is positioned between the heat-sealant layer of the second film (which comprises antifog agent(s)) and the glue layer of the glue laminate, migration of the antifog agent(s)

[0210] - 1 - into the glue layer is prevented, and their blooming at the surface of the sealant layer directed towards the product is favoured.

[0211] The laminate film of the invention has a total content of polyethylene polymers, of at least 85 wt% in respect of the total weight of the laminate. In preferred embodiments, the content of polyethylene polymers can be of at least 90 wt%.

[0212] For sustainability issues, said polyethylene polymers are suitably selected among polyethylene homopolymers, ethylene-alpha olefin copolymers, blends and combinations thereof. A “blend” is meant to be a mixture of polymers in the same layer, while a “combination” may refer to the presence of one or more said polyethylene polymers in different layers of a multilayer film.

[0213] Polyethylene copolymers other than ethylene-alpha olefins (such as EVA, ethylene-(meth)acrylic acid copolymers, ethylene-alkyl (meth)acrylate copolymers) should preferably be present in the laminate in a total amount lower than 4 wt% in respect to the weight of the laminate, preferably lower than 3 wt% or lower than 2 wt%.

[0214] The total thickness of the laminate may vary within wide limits. It is preferably from 20 to 200 micron, more preferably from 30 to 100 micron, even more preferably from 35 to 80 micron. In some embodiments, it may be comprised between 40 and 65 micron. In some embodiments, the total thickness of the laminate can be lower than 70 micron, than 65 micron, than 60 micron, than 55 micron. In some preferred embodiments, the total thickness of the laminate can be at least 40 or at least 45 micron.

[0215] Advantageously, the laminate of the present invention does not comprise any polyamides and / or polyesters.

[0216] The laminate film of the invention has a gel content of at least 10% measured with the test method described in the experimental section of the present application. In embodiments, the gel content of the laminate can be at least 11 %, or at least 12%, or at least 13%, or at least 14%, or at least 15%, or at least 17%, or at least 20% or at least 25%. The gel content of the laminate should not exceed 30%, optionally 25% to improve recyclability of the material. Within these limits, the gel content should be adjusted by the skilled person to balance the desired or needed heat resistance of the laminate and the sustainability requirements.

[0217] Preferably, the thickness ratio between the first and the second film of the present laminate film is from 2:1 to 0.5:1 , preferably from 1.5:1 to 1 :1.5.

[0218] The laminate of the present invention can be printed. To this aim, one or more layers of ink can suitably be printed onto the first outer film and / or the second sealant film, preferably onto the internal surface thereof. With internal surface, the surface of a film which is adhered to the other film in the lamination process is meant. This printing process, known in the art as trapped printing, advantageously results in a high-quality printing and protects the printed image from deterioration due to abrasion or contact with environmental agents. Such a printing step is made before the lamination step.

[0219] In preferred embodiments, the printed film is the first, outer film, but in some embodiments, the printed film is the second, sealant film.

[0220] Optionally, the surface(s) of the first film and / or of the second film to be printed can undergo a corona discharge treatment to improve the print receptivity characteristics of the film surface. Preferably, however, the films are not corona treated for printing purposes.

[0221] Methods for printing the first and / or the second polyethylene film include any conventional method of printing of plastic materials well known in the art. Inks that can be used in the printing process include typically polyurethane inks.

[0222] The polyethylene laminate film of the present invention is peelable, namely it can easily be removed by pulling without tearing, when sealed over polyethylene containers.

[0223] The laminate film of the present invention is considered to be recycle-ready, as it can successfully be treated in the known mechanical recycling processes. The percentage content of polyethylene makes the laminate of the invention recyclable in the polyethylene stream.

[0224] The present laminate does not contain contaminant polymers (i.e. polymers other than polyethylene) in such amounts or of such types which may impair its recyclability.

[0225] However, recycling of the laminate according to some embodiments may require the use of compatibilizers. Compatibilizers are molecules that stabilize immiscible polymer mixtures by reducing the interfacial tension between the two polymers. This enhances the processability and mechanical properties of the mixture and offers a pathway for successful mechanical recycling with mixed waste streams.

[0226] The need for compatibilizers may be due to the presence, e.g. of EVOH, of specific components (e.g. some specific polyurethanes) of the glue layer in case of glue laminates, of inks. In general, as it is known in the art, compatibilizers also help to increase the recyclability of cross-linked materials.

[0227] Compatibilizers can be added to the materials to be mechanically recycled, in the necessary amounts, during the recycling process. However, compatibilizers can also be incorporated directly into the thermoplastic films making up the laminate, during (co-)extrusion, together with the polymers forming the films.

[0228] Suitable compatibilizers for polyethylene-based materials are anhydride-modified polyethylene polymers, preferably selected from ethylene homo-polymers, ethylene alpha olefin copolymers and blends thereof. Preferably, the polyethylene polymers are modified with a maleic anhydride functionality. To maximize the compatibilization effect and improve the recyclability of the laminate, the compatibilizers can be incorporated into the film of the laminate which comprises the barrier layer. Typically, the compatibilizers can be incorporated into the tie layers directly adhered to the barrier layers.

[0229] The weight ratio between the amount of compatibilizer and the amount of the resin which makes up the barrier layer, typically EVOH, is typically in the range from 0.2:1 to 1.2:1. Thus, if the amount of EVOH into one of the films of the laminate is, e.g. 5 wt% in respect to the weight of the film, the amount of compatibilizer should advantageously be comprised between 1 % and 6%.

[0230] The laminate film of the invention may be manufactured according to a process that comprises:

[0231] - providing a support film, and

[0232] - laminating a laminating film onto said support film, wherein either the support film is the first, mono- or bi-axially oriented and cross-linked polyethylenebased outer film and the laminating film is the second, non-cross-linked polyethylene-based sealant film, or the support film is the second, non-cross-linked polyethylene-based sealant film, and the laminating film is the first, mono- or bi-axially oriented and cross-linked polyethylene-based outer film.

[0233] In embodiments, the first, mono- or bi-axially oriented and cross-linked polyethylene-based outer film comprises at least 90%, preferably at least 95%, preferably at least 98% by weight in respect of the total weight of the first film of one or more polyethylene polymers.

[0234] The second, non-crosslinked polyethylene-based sealant film comprises at least 90%, preferably at least 95%, preferably at least 98% by weight in respect of the total weight of the second film of one or more polyethylene polymers.

[0235] In preferred embodiments, the support film is the first, outer film and the laminating film is the second, sealant film.

[0236] Lamination of the first outer film with the second sealant film can be made using conventional techniques.

[0237] Glue lamination is preferred, and is carried out by applying a glue layer onto the support film, followed by adhesion of the laminating film to it. In these embodiments, the support film to which the glue layer is applied is preferably the first, outer film. Glue lamination can be solvent-less or solvent based, as it is well known in the art.

[0238] If a printed laminate film is desired, the process may further comprise an optional step of printing one or more ink layers onto a surface of the first film and / or of the second film. Preferably, the surface of the first film and / or of the second film that will be laminated (and thus directly adhered to the other film) may be printed with one or more ink layers. Such a printing step is made before the lamination step. Methods for printing the first and / or the second film include any conventional method of printing of plastic materials well known in the art.

[0239] The process may further optionally comprise a corona discharge treatment of the surfaces of either the first or the second film to be printed, or both. As common in the art, corona discharge treatment refers to subjecting the surfaces of a polymeric material, such as a polyethylene film, to corona discharge, i.e. the ionization of a gas such as air in close proximity to a film surface, the ionization initiated by a high voltage passed through a nearby electrode, and causing oxidation and other changes to the film surface. Either of two types of corona treatment may be employed. A bare electrode may be used in combination with an insulated roll, e.g. a rubber insulated roll. Alternatively, a glass electrode may be used in conjunction with a bare metal roll.

[0240] The first and the second polyethylene films may be manufactured according to any suitable methods known in the art. Typically they can be manufactured by extrusion, or, in case they are multilayer films, by coextrusion, extrusion-coating, hot-lamination. Coextrusion is preferred.

[0241] Films to be used as outer first films undergo orientation (either mono- or bi-directional orientation), optional annealing and cross-linking as described in details above.

[0242] Films suitable for use as outer first films are also commercially available and are disclosed above. Generally, such films are available on the market as oriented, non-crosslinked films; accordingly, such films must undergo cross-linking, preferably through ionizing radiation such as high-energy electron beam, as described above, before they can be laminated to a suitable second sealant film.

[0243] Films suitable for use as second sealant films are also commercially available and are disclosed above.

[0244] In a further object, the present invention regards a flexible container obtainable by heat-sealing the laminate according to the invention on itself, or by heat-sealing a portion of a laminate according to the invention to a portion of another film or laminate.

[0245] In one embodiment, said another film or laminate is a laminate according to the invention.

[0246] In another embodiment, said another film or laminate is not a laminate according to the invention; in these embodiments, said another film or laminate is preferably a polyethylene film or laminate.

[0247] In the flexible containers of the invention, the second, sealant film of the laminate faces the inside of the container and the first, crosslinked film of the laminate faces the external environment.

[0248] The flexible container may be for example in the form of a bag or a pouch. Any conventional method for making bags and pouches known in the art may be employed to make flexible containers from the laminate according to the present invention.

[0249] A further object of the present invention is a package comprising the laminate of the invention or the flexible container according to the invention, and a product packaged therein. In a first embodiment, the package of the present invention is a lidded package comprising a support, a product placed onto the support, and a lid made of the laminate of the present invention (lidding laminate). In such lidded package, the sealant, second film of the laminate is in contact with, or faces, the product. The laminate is hermetically sealed all around onto said support, thus enclosing the product.

[0250] Typically, the support is a container. For example, the container can be a preformed tray (in the so- called “tray lidding” applications) or a flexible support that is thermoformed in line to assume the shape of the product to be packaged (in the “thermoform lidding” applications).

[0251] The laminate is sealed onto a continuous peripheral rim extending all around the container.

[0252] The support, the container, or the tray is typically rigid or semi-rigid for tray-lidding applications, and flexible for thermoform-lidding applications.

[0253] Typically, the support, or at least the surface of the support in contact with the product and involved in the formation of the seal with the lidding laminate of the invention, consists, or consist essentially of polyethylene (PE) or polypropylene (PP) either foamed or not-foamed, i.e. solid. The support can also be made of cardboard, or of resins even different from those listed above, having a liner or a coating consisting, or consisting essentially of PP or PE on the surface of the support involved in the formation of the seal with the lidding laminate.

[0254] The lidded package according to the invention is produced by techniques well known to those skilled in the art.

[0255] For example, in tray lidding applications, once the product, preferably the food product to be packaged has been placed on the support, or in the container, the laminate according to the invention is placed on the support or container such that its sealant film is in contact with the surface of the support or with the rim or the peripheral lip / flange of the container. The laminate is then sealed to the support by means of temperature and / or pressure using conventional techniques and equipment.

[0256] Sealing is generally carried out by means of a heated frame at temperatures of from 100°C to 180°C, preferably from 110°C to 160°C, more preferably from 120°C to 150°C, at a pressure of 2 to 10 bar, preferably 4 to 8 bar. Sealing times are typically in the order of 0.3 to 2.0 seconds, 0.5 to 1 .0 seconds. For example, the support 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 laminate of the invention is provided over the top of the support. The lower chamber and the upper chamber are then closed together, the air in-between the support and the lidding laminate is optionally replaced by a suitable gas or gas admixture, with or without prior air evacuation, and then the lidding laminate of the invention is sealed to the surface of the support or to the rim or the peripheral lip / flange of the container by means of the combination of a heated frame or plate above the lidding laminate and a similarly framed anvil supporting the support, that are pressed together. The lidding laminate is cut almost at the same time as the lid is sealed.

[0257] Lidding machines that can be suitable fortray lidding process include for instance Proseal GTO Tooling 1218 OC, 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, Mecaplastic 1000, Meca-2002 or Meca-2003 by Mecaplastic, the tray lidding machines of Sealpac (e.g. SealPac A7) and similar machines.

[0258] The optional replacement of air by a suitable gas or gas admixture (Modified Atmosphere Packaging, MAP) is performed depending on the specific needs of the product to be packaged and typically is used for products like fruits and vegetables, fresh meat, processed meat.

[0259] In thermoform lidding applications, the flexible support is thermoformed “in-line” on the so-called “Rollstock” packaging machines, a product is loaded in the thermoformed support and then a lid of the laminate of the invention is sealed to the rim of the thermoformed support, as disclosed above for traylidding applications. In thermoform lidding applications, the lidding laminate of the invention may also be thermoformed into a thermoformed lidding laminate before being sealed to the thermoformed support. Machines suitable for thermoforming and lidding process include for example Tiromat Powerpack 660 by GEA, TFS80, TFS300, TFS400, TFS700 by Ulma, Thera 450, Thera 500 by Colimatic, R145 by Multivac.

[0260] Such thermoformed packages are typically used for packaging products like cheese, fresh meat, processed meat, salami, sausages, etc.

[0261] In another embodiment, the package of the present invention is a flexible package comprising the flexible container according to the invention that encloses a product. Optionally, the product can be placed on a rigid or semi-rigid support, preferably in a rigid or semi-rigid container.

[0262] For example, the flexible container may be a bag made of the laminate of the invention; in packaging, the product is loaded into such bag, the bag is generally evacuated, and the open end thereof is closed by heat-sealing or by applying a clip, e.g. of metal. This process is advantageously carried out within a vacu urn chamber where the evacuation and application of the clip or heat seal is done automatically. In one embodiment, the package of the present invention is an overwrapped package.

[0263] In a first embodiment of the overwrapped package, the package comprises a product and a laminate according to the invention wrapped around the product.

[0264] Such overwrapped package is typically used for packaging portions of cheese, processed meat, salami, etc. In such overwrapped package, the sealant film of the laminate of the invention is in contact with the product. In a second embodiment of the overwrapped package, the package comprises a rigid or semi-rigid support, preferably a container, a product placed onto said support or into said container and a laminate according to the invention wrapped around both the support and the product.

[0265] In such overwrapped package, the sealant film of the laminate of the invention is in contact with, or faces, the product and the support.

[0266] Preferably, the overwrapped package according to the invention is hermetic. In such overwrapped hermetic package, the laminate film of the invention is sealed to itself. Preferably, the film in said overwrapped hermetic package is sealed to itself along one longitudinal seal and two transverse seals, to give a pouch.

[0267] The overwrapped hermetic package according to the invention can be produced by techniques well known to those skilled in the art, for example through Horizontal Form Fill Seal (HFFS) or Vertical Form Fill Seal (VFFS) machines.

[0268] For instance, an overwrapped hermetic package can be obtained by a flowpack packaging method by means of a Horizontal Form-Fill-Seal (HFFS) machine. Such method conventionally comprises:

[0269] - providing the laminate film according to the present invention,

[0270] - running the laminate through a former thus forming a tube,

[0271] - inserting a product, optionally placed in a container or onto a support, into the tube,

[0272] - sealing the tube longitudinally,

[0273] - sealing and cutting the tube transversally at the beginning and at the end of the package, optionally

[0274] - gas-flushing or vacuumizing the tube before closing it.

[0275] In detail, in a flowpack packaging method the product, optionally onto a support or in a container like a tray, is wrapped into an envelope made from a laminate film of the present invention, optionally under a suitable and predetermined atmosphere. To create the envelope, the flat laminate is first folded around a former and longitudinally sealed to form a tube. The product, optionally positioned in a container, is placed in such a tube where the leading edge has been closed and optionally gas flushed with the suitably selected gas or gas mixture. The excess gas is generally removed by a gentle pressure on top of the package and the open end of the envelope is then sealed and the package separated from the tubing.

[0276] As an alternative, pouches can be made with a Vertical Form Fill Seal (VFFS) packaging system that has proven to be very useful in packaging a wide variety of flowable products. The VFFS process is known to those of skilled in the art and described for instance in US4589247. A flowable product is introduced through a central, vertical fill tube to a tubular formed with the laminate of the invention, which has been sealed transversely at its lower end, and longitudinally. The pouch is then completed by sealing the upper end of the tubular segment, and severing the pouch from the tubular laminate above it.

[0277] A FFS machine, either Horizontal or Vertical, typically includes a former for forming a flat web of laminate film into a tubular configuration, a longitudinal sealer to seal the overlapped longitudinal edges of the laminate film in the tubular configuration, a conveyor for feeding the products into the tubular laminate film one after the other in suitably spaced configuration, or a feeding tube for soft, fluid or powder products (flowable products) in case of a VFFS machine, and a transverse sealer for sealing the tubular laminate film in a cross-wise direction to separate the products into discrete packages. Suitable machines for the flowpack process include llapak Delta 2000 and 3000 or Ulma Baltic, Artic or Pacific.

[0278] In the packages according to the present invention described above, the product is preferably a food product, preferably a fresh food product which is generally packaged in the packages described above. Examples of these products are fresh meat, processed meat, fish, cheese, fruits, vegetables, frozen products, salami, ready meals.

[0279] A further object of the present invention is the use of the laminate film according to the present invention for packaging a product, preferably in lidding or flowpack (HFFS or VFFS) applications. Typically, food products that can advantageously be packaged with the film of the invention are fresh food products such as fresh meat, processed meat, fish, cheese, fruits, vegetables, frozen products, salami and ready meals.

[0280] EXAMPLES

[0281] 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 present invention.

[0282] Materials In the following examples, the polymers and materials in Table 1 below have been employed.

[0283] Table 1

[0284] FILM 3: Multilayer LLDPE film, with antiblock and slip, thickness 25 micron, oriented in machine direction. FILM 4: Multilayer LLDPE film, thickness 25 micron, containing an antifog additive.

[0285] FILM 5: Three-layered barrier film PE / EVOH / PE, thickness 25 micron, oriented in machine direction.

[0286] FILM 6: Three-layered LLDPE film, thickness 25 micron, oriented in machine direction.

[0287] PU1 : aromatic isocyanate for solventless, two-part polyurethane glue; density 1.13 g / cc, viscosity 2750 mPa*s. PU2: polyol-polyether coreactant for solventless, two-part polyurethane glue; density 1.15 g / cc, viscosity 750 mPa*s.

[0288] PU3: aliphatic isocyanate for solvent based polyurethane glue; Density 1 .02 g / cc.

[0289] PU4: polyol-polyether coreactant for solvent based polyurethane glue; Density 1.12 g / cc.

[0290] EtAc: Ethyl acetate solvent; Density 0.899 g / cc.

[0291] LLDPE1 : Linear Low Density Polyethylene (Ethylene / Hexene Copolymer), Density 0.918 g / cc, Melt Flow Rate (190°C / 02.16 kg) 2.0 g / 10 min, Melting point 11 TO,.

[0292] LLDPE2: Linear Low Density Polyethylene (Ethylene / Hexene Copolymer), Density 0.919 g / cc, Melt Flow Rate (190°C / 02.16 kg) 2.1 g / 10 min.

[0293] LLDPE3: antifog and antiblock masterbatch, additives content 10%, fatty acid esters and silica in LLDPE; density 0.920 g / cc, Melt Flow Rate (190°C / 02.16 kg) 3.0 g / 10 min.

[0294] LLDPE4: slip masterbatch, amide wax (erucamide) in LDPE, additives content 20%, Density 0.919 g / cc, Melt Flow Rate (190°C / 02.16 kg) 38 g / 10 min.

[0295] LLDPE5: Linear Low Density Polyethylene (Ethylene / Octene Copolymer), Density 0.935 g / cc, Melt Flow Rate (190°C / 02.16 kg) 2.6 g / 10 min, Melting Point 128°C.

[0296] VLDPE1 : Very Low Density Ethylene / Octene copolymer; Density 0.902 g / cc; Melt Flow Rate (190°C / 02.16 kg) 1.1 g / 10 min; Melting Point 99°C.

[0297] LDPE1 : Processing aid masterbatch (fluoropolymer in LDPE); Density 0.918 g / cc.

[0298] LDPE2: Antioxidant masterbatch in LDPE; Density 0.930 g / cc.

[0299] LDPE3: Low density Polyethylene Homopolymer; Density 0.922 g / cc; Melt Flow Rate (190°C / 02.16 kg) 0.85 g / 10 min.

[0300] LDPE4: Low density Polyethylene Homopolymer with antiblock and slip agents; Density 0.922 g / cc;

[0301] Melt Flow Rate (190°C / 02.16 kg) 0.85 g / 10 min.

[0302] LLDPE-md1 : Maleic Anhydride-Modified Ethylene / Octene Copolymer, Density 0.915 g / cc, Melt Flow Rate (190°C / 02.16 kg) 1 .3 g / 10 min, Vicat softening point 72°C.

[0303] LLDPE-md2: Maleic Anhydride-Modified LLDPE, Density 0.910 g / cc, Melt Flow Rate (190°C / 02.16 kg) 3.1 g / 10 min, Melting point 118°C.

[0304] LLDPE-comp: Maleic Anhydride-Modified LLDPE (compatibilizer), Density 0.87 g / cc, Glass Transition Temperature -58°C, Melting point 68°C.

[0305] EVOH1 : Ethylene / Vinyl Alcohol Copolymer, Ethylene content between 30-40 mole %, Density 1.15 g / cc, Melt Flow Rate (200°C / 02.16 kg) 4 g / 10 min.

[0306] EVOH2: Ethylene / Vinyl Alcohol Copolymer, Ethylene content between 30-40 mole %, Density 1.17 g / cc, Melt Flow Rate (200°C / 02.16 kg) 4.1 g / 10 min. Films

[0307] FILM 1 , FILM 2 and FILM 7 having composition and characteristics shown in Table 2 were manufactured:

[0308] Table 2 FILM 1 was manufactured through a round coextrusion process followed by orientation, on a double bubble line. The oriented film was then annealed by passing it onto a series of annealing rolls. Main operating conditions used to orient and anneal the film are:

[0309] MD orientation ratio: 3.8:1

[0310] TD orientation ratio: 3.8:1

[0311] Pre-heating temperature: 108°C;

[0312] Orientation temperature: 112°C;

[0313] Annealing temperature: 70°C.

[0314] The film so obtained was cooled down first by an air flow at 10°C and then by passing onto a cooling roll that was cooled with water and kept at 10°C.

[0315] The film was then irradiated by electron-beam irradiation, with a radiation dosage of 65 kGy thus obtaining the final, cross-linked film to be used as an outer first film in the laminates of the invention (FILM 1-X).

[0316] In FILM 1 / FILM 1-X, layer 7 is the layer that is laminated to form the laminate film, layer 1 will be directed towards the outer environment.

[0317] FILM 2 and FILM 7 were manufactured through a round coextrusion process on a hot blown line. After coextrusion, the films were hot blown, with a blow-up ratio of approximately 3, cooled down first by an air flow at 10°C and then by passing it onto a cooling roll that was cooled with water and kept at 10°C. Film 2 and Film 7 are not oriented.

[0318] In FILM 2 and FILM 7, layer 5 is the layer that is laminated to form the laminate film, layer 1 is the sealant layer, that will face or contact the packaged product.

[0319] Commercially available FILM 3 (MDOPE 100UEX, mono-oriented and non-cross-linked) was irradiated by electron-beam irradiation, with a radiation dosage of 45 kGy, thus obtaining a cross-linked film to be used as an outer first film in the laminates of the invention (FILM 3-X).

[0320] Commercially available FILM 6 (SUSTILEN MDO PE 100U EX XXL) mono-oriented and non-cross- linked) was irradiated by electron-beam irradiation, with a radiation dosage of 45 kGy, thus obtaining a cross-linked film to be used as an outer first film in the laminates of the invention (FILM 6-X).

[0321] Laminates

[0322] Some laminates according to the invention and comparative laminates were manufactured by laminating a first outer film to a second sealant film as described in the following Table 3:

[0323] Table 3

[0324] Laminates 1 , C1 , 2, 4 and 5 were manufactured by applying a glue composition containing 67% PU1 and 33% PU2 onto an outer surface of the respective first outer film to form a glue layer, followed by coupling with the respective second sealant film. Specifically, for FILM 1-X which has an asymmetrical structure, the glue composition was applied onto the external surface of layer 7. The glue composition was applied with solventless technique, through a coater provided with a couple of opposed rolls rotating in directions contrary to one another. As the film passed through the rolls of the coater, at the opposition site between the rolls, the glue composition was applied to a surface thereof.

[0325] The thickness of the glue layer was 2 micron in laminates 1 , C1 and 2, and 1 micron in laminates 4 and 5.

[0326] Laminate 3 was manufactured by applying a glue composition containing 54.05% EtAc, 7.34% PU3 and 38.61 % PU4 onto a surface of FILM 3-X, evaporating the solvent and then coupling with FILM 2. The glue composition was applied through a coater provided with a couple of opposed rolls rotating in directions contrary to one another. As the film passed through the rolls of the coater, at the opposition site between the rolls, the solvent-containing glue composition was applied to a surface thereof. After application of the glue composition, the film was passed through an evaporation drying chamber to remove the solvent so that a dry glue layer remained onto the film. The thickness of the glue layer was 1 micron.

[0327] Laminates 3, 4 and 5 are antifog laminates, comprising an antifog agent in the sealing layer 1 of the second, sealant FILM 2 or sealant FILM 7, respectively, which are barrier films.

[0328] An antifog agent is also present in the second sealant FILM 4 of laminates 1 , 2 and C1 , but FILM 4 is not a barrier film. TESTS AND RESULTS

[0329] Gel content determination

[0330] The gel content expresses the percentage of a polymeric material insoluble in toluene and it is an index of the level of cross-linking of the polymer in that material.

[0331] In case the material is a multilayer film, the test may be carried out on the entire film - if all the polymers making the film, before cross-linking, are toluene-soluble - or on the part of it made of polymers which before cross-linking are toluene-soluble - by delaminating the desired layers and not submitting to the test those layers whose polymers are per se not soluble in toluene, such as for instance EVOH.

[0332] If the gel content is evaluated on the toluene-soluble part of the film only, as explained above, the result represents a good index of irradiation for the whole film, including for the layers not subjected to the analysis. In fact, as the present films making up the laminates are generally prepared by coextrusion of all layers followed by irradiation, it follows that all the layers have been accordingly subjected to the same irradiation.

[0333] The result is expressed as percentage by weight of the undissolved material (i.e. the cross-linked material) after toluene treatment with respect to the total weight of the initial material. The test was performed according to the following procedure.

[0334] A square of wire metal gauze (80 mesh, 15 cm x 15 cm) was cut and cleaned by submersion in a beaker containing toluene. After solvent evaporation, the wire gauze was given a funnel shape and weighted (weight B). 120 ml of toluene were put in a 200 ml beaker and heated on a hot plate.

[0335] A sample of the material of about 150 mg was weighted (weight A) and put it in the boiling toluene for 30 minutes, under stirring. The solution was then filtered on the wire gauze and the gel remained on the wire gauze. The wire gauze with the gel was dried under hood, weighted (weight C) after 24 h and 48 h up to a constant weight.

[0336] The gel content percentage was calculated for each weighing with the following formula: (C - B) / A x 100 and the average value was calculated. The analysis was repeated twice for each material.

[0337] The gel contents, measured according to the method described hereinabove, of the outer, cross-linked films used for manufacturing the laminates of the examples are reported in the following Table 4.

[0338] Table 4 Starting from the measured gel content of the outer, crosslinked film, the gel content can be calculated for the whole laminate film by dividing the gel content of the crosslinked film by a factor corresponding to the ratio between the total thickness of the film and the thickness of the crosslinked film.

[0339] In the laminates, the gel content of the cross-linked films is “diluted” due to the presence of noncrosslinked film. The “dilution” is proportional to the thickness of the crosslinked film in respect to the total thickness of the laminate.

[0340] The crosslinked film 1-X has a thickness of 21 micron.

[0341] Laminate 1 has a total thickness of 48 microns. Thus the reduction of the gel content is by a factor 2.3 (48 : 21).

[0342] Accordingly, the gel content of laminate 1 is calculated to be reduced to 13% (30% : 2.3).

[0343] The crosslinked Film 3-X has a thickness of 25 micron.

[0344] Laminate 2 has a total thickness of 52 microns. Thus the reduction of the gel content is by a factor 2.1 (52 : 25).

[0345] Accordingly, the gel content of laminate 2 is calculated to be reduced to 11 .9% (25% : 2.1).

[0346] Laminates 3 and 4 both have a total thickness of 51 microns. Thus the reduction of the gel content is by a factor 2.04 (51 : 25).

[0347] Accordingly, the gel content of laminates 3 and 4 is calculated to be reduced to 12.3% (25% : 2.04).

[0348] The crosslinked Film 6-X has a thickness of 25 micron.

[0349] Laminate 5 has a total thickness of 51 microns. Thus the reduction of the gel content is by a factor 2.04 (51 : 25).

[0350] Accordingly, the gel content of laminate 5 is calculated to be reduced to 10.3% (21 % : 2.04).

[0351] Machinability

[0352] Laminates 1 and 2 of the invention and comparative laminate C1 were tested for their machinability on two different HFFS machines: Artic by Ulma and Delta 3000 by llapack, at the following operating conditions:

[0353] - sealing rolls (longitudinal) and bars (transversal) temperature: from 120°C to 170°C

[0354] - machine speed: from 10 m / min to 25 m / min (maximum speed tested), for both HFFS machines.

[0355] Laminate 1 , having a multilayer, barrier, bi-oriented and cross-linked polyethylene outer first film, ran on both HFFS machines in a smooth way, without any jam or slipping of the material up to the maximum speed tested and at any temperature. Laminate 1 did not show sticking to the sealing bars / rolls up to the maximum speed tested and at any temperature. Comparative laminate C1 , having a multilayer, barrier, mono-oriented but not cross-linked outer first film did not prove suitable for use on either HFFS machines, as it sticked to the sealing bars / rolls as soon as the machines started to run.

[0356] Laminate 2, having a multilayer, mono-oriented and cross-linked polyethylene outer first film, was well machinable on both HFFS machines. No sticking to the sealing bars / rolls was shown, at any sealing temperature and machine speed.

[0357] Laminates 3, 4 and 5 were also tested for their machinability on HFFS machines Artic by Ulma and Delta 3000 by llapack, at the following operating conditions:

[0358] - sealing rolls (longitudinal) and bars (transversal) temperature: from 140°C to 180°C

[0359] - machine speed: 15 m / min (for llapak Delta 3000); 16.5 m / min (for Ulma Artic).

[0360] Laminates 3, 4 and 5, having a multilayer, mono-oriented and cross-linked polyethylene outer first film showed a good machinability on both packaging equipment. No issues occurred during unwinding of the rolls and no sticking to the sealing bars / rolls was observed at ant temperature tested, up to 180°C. Hermeticity of the sealed packages was checked with the Dopack system and proved to be good for materials sealed at temperatures up to 160°C (sealing rolls). The limit of acceptability of the Dopack test was considered -0.4 bar.

[0361] Clarity, Haze and Gloss 60°

[0362] The optical properties were evaluated for Laminate 3 and Laminate 4.

[0363] Clarity and haze were evaluated according to the standard test method ASTM D1003.

[0364] The gloss 60° was evaluated according to the standard test method ASTM D2457.

[0365] The results of the tests are reported in the following Table 5. The values are the average over 9 readings (clarity and haze) and over 18 readings (gloss 60°).

[0366] Table 5

[0367] As can be seen from the data above, both Laminate 3 and Laminate 4 according to the invention show good optical properties, in terms of clarity, haze and gloss. In particular, the clarity, haze and gloss values are in line with values typically measured for laminate films. This outcome is particularly good considering that the second, sealant film of Laminates 3 and 4 (FILM 2) comprises antifog agents in its sealant layer 1 . Accordingly, the presence of antifog in the sealing film of laminates of the present invention does not negatively affect the optical properties of the laminate. Antifoq Test (score)

[0368] A packaging material is defined as “antifog” if its surface directed towards the product allows the droplets of water to lay as a smooth and uniform layer, thus allowing visual inspection of the packaged product.

[0369] An internal test method was used to evaluate the antifog performance of Laminates 3, 4 and 5, which comprise a barrier antifog film (FILM 2 or FILM 7) as the second sealant film, and of Laminate C1 , which comprises a non-barrier antifog film (FILM 4) as the second sealant film.

[0370] Rolls of Laminate 3, Laminate 4, Laminate 5 and Comparative Laminate C1 were left to age for 1 week after their manufacturing under thermostatic conditions (23°C, atmospheric pressure).

[0371] After aging, for each laminate film, four samples (20 x 20 cm) were cut from the roll and were secured tightly through a rubber band over 900 ml glass vessels, each containing 250 ml of water, with the second, sealant film of the laminate towards the water without contacting the liquid. The resulting vessels were placed in a refrigerated cooler at 2-4°C.

[0372] The samples were observed 1 hour, 3 hours, 6 hours, 24 hours and 72 hours after being placed in the cooler. The quality of the antifog properties was scored by three panelists according to the following rating scale, ordered from very poor to excellent antifog properties: score 1 - very poor: opaque layer of small fog droplets; score 2 - poor: opaque or transparent layer of large droplets; score 3 - acceptable: complete layer of large transparent droplets; score 4 - good: randomly distributed or large transparent droplets; score 5 - excellent: transparent film without visible water.

[0373] The results of the antifog test are reported in the following Table 6. The antifog score reported in the table is the average of the ratings given by the three panelists.

[0374] Table 6

[0375] Laminates 3, 4 and 5 showed excellent antifog properties, demonstrating that the antifog agent incorporated in the sealant layer of FILM 2 or FILM 7 succeeds in reaching the external surface (towards the product) of the sealant FILM 2 or FILM 7. The presence of a barrier layer (EVOH) in FILM 2 and FILM 7 prevents the antifog agent from migrating from the sealant layer 1 into the glue layer, even some days (1 week) after manufacture of the laminates, thus maximizing the antifog properties of the laminate.

[0376] Laminates 3, 4 and 5 visually appeared as non-fogged, transparent and with very good see-through properties.

[0377] Laminate C1 showed very poor antifog properties even 1 hour after refrigeration. This unacceptable result indicates that, during the aging period of the roll (as short as 1 week), the antifog agent, in the absence of a barrier layer, migrated from the sealant film (FILM 4) into the glue layer and was sequestered therein, being thus not available to reach the external surface (towards the water containing vessel) of the laminate.

[0378] It is noted that the fact that laminate C1 does not have a cross-linked first outer film does not affect the antifog behavior, which only depends on the structure and composition (presence or absence of a barrier layer) of the second, sealant film of the laminate.

[0379] Tensile Strength, Elongation at break, Elastic modulus at 23°C:

[0380] Tensile strength, Elongation at break and Elastic modulus at 23°C were evaluated for Laminate 3, in accordance to ASTM D 882.

[0381] Tensile strength represents the maximum tensile load per unit area of the original cross-section of the test specimen required to break it, expressed as kg / cm2.

[0382] Elongation at break represents the increase in length of the specimen, measured at the moment of rupture expressed as percentage of the original length. Measurements were performed with Instron tensile tester equipped with a load cell type CM (1-50 kg), in an environmental chamber set at 23°C, on specimens previously stored at 23°C and 50% RH for minimum of 24 hours. Tensile and elongation measurements were recorded simultaneously and the reported results are the average values.

[0383] The results of the tests are reported in Table 7.

[0384] Table 7

[0385] The measured values for elastic modulus at 23°C are good and in line with the properties of laminates. Also the values for Tensile strength and elongation at break are very satisfactory. These values are unbalanced between the longitudinal direction and the transverse direction because of monoaxial orientation of the outer, first film (FILM 3-X).

[0386] Recyclability Test

[0387] Laminate 3 and Laminate 4 have been tested for compatibility with, and recyclability into, a LDPE flexible recycle stream following the recyclability evaluation protocol for polyethylene films from RecyClass (Version 5.0 updated on January 2024).

[0388] As a control film, a polyethylene film made from LDPE 310E (by DOW, melt flow rate 0.75 g / 10 min (190°C, 2.16 kg), density 0.923 g / cc) was used).

[0389] Samples of Laminate 3, Laminate 4 and control film were grinded using an Adler AMG 25 granulator, and flakes were collected.

[0390] Following the RecyClass protocol, control flakes and flakes of each material to be tested (test flakes) were combined to obtain the following samples:

[0391] Samples P0: 100 wt% control film flakes

[0392] Samples P50 (no compatibilizer): 50 wt% control flakes + 50 wt% test flakes

[0393] Samples P50 (with 5 wt% compatibilizer): 45 wt% control flakes + 5 wt% compatibilizer + 50 wt% test flakes.

[0394] As the compatibilizer, maleic anhydride-modified LLDPE Retain 3000 by DOW was used.

[0395] For Samples P50, the ground flakes were mixed together until a uniform blended appearance was achieved.

[0396] For each sample, the flakes were fed into a Brabender TwinLab-C 20 / 40 FT12 extruder. The twin screw was outfitted with the strand die and pellets were prepared by extruding at a melt temperature of 230°C and melt filtering the extrudate 110 microns, according to the RecyClass protocol. The extrusion runs were performed for a time of 40 minutes.

[0397] The following two criteria of the RecyClass benchmark recommendation for pellet properties characterization were evaluated:

[0398] - the end pressure should be no greater than 25% over the starting pressure value for each sample All pellets samples satisfied this criterion.

[0399] - no build-up on screen and no more than a 25% pressure Increase overPO control sample

[0400] All pellets samples satisfied this criterion.

[0401] The pellets from P0, P50 (no compatibilizer) and P50 (with 5% compatibilizer) were tested for their melt flow rate following the ASTM D1238 method, at 2.16 kg and 190°C. The RecyClass guidance protocol recommends that the melt flow delta of the test pellets versus the P0 control should be <0.75 g / 10 min. Test pellets P50 (no compatibilizer) and P50 (with compatibilizer) for both Laminate 3 and Laminate 4 satisfied the recommendation (see results in Table 8 below).

[0402] Table 8

[0403] Thus, both Laminate 3 and Laminate 4 passed the RecyClass test for pellet properties characterization.

[0404] For each material to be tested, the PO and P50 pellets were mixed 1 :1 with virgin resin control pellets (LDPE 31 OE) to create film blend mixtures FO, F25 (no compatibilizer) and F25 (with compatibilizer). The pellet blends were thoroughly mixed to ensure uniformity.

[0405] The film blend mixtures were blown into films using the Brabender TwinLab-C 20 / 40 FT12 twin screw extruder, outfitted with a film blowing die (diameter of blown film die: 25 mm).

[0406] The blow-up ratio was selected between 2.5 and 3, melt temperature was 230°C and a target thickness of 25 micron was set for 30 minutes, followed by a target thickness of 50 micron for 30 minutes.

[0407] The 25-micron films were evaluated for their visual aspect as reported in the Annex 3 of RecyClass protocol {“PE Film surface impression evaluation and impurity visual inspection”). Specifically, the following properties were evaluated: texture, gels, specks, fisheyes, holes. All test films passed the benchmark recommendations provided by the RecyClass protocol.

[0408] The 50-micron films were characterized for tensile strength and elongation at break, in accordance with ASTM D-882. In general, the Protocol “aims to assess the highest value recyclate application, i.e. blown film production”. The following RecyClass benchmark recommendations for blown films characterization were evaluated:

[0409] - the physical measurements must be “no more than a 25% reduction to the control film (F0)” to pass the test (only a decrease in properties is used to determine failure of the RecyClass test)

[0410] All films samples satisfied this criterion.

[0411] - Tensile strength at break (TD, LD) higher than 10 MPa - Elongation at break (TD) higher than 400%

[0412] - Elongation at break (LD) higher than 250%

[0413] All films samples satisfied these criteria (see results in Table 9 below).

[0414] Thus, both Laminate 3 and Laminate 4 passed the RecyClass test for film properties characterization. Table 9

[0415] Also Laminate 5 has been tested for compatibility with, and recyclability into, a LDPE flexible recycle stream following the recyclability evaluation protocol for polyethylene films from RecyClass (Version 5.0 updated on January 2024). As a control film, a polyethylene film made from LDPE 31 OE (by DOW, melt flow rate 0.75 g / 10 min (190°C, 2.16 kg), density 0.923 g / cc) was used).

[0416] Samples of Laminate 5 and control film were grinded using an Adler AMG 25 granulator, and flakes were collected.

[0417] Following the RecyClass protocol, control flakes and flakes of Laminate 5 (test flakes) were combined to obtain the following samples:

[0418] Samples P0: 100 wt% control film flakes Samples P25: 75 wt% control flakes + 25 wt% test flakes

[0419] Samples P50: 50 wt% control flakes + 50 wt% test flakes.

[0420] No additional compatibilizers were added to the samples, as Laminate 5 comprises compatibilizer resin in its structure (namely, Retain 3000 by DOW). The amount of compatibilizer in Laminate 5 is 2.25 wt% in respect to the weight of the whole film.

[0421] The ground flakes were mixed together until a uniform blended appearance was achieved.

[0422] For each sample, the flakes were fed into a Brabender TwinLab-C 20 / 40 FT12 extruder. The twin screw was outfitted with the strand die and pellets were prepared by extruding at a melt temperature of 230°C and melt filtering the extrudate 110 microns, according to the RecyClass protocol. The extrusion runs were performed for a time of 2 hours.

[0423] The following two criteria of the RecyClass benchmark recommendation for pellet properties characterization were evaluated:

[0424] - the end pressure should be no greater than 25% over the starting pressure value for each sample All pellets samples exhibited stable pressures during the pelletization runs and satisfied this criterion.

[0425] - no build-up on screen and no more than a 25% pressure increase overPO control sample

[0426] All pellets samples satisfied this criterion.

[0427] The pellets from P0, P25 and P50 were tested for their melt flow rate following the ASTM D1238 method, at 2.16 kg and 190°C. The RecyClass guidance protocol recommends that the melt flow delta of the test pellets versus the P0 control should be <0.75 g / 10 min.

[0428] Test pellets P25 and P50 satisfied the recommendation (see results in Table 10 below).

[0429] Table 10

[0430] Laminate 5 passed the RecyClass test for pellet properties characterization.

[0431] The P0, P25 and P50 pellets were mixed 1 :1 with virgin resin control pellets (LDPE 310E) to create film blend mixtures F0, F12.5 and F25. The pellet blends were thoroughly mixed to ensure uniformity. The film blend mixtures were blown into films using the Brabender MetaStation 4E & Extruder 19 / 25 D single screw extruder, outfitted with a film blowing die (diameter of blown film die: 50 mm).

[0432] The blow-up ratio was selected between 2.5 and 3, melt temperature was 230°C and a target thickness of 25 micron was set for 30 minutes, followed by a target thickness of 50 micron for 30 minutes. The 25-micron films were evaluated for their visual aspect as reported in the Annex 3 of RecyClass protocol (“PE Film surface impression evaluation and impurity visual inspection"). Specifically, the following properties were evaluated: texture, gels, specks, fisheyes, holes. All test films passed the benchmark recommendations provided by the RecyClass protocol.

[0433] The 50-micron films were characterized for tensile strength and elongation at break, in accordance with ASTM D-882, dart impact in accordance with ASTM D-1709, Method A and Tear strength in accordance with ISO 6383-2.

[0434] In general, the Protocol “aims to assess the highest value recyclate application, i.e. blown film production”. The following RecyClass benchmark recommendations for blown films characterization were evaluated:

[0435] - the physical measurements must be “no more than a 25% reduction to the control film (FO)” to pass the test (only a decrease in properties is used to determine failure of the RecyClass test)

[0436] All films samples satisfied this criterion.

[0437] - Tensile strength at break (TD, LD) higher than 10 MPa

[0438] - Elongation at break (TD) higher than 400%>

[0439] - Elongation at break (LD) higher than 250%>

[0440] - Dart impact > 50 g

[0441] Results of the tests on tensile strength and elongation at break (12 specimens for each blown film sample) are shown in the following Table 11 :

[0442] Table 11

[0443] Results of the Dart Impact test (20 specimens for each blown film sample) are shown in the following

[0444] Table 12: Table 12

[0445] Results of the test on tear strength (20 specimens for each blown film sample) are shown in the following Table 13. In the test on tear strength, samples were cut using constant radius test specimen. Weight of the pendulum 200 gf + extra weight 400 gf.

[0446] Table 13

[0447] All films samples satisfied the mechanical properties criteria. Laminate 5 passed the RecyClass test for film properties characterization.

Claims

1. CLAIMS1 . A polyethylene based laminate film, comprising:- a first, oriented and cross-linked polyethylene-based outer film, and- a second, non-cross-linked polyethylene-based sealant film, wherein the polyethylene based laminate film has a gel content of at least 10%, measured with the method disclosed in the present application.

2. The polyethylene based laminate film of claim 1 , having a total content of polyethylene polymers of at least 85 wt%, preferably at least 90 wt% in respect of the total weight of the laminate.

3. The polyethylene based laminate film of claim 1 or claim 2, wherein the polyethylene polymers are selected among polyethylene homopolymers, preferably HDPE or LDPE, ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE, blends and combinations thereof.

4. The polyethylene based laminate film of any one of the previous claims, wherein:- the thickness of the laminate is comprised between 30 and 100 micron, preferably between 35 and 80 micron, more preferably between 40 and 65 micron; and / or- the thickness of the first outer film is comprised between 15 and 40 micron, preferably between 20 and 35 micron; and / or- the thickness of the second, sealant film is comprised between 15 and 40 micron, preferably between 20 and 35 micron, and / or- the thickness ratio between the first outer film and the second sealant film is from 2:1 to 0.5:1 , preferably from 1.5:1 to 1 :1.5.

5. The polyethylene based laminate film of any one of the previous claims, wherein the first outer film and the second sealant film independently comprise at least 90%, preferably at least 95% by weight in respect of the total weight of the first film and of the second film, respectively, of one or more polyethylene polymers, optionally wherein said one or more polyethylene polymers are selected among polyethylene homopolymers, preferably HDPE or LDPE, ethylene-alpha olefin copolymers, preferably LLDPE or VLDPE, blends and combinations thereof.

6. The polyethylene based laminate film of any one of the previous claims, wherein the first outer film has a gel content of not less than 20%, not less than 25%, not less than 30% or not less than 40%, measured according to the test method reported in the present description.

7. The polyethylene based laminate film of any one of the previous claims, wherein at least one of the first outer film and the second sealant film is a barrier film.

8. The polyethylene based laminate film of claim 7 wherein the barrier film is a multilayer film which comprises a barrier layer.

9. The polyethylene based laminate film of claims 7 or 8, wherein the barrier film is the second sealant film.

10. The polyethylene based laminate film of claim 9 wherein the second sealant film comprises a barrier layer, an outer, heat sealant layer, and an internal layer, wherein:- said heat sealant layer comprises one or more antifog agents, and- said barrier layer is positioned between said heat sealant layer and the internal layer, the internal layer being the layer which is laminated to the first, outer film.11 . The polyethylene based laminate film of any one of the previous claims wherein the second sealant film is a monolayer second sealant film, or wherein the second sealant film is a multilayer second sealant film which comprises a heat sealant layer, wherein said monolayer second sealant film or said heat sealant layer of said multilayer second sealant film comprises at least 90%, preferably at least 95% by weight of one or more polyethylene polymers with a melting point below 115°C, preferably below 105°C, more preferably below 100°C.

12. A process for manufacturing the laminate of any one of the previous claims comprising the steps of:- providing a support film, and- laminating a laminating film onto said support film, wherein either the support film is the first, mono- or bi-axially oriented and cross-linked polyethylenebased outer film and the laminating film is the second, non-cross-linked polyethylene-based sealant film, orthe support film is the second, non-cross-linked polyethylene-based sealant film, and the laminating film is the first, mono- or bi-axially oriented and cross-linked polyethylene-based outer film.

13. The process of claim 12, wherein the step of laminating the laminating film onto the support film is carried out by applying a glue layer onto the support film, followed by adhesion of the laminating film to the support film, preferably wherein the support film is the first, outer film and the laminating film is the second, sealant film.

14. A flexible container obtainable by heat-sealing the laminate film according to any one of claims 1 to 11 on itself, or by heat-sealing a portion of the laminate according to any one of claims 1 to 11 to a portion of another film or laminate, wherein said another film or laminate is a laminate film according to any one of claims 1 to 11 or a different film or laminate, preferably a polyethylene film or laminate, wherein the second sealant film of the laminate according to any one of claims 1 to 11 faces the inside of said flexible container.

15. A package comprising the laminate film according to any one of claims 1 to 11 or the flexible container according to claim 14, and a product packaged therein.

16. The package according to claim 15 comprising a support, preferably a container, more peferably a tray, a product placed onto said support, and a lid made of the laminate film according to any one of claims 1 to 11 , wherein the second, sealant film of the laminate is in contact with or faces the product, and the laminate film is hermetically sealed onto said support, wherein the support is preferably selected from polyethylene and polypropylene supports.

17. The package according to claim 16 wherein the lid made of the laminate film according to any one of claims 1 to 11 is thermoformed.

18. The package according to claim 15 comprising the flexible container according to claim 14 and a product placed into said flexible container, optionally wherein the product is placed on a rigid or semi-rigid support.

19. The package according to claim 15 comprising a product and the laminate film according to any one of claims 1 to 11 wrapped around such product, wherein the second, sealant film of the laminate is in contact with or faces the product.

20. The package according to claim 15 comprising a rigid or semi-rigid support, preferably a container, more preferably a tray, a product placed onto said support and the laminate film according to any one of claims 1 to 11 wrapped around both said support and said product, wherein the second, sealant film of the laminate is in contact with or faces the product.21 . The package according to any one of claims 15 to 20 wherein the packaged product is a food product, preferably selected from the group consisting of fresh red meat, processed meat, fish, poultry, cheese, fruits and vegetables.

22. Use of the laminate film according to any one of claims 1 to 11 for packaging products, preferably food products, more preferably selected from the group consisting of fresh red meat, processed meat, fish, poultry, cheese, fruits and vegetables.

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