Extrusion Single Layer Coating

Abstract

The present invention relates to a polymer composition for extrusion coating of metal sheets, to a process for producing a coated metal sheet using such a polymer composition, to a coated metal sheet obtainable by such a process, and to the use of such a coated metal sheet for the production of food or beverage containers, preferably beverage cans.

Description

[Technical field]

[0001] The present invention relates to a polymer composition for extrusion coating of metal sheets, to a process for producing coated metal sheets using such a polymer composition, to coated metal sheets obtainable by such a process, and to the use of such coated metal sheets for the manufacture of food and beverage containers, preferably beverage cans. [Background technology]

[0002] Metal sheets in general are usually coated with the aim of improving the surface functionality of the substrate and / or protecting it from external influences. Metal sheets, especially aluminum sheets used in particular for the production of food and / or beverage containers such as beverage cans, need to be particularly protected against corrosion caused by the food / beverage contents, especially in the production of the can ends. For this purpose, traditionally lacquer systems are used to coat the ends of can strips, especially in beverage cans, which must be followed by a baking step, generally via roll-to-roll application. In addition to the high solvent consumption and the complex treatment of the exhaust from such equipment, the aluminum strip is also subject to a significant softening due to the relatively high baking temperatures required in the lacquer systems, which range from 230°C to 270°C. Thus, in order to provide a sufficient stability and strength, it is necessary to use expensive aluminum alloys with a high magnesium content, which are even more susceptible to corrosion. An alternative coating application method is lamination, which requires preconditioning of the metal parts in the form of the application of one or more adhesion / primer coatings. Furthermore, both roll-to-roll coating and lamination suffer from the drawback of being slow processes. Summary of the Invention [Problem to be solved by the invention]

[0003] Thus, there is a need for a method of producing coated metal sheet, such as coated aluminum sheet, that consumes less overall energy and time and does not require solvent processing, curing and / or waste management. [Means for solving the problem]

[0004] This need is met by the object of the present invention and is solved by a polymer composition for extrusion coating of metal sheets, as well as a method for producing coated metal sheets using such a polymer composition, as described herein.

[0005] Thus, in one embodiment, the present invention relates to a polymer composition for extrusion coating metal sheets, comprising at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group, the at least one olefin copolymer being present in an amount of about 2-99 wt.%, preferably about 10-95 wt.%, more preferably about 20-80 wt.%, even more preferably about 25-60 wt.%, especially about 30-60 wt.%, based on the total weight of the polymer composition.

[0006] In another aspect, the present invention relates to a method for making a coated metal sheet, comprising: i) feeding a metal sheet into an extrusion coating arrangement; and ii) obtaining a coated metal sheet by extrusion coating at least one surface of the metal sheet with the polymer composition according to the invention; Includes.

[0007] In yet another aspect, the present invention relates to a metal sheet obtainable by the process of the present invention.

[0008] In yet another aspect, the present invention further relates to the use of the coated metal sheet of the present invention for the manufacture of food or beverage containers, preferably beverage cans.

[0009] The embodiments of the present invention are as follows, but the present invention is not limited thereto. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Many modifications and adaptations will be readily apparent to those skilled in the art without departing from the scope of the present invention.

[0010] The term "one or more" as used herein refers to at least one, and includes one, two, three, four, five, six, seven, eight, nine, or more of the referenced species. Similarly, the term "at least one" means one or more, i.e., one, two, three, four, five, six, seven, eight, nine, or more. The term "at least one" as used herein with respect to any moiety refers to the number of chemically distinct molecules, i.e., the number of different types of the referenced species, and not the total number of molecules.

[0011] As used herein, the terms "a" and "an" and "at least one" are synonymous and interchangeable with the term "one or more."

[0012] The term "about" as used herein in relation to numerical values ​​means the stated value ±10%, preferably ±5%.

[0013] All percentages given in this specification with respect to compositions or preparations relate to % by weight based on the total weight of the respective composition or preparation, unless expressly stated otherwise.

[0014] In a first aspect, the present invention relates to a polymer composition for extrusion coating of metal sheets. The polymer composition according to the present invention comprises at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and containing at least one free carboxyl group. The at least one olefin copolymer is present in an amount of about 2-99% by weight, for example 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,30,35,40,45,50,55,60,65,70,75,80,85,90,95 or 99% by weight, preferably about 10-95% by weight, more preferably about 20-80% by weight, even more preferably about 25-60% by weight, especially about 30-60% by weight, based on the total weight of the polymer composition.

[0015] The olefin is preferably ethylene or an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, ... Examples of the olefin-based compounds include 1-pentene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and combinations thereof. The olefin-based compounds may be used alone or in combination of two or more. In various embodiments, the olefin is preferably ethylene.

[0016] In the context of the present invention, the term "compounds copolymerizable with olefins and containing at least one free carboxyl group" means compounds capable of copolymerization with olefins to obtain olefin copolymers and containing at least one free carboxyl group, for example 1, 2 or 3 free carboxyl groups, preferably one free carboxyl group. The term "free carboxyl group" includes the acid form and, if more than one free carboxyl group is present, also the anhydride form of two free carboxyl groups essentially reacted to form an anhydride. Thus, in the context of the present invention, the anhydride group contained in a compound copolymerizable with olefins represents two free carboxyl groups. In the context of the present invention, the term "compounds copolymerizable with olefins and containing at least one free carboxyl group" also means carboxylic acids such as maleic acid, as well as acid anhydrides such as maleic anhydride. In the context of the present invention, the term "compounds copolymerizable with olefins and containing at least one free carboxyl group" includes compounds that can be grafted onto the backbone contained in olefins, for example maleic anhydride. Examples of compounds that are copolymerizable with olefins and contain at least one free carboxy group include, but are not limited to, unsaturated carboxylic acids or anhydrides thereof, and vinyl carboxylates, particularly unsaturated carboxylic acids or anhydrides thereof selected from the group consisting of acrylic acid, methacrylic acid, and maleic acid. Thus, in various embodiments, the at least one compound that is copolymerizable with olefins and contains at least one free carboxy group is selected from the group consisting of acrylic acid, methacrylic acid, and maleic acid, preferably from the group consisting of acrylic acid and methacrylic acid.

[0017] In various embodiments, in the present invention, olefin copolymers are preferred, and the amount of the compound copolymerizable with olefin and containing at least one free carboxyl group in the olefin copolymer is in the range of about 1 to about 40% by weight, preferably about 2 to about 30% by weight, more preferably about 3 to about 25% by weight, based on the total weight of the olefin copolymer, for example, about 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 or 25% by weight, but not limited thereto. In particular, the amount of the compound copolymerizable with olefin and containing at least one free carboxyl group in the olefin copolymer is about 3 to about 30% by weight, preferably about 5 to about 25% by weight, for example, about 7 to about 20% by weight.

[0018] Exemplary ethylene-acrylic acid (E-AA) and ethylene-methacrylic acid (E-MAA) copolymers are available under the tradenames PRIMACOR™, available from The Dow Chemical Company, NUCREL™, available from EI DuPont de Nemours, and ESCOR™, available from ExxonMobil Chemical Company, and are described in U.S. Pat. Nos. 4,599,392, 4,988,781, and 5,938,437. Further non-limiting examples include the Lucalen™ series of low / medium / high density ethylene / acrylic acid / acrylate copolymers and ethylene / butyl / acrylate copolymers available from Lyondellbasell, the Licocene™ series of maleic anhydride modified low crystalline metallocene propylene-ethylene copolymers available from Clariant, and the Lotader™ and Orevac™ series of ethylene terpolymers with reactive functional groups such as maleic anhydride or epoxides (glycidyl methacrylate) available from SK Functional Polymers.

[0019] In various embodiments, the polymer composition according to the present invention preferably further comprises at least one olefin homopolymer and / or at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group, i.e. the polymer composition according to the present invention may comprise a further olefinic polymer component, which is different from said at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group.

[0020] In the context of this specification, the olefin may be selected from ethylene and α-olefins having 3 to 20 carbon atoms, such as α-olefins having 4 to 12 carbon atoms, such as α-olefins having 4 to 8 carbon atoms, such as 1-butene, 1-hexene or 1-octene.

[0021] Any comonomer may be selected from non-polar components, particularly from the list of olefin monomers above, but any comonomer may alternatively be selected from polar comonomers copolymerizable with olefins. As polar comonomers, comonomers containing hydroxyl, alkoxy, carbonyl, ether or ester groups, or mixtures thereof, may be used. In particular, comonomers containing ester groups may be used as polar comonomers.

[0022] In various embodiments, the additional olefinic polymer component, different from the at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group, is selected from the group consisting of ethylene homopolymers, propylene homopolymers, and mixtures of one or more ethylene homopolymers and one or more propylene homopolymers.

[0023] In various embodiments, the additional olefinic polymer component may be selected from the group consisting of low density polyethylene (LDPE) homopolymers or copolymers, linear low density polyethylene (LLDPE) homopolymers and copolymers, medium density polyethylene (MDPE) homopolymers and copolymers, high density polyethylene (HDPE) homopolymers and copolymers, high molecular weight polyethylene (PE-HMW) homopolymers and copolymers, ultra-high molecular weight polyethylene (PE-UHMW) homopolymers, and polypropylene homopolymers and copolymers, and mixtures thereof.

[0024] Thus, in various embodiments, the additional olefinic polymer component, which is different from the at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and containing at least one free carboxyl group, can generally be a homopolymer or a copolymer. If it is a copolymer, such as a polyethylene (PE) or polypropylene (PP) copolymer, it can be a binary copolymer, i.e., the polymer contains ethylene or propylene, respectively, and one comonomer, or a terpolymer, i.e., the polymer contains ethylene or propylene, respectively, and two or three comonomers.

[0025] Examples of suitable polyolefins, different from the at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and containing at least one free carboxyl group, include polyethylenes available under the trademarks Alathon™, Dyneema™, Polythen™, Spectra™, Trolen™, and Vestolen™ from Lyondellbasell and Lupolen™ from Lyondellbasell.

[0026] In various embodiments, the at least one olefinic polymer component, different from the at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group, is present in the polymer composition in an amount of about 1 to 98 wt.%, such as about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 98 wt.%, preferably about 3 to 90 wt.%, more preferably about 5 to 80 wt.%, even more preferably about 7 to 70 wt.%, and especially about 10 to 65 wt.%, based on the total weight of the polymer composition.

[0027] Methods for producing the aforementioned olefinic polymers are generally known in the art. Further details of the production of ethylene (co)polymers by high pressure radical polymerization can be found, inter alia, in Encyclopedia of Polymer Science and Engineering, Vol. 6 (1986), pages 383-410, and Encyclopedia of Materials: Science and Technology, 2001 Elsevier Science Ltd.: “Polyethylene: High-pressure, R. Klimesch, D. Littmann and F.-O. Maehling, pages 7181-7184.

[0028] In various embodiments, the polymer composition has a T of at least 85° C., preferably at least 90° C., more preferably at least 100° C., even more preferably at least 120° C., and particularly at least 130° C. g At least 85°C T g is preferred from the standpoint of pasteurization compatibility, and a T of at least 130° C. g is preferred from the standpoint of sterility of the resulting product.

[0029] The physical properties of the polymer composition, such as melt viscosity, rheology, tensile strength, surface hardness, coefficient of friction, abrasion resistance, and crystallinity, may be further tailored and modified by the incorporation of one or more additional components, including, but not limited to, additives selected from the group consisting of additional polymers, tackifiers, antistatic agents, slip / release agents, waxes, stabilizers, antioxidants, plasticizers, nucleating agents, thixotropic agents, pigments and colorants, dyes, fluorescent agents, and fillers including nanofillers. Typically, these additives may be present at less than 5 wt.% each, more preferably less than 2 wt.%, and even more preferably less than 0.5 wt.% each, based on the total weight of the polymer composition.

[0030] For example, the incorporation of one or more waxes can help modify the coefficient of friction. Suitable waxes for use in the present invention include paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, by-product polyethylene wax, Fischer-Tropsch wax, oxidized Fischer-Tropsch wax, and functionalized waxes such as hydroxystearamide wax and fatty amide wax. High density low molecular weight polyethylene wax, by-product polyethylene wax, and Fischer-Tropsch wax are conventionally referred to in the art as synthetic high melting point waxes. Modified waxes, including vinyl acetate modified waxes such as AC-400 (Honeywell) and MC-400 (available from Marcus Oil and Company), Epolene C-18 (available from Eastman Chemical), and maleic anhydride modified waxes and oxidized waxes such as AC-575A and AC-575P (available from Honeywell), are also useful in the practice of the invention. Callista® 122, 158, 144, 435 and 152 available from Shell Lubricants, Houston, Texas; Fischer-Tropsch waxes Sasolwax C80 and Sasolwax H-1, H-4 and H-8 available from Sasol Wax are also preferred waxes for use in the practice of the present invention. Hydrogenated castor oil is also suitable for use in this context.

[0031] Paraffin waxes that can be used in the practice of the present invention include Pacemaker® 30, 32, 35, 37, 40, 42, 45 and 53 available from Citgo Petroleum, Co.; Astor Okerin® 236 available from Honeywell; R-7152 Paraffin Wax available from Moore & Munger; R-2540 available from Moore & Munger; and other paraffin waxes available from Sasol Wax, for example under the product names Sasolwax 5603, 6203 and 6805.

[0032] Microcrystalline waxes useful in the context of the present invention include those having 50% or more by weight of cyclic or branched alkanes having between 30 and 100 carbon atoms. They are generally less crystalline than paraffin and polyethylene waxes and have melting points greater than about 70° C. Examples include Victory® Amber Wax, a wax with a melting point of 70° C. available from Baker Petrolite Corp.; Bareco® ES-796 Amber Wax, a wax with a melting point of 70° C. available from Bareco; Besquare® 175 Amber Waxes and Besquare® 195 Amber Waxes, both microcrystalline waxes with melting points of 80° C. and 90° C. available from Baker Petrolite Corp.; Indramic® 91, a wax with a melting point of 90° C. available from Industrial Raw Materials; and Petrowax® 9508 Light, a wax with a melting point of 90° C. available from Petrowax. Other examples of microcrystalline waxes include Sasolwax 3971 available from Sasol Wax, and Microwax K4001 available from Alfred Kochem GmBH.

[0033] Exemplary high density, low molecular weight polyethylene waxes that fall into this category include Polywax™ 500, Polywax™ 1500, and Polywax™ 2000, which are ethylene homopolymers available from Backer Petrolite Corp. Polywax™ 2000 has a molecular weight of approximately 2000, a Mw / Mn of approximately 1.0, and a viscosity of about 0.97 g / cm at 16° C. 3 It has a density of 100 and a melting point of approximately 126 °C.

[0034] The incorporation of one or more polyorganosiloxanes, particularly silanol-terminated polydialkylsiloxanes as well as end-capped polyorganosiloxanes, can improve the abrasion resistance of the resulting coating. Non-limiting examples of commercially available polyorganosiloxanes suitable for use in the context of the present invention include:

[0035] Stabilizers and / or antioxidants may be added to protect the polymer composition from degradation caused by reactions with oxygen induced by such things as heat and light.

[0036] Among suitable applicable stabilizers or antioxidants, mention may be made of high molecular weight hindered phenols and polyfunctional phenols such as phenols containing sulfur and phosphorus. Hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that also contain sterically bulky groups in close proximity to their phenolic hydroxyl groups. In particular, tertiary butyl groups are generally substituted on the benzene ring in at least one of the ortho positions relative to the phenolic hydroxyl group. The presence of these sterically bulky substituents in the vicinity of the hydroxyl group leads to a retardation of its stretching frequency and, accordingly, reactivity; thus, this hinderance confers phenolic compounds with stabilizing properties. Representative hindered phenols include 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene; pentaerythrityl tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; 4,4'-methylenebis(2,6-tert-butyl-phenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5 triazine; di-n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxy-benzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionate].

[0037] The performance of these antioxidants may be further enhanced by utilizing known synergists, such as thiodipropionic acid esters and thiodipropionic acid phosphites, in conjunction with the above antioxidants. Distearyl thiodipropionate is particularly useful.

[0038] Such antioxidants are commercially available from Ciba Specialty Chemicals and include Irganox® 565, 1010, 1076 and 1726, which are hindered phenols. These are primary antioxidants that act as radical scavengers and may be used alone or in combination with other antioxidants, such as phosphite antioxidants, such as Irgafos® 168, available from Ciba Specialty Chemicals. Phosphite catalysts are considered secondary catalysts and are generally not used alone. They are primarily used as decomposers of peroxides. Other available catalysts are Cyanox® LTDP, available from Cytec Industries, and Ethanox® 330, available from Albemarle Corp. Many such antioxidants are available either alone or in combination with other such antioxidants.

[0039] Fillers suitable for use in the context of the present invention are generally known in the art and can be classified as organic and inorganic fillers, non-limiting examples of which include silicates, talc, calcium carbonate, clay and carbon black. For example, the use of layered silicates allows the adjustment of the mechanical strength of the coating, allowing the adjustment of processing and final end-use properties.

[0040] Thus, particularly suitable and preferred polymer compositions of the invention, which when applied to metal sheets, preferably selected from aluminium sheets and / or aluminium alloy sheets, provide high adhesive strength of the coating, comprise or consist of: i) one or more olefin copolymers comprising a compound copolymerizable with olefins and containing at least one free carboxyl group, preferably one or more olefin copolymers selected from ethylene acrylic acid (E-AA) and ethylene methacrylic acid (E-MAA) copolymers, in total at least 30% by weight based on the total weight of the polymer composition, wherein the amount of said copolymerizable compound is in the range of 3 to 30% by weight, preferably 5 to 25% by weight, more preferably 7 to 20% by weight, based on the total weight of the olefin copolymer; ii) at least 10% by weight, preferably at least 30% by weight, more preferably at least 40% by weight, but not more than 70% by weight, in total, relative to the total weight of the polymer composition, of one or more olefin homopolymers and / or one or more olefin copolymers of at least one olefin and at least one compound copolymerizable with the olefin and not containing free carboxyl groups, preferably selected from ethylene homopolymers, propylene homopolymers and mixtures of one or more ethylene homopolymers and one or more propylene homopolymers, particularly preferably selected from high density polyethylene (HDPE) homopolymers; and iii) additives different from compounds i) and ii) which together amount to less than 20% by weight, preferably less than 15% by weight, relative to the total weight of the polymer composition, wherein preferably each additive is present in an amount of less than 5% by weight, more preferably less than 2% by weight, relative to the total weight of the polymer composition.

[0041] In a further aspect, the present invention further comprises the steps of: i) feeding a metal sheet into an extrusion coating apparatus; and ii) extrusion coating at least one surface of the metal sheet with a polymer composition according to the invention, as described herein above, to obtain a coated metal sheet. The present invention provides a method for producing a coated metal sheet, comprising:

[0042] In various embodiments, the metal sheet is an aluminum sheet or an aluminum alloy sheet.

[0043] In various embodiments, the metal sheet may be preheated prior to step i) of the present invention. Preheating the metal sheet can improve adhesion of the polymer composition extruded thereon. For example, the metal sheet may be heated to a temperature of about 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170° C.

[0044] The polymer composition may be applied to only one surface of the metal sheet, or to more than one surface of the metal sheet. If more than one surface of the metal sheet is coated with the polymer composition of the present invention, this can be achieved by single-sided or double-sided extrusion coating.

[0045] The advantageous physical properties of the polymer compositions of the present invention allow them to be extrusion applied to the surface of metal sheets in the form of a curtain, thus covering the entire width of the metal sheets fed into and passing through the extrusion device, and eliminating the need to distribute the coating composition by means of rolls or the like. This speeds up the entire process, making the coating process more time-, energy- and resource-efficient compared to current methods. Thus, in various embodiments, the polymer composition is applied in the form of a curtain. Typically, this is achieved by positioning and adapting the extruder nozzle to discharge a curtain of extruded product.

[0046] Once the polymer composition of the present invention has been extrusion coated onto at least one surface of the metal sheet, the coated metal sheet may be cooled, for example, using an air-based and / or water-based cooling system. Thus, in various embodiments, the method of the present invention comprises step iii) of cooling the coated metal sheet. Prior to that, or alternatively, according to some embodiments, the coated metal sheet obtained after step ii) of the present invention may be heated immediately after extrusion coating of the polymer composition onto the metal sheet surface to a temperature 10 or 20° C. higher, preferably 30° C. higher than the melting point of the polymer composition, for a time of about 0.5 to 10 seconds, in particular 0.5 to 3 seconds, which results in an optimized adhesion of the coating to the metal sheet and relaxation of the entire extruded coating.

[0047] According to a preferred embodiment, the resulting coating has a thickness of about 0.2-30 μm, preferably about 0.5-20 μm, more preferably about 1-15 μm, even more preferably 2-12 μm, for example about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 μm.

[0048] Moreover, according to various embodiments, the method of the present invention further comprises the step of subjecting the metal sheet to a pretreatment process, preferably a chromium-free pretreatment process, prior to step i).

[0049] In various embodiments, the method of the present invention preferably does not include the application of an adhesive layer prior to step ii) or of an additional and different polymeric material coextruded with the polymer composition in step ii) In further various embodiments, the method of the present invention preferably does not include a pretreatment step of the metal sheet prior to step i).

[0050] It is understood that all embodiments relating to the compositions, methods and uses of the invention disclosed herein are equally applicable to articles formed therefrom / thereby, and vice versa.

[0051] Thus, according to a further aspect, the present invention also relates to a coated metal sheet obtainable in a method as described herein.

[0052] In yet another aspect, the present invention relates to the use of the coated metal sheet of the present invention for producing food or beverage containers, preferably beverage cans, and more particularly beverage can ends.

Claims

1. 1. A polymer composition for extrusion coating metal sheets, comprising at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and comprising at least one free carboxy group, the at least one olefin copolymer is present in an amount of about 2 to 99 wt.%, for example 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 99 wt.%, preferably in an amount of about 10 to 95 wt.%, more preferably about 20 to 80 wt.%, even more preferably about 25 to 60 wt.%, and especially about 30 to 60 wt.%, based on the total weight of the polymer composition; Polymer compositions.

2. 2. The polymer composition of claim 1, wherein the amount of the compound copolymerizable with the olefin and comprising at least one free carboxy group in the olefin copolymer ranges from about 1 to about 40 wt %, preferably from about 2 to about 30 wt %, and more preferably from about 3 to about 25 wt %, based on the total weight of the olefin copolymer.

3. T of composition ｇ 2. The polymer composition according to claim 1, wherein the temperature is at least 85°C, preferably at least 90°C, more preferably at least 100°C, even more preferably at least 120°C, especially at least 130°C.

4. 10. The polymer composition of claim 1, further comprising at least one olefin homopolymer and / or at least one olefin copolymer of at least one olefin and at least one compound copolymerizable with the olefin and not containing a free carboxy group.

5. 5. The polymer composition of claim 4, comprising at least one polymer selected from the group consisting of ethylene homopolymers or copolymers, propylene homopolymers or copolymers, and mixtures of one or more ethylene homopolymers and / or copolymers with one or more propylene homopolymers and / or copolymers.

6. 6. The polymer composition of claim 5, comprising at least one ethylene homopolymer selected from the group consisting of low density polyethylene (LDPE) homopolymers or copolymers, linear low density polyethylene (LLDPE) homopolymers and copolymers, medium density polyethylene (MDPE) homopolymers and copolymers, high density polyethylene (HDPE) homopolymers and copolymers, high molecular weight polyethylene (PE-HMW) homopolymers and copolymers, ultra-high molecular weight polyethylene (PE-UHMW) homopolymers, and polypropylene homopolymers and copolymers, and mixtures thereof.

7. i) comprising a total of at least 30 wt. % of one or more olefin copolymers copolymerizable with olefins and containing at least one free carboxy group, based on the total weight of the polymer composition, wherein the amount of copolymerizable compound ranges from 3 to 30 wt. % based on the total weight of the olefin copolymer; ii) comprising a total of at least 10 wt. % but not more than 70 wt. % of one or more olefin homopolymers and / or one or more olefin copolymers of at least one olefin and at least one compound copolymerizable with the olefin and not containing a free carboxy group, based on the total weight of the polymer composition; and iii) additives different from compounds i) and ii) in an amount of less than 20 wt. % in total relative to the total weight of the polymer composition, preferably each additive being present in an amount of less than 5 wt. % relative to the total weight of the polymer composition; The polymer composition of claim 1.

8. i) feeding a metal sheet into an extrusion coating apparatus; and ii) extrusion coating at least one surface of a metal sheet with the polymer composition of any one of claims 1 to 6 to obtain a coated metal sheet.

1. A method for producing a coated metal sheet, comprising:

9. 9. The method of claim 8, wherein the metal sheet is an aluminum sheet or an aluminum alloy sheet.

10. iii) cooling the coated metal sheet 9. The method of claim 8, comprising:

11. The method of claim 8, wherein the thickness of the coating is about 0.2 to 30 μm, preferably about 0.5 to 20 μm, more preferably about 1 to 15 μm, and even more preferably about 2 to 12 μm.

12. 9. The method according to claim 8, further comprising the step of subjecting the metal sheet to a pretreatment process, preferably a chromium-free pretreatment process, before step i).

13. does not include the application of an adhesive layer before step ii), - does not involve the co-extrusion of an additional polymeric material different from the polymer composition according to any one of claims 1 to 7 during step ii), and / or does not include a step of pretreating the metal sheet prior to step i), The method of claim 8.

14. A coated metal sheet obtainable by the method of claim 8.

15. 15. Use of the coated metal sheet according to claim 14 for the manufacture of food or beverage containers, preferably beverage cans.