Articles containing polyethylene-based ionomers

Abstract

The present invention relates to an article comprising an ethylene polymer, wherein the ethylene polymer comprises or consists of: a) polymer units derived from ethylene; b) polymer units derived from a cationic monomer; c) polymer units derived from at least one anionic monomer; (i) wherein the total content (IPC) of polymer units derived from the cationic monomer and the anionic monomer is > 2.5 and < 9.0 wt.-% relative to the total weight of the ethylene polymer; (ii) wherein the melt flow index (MFI2) of the ethylene polymer is > 0.01 and < 20.0 dg / min, wherein MFI2 is the melt flow index determined according to ISO 1133-1 :2011 at 190 °C and measured at 2.16 kg; and (iii) wherein the value of MFI2 / IPC is > 0.01 and < 8.0, wherein IPC and MFI2 are as defined herein.

Description

Technical Field

[0001] This invention relates to an article comprising an ethylene polymer derived from ethylene and specific cationic and anionic monomers. The invention also relates to a method for preparing such an article and its use. Background Technology

[0002] For many products, such as those in automotive, consumer goods, and packaging applications, a key design requirement for manufacturing these products is lightweighting while maintaining the necessary tensile strength. Another recent requirement is the development of materials that can be relatively easily recycled.

[0003] Lightweighting can be achieved by using suitable polymers, such as polyethylene, to form such articles. Polyethylene, or ethylene polymer, is a versatile polymer and finds applications in a wide range of things, from films to pipes to cable insulation. Products made from polyethylene can provide the desired lightweighting and have historically been used as alternatives to metals and rubber, and can be easily recycled through conventional mechanical and chemical processing. While ethylene polymers provide the desired lightweighting, this polymer may not always provide the necessary tensile properties, such as tensile stress at break, tensile strain at break, and modulus of elasticity (Young's modulus). Typically, to obtain these properties, fillers such as talc or carbon black, or reinforcing fibers such as glass fiber or carbon fiber, must be introduced into the ethylene polymer.

[0004] However, adding these fillers not only increases the production cost of the polymer, but also often comes at the expense of deteriorating other properties, such as color stability and transparency, while improving certain mechanical properties. In some cases, including these fillers in the polymer may encounter health regulatory hurdles when articles made from this polymer are to be commercially sold.

[0005] Another possible way to increase the mechanical properties of polymers is to crosslink the polymer chains. For example, XLPE (crosslinked polyethylene) is obtained through a free radical reaction using dicumyl peroxide as an initiator, forming a chemically bonded molecular network. This reaction generates byproducts such as water, methane, and α-methylstyrene, making XLPE products unsuitable for food contact packaging applications.

[0006] Furthermore, products such as cross-linked polymers are difficult to recycle, making them less suitable for use in situations where there is a growing demand for product recyclability and sustainability. Additionally, there is a need to improve the tensile properties of membranes containing recycled polymers without compromising their tensile strength.

[0007] Therefore, the object of the present invention is to provide an article which can be prepared from an ethylene polymer that can impart suitable tensile properties without the introduction of fillers or crosslinking of the ethylene polymer. Summary of the Invention

[0008] Therefore, the object of the present invention is achieved by an article comprising an ethylene polymer, wherein the ethylene polymer comprises or is composed of the following:

[0009] (a) Polymer units derived from ethylene; and

[0010] (b) Polymer units of cationic monomers derived from free formula (I)

[0011] (I)

[0012] R1 is independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms;

[0013] 'X' is independently selected from 'O' or 'NH', preferably 'X' is 'O';

[0014] R2 is an alkyl group having 1-40 carbon atoms, preferably 1-5 carbon atoms;

[0015] R3 and R4 are each independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms; and

[0016] R5 is independently selected from hydrogen or alkyl groups having 1-20 carbon atoms, preferably 1-5 carbon atoms.

[0017] Preferably, each of R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen; and

[0018] (c) Polymer units derived from at least one anionic monomer selected from the following formulas.

[0019] (II)

[0020] (III)

[0021] (IV)

[0022] (V)

[0023] Each of R6, R7 and R9 is independently selected from hydrogen or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms;

[0024] R8 and R 10 Each is independently selected from alkyl groups having 1-40 carbon atoms;

[0025] 'Y', 'V', and 'W' are independently selected from 'O' or 'NH'; 'n' is a number from 1 to 20, preferably 1 to 10, preferably 1 to 5; 'Z' is independently selected from -SO3 or -C(O)O;

[0026] The preferred anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and

[0027] Cationic monomers are , where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0028] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5% by weight and ≤9.0% by weight relative to the total weight of the ethylene polymer, preferably ≥3.0% by weight and ≤8.5% by weight, preferably ≥3.0% by weight and ≤7.5% by weight, and preferably ≥4.0% by weight and ≤7.0% by weight;

[0029] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, preferably ≥0.01 and ≤15.0 dg / min, preferably ≥0.08 and ≤14.0 dg / min, preferably ≥0.05 and ≤5.0 dg / min, preferably ≥0.08 and ≤5.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0030] (iii) Wherein the value of MFI2 / IPC is ≥0.01 and ≤8.0, preferably ≥0.001 and ≤6.0, preferably ≥0.01 and ≤4.7, preferably ≥0.02 and ≤4.0, preferably ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.02 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

[0031] Preferably, the article comprises an ethylene polymer, wherein the ethylene polymer comprises or is composed of the following:

[0032] (a) Polymer units derived from ethylene; and

[0033] (b) Polymer units of cationic monomers derived from free formula (I):

[0034] (I)

[0035] R1 is independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms;

[0036] 'X' is independently selected from 'O' or 'NH', preferably 'X' is 'O';

[0037] R2 is an alkyl group having 1-40 carbon atoms, preferably 1-5 carbon atoms;

[0038] R3 and R4 are each independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms; and

[0039] R5 is independently selected from hydrogen or alkyl groups having 1-20 carbon atoms, preferably 1-5 carbon atoms.

[0040] Preferably, each of R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen; and

[0041] (c) Polymer units derived from at least one anionic monomer selected from the following formulas.

[0042] (II)

[0043] (III)

[0044] (IV)

[0045] (V)

[0046] Each of R6, R7 and R9 is independently selected from hydrogen or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms;

[0047] R8 and R 10 Each of them is independently selected from alkyl groups having 1 to 40 carbon atoms;

[0048] 'Y', 'V', and 'W' are independently selected from 'O' or 'NH'; 'n' is a number from 1 to 20, preferably 1 to 10, preferably 1 to 5; 'Z' is independently selected from -SO3 or -C(O)O;

[0049] Preferably, the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0050] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5% and ≤9.0% by weight relative to the total weight of the ethylene polymer.

[0051] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0052] (iii) where the value of MFI2 / IPC is ≥0.01 and ≤8.0, and IPC and MFI2 are as defined herein.

[0053] Preferably, the article comprises >80.0% by weight of an ethylene polymer relative to the total weight of the article.

[0054] Preferably, R8 and R 10 Each of them is independently selected from alkyl groups having 1-20, preferably 1-10, preferably 1-5 carbon atoms.

[0055] Preferably, the article comprises ≥88.0% by weight, preferably ≥90.0% by weight, preferably ≥95.0% by weight, and preferably ≥95.0% by weight and ≤100.0% by weight of ethylene polymer relative to the total weight of the article.

[0056] Polymer units derived from cationic and anionic monomers can be derived from specific ion-pair compounds copolymerized with ethylene. Particularly preferred is that the article is substantially free of fillers selected from talc, carbon black, and reinforcing fibers. Particularly preferred is that the ethylene polymer is substantially free of fillers selected from talc, carbon black, and reinforcing fibers.

[0057] The terms used herein do not substantially imply that the concentration of fillers such as talc, carbon black, or reinforcing fibers is less than 100 ppm by weight, preferably 50 ppm by weight, and preferably 0 ppm by weight of the article or the ethylene polymer.

[0058] The inventors have surprisingly discovered that articles made from the ethylene polymer exhibit excellent tensile properties even without the use of conventional fillers typically used to improve the tensile and other mechanical properties of polymers, or even without crosslinking the ethylene polymer. In another aspect of the invention, the invention relates to the use of the ethylene polymer defined herein for improving the tensile properties of multilayer sheets or films, preferably wherein such tensile properties are any one of tensile modulus, tensile stress at break, and tensile strain at break.

[0059] Specifically, the inventors have surprisingly discovered that by copolymerizing ethylene polymers with ionomers in a high-pressure reactor at a temperature of ≥150°C and ≤255°C, at a pressure of ≥190 MPa and ≤210 MPa, and in the presence of one or more free radical initiators at a concentration of ≥0.27 mmol% and ≤0.6 mmol% relative to the total amount of ethylene monomers, and in the presence of >0.01 and <0.1 mol%, preferably ≥0.05 and ≤0.1 mol%, of a chain transfer agent (CTA), ethylene polymers with specific melt flow indices and ionomer contents are obtained, which helps to impart desired properties.

[0060] Particularly preferred is that the ethylene polymer is free of crosslinks. The term "free of crosslinks" means that the ethylene polymer chains are not crosslinked using crosslinking agents, such as peroxides or azo compounds.

[0061] In one aspect of the invention, the present invention relates to the use of the article for improving the tensile properties of multilayer sheets or multilayer films. For example, tensile properties include tensile modulus, tensile stress at break, and tensile strain at break.

[0062] For example, the article of the present invention is selected to have:

[0063] (a) Tensile modulus ≥550 MPa and ≤1100 MPa when measured according to ISO 527-1; and

[0064] (b) The tensile stress at break, ≥150 MPa and ≤300 MPa, as determined according to ISO 527-1; and

[0065] (c) Tensile strain at break of ≥600% and ≤1500% as determined by ISO 527-1.

[0066] The article can be any suitable article that can be prepared by extruding ethylene polymers. The extrusion process can also include reactive extrusion, co-extrusion, extrusion coating, and cast film extrusion processes. Preferably, the article is selected from layers of packaging articles, containers, tubes, hygiene products, automotive parts, sheets, hinge components, cable insulation layers, cable sheaths, co-extruded multilayer films or multilayer sheets, and preferably, the article is a multilayer film or multilayer sheet.

[0067] Preferably, the article comprises an ethylene polymer, which includes or is composed of the following:

[0068] (a) Polymer units derived from ethylene;

[0069] (b) Polymer units of anionic monomers derived from free-form representations:

[0070]

[0071] R6 is an alkyl group having 1-5 carbon atoms; and

[0072] (c) Polymer units of cationic monomers derived from free formulas:

[0073] Where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0074] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5 and ≤9.0 wt% relative to the total weight of the ethylene polymer, preferably ≥3.0 and ≤8.5 wt%, preferably ≥3.0 and ≤7.5 wt%, preferably ≥4.0 and ≤7.0 wt%;

[0075] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, preferably ≥0.01 and ≤15.0 dg / min, preferably ≥0.08 and ≤14.0 dg / min, preferably ≥0.05 and ≤5.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0076] (iii) Where the value of MFI2 / IPC is ≥0.01 and ≤8.0, preferably ≥0.001 and ≤6.0, preferably ≥0.01 and ≤4.7, preferably ≥0.02 and ≤4.0, preferably ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.02 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

[0077] Preferably, the article containing the ethylene polymer comprises or is composed of the following substances:

[0078] (a) Polymer units derived from ethylene;

[0079] (b) Polymer units of anionic monomers derived from free-form representations:

[0080]

[0081] R6 is an alkyl group having 1-5 carbon atoms; and

[0082] (c) Polymer units of cationic monomers derived from free formulas:

[0083] Where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0084] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5% and ≤9.0% by weight relative to the total weight of the ethylene polymer.

[0085] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0086] (iii) where the value of MFI2 / IPC is ≥0.01 and ≤8.0, and IPC and MFI2 are as defined herein.

[0087] Preferably, the article containing the ethylene polymer comprises or is composed of the following:

[0088] (a) Polymer units derived from ethylene;

[0089] (b) Polymer units of anionic monomers derived from free-form representations:

[0090]

[0091] R6 is an alkyl group having 1-5 carbon atoms; and

[0092] (c) Polymer units of cationic monomers derived from free formulas:

[0093] Where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0094] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5% and ≤9.0% by weight relative to the total weight of the ethylene polymer.

[0095] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0096] (iii) where the value of MFI2 / IPC is ≥0.01 and ≤8.0, and IPC and MFI2 are as defined herein.

[0097] Preferably, the cationic monomer and the anionic monomer are present in a stoichiometric ratio of 1:1.

[0098] Therefore, the content of MFI2 and the content of cationic and anionic monomers (IPC) must be selected such that the MFI2 / IPC value is between ≥0.01 and ≤8.0.

[0099] Preferably, the article containing the ethylene polymer comprises or is composed of the following:

[0100] (a) Polymer units derived from ethylene;

[0101] (b) Polymer units of anionic monomers derived from free-form representations:

[0102]

[0103] R6 is an alkyl group having 1-5 carbon atoms; and

[0104] (c) Polymer units of cationic monomers derived from free formulas:

[0105] Where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0106] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤8.5% by weight relative to the total weight of the ethylene polymer, preferably ≥3.0 and ≤7.5% by weight, and more preferably ≥4.0 and ≤7.0% by weight;

[0107] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, and more preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and

[0108] (iii) Where the value of MFI2 / IPC is ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.02 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

[0109] Preferably, the article containing the ethylene polymer comprises or is composed of the following:

[0110] (a) Polymer units derived from ethylene;

[0111] (b) Polymer units of anionic monomers derived from free-form representations:

[0112]

[0113] R6 is an alkyl group having 1-5 carbon atoms; and

[0114] (c) Polymer units of cationic monomers derived from free formulas:

[0115] Where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen;

[0116] (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤8.5% by weight relative to the total weight of the ethylene polymer;

[0117] (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤14.0 dg / min, preferably ≥0.05 and ≤5.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index determined according to ISO 1133-1:2011 at 190°C and measured at 2.16 kg; and

[0118] (iii) Where the value of MFI2 / IPC is ≥0.01 and ≤4.7, preferably ≥0.02 and ≤4.0, preferably ≥0.01 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

[0119] Preferably, the article comprises >80.0% by weight of an ethylene polymer relative to the total weight of the article.

[0120] Preferably, R2 is ethyl, R5 is hydrogen, and R3 and R4 are methyl. Preferably, R2 is ethyl, R5 is hydrogen, and R3 and R4 are methyl. Preferably, R2 is ethyl, R5 is hydrogen, and R3 is tert-butyl and R4 is hydrogen. Preferably, R2 is ethyl, and R3, R4 and R5 are hydrogen.

[0121] The MFI2 / IPC value indicates the need to select a suitable ethylene polymer—one with a specific combination of melt flow index and the amount of polymer units derived from anionic and cationic monomers. Therefore, only specific ethylene polymers with a specific combination of melt flow index (MFI2) and the amount of polymer units derived from ion-pair compounds will possess the desired tensile properties.

[0122] The ethylene polymer has (i) a total content (IPC) of polymer units derived from cationic and anionic monomers of ≥2.5 and ≤9.0 wt% relative to the total weight of the ethylene polymer, preferably ≥3.0 and ≤8.5 wt%, preferably ≥3.0 and ≤7.5 wt%, preferably ≥4.0 and ≤7.0 wt%; and (ii) a total content of ethylene-derived polymer units of ≥91.0 and ≤97.5 wt% relative to the total weight of the ethylene polymer, preferably ≥91.5 and ≤97.0 wt%, preferably ≥92.5 and ≤97.0 wt%, preferably ≥93.0 and ≤96.0 wt%.

[0123] Preferably, the ethylene polymer has (i) a total content (IPC) of polymer units derived from cationic and anionic monomers of ≥3.0 and ≤7.5 by weight relative to the total weight of the ethylene polymer; and (ii) a total content of polymer units derived from ethylene of ≥92.5 and ≤97.0 by weight relative to the total weight of the ethylene polymer.

[0124] Preferably, the ethylene polymer has (i) a total content (IPC) of polymer units derived from cationic and anionic monomers of ≥4.0 and ≤7.0 by weight relative to the total weight of the ethylene polymer; and (ii) a total content of polymer units derived from ethylene of ≥93.0 and ≤96.0 by weight relative to the total weight of the ethylene polymer.

[0125] Preferably, (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤14.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, and more preferably ≥0.08 and ≤2.0 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) the MFI2 / IPC value is ≥0.01 and ≤4.7, preferably ≥0.01 and ≤1.0, and more preferably ≥0.01 and ≤0.4, wherein IPC and MFI2 are as defined herein.

[0126] Preferably, (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤14.0 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5 wt% relative to the total weight of the ethylene polymer; and (c) the MFI2 / IPC value is ≥0.01 and ≤4.7, wherein IPC and MFI2 are as defined herein.

[0127] Preferably, (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤2.0 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5 wt% relative to the total weight of the ethylene polymer; and (c) the MFI2 / IPC value is ≥0.01 and ≤1.0, wherein IPC and MFI2 are as defined herein.

[0128] Preferably, (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤14.0 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5 wt% relative to the total weight of the ethylene polymer; and (c) the MFI2 / IPC value is ≥0.026 and ≤4.7, wherein IPC and MFI2 are as defined herein.

[0129] Particularly preferred is that the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , wherein 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen, (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) wherein the value of MFI2 / IPC is ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.3, wherein IPC and MFI2 are as defined herein.

[0130] Preferably, (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, preferably ≥0.09 and ≤0.5 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) the MFI2 / IPC value is ≥0.01 and ≤0.4, preferably ≥0.01 and ≤0.3, preferably ≥0.02 and ≤0.2, wherein IPC and MFI2 are as defined herein.

[0131] Preferably, the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , wherein 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen, (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.09 and ≤0.5 dg / min; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5 wt% relative to the total weight of the ethylene polymer; and (c) wherein the value of MFI2 / IPC is >0.02 and <0.4, wherein IPC and MFI2 are as defined herein.

[0132] Preferably, the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , wherein 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen, (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.09 and ≤0.5 dg / min; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥4.0 and ≤7.0 wt% relative to the total weight of the ethylene polymer; and (c) wherein the value of MFI2 / IPC is >0.01 and <0.2, wherein IPC and MFI2 are as defined herein.

[0133] Preferably, the article comprises ≥88.0% by weight, preferably ≥90.0% by weight, preferably ≥95.0% by weight, and ≤100.0% by weight, relative to the total weight of the article; and / or the article is substantially free of fillers selected from talc, carbon black, and reinforcing fibers. Non-limiting examples of reinforcing fibers include glass, including short glass fibers and carbon fibers. Preferably, the article comprises ≤12.0% by weight, preferably ≤10.0% by weight, preferably ≤5.0% by weight, and preferably ≥0% by weight and ≤5.0% by weight, relative to the total weight of the article, additives selected from pigments, UV stabilizers, antioxidant stabilizers, and combinations thereof.

[0134] cationic monomers

[0135] The cationic monomer shown in formula (I) can be derived from the quaternized form of a free base selected from the following:

[0136] 2-(dimethylamino)ethyl acrylate,

[0137] 2-(diethylamino)ethyl acrylate,

[0138] 2-(diethylamino)ethyl methacrylate,

[0139] 2-(dimethylamino)ethyl methacrylate,

[0140] 2-(tert-butylamino)ethyl methacrylate,

[0141] N-[3-(hexahydro-1H-azaphosphon-1-yl)-1,1-dimethylpropyl]-2-acrylamide,

[0142] N-[2-(tetrahydro-1,4-oxazapyridine-4(5H)-yl)ethyl]-2-acrylamide,

[0143] N-[2-[methyl(tetrahydro-2H-pyran-4-yl)amino]ethyl]-2-acrylamide,

[0144] N-[3-(hexahydro-4-methyl-1H-1,4-diaza-1-yl)propyl]-2-acrylamide,

[0145] N-[1-Methyl-2-(methylamino)propyl]-2-acrylamide,

[0146] N-[2-(methylamino)propyl]-2-acrylamide,

[0147] N-[2-Methyl-2-(methylamino)propyl]-2-acrylamide,

[0148] N-[1-Methyl-2-(methylamino)ethyl]-2-acrylamide,

[0149] N-[1-Methyl-3-(methylamino)butyl]-2-acrylamide, and

[0150] N-[1-Methyl-2-(methylamino)propyl]-2-acrylamide.

[0151] Preferably, the cationic monomer of formula (I) is derived from a quaternized form of a free base selected from the following: 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate and 2-(tert-butylamino)ethyl methacrylate.

[0152] The term "quaternized form of free base" refers to quaternary ammonium compounds formed from free bases.

[0153] Anionic monomers

[0154] Anionic monomers can be derived from deprotonated forms of free acids selected from the following:

[0155] acrylic acid,

[0156] Methacrylic acid,

[0157] 2-Methyl-2-[(1-oxo-2-propen-1-yl)amino]-1-propanesulfonic acid,

[0158] 2-Methyl-1-[(1-oxo-2-propen-1-yl)amino]-1-propanesulfonic acid,

[0159] 1-[(1-oxo-2-propen-1-yl)amino]-2-butyric acid and 2-[(2-methyl-1-oxo-2-propen-1-yl)amino]-2-propanesulfonic acid,

[0160] 1-[(1-oxo-2-propen-1-yl)amino]-ethanesulfonic acid,

[0161] 2-(phosphonoyloxy)ethyl ester-2-acrylic acid,

[0162] 2-Acrylic acid, 2-methyl, 2-(phosphono)ethyl ester,

[0163] 2-Methyl-,1-methyl-3-(phosphono)propyl ester-2-acrylic acid,

[0164] 2-Methyl-,1-[(phosphonooxy)methyl]propyl 2-acrylic acid,

[0165] 2-Methyl-N-[7-(phosphonooxy)heptyl]-2-acrylamide,

[0166] 4-(phosphonoyloxy)butyl ester-2-acrylic acid,

[0167] 2-Methyl-,12-(phosphono)dodecyl ester-2-acrylic acid,

[0168] 2-Methyl-,10-(phosphono)decyl ester-2-acrylic acid,

[0169] 2-Methyl-,6-(phosphono)hexyl ester-2-acrylic acid,

[0170] 2-Methyl-,3-(phosphono)propyl ester-2-acrylic acid,

[0171] 2-Methyl-,1-methyl-2-(phosphonoyloxy)ethyl ester-2-acrylic acid,

[0172] 3-(phosphonoyloxy)propyl ester-2-acrylic acid,

[0173] 2-Methyl-,4-(phosphono)butyl ester-2-acrylic acid,

[0174] 2-Oxo-2-[[[(1-Oxo-2-propen-1-yl)amino]methyl]amino]-ethanesulfonic acid, and

[0175] 2-[[[(2-methyl-1-oxo-2-propen-1-yl)amino]methyl]amino]-2-oxo-ethanesulfonic acid.

[0176] Preferably, the anionic monomer is derived from a deprotonated form of either acrylic acid or methacrylic acid.

[0177] Preferably, the anionic monomer is derived from a deprotonated form of either acrylic acid or methacrylic acid; and wherein the cationic monomer is derived from a quaternized form of a free base selected from 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate and 2-(tert-butylamino)ethyl methacrylate.

[0178] Preferably, the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate.

[0179] Preferably, the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate: (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, preferably ≥0.01 and ≤15.0 dg / min, preferably ≥0.08 and ≤14.0 dg / min, preferably ≥0.05 and ≤5.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index measured at 190°C and 2.16 kg according to ISO 1133-1:2011. (a) Motion index; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5 and ≤9.0 wt% relative to the total weight of the ethylene polymer, preferably ≥3.0 and ≤8.5 wt%, preferably ≥3.0 and ≤7.5 wt%, preferably ≥4.0 and ≤7.0 wt%; and (c) wherein the value of MFI2 / IPC is ≥0.01 and ≤8.0, preferably ≥0.001 and ≤6.0, preferably ≥0.01 and ≤4.7, preferably ≥0.02 and ≤4.0, preferably ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.02 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

[0180] Preferably, the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate; and (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, preferably ≥0.09 and ≤0.5 dg / min; and (b) wherein the total content (IPC) of the aggregate units derived from the cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) wherein the MFI2 / IPC value is ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.01 and ≤0.3, preferably >0.01 and <0.2, preferably ≥0.02 and ≤0.2, wherein IPC and MFI2 are as defined herein.

[0181] Preferably, the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate; and (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.09 and ≤0.5 dg / min; and (b) wherein the total content (IPC) of aggregate units derived from the cationic and anionic monomers is ≥4.0 and ≤7.0 wt% relative to the total weight of the ethylene polymer; and (c) wherein the MFI2 / IPC value is >0.01 and <0.2, wherein IPC and MFI2 are as defined herein.

[0182] Preparation of ethylene polymers

[0183] Ethylene polymers are obtained by copolymerizing ethylene with cationic and anionic monomers. Preferably, the cationic and anionic monomers exist as ion-pair compounds carrying opposite charges that cancel each other out. As used herein, the term "ion-pair compound" refers to the ion-pair compound according to patent application WO2021009274A1.

[0184] The molar ratio of the cationic monomer to the anionic monomer that can copolymerize with ethylene can be from 10:1 to 1:10, preferably from 2:1 to 1:2, more preferably from 1.5:1 to 1:1.5, and even more preferably from 1.1:1 to 1:1.1. Preferably, the molar ratio of the cationic monomer to the anionic monomer is from 3:1 to 1:1, more preferably from 2.5:1 to 1.5:1, and even more preferably from 2.1:1 to 1.9:1.

[0185] Preferably, the cationic monomer and the anionic monomer are present in the ethylene polymer in stoichiometric amounts. More preferably, the cationic monomer and the anionic monomer are present in stoichiometric amounts, depending on the stoichiometric ratio of the formed ion pairs being 1:1 or 1:2.

[0186] For example, cationic and anionic monomers can have the following forms: , wherein the cationic monomer is represented by the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is represented by the deprotonated form of methacrylate.

[0187] Ion-pair compounds can also be represented by the following formula: where the cationic monomer is represented by the quaternized form of 2-(tert-butylamino)ethyl methacrylate, and the anionic monomer is represented by the deprotonated form of methacrylate.

[0188] Ion-pair compounds can also be represented by the following formula: where the cationic monomer is represented by the quaternized form of 2-(diethylamino)ethyl methacrylate, and the anionic monomer is represented by the deprotonated form of methacrylate.

[0189] Ion-pair compounds can be represented as:

[0190] .

[0191] Alternatively, ion-pair compounds can be represented as:

[0192] .

[0193] Preferably, the ethylene polymer used in this application is obtained by copolymerizing ethylene with an ion-pair compound consisting of a cation of formula (I) and an acid anion of formula (II).

[0194] The ion-pair compounds according to the present invention can be dissolved in various types of common polar organic solvents such as isopropanol, acetonitrile, and ethyl acetate, and can be injected as solutions into the polymerization reactor.

[0195] Copolymerization methods and preparation

[0196] Copolymerization can be carried out using known methods. However, the inventors have discovered that when a suitable combination of free radical initiators and chain transfer agents is used and polymerization is carried out at a suitable temperature, the ethylene polymer used in the articles according to the present invention is obtained.

[0197] Preferably, the ethylene polymer according to the invention is generated during a high-pressure free radical polymerization process. The advantage of polymerization during such a high-pressure free radical process is that polymerization can be carried out under conditions where a catalyst is not required. This allows the use of certain comonomers, such as polar comonomers, which are generally unsuitable as comonomers for producing ethylene copolymers via catalytic processes (such as the use of Ziegler-Natta type catalysts).

[0198] Another advantage of preparing ethylene polymers during high-pressure free radical polymerization is that the resulting polymers have a certain degree of long-chain branching.

[0199] To qualify for certain applications, including extrusion coating, the ethylene polymer is required to possess a certain degree of long-chain branching. Understanding the presence of this long-chain branching contributes to the desired melt processing properties. Therefore, it is preferred that the ethylene copolymer according to the invention be prepared via a high-pressure free radical polymerization process.

[0200] The pressure during such high-pressure free radical polymerization is preferably in the range of ≥180MPa and ≤350MPa, preferably ≥190MPa and ≤210MPa, and preferably ≥200MPa and ≤300MPa. More preferably, the pressure during such high-pressure free radical polymerization is in the range of ≥190MPa and ≤210MPa.

[0201] The temperature during such high-pressure free radical polymerization is preferably within the range of ≥100℃ and ≤350℃, more preferably ≥150℃ and ≤310℃, more preferably ≥190℃ and ≤260℃, and even more preferably ≥200℃ and ≤255℃. Preferably, the temperature during such high-pressure free radical polymerization is within the range of ≥150℃ and ≤255℃, and more preferably ≥170℃ and ≤190℃.

[0202] Such high-pressure free radical polymerization can be carried out in a tubular reactor or an autoclave reactor. A tubular reactor can be, for example, the reactor described in Nexant PERP Report 2013-2, “Low-density polyethylene”, pages 31-48.

[0203] Such tubular reactors can operate at pressures of 150-300 MPa. The tubular reactor can have a tube length of, for example, ≥1000 m and ≤5000 m. The tubular reactor can have a length-to-inner-diameter ratio of, for example, ≥1000:1, alternatively ≥10000:1, or alternatively ≥25000:1, for example, ≥10000:1 and ≤50000:1, or alternatively ≥25000:1 and ≤35000:1. The residence time in the tubular reactor can be, for example, ≥30 seconds and ≤300 seconds, or alternatively ≥60 seconds and ≤200 seconds.

[0204] Such a tubular reactor may, for example, have an inner tube diameter of ≥0.01 m and ≤0.20 m, or alternatively ≥0.05 m and ≤0.15 m. The tubular reactor may, for example, have one or more inlets and one or more outlets. The feed composition may be fed into the tubular reactor, for example, at the inlet. The stream exiting the tubular reactor from the outlet may, for example, contain ethylene copolymers. The stream exiting the tubular reactor from the outlet may, for example, contain unreacted feed composition. Such unreacted feed composition may be recycled back into the tubular reactor through one or more inlets.

[0205] High-pressure free radical polymerization is carried out in the presence of one or more free radical initiators. Preferably, the free radical initiator is selected from organic peroxides and / or azo compounds.

[0206] Preferably, the free radical initiator is selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylperoxyneopentate (t-BPP) and / or tert-butylperoxybenzoate (t-BPB).

[0207] Such initiators can be fed into the tubular reactor, for example, in pure form or as a solution in a solvent. As a solvent, C2-C can be used, for example. 20 n-chain alkanes or C2-C 20 Isoparaffins. For example, such a solution may contain ≥2.0% by weight and ≤65.0% by weight, or alternatively ≥5.0% by weight and ≤40.0% by weight, or alternatively ≥10.0% by weight and ≤30.0% by weight, relative to the total weight of the solution.

[0208] Such an initiator can be introduced into the polymerization reactor, for example, in an amount of ≤300 ppm, preferably ≤200 ppm, relative to the total weight of the material fed into the polymerization reactor.

[0209] In addition, other modifiers can be fed into the tubular reactor or autoclave. Examples of such modifiers may include inhibitors, scavengers, and / or chain transfer agents, such as alcohols, aldehydes, ketones, and aliphatic hydrocarbons. Such modifiers can be fed into the tubular reactor or autoclave, for example, in pure form or as a solution in a solvent.

[0210] High-pressure free radical polymerization is carried out in the presence of one or more free radical initiators. Preferably, the free radical initiator is selected from organic peroxides and / or azo compounds.

[0211] Preferably, the method for preparing the article of the present invention includes the following steps:

[0212] (a) copolymerizing ethylene with a cationic monomer represented by formula (I) and one or more anionic monomers represented by formulas (II), (III), (IV) and (V) to obtain an ethylene polymer; and

[0213] (b) Extruding the ethylene polymer to obtain the article;

[0214] Polymerization is carried out in a high-pressure reactor:

[0215] At temperatures ≥100℃ and ≤350℃, preferably ≥150℃ and ≤310℃, preferably ≥190℃ and ≤260℃, more preferably ≥200℃ and ≤255℃; and

[0216] At pressures ≥190MPa and ≤210MPa; and

[0217] In the presence of one or more free radical initiators in an amount ≥0.27 mmol% and ≤0.6 mmol% relative to the total amount of ethylene monomer in the high-pressure reactor; and

[0218] In the presence of one or more chain transfer agents (CTAs) in an amount >0.01 and <0.1 mol%, preferably ≥0.05 and ≤0.1 mol%, relative to the total amount of ethylene monomer in the high-pressure reactor.

[0219] Preferably, polymerization is carried out in the presence of a chain transfer agent (CTA) selected from methanol, propionaldehyde, n-heptane, propane, isopropanol, and acetone.

[0220] The amount of chain transfer agent is preferably in the range of 0.01-2.0 mol% relative to the total weight of ethylene monomers fed into the polymerization reactor, and more preferably 0.01-0.1 mol%.

[0221] Preferably, polymerization is carried out in the presence of a chain transfer agent (CTA) in an amount >0.01 and <0.1 mol% relative to the total amount of ethylene monomer in the high-pressure reactor, preferably ≥0.05 and ≤0.1 mol%.

[0222] Preferably, the article is an extruded coated article, a film, an automotive part, a high-pressure pipe, a molded article, a 3D printed article, a metal article, or a polymer alloy or combination thereof. Preferably, the article is a film.

[0223] Ethylene polymers can be extruded using any known extrusion process, such as that described in "Film Extrusion Manual" (TAPPI PRESS, 2005, ISBN 1-59510-075-X, edited by Butler, pp. 413-435). For example, extrusion processes can include co-extrusion. In co-extrusion, various resins can first be melted in separate extruders and then combined together in a feed block. The feed block is a series of flow channels that bind the layers together to form a uniform flow. From this feed block, the multilayer material then passes through an adapter and exits from the die. The blow molding die can be an annular die. The die diameter can range from a few centimeters to more than three meters.

[0224] Molten plastic is pulled upwards by a pair of pressure rollers located above the die (e.g., from 4 meters to over 20 meters). Changing the speed of these rollers changes the dimensions (wall thickness) of the film. An air ring can be provided around the die. Air discharged from the air ring cools the film as it travels upwards. An air outlet can be provided at the center of the die, from which compressed air can be forced into the center of the extruded circular profile, thus creating a bubble. This expands the extruded circular cross-section by a certain ratio (a multiple of the die diameter). This ratio, called the "expansion rate," can be from only a few percent of the original diameter to, for example, over 300%. The pressure rollers flatten the bubble into a double-layered film with a width (called "flatness") equal to half the circumference of the bubble. This film can then be rolled or printed on, cut into shapes, and heat-sealed into bags or other items.

[0225] Alternatively, cast film extrusion can be used. The process for cast film extrusion can be performed according to Roy J. Crawford and Peter J. Martin, "Processing Plastics", Plastics Engineering (4th Edition), 2020.

[0226] If the ethylene polymer is subjected to extrusion coating, the conditions may be as described in publications such as RAV Raff and KWDoak's Crystalline Olefin Polymers, Part II (Interscience Publishers, 1964), pp. 478-484, or Vieweg, Schley and Schwarz: Kunststoff Handbuch, Band IV, Polyolefine, Carl Hanser Verlag (1969), 20, pp. 412-420.

[0227] In one aspect of the invention, the invention relates to articles obtained or obtainable by the method of the invention.

[0228] The invention will now be illustrated by the following non-limiting embodiments.

[0229] Example

[0230] Purpose : To evaluate the tensile properties of a specific ethylene polymer as defined in this invention.

[0231] Material Preparation of ethylene polymers: Ethylene is copolymerized with a quaternary ammonium compound derived from 2-(dimethylamino)ethyl methacrylate (a cationic monomer) and an ion-pair compound of deprotonated methacrylic acid (MA). The properties of the ethylene polymer samples are tuned by the amount of polymer units derived from ethylene and the ion-pair compounds (IPCs) (i.e., cationic and anionic monomers).

[0232] Samples IE1-IE5 represent inventive samples according to the present invention, while samples CE1-CE6 are derived from ethylene polymers having properties outside the scope of the present invention.

[0233] Preparation of ion-pair compounds containing cationic and anionic monomers:

[0234] In a round-bottom flask equipped with an ice bath, containing 510.9 g (5.935 mol) of methacrylic acid, 1000 mL (5.935 mol) of 2-(dimethylamino)ethyl methacrylate was added dropwise while maintaining the temperature below 20 °C. No purification was required, and the ion-pair compound was obtained in a quantitative yield (1.44 kg, 100%).

[0235] Preparation of ethylene polymers

[0236] For each sample of the ion-pair compound, the ethylene polymer was prepared using the following procedure: the obtained ion-pair compound sample was dissolved in methanol (50 wt%) and mixed with ethylene under high pressure (2000 bar) via a static mixer. Subsequently, the peroxide initiator Luperox® 11M75 (1.5 g / L) and propionaldehyde as a chain transfer agent (CTA) were added to the mixture, and the mixture was heated at 60 °C before being injected into a reactor set to a temperature of 180 °C to 270 °C to obtain an ethylene polymer having polymer units derived from ethylene and the ion-pair compound (i.e., cationic and anionic units).

[0237] The melt flow index and the final content of comonomers were controlled by adjusting various process parameters, including (i) the reaction temperature inside the reactor, where adjustments were made between monomers, (ii) the concentration of the chain transfer agent (CTA), and (iii) the peroxide initiator added to the reactor. The values ​​for different processing conditions are shown in Table 1 below. The total content (IPC) of polymer units derived from both cationic and anionic monomers and the melt flow index (MFI2) of the ethylene polymer were determined.

[0238] The reaction scheme can be represented by the following diagram:

[0239]

[0240] Using known techniques such as elemental analysis or 1 ¹H NMR was used to determine the total amount (IPC) of polymer units derived from cationic and anionic monomers in ethylene polymers.

[0241] The table below provides the reaction conditions used to prepare the samples:

[0242] Table 1

[0243]

[0244] Following the polymerization step, films for testing were prepared using an Xplore extruder via a cast film extruder. The extruder temperature was set to 155-170°C, and a film thickness of 50 mm was prepared for each sample (IE1-IE5, CE1-CE6).

[0245] Tensile properties

[0246] The obtained ethylene polymer sample was compressed and molded, and then subjected to a tensile test.

[0247] Tensile testing was performed according to ISO 527-1. Specifically, a device equipped with a 1kN load cell was used. Zwick Tensile tests were performed using a Z020 tensile testing machine. The test was conducted on a membrane strip with dimensions of 40mm (length) × 5mm (height) × 0.05mm (width). A clamping distance of 20mm was used. The sample was pre-stressed to 0.1N, and then tested at a constant crosshead speed of 500mm·min. -1 load.

[0248] The melt flow index (MFI2) was determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011. For the purposes of this invention, the terms melt flow index and melt flow rate (MFR) are used interchangeably.

[0249] The results of the above tests are reported as follows:

[0250] Table 2. Tensile Test

[0251]

[0252] Compared to the samples designated as comparative examples, samples IE1-IE5 prepared from the ethylene polymer according to the invention exhibited an improved balance of tensile properties. The inventive samples meet the following criteria:

[0253] (a) Tensile modulus ≥550 MPa and ≤1100 MPa as determined according to ISO 527-1; and

[0254] (b) Tensile stress at break ≥150 MPa and ≤300 MPa, as determined according to ISO 527-1; and

[0255] (c) Tensile strain at break ≥600% and ≤1500% when measured according to ISO 527-1.

[0256] Samples IE1-IE5 prepared from the ethylene polymer according to the invention exhibit an improved balance of tensile properties compared to the samples designated as comparative examples. Specifically, for samples IE1 and IE4, the property balance is particularly significant for the desired level of tensile stress at break, while maintaining tensile modulus and tensile strain. Advantageously, such properties are obtained without the use of mechanical fillers such as carbon black, glass, and other equivalent fillers.

Claims

1. An article comprising an ethylene polymer, wherein the ethylene polymer comprises or consists of: (a) Polymer units derived from ethylene; and (b) Polymer units of cationic monomers derived from free formula (I) (I) R1 is independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms; 'X' is independently selected from 'O' or 'NH', preferably 'X' is 'O'; R2 is an alkyl group having 1-40 carbon atoms, preferably 1-5 carbon atoms; R3 and R4 are each independently selected from hydrogen or alkyl groups having 1-10 carbon atoms, preferably 1-5 carbon atoms; and R5 is independently selected from hydrogen or alkyl groups having 1-20 carbon atoms, preferably 1-5 carbon atoms. Preferably, each of R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen; and (c) Polymer units derived from at least one anionic monomer selected from the following formulas. (II) (III) (IV) (V) Each of R6, R7 and R9 is independently selected from hydrogen or an alkyl group having 1 to 10 carbon atoms; R8 and R 10 Each is independently selected from alkyl groups having 1-40 carbon atoms; 'Y', 'V', and 'W' are independently selected from 'O' or 'NH'; 'n' is a number from 1 to 20; 'Z' is independently selected from -SO3 or -C(O)O; The preferred anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and Cationic monomers are , where 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen; (i) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥2.5 and ≤9.0% by weight relative to the total weight of the ethylene polymer, preferably ≥3.0 and ≤8.5% by weight, more preferably ≥3.0 and ≤7.5% by weight, and even more preferably ≥4.0 and ≤7.0% by weight; (ii) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.01 and ≤20.0 dg / min, preferably ≥0.01 and ≤15.0 dg / min, preferably ≥0.08 and ≤14.0 dg / min, preferably ≥0.05 and ≤5.0 dg / min, preferably ≥0.08 and ≤5.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, wherein MFI2 is the melt flow index determined at 190°C and measured at 2.16 kg according to ISO 1133-1:2011; and (iii) Where the value of MFI2 / IPC is ≥0.01 and ≤8.0, preferably ≥0.001 and ≤6.0, preferably ≥0.01 and ≤4.7, preferably ≥0.02 and ≤4.0, preferably ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.02 and ≤1.0, preferably ≥0.02 and ≤0.8, preferably ≥0.2 and ≤0.8, wherein IPC and MFI2 are as defined herein.

2. The article of claim 1, wherein (a) the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤14.0 dg / min, preferably ≥0.08 and ≤3.0 dg / min, more preferably ≥0.08 and ≤2.0 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight, preferably ≥4.0 and ≤7.0% by weight, relative to the total weight of the ethylene polymer; and (c) the MFI2 / IPC value is ≥0.01 and ≤4.7, preferably ≥0.01 and ≤1.0, more preferably ≥0.01 and ≤0.4, wherein IPC and MFI2 are as defined herein.

3. The article according to claims 1-2, wherein the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , wherein 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen, (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) wherein the value of MFI2 / IPC is ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.3, wherein IPC and MFI2 are as defined herein.

4. The article of manufacture according to any one of claims 1-3, wherein: (a) The melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤2.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, preferably ≥0.09 and ≤0.5 dg / min; and (b) The total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight, preferably ≥4.0 and ≤7.0% by weight, relative to the total weight of the ethylene polymer; and (c) Wherein the value of MFI2 / IPC is ≥0.01 and ≤0.4, preferably ≥0.01 and ≤0.3, preferably ≥0.02 and ≤0.2, wherein IPC and MFI2 are as defined herein.

5. The article according to claims 1-4, wherein the anionic monomer is (II), where R6 is an alkyl group having 1-5 carbon atoms, and the cationic monomer is , wherein 'X' is 'O', and each of R2, R3 and R4 is an alkyl group having 1-5 carbon atoms, and R5 is hydrogen, (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.09 and ≤0.5 dg / min; and (b) the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥4.0 and ≤7.0 wt% relative to the total weight of the ethylene polymer; and (c) wherein the value of MFI2 / IPC is >0.01 and <0.2, wherein IPC and MFI2 are as defined herein.

6. The article according to any one of claims 1-5, wherein the cationic monomer represented by formula (I) is derived from a quaternized form of a free base selected from: 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate, 2-(tert-butylamino)ethyl methacrylate, N-[3-(hexahydro-1H-azaphosphon-1-yl)-1,1-dimethylpropyl]-2-acrylamide, N-[2-(tetrahydro-1,4-oxahydro-4(5H)-yl)ethyl]-2-acrylamide, N-[2-[methyl(tetrahydro-2H-pyran-4-yl)amino]ethyl]-2-acrylamide, N-[3-(hexahydro-4-methyl-1H-1,4-diaza-1-yl)propyl]-2-acrylamide, N-[1-Methyl-2-(methylamino)propyl]-2-acrylamide, N-[2-(methylamino)propyl]-2-acrylamide, N-[2-Methyl-2-(methylamino)propyl]-2-acrylamide, N-[1-Methyl-2-(methylamino)ethyl]-2-acrylamide, N-[1-Methyl-3-(methylamino)butyl]-2-acrylamide, and N-[1-Methyl-2-(methylamino)propyl]-2-acrylamide, Preferably, the cationic monomer of formula (I) is derived from a quaternized form of a free base selected from the following: 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate and 2-(tert-butylamino)ethyl methacrylate.

7. The article according to any one of claims 1-6, wherein the anionic monomer is derived from a deprotonated form of a free acid selected from: acrylic acid, Methacrylic acid, 2-Methyl-2-[(1-oxo-2-propen-1-yl)amino]-1-propanesulfonic acid, 2-Methyl-1-[(1-oxo-2-propen-1-yl)amino]-1-propanesulfonic acid, 1-[(1-oxo-2-propen-1-yl)amino]-2-butyric acid and 2-[(2-methyl-1-oxo-2-propen-1-yl)amino]-2-propanesulfonic acid, 1-[(1-oxo-2-propen-1-yl)amino]-ethanesulfonic acid, 2-(phosphonoyloxy)ethyl ester-2-acrylic acid, 2-Acrylic acid, 2-methyl-,2-(phosphonooxy)ethyl ester, 2-Methyl-,1-methyl-3-(phosphono)propyl ester-2-acrylic acid, 2-Methyl-,1-[(phosphonooxy)methyl]propyl 2-acrylic acid, 2-Methyl-N-[7-(phosphonooxy)heptyl]-2-acrylamide, 4-(phosphonoyloxy)butyl ester-2-acrylic acid, 2-Methyl-,12-(phosphono)dodecyl ester-2-acrylic acid, 2-Methyl-,10-(phosphono)decyl ester-2-acrylic acid, 2-Methyl-,6-(phosphono)hexyl ester-2-acrylic acid, 2-Methyl-,3-(phosphono)propyl ester-2-acrylic acid, 2-Methyl-,1-methyl-2-(phosphonoyloxy)ethyl ester-2-acrylic acid, 3-(phosphonoyloxy)propyl ester-2-acrylic acid, 2-Methyl-,4-(phosphono)butyl ester-2-acrylic acid, 2-Oxo-2-[[[(1-Oxo-2-propen-1-yl)amino]methyl]amino]-ethanesulfonic acid, and 2-[[[(2-methyl-1-oxo-2-propen-1-yl)amino]methyl]amino]-2-oxo-ethanesulfonic acid; Preferably, the anionic monomer is derived from the deprotonated form of either acrylic acid or methacrylic acid.

8. The article according to any one of claims 1-7, wherein the anionic monomer is derived from a deprotonated form of any one of acrylic acid or methacrylic acid; and wherein the cationic monomer is derived from a quaternized form of a free base selected from: 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate and 2-(tert-butylamino)ethyl methacrylate.

9. The article according to any one of claims 1-8, wherein the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate.

10. The article according to any one of claims 1-9, wherein the cationic monomer is derived from the quaternized form of 2-(dimethylamino)ethyl methacrylate, and the anionic monomer is derived from the deprotonated form of methacrylate; and (a) wherein the melt flow index (MFI2) of the ethylene polymer is ≥0.08 and ≤3.0 dg / min, preferably ≥0.08 and ≤0.5 dg / min, and more preferably ≥0.09 and ≤0.5 dg / min; and (b) wherein the total content (IPC) of polymer units derived from cationic and anionic monomers is ≥3.0 and ≤7.5% by weight relative to the total weight of the ethylene polymer, preferably ≥4.0 and ≤7.0% by weight; and (c) wherein the value of MFI2 / IPC is ≥0.01 and ≤1.0, preferably ≥0.01 and ≤0.4, preferably ≥0.01 and ≤0.3, preferably >0.01 and <0.2, and more preferably ≥0.02 and ≤0.2, wherein IPC and MFI2 are as defined herein.

11. The article of claim 1-10, wherein the article is selected to have: (a) Tensile modulus ≥550 MPa and ≤1100 MPa when measured according to ISO 527-1; and (b) The tensile stress at break, ≥150 MPa and ≤300 MPa, as determined according to ISO 527-1; and (c) Tensile strain at break ≥600% and ≤1500% when measured according to ISO 527-1.

12. The article according to any one of claims 1-11, wherein the article comprises ≥88.0% by weight, preferably ≥90.0% by weight, preferably ≥95.0% by weight, and ≤100.0% by weight of ethylene polymer relative to the total weight of the article; and / or the article is substantially free of fillers selected from talc, carbon black, and reinforcing fibers.

13. The article according to any one of claims 1-12, wherein the ethylene polymer is not cross-linked, preferably wherein the article is selected from layers, multilayer films or multilayer sheets of packaging articles, containers, tubes, sanitary products, automotive parts, sheets, hinge parts, cable insulation layers, cable sheaths, co-extruded multilayer films or multilayer sheets, preferably the article is a multilayer film or multilayer sheet.

14. A method for preparing the article of any one of claims 1-13, wherein the method comprises the following steps: (a) Polymerizing ethylene with a cationic monomer represented by formula (I) and one or more anionic monomers represented by formulas (II), (III), (IV) and (V) to obtain an ethylene polymer; and (b) Extruding an ethylene polymer to obtain an article; Polymerization is carried out in a high-pressure reactor: At temperatures ≥100℃ and ≤350℃, preferably ≥150℃ and ≤310℃, preferably ≥190℃ and ≤260℃, and more preferably ≥200℃ and ≤255℃; and Under pressures ≥190MPa and ≤210MPa; and In the presence of one or more free radical initiators in an amount ≥0.27 mmol% and ≤0.6 mmol% relative to the total amount of ethylene monomer in the high-pressure reactor; and In the presence of one or more chain transfer agents (CTAs) in an amount >0.01 and <0.1 mol%, preferably ≥0.05 and ≤0.1 mol%, relative to the total amount of ethylene monomer in the high-pressure reactor.

15. Use of the ethylene polymer according to any one of claims 1-13 for improving the tensile properties of multilayer sheets or multilayer films, preferably wherein the tensile properties are any one of tensile modulus, tensile stress at break, and tensile strain at break.

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