Process for producing a polyethylene composition for an oriented polyethylene film, polyethylene composition and film thereof

Abstract

A process for producing an oriented film of a polyethylene composition, which comprises: providing a linear low density polyethylene resin in an amount from 60 to 90% by weight; the linear low density polyethylene resin having an MI2 in the range from 0.9 to 4.0 g / 10 min; a density in the range from 0.910 to 0.930 g / cm 3 ; an Mw / Mn of at least 2.5; a z-average molecular weight (Mz) of at most 310,000 g / mol; and the linear low density polyethylene resin being a copolymer of ethylene and one or more comonomers, wherein based on the linear low density polyethylene resin, the one or more comonomers are present in an amount in the range from 7.0 to 11.0% by weight; providing a high density polyethylene resin in an amount from 10 to 40% by weight; the high density polyethylene resin having an MI2 in the range from 0.5 to 1.6 g / 10 min; a density in the range from 0.950 to 0.965 g / cm 3 ; and melt blending the linear low density polyethylene resin with the high density polyethylene resin to produce a polyethylene composition.

Description

Technical Field

[0001] The present disclosure relates to polyethylene compositions and articles made from such polyethylene compositions, such as oriented films (i.e., biaxially oriented polyethylene films or uniaxially oriented polyethylene films). The present disclosure also relates to processes for producing the polyethylene compositions. Background Art

[0002] Polyethylene compositions comprising linear low density polyethylene (LLDPE) are known from the prior art for use in producing oriented films.

[0003] For example, US8247065 discloses blends of linear low density polyethylene (LLDPE) copolymers with very low density, low density, medium density, high density (HDPE) and differentiated polyethylenes and other polymers. This document discloses the use of metallocene-catalyzed LLDPE in such blends, where the LLDPE preferably has a comonomer content of up to about 5 mol%; an MI2 ranging from 0.1 to 300 g / 10 min; a melt index ratio from 15 to 45, a Mw from 20,000 to 200,000 g / mol, an Mw / Mn ranging from 2.0 to 4.5, an Mz / Mw ranging from 1.7 to 3.5 and a density ranging from 0.910 to 0.955 g / cm 3 3. LLDPE-HDPE blends are also disclosed, where the HDPE can be present in amounts ranging from 0.1 to 99.9 wt%. In Examples 63 - 84 of US8247065, the content of HDPE is 10 wt%. The HDPE resin used was produced by a conventional metallocene catalyst, has a narrow MWD, and is a homopolymer with a melt index ranging from 1 up to 200 g / 10 min. Films produced from these blends were also produced. They exhibit an interesting balance of properties, but there is still a need to improve the said balance of properties. For example, the optical properties or impact resistance properties can be improved. In addition, the document does not mention sealing properties such as hot tack.

[0004] The present disclosure aims to provide a solution to one or more of the above disadvantages and problems. In particular, the present disclosure provides polyethylene compositions for oriented films and processes for producing such polyethylene compositions, which allow obtaining an improved balance of properties including mechanical properties (such as stiffness or impact resistance), processability, optical properties and sealing properties (such as hot tack properties) compared to non-oriented PE films. Summary of the Invention

[0005] Surprisingly, it has been found that by using a specific polyethylene composition in a biaxially oriented polyethylene (BOPE) film or a monoaxially oriented polyethylene (MDO) film, the above objects can be achieved individually or in any combination.

[0006] According to a first aspect, the present disclosure provides a process for producing a polyethylene composition for a biaxially oriented polyethylene film or a monoaxially oriented polyethylene film, characterized in that it comprises:

[0007] - Providing from 60 to 90% by weight of a linear low density polyethylene resin, based on the total weight of the polyethylene composition; wherein the linear low density polyethylene resin has: an MI2 in the range from 0.9 to 4.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density in the range from 0.910 to 0.930 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012; an Mw / Mn of at least 2.5 when determined by gel permeation chromatography; a z-average molecular weight (Mz) of at most 310,000 g / mol when determined by gel permeation chromatography; and the linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers, wherein the one or more comonomers are present in an amount in the range from 7.0 to 11.0% by weight, based on the linear low density polyethylene resin.

[0008] - Providing from 10 to 40% by weight of a high density polyethylene resin, based on the total weight of the polyethylene composition; wherein the high density polyethylene resin has: an MI2 in the range from 0.5 to 1.6 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density in the range from 0.950 to 0.965 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012, wherein the high density polyethylene resin is selected to have an MI2 that is below or equal to the MI2 of the linear low density polyethylene resin; and

[0009] - Melting and blending the linear low density polyethylene resin with the high density polyethylene resin to produce a polyethylene composition.

[0010] In one embodiment, based on the total weight of the polyethylene composition, the process comprises providing from 65 to 85% by weight of a linear low density polyethylene resin.

[0011] In one embodiment, based on the total weight of the polyethylene composition, the process comprises providing from 15 to 35 wt% of a high-density polyethylene resin.

[0012] One or more of the following may be used to further define the linear low-density polyethylene resin (LLDPE).

[0013] For example, the LLDPE is a copolymer of ethylene and one or more comonomers selected from propylene, 1-butene, 1-hexene, and 1-octene; preferably selected from 1-butene, 1-hexene, and 1-octene.

[0014] For example, the LLDPE is a copolymer of ethylene and one or more comonomers, wherein based on the linear low-density polyethylene resin, the one or more comonomers are present in an amount ranging from 7.5 to 9.5 wt%.

[0015] For example, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the LLDPE has an MI2 ranging from 1.0 to 3.5 g / 10 min.

[0016] For example, when measured at 23 °C according to ISO 1183-1:2012, the LLDPE has a density ranging from 0.912 to 0.928 g / cm 3 3.

[0017] For example, when measured by gel permeation chromatography, the LLDPE has an Mw / Mn ranging from 3.5 to 6.0.

[0018] For example, when measured by gel permeation chromatography, the LLDPE has a z-average molecular weight (Mz) ranging from 180,000 to 280,000 g / mol.

[0019] For example, the LLDPE is metallocene-catalyzed.

[0020] For example, the LLDPE has a bimodal molecular weight distribution.

[0021] One or more of the following may be used to further define the high-density polyethylene resin (HDPE).

[0022] For example, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the HDPE has an MI2 ranging from 0.6 to 1.5 g / 10 min.

[0023] For example, when measured at 23 °C according to ISO 1183-1:2012, the HDPE has a density in the range from 0.952 to 0.964 g / cm 3 3.

[0024] According to a second aspect, the present disclosure provides a polyethylene composition, characterized in that it is produced by the process according to the first aspect.

[0025] According to a third aspect, the present disclosure provides a polyethylene composition, characterized in that it has:

[0026] - an MI2 in the range from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005;

[0027] - a density in the range from 0.915 to 0.935 g / cm 3 3 when measured at 23 °C according to ISO 1183-1:2012;

[0028] - an Mw / Mn in the range from 3.0 to 6.0 when measured by gel permeation chromatography;

[0029] - a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography;

[0030] - in the TREF curve, a main elution peak below 85 °C and a secondary elution peak above 95 °C; and

[0031] - when measured by 13 13C-NMR analysis, a comonomer content in the range from 4.2 to 9.1 wt% based on the total weight of the polyethylene composition.

[0032] According to a third aspect, the present disclosure provides a film, which is a single-layer film or a multi-layer film, characterized in that at least one of one layer or multiple layers is made of the polyethylene composition according to the second aspect or according to the third aspect; and the film is a biaxially oriented polyethylene film or a uniaxially oriented polyethylene film.

[0033] The following can be used to further define the polyethylene composition according to the first, second or third aspect or for use in the film according to the fourth aspect.

[0034] Preferably, the polyethylene composition has

[0035] - an MI2 in the range from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005;

[0036] - A density in the range from 0.915 to 0.935 g / cm³ when measured at 23 °C in accordance with ISO 1183-1:2012; 3 ;

[0037] - An Mw / Mn in the range from 3.0 to 6.0 when determined by gel permeation chromatography;

[0038] - A z-average molecular weight (Mz) of at most 370,000 g / mol when determined by gel permeation chromatography;

[0039] - In the TREF curve, a main elution peak below 85 °C and a secondary elution peak above 95 °C; and

[0040] - When determined by 13 C-NMR analysis, a comonomer content in the range from 4.2 to 9.1 wt% based on the total weight of the polyethylene composition.

[0041] For example, when measured at 190 °C under a load of 2.16 kg in accordance with ISO 1133-2005, the polyethylene composition has an MI2 in the range from 1.0 to 2.6 g / 10 min.

[0042] For example, when measured at 23 °C in accordance with ISO 1183-1:2012, the polyethylene composition has a density in the range from 0.920 to 0.935 g / cm³. 3 ;

[0043] For example, when determined by 13 C-NMR analysis, the polyethylene composition has a comonomer content in the range from 4.9 to 8.5 wt% based on the total weight of the polyethylene composition.

[0044] For example, when determined in accordance with ISO 11357-3:2018, the polyethylene composition has a main melting temperature peak Tm of at least 120 °C.

[0045] For example, in the TREF curve, the polyethylene composition has two elution peaks from 60 to 120 °C.

[0046] For example, in the TREF curve, the polyethylene composition has a main elution peak below 85 °C and a secondary elution peak above 95 °C.

[0047] For example, based on the total weight of the polymer, the polyethylene composition has 60 to 90% by weight of the polymer eluting at a temperature in the range from 50 to 95 °C, and 10 to 40% by weight of the polymer eluting at a temperature in the range from above 95 to 120 °C.

[0048] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mw / Mn in the range from 3.2 to 5.8.

[0049] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mz / Mw in the range from 2.0 to 5.0.

[0050] For example, when measured by gel permeation chromatography, the polyethylene composition has a z-average molecular weight (Mz) of at most 350,000 g / mol.

[0051] According to a fifth aspect, the present disclosure provides a process for producing a biaxially oriented polyethylene film according to the fourth aspect, which comprises:

[0052] a) producing a polyethylene composition having:

[0053] - an MI2 in the range from 0.9 to 3.0 g / 10 min when measured according to ISO 1133-2005 at 190 °C under a load of 2.16 kg;

[0054] - a density in the range from 0.915 to 0.935 g / cm 3 when measured according to ISO 1183-1:2012 at 23 °C;

[0055] - an Mw / Mn in the range from 3.0 to 6.0 when measured by gel permeation chromatography;

[0056] - a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography;

[0057] - in the TREF curve, a main elution peak below 85 °C and a secondary elution peak above 95 °C; and

[0058] - a comonomer content in the range from 4.2 to 9.1% by weight based on the total weight of the polyethylene composition when measured by 13 C-NMR analysis.

[0059] b) extruding or casting a film comprising the polyethylene composition

[0060] c) Stretch the film in the machine direction and in the transverse direction to produce a biaxially oriented polyethylene film, wherein the draw ratio for stretching in the machine direction is from 4.5 to 7.0, and the draw ratio for stretching in the transverse direction is in the range from 6.0 to 10.0; preferably, the draw ratio for stretching in the machine direction is from 5.0 to 6.0 and / or the draw ratio for stretching in the transverse direction is in the range from 7.5 to 9.5.

[0061] In one embodiment, step b) comprises extruding or casting a film having a thickness in the range from 500 µm to 1.5 mm as measured by DIN ISO 4593: 1993.

[0062] In one embodiment, stretching the film in the machine direction and in the transverse direction is carried out by sequential stretching, wherein stretching is carried out in the machine direction and subsequently in the transverse direction.

[0063] In one embodiment, stretching the film in the machine direction and in the transverse direction is carried out by simultaneous stretching in both directions. Description of the Drawings

[0064] Figure 1 A graph showing the TREF (temperature rising elution fractionation) of a polyethylene composition drawn according to the present disclosure.

[0065] Figure 2 Showing hot tack sealing properties. Detailed Description

[0066] When describing the polymers, uses, and processes of the present disclosure, the terms employed will be understood according to the following definitions, unless the context indicates otherwise. For the present disclosure, the following definitions are provided:

[0067] As used herein, the singular forms "a", "an", and "the" include singular and plural referents unless the context indicates otherwise. By way of example, "a resin" means one resin or more than one resin.

[0068] The terms "comprising" and "comprised of" as used herein are synonymous with "including" or "containing" and are inclusive or open-ended and do not exclude additional unrecited members, elements, or method steps. It will be understood that the terms "comprising" and "comprised of" as used herein include the term "consisting of".

[0069] Numerical ranges expressed by endpoints include all integers and, where appropriate, fractions included within the range (e.g., when referring to, for example, the number of elements, 1 to 5 can include 1, 2, 3, 4, 5, and can also include 1.5, 2, 2.75, and 3.80 when referring to, for example, measured values). The recitation of endpoints also includes the endpoint values themselves (e.g., from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0070] All references cited in this specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references specifically mentioned herein are incorporated by reference.

[0071] References to "an embodiment" or "embodiments" throughout this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present disclosure. Thus, the phrases "in one embodiment" or "in embodiments" that appear in multiple places throughout this specification are not necessarily all referring to the same embodiment, but may refer to the same embodiment. Additionally, in one or more embodiments, as will be apparent to those skilled in the art from the present disclosure, the particular features, structures, or characteristics may be combined in any suitable manner. Moreover, although some embodiments described herein include some features that are not included in other embodiments, combinations of features of different embodiments are intended to be within the scope of the present disclosure and form different embodiments, as will be understood by those skilled in the art.

[0072] The terms "polyethylene" (PE) and "ethylene polymer" may be used synonymously. The term "polyethylene" encompasses ethylene homopolymers as well as ethylene copolymer resins that may be derived from ethylene and one or more comonomers selected from C3-C 20 α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0073] The term "high density polyethylene", which may be abbreviated as "HDPE", is generally used to denote polyethylene having a density of at least 0.940 g / cm when measured at 23 °C in accordance with ISO 1183-1:2012 3 of density.

[0074] The terms "polyethylene resin", "ethylene homopolymer resin" or "ethylene copolymer resin" refer to polyethylene fluff (flock) or powder, which is extruded and / or melted and / or pelletized and can be produced by compounding and homogenizing polyethylene resins as taught herein, for example, using mixing and / or extruder equipment. As used herein, the term "polyethylene" may be used as an abbreviation for "polyethylene resin". The terms "fluff" or "powder" refer to a polyethylene material having a hard catalyst particle at the core of each grain and are defined as the polymer material after it exits the polymerization reactor (or the final polymerization reactor in the case of multiple reactors connected in series).

[0075] Under normal production conditions in the production equipment, it is expected that the melt index (MI2, HLMI, MI5) of the fluff will be different from that of the polyethylene resin. Under normal production conditions in the production equipment, it is expected that the density of the fluff will be slightly different from that of the polyethylene resin. Unless otherwise indicated, the density and melt index of the polyethylene resin refer to the density and melt index measured on the polyethylene resin as defined above.

[0076] The present disclosure provides a process for producing a biaxially oriented polyethylene film or a uniaxially oriented polyethylene film, characterized in that it comprises:

[0077] - Providing from 60 to 90% by weight of a linear low density polyethylene resin, based on the total weight of the polyethylene composition; wherein the linear low density polyethylene resin has: an MI2 in the range from 0.9 to 4.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density in the range from 0.910 to 0.930 g / cm3 when measured at 23 °C according to ISO 1183-1:2012; an Mw / Mn of at least 2.5 when determined by gel permeation chromatography; a z-average molecular weight (Mz) of at most 310,000 g / mol when determined by gel permeation chromatography; and the linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers, wherein the one or more comonomers are present in an amount in the range from 7.0 to 11.0% by weight, based on the linear low density polyethylene resin.

[0078] - Providing from 10 to 40% by weight of a high density polyethylene resin, based on the total weight of the polyethylene composition; wherein the high density polyethylene resin has: an MI2 in the range from 0.5 to 1.6 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density in the range from 0.950 to 0.965 g / cm3 the density, wherein the high density polyethylene resin is selected to have an MI2 that is less than or equal to the MI2 of the linear low density polyethylene resin; and

[0079] - melt blending the linear low density polyethylene resin and the high density polyethylene resin to produce a polyethylene composition.

[0080] In a preferred embodiment, based on the total weight of the polyethylene composition, the process comprises providing from 62 to 88 wt%, preferably from 65 to 85 wt%, more preferably from 68 to 82 wt%, and even more preferably from 70 to 80 wt% of the linear low density polyethylene resin.

[0081] In a preferred embodiment, based on the total weight of the polyethylene composition, the process comprises providing from 12 to 38 wt%; preferably from 15 to 35 wt%; more preferably from 18 to 32 wt%; and even more preferably from 20 to 30 wt% of the linear low density polyethylene resin.

[0082] The present disclosure also provides a process for producing a biaxially oriented polyethylene film, which comprises:

[0083] a) producing a polyethylene composition having:

[0084] - an MI2 in the range from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005;

[0085] - a density in the range from 0.915 to 0.935 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012;

[0086] - an Mw / Mn in the range from 3.0 to 6.0 when measured by gel permeation chromatography;

[0087] - a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography;

[0088] - a main elution peak below 85 °C and a secondary elution peak above 95 °C in the TREF curve; and

[0089] - a comonomer content in the range from 4.2 to 9.1 wt% based on the total weight of the polyethylene composition when measured by 13 C-NMR analysis.

[0090] b) Extruding or casting a film comprising the polyethylene composition

[0091] c) Stretching the film in the machine direction and in the transverse direction to produce a biaxially oriented polyethylene film, wherein the draw ratio for stretching in the machine direction is from 4.5 to 7.0, and the draw ratio for stretching in the transverse direction is in the range from 6.0 to 10.0; preferably, the draw ratio for stretching in the machine direction is from 5.0 to 6.0 and / or the draw ratio for stretching in the transverse direction is in the range from 7.5 to 9.5.

[0092] In one embodiment, step b) comprises extruding or casting a film having a thickness in the range from 500 µm to 1.5 mm as measured by DIN ISO 4593.

[0093] In one embodiment, stretching the film in the machine direction and in the transverse direction is carried out by sequential stretching, wherein stretching is carried out in the machine direction and subsequently in the transverse direction.

[0094] In one embodiment, stretching the film in the machine direction and in the transverse direction is carried out by simultaneous stretching in both directions.

[0095] Selection of linear low density polyethylene resin

[0096] According to the present disclosure, the linear low density polyethylene resin (LLDPE) is selected to have an MI2 in the range from 0.9 to 4.0 g / 10 min as measured at 190 °C under a load of 2.16 kg according to ISO1133 - 2005; a density in the range from 0.910 to 0.930 g / cm 3 as measured at 23 °C according to ISO 1183 - 1:2012; an Mw / Mn of at least 2.5 as measured by gel permeation chromatography; a z - average molecular weight (Mz) of at most 310,000 g / mol as measured by gel permeation chromatography; and the linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers, wherein the one or more comonomers are present in an amount in the range from 7.0 to 11.0 wt% based on the linear low density polyethylene resin.

[0097] For example, the linear low density polyethylene resin is selected such that it has an MI2 of at least 0.9 g / 10 min; preferably at least 1.0 g / 10 min; more preferably at least 1.1 g / 10 min; even more preferably at least 1.2 g / 10 min; most preferably at least 1.3 g / 10 min; and even most preferably at least 1.4 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005.

[0098] For example, the linear low density polyethylene resin is selected such that it has an MI2 of at most 4.0 g / 10 min; preferably at most 3.8 g / 10 min; more preferably at most 3.5 g / 10 min; even more preferably at most 3.2 g / 10 min; most preferably at most 3.0 g / 10 min and even most preferably at most 2.8 g / 10 min or at most 2.5 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005.

[0099] Preferably, the linear low density polyethylene resin is selected such that it has an MI2 in the range of from 0.9 to 4.0 g / 10 min; preferably from 0.9 to 3.8 g / 10 min; more preferably from 1.0 to 3.5 g / 10 min; even more preferably from 1.1 to 3.2 g / 10 min; most preferably from 1.2 to 3.0 g / 10 min and even most preferably from 1.3 to 2.8 g / 10 min or from 1.4 to 2.5 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005.

[0100] For example, the linear low density polyethylene resin is selected such that it has a density of at least 0.910 g / cm 3 ; preferably at least 0.912 g / cm 3 ; more preferably at least 0.914 g / cm 3 ; even more preferably at least 0.915 g / cm 3 ; and most preferably at least 0.916 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012.

[0101] For example, the linear low density polyethylene resin is selected such that it has a density of at most 0.930 g / cm 3; Preferably, at most 0.928 g / cm3; More preferably, at most 0.925 g / cm 3 ; Even more preferably, at most 0.923 g / cm 3 ; And most preferably, at most 0.920 g / cm 3 of density.

[0102] Preferably, the linear low density polyethylene resin is selected such that it has a density in the range of from 0.910 to 0.930 g / cm when measured according to ISO 1183-1:2012 at 23 °C 3 ; Preferably, from 0.912 to 0.928 g / cm 3 ; More preferably, from 0.914 to 0.925 g / cm 3 ; Even more preferably, from 0.915 to 0.923 g / cm 3 ; And most preferably from 0.916 to 0.920 g / cm 3 of density.

[0103] The linear low density polyethylene resin is preferably a copolymer of ethylene and one or more comonomers. Suitable comonomers include but are not limited to aliphatic C3-C 20 α-olefins. Examples of suitable aliphatic C3-C 20 α-olefins include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Preferably, the one or more comonomers are selected from propylene, 1-butene, 1-hexene, and 1-octene. Preferably, the one or more comonomers are selected from propylene, 1-butene, and 1-hexene. More preferably, the comonomer is 1-butene and / or 1-hexene.

[0104] The term "copolymer" refers to a polymer made by linking ethylene and at least one comonomer in the same polymer chain.

[0105] Preferably, when determined by 13 C-NMR analysis, based on the total weight of the linear low density polyethylene resin, the linear low density polyethylene is an ethylene copolymer and contains at least 7.0 wt%; preferably at least 7.2 wt%; more preferably at least 7.5 wt%; even more preferably at least 7.8 wt%; most preferably at least 8.0 wt%; even most preferably at least 8.2 wt% of one or more comonomers.

[0106] Preferably, when by 13When measured by ¹³C-NMR analysis, based on the total weight of the linear low density polyethylene resin, the linear low density polyethylene is an ethylene copolymer and contains up to 11.0% by weight; preferably up to 10.0% by weight; preferably up to 9.5% by weight; more preferably up to 9.0% by weight; and even more preferably up to 8.8% by weight of one or more comonomers.

[0107] In a preferred embodiment, when measured by 13 ¹³C-NMR analysis, based on the total weight of the linear low density polyethylene resin, the one or more comonomers are present in the linear low density polyethylene resin in an amount ranging from 7.0 to 11.0% by weight; preferably from 7.2 to 10.0% by weight; more preferably from 7.5 to 9.5% by weight; and even more preferably from 8.0 to 9.0% by weight.

[0108] In one embodiment, the linear low density polyethylene is metallocene-catalyzed.

[0109] In one embodiment, the linear low density polyethylene resin has a multimodal or bimodal molecular weight distribution.

[0110] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw / Mn of at least 2.5; preferably at least 2.7; preferably at least 3.0; preferably at least 3.2; preferably at least 3.5; preferably at least 3.6; more preferably at least 3.8; even more preferably at least 4.0; most preferably at least 4.2.

[0111] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw / Mn of at most 6.0; preferably at most 5.8; more preferably at most 5.5; even more preferably at most 5.2; most preferably at most 5.0.

[0112] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw / Mn ranging from 2.7 to 6.0; preferably ranging from 3.5 to 6.0; more preferably ranging from 4.0 to 5.0.

[0113] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has a z-average molecular weight (Mz) of at most 310,000 g / mol; preferably at most 300,000 g / mol; more preferably at most 280,000 g / mol; and even more preferably at most 260,000 g / mol.

[0114] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has a z-average molecular weight (Mz) of at least 160,000 g / mol; preferably at least 180,000 g / mol; more preferably at least 200,000 g / mol; and even more preferably at least 220,000 g / mol.

[0115] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has a z-average molecular weight (Mz) in the range of from 160,000 to 310,000 g / mol; preferably from 180,000 to 280,000 g / mol.

[0116] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw of at most 110,000 g / mol; preferably at most 100,000 g / mol; more preferably at most 95,000 g / mol; and even more preferably at most 90,000 g / mol.

[0117] For example, when measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw of at least 60,000 g / mol; preferably at least 65,000 g / mol; more preferably at least 70,000 g / mol; and even more preferably at least 75,000 g / mol.

[0118] Selection of high density polyethylene resin

[0119] The high density polyethylene resin has an MI2 in the range of from 0.5 to 1.6 g / 10 min when measured according to ISO 1133-2005 at 190 °C under a load of 2.16 kg, and a density in the range of from 0.950 to 0.965 g / cm 3 when measured according to ISO 1183-1:2012 at 23 °C.

[0120] For example, when measured according to ISO 1133-2005 at 190 °C under a load of 2.16 kg, the high density polyethylene resin is selected to have an MI2 of at least 0.5 g / 10 min; preferably at least 0.6 g / 10 min; more preferably at least 0.7 g / 10 min; even more preferably at least 0.8 g / 10 min.

[0121] For example, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the high-density polyethylene resin is selected to have an MI2 of at most 1.6 g / 10 min; preferably at most 1.5 g / 10 min; more preferably at most 1.4 g / 10 min; even more preferably at most 1.3 g / 10 min.

[0122] Preferably, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the high-density polyethylene resin is selected to have an MI2 in the range of from 0.5 to 1.6 g / 10 min; preferably from 0.6 to 1.5 g / 10 min; more preferably from 0.7 to 1.4 g / 10 min; even more preferably from 0.8 to 1.3 g / 10 min.

[0123] For example, when measured at 23 °C according to ISO 1183-1:2012, the high-density polyethylene resin is selected to have a density of at least 0.950 g / cm 3 ; preferably at least 0.952 g / cm 3 ; more preferably at least 0.954 g / cm 3 ; and even more preferably at least 0.955 g / cm 3 of density.

[0124] For example, when measured at 23 °C according to ISO 1183-1:2012, the high-density polyethylene resin is selected to have a density of at most 0.965 g / cm 3 ; preferably at most 0.964 g / cm 3 ; more preferably at most 0.962 g / cm 3 ; and even more preferably at most 0.960 g / cm 3 of density.

[0125] Preferably, when measured at 23 °C according to ISO 1183-1:2012, the high-density polyethylene resin is selected to have a density in the range of from 0.950 to 0.965 g / cm 3 ; preferably from 0.952 to 0.964 g / cm 3 ; more preferably from 0.954 to 0.962 g / cm 3 ; and even more preferably from 0.955 to 0.960 g / cm 3 of density.

[0126] The high-density polyethylene resin is selected from homopolymers and copolymers of ethylene with one or more comonomers; preferably homopolymers.

[0127] Suitable comonomers include, but are not limited to, aliphatic C3-C 20 α-olefins. Examples of suitable aliphatic C3-C 20 α-olefins include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Preferably, the one or more comonomers are selected from propylene, 1-butene, 1-hexene, and 1-octene. Preferably, the one or more comonomers are selected from propylene, 1-butene, and 1-hexene. More preferably, the comonomer is 1-butene and / or 1-hexene.

[0128] The term "copolymer" refers to a polymer made by linking ethylene and at least one comonomer in the same polymer chain. The term "homopolymer" refers to a polymer made in the absence of a comonomer or with less than 0.1 wt%, more preferably less than 0.05 wt% of a comonomer.

[0129] Preferably, the high density polyethylene is an ethylene copolymer and when determined by 13 C-NMR analysis, based on the total weight of the high density polyethylene, the high density polyethylene contains at least 0.1 wt%, preferably at least 0.5 wt%; more preferably at least 0.8 wt%; even more preferably at least 1.0 wt%, most preferably at least 1.2 wt%; and even most preferably at least 1.5 wt% of one or more comonomers.

[0130] Preferably, the high density polyethylene is an ethylene copolymer and when determined by 13 C-NMR analysis, based on the total weight of the high density polyethylene, the high density polyethylene contains at most 2.5 wt%; preferably at most 2.2 wt%; more preferably at most 2.0 wt%; and even more preferably at most 1.8 wt% of one or more comonomers.

[0131] In a preferred embodiment, when determined by 13 C-NMR analysis, based on the total weight of the high density polyethylene, the one or more comonomers are present in the high density polyethylene in an amount ranging from 0.1 to 2.5 wt%; preferably from 0.5 to 2.5 wt%; more preferably 0.8 to 2.2 wt%; and even more preferably from 1.0 to 2.2 wt%.

[0132] For example, HDPE is chromium-catalyzed, Ziegler-Natta-catalyzed, or metallocene-catalyzed.

[0133] Polyethylene composition

[0134] Preferably, the linear low density polyethylene resin and the high density polyethylene resin and their respective contents are selected such that the polyethylene composition has an MI2 in the range of from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, and a density in the range of from 0.915 to 0.935 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012; an Mw / Mn in the range of from 3.0 to 6.0 when measured by gel permeation chromatography; a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography; and a comonomer content in the range of from 4.2 to 9.1 wt% based on the total weight of the polyethylene composition when measured by 13 C-NMR analysis.

[0135] For example, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the polyethylene composition has an MI2 of at least 0.9 g / 10 min; preferably at least 1.0 g / 10 min; and more preferably at least 1.1 g / 10 min.

[0136] For example, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the polyethylene composition has an MI2 of at most 3.0 g / 10 min; preferably at most 2.8 g / 10 min; more preferably at most 2.6 g / 10 min; even more preferably at most 2.4 g / 10 min.

[0137] Preferably, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the polyethylene composition has an MI2 in the range of from 0.9 to 3.0 g / 10 min; preferably from 0.9 to 2.8 g / 10 min; more preferably from 1.0 to 2.6 g / 10 min; even more preferably from 1.1 to 2.4 g / 10 min.

[0138] For example, when measured at 23 °C according to ISO 1183-1:2012, the polyethylene composition has a density of at least 0.920 g / cm 3 ; preferably at least 0.922 g / cm 3 ; more preferably at least 0.924 g / cm 3 ; and even more preferably at least 0.925 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012.

[0139] For example, when measured at 23 °C in accordance with ISO 1183-1:2012, the polyethylene composition has a density of at most 0.935 g / cm 3 ; preferably, at most 0.934 g / cm 3 ; more preferably, at most 0.932 g / cm 3 ; and even more preferably, at most 0.930 g / cm 3 .

[0140] Preferably, when measured at 23 °C in accordance with ISO 1183-1:2012, the polyethylene composition has a density in the range from 0.915 to 0.935 g / cm 3 ; preferably, from 0.920 to 0.934 g / cm 3 ; more preferably, from 0.924 to 0.932 g / cm 3 ; and even more preferably, from 0.925 to 0.930 g / cm 3 .

[0141] Preferably, when determined by 13 C-NMR analysis, based on the total weight of the polyethylene composition, the polyethylene composition contains at least 4.2% by weight, preferably at least 4.5% by weight; more preferably at least 4.9% by weight; even more preferably at least 5.0% by weight, most preferably at least 5.2% by weight; even most preferably at least 5.5% by weight or at least 5.7% by weight of one or more comonomers.

[0142] Preferably, when determined by 13 C-NMR analysis, based on the total weight of the polyethylene composition, the polyethylene composition contains at most 9.1% by weight; preferably at most 8.5% by weight; more preferably at most 7.5% by weight; and even more preferably at most 6.5% by weight of one or more comonomers.

[0143] In a preferred embodiment, when determined by 13 C-NMR analysis, based on the total weight of the polyethylene composition, the one or more comonomers are present in the polyethylene composition in an amount in the range from 4.2 to 9.1% by weight; preferably from 4.5 to 9.2% by weight; more preferably from 4.9 to 8.5% by weight; even more preferably from 5.0 to 7.5% by weight, and most preferably from 5.2 to 6.5% by weight.

[0144] For example, in the TREF curve, the polyethylene composition has two elution peaks from 60 to 120 °C, excluding the purge peak.

[0145] For example, in the TREF curve, the polyethylene composition has a main elution peak below 85°C. Preferably, in the TREF curve, the polyethylene composition has a main elution peak below 82°C, preferably below 80°C.

[0146] For example, in the TREF curve, the polyethylene composition has a secondary elution peak above 95°C. Preferably, in the TREF curve, the polyethylene composition has a main elution peak above 98°C, preferably above 100°C.

[0147] For example, based on the total weight, the polyethylene composition has 60 to 90 wt% of the polymer eluting at a temperature in the range from 50 to 95°C, and 10 to 40 wt% of the polymer eluting at a temperature in the range from above 95 to 120°C; preferably, based on the total weight, 65 to 85 wt% of the polymer eluting at a temperature in the range from 50 to 95°C, and 15 to 35 wt% of the polymer eluting at a temperature in the range from above 95 to 120°C.

[0148] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mw / Mn of at least 3.0; preferably at least 3.2; more preferably at least 3.5; even more preferably at least 3.8; most preferably at least 4.0.

[0149] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mw / Mn of at most 6.0; preferably at most 5.8; more preferably at most 5.5; even more preferably at most 5.2; most preferably at most 5.0.

[0150] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mw / Mn in the range from 3.0 to 6.0; preferably in the range from 4.0 to 5.0.

[0151] For example, when measured by gel permeation chromatography, the polyethylene composition has a z-average molecular weight (Mz) of at most 370,000 g / mol; preferably at most 360,000 g / mol, more preferably at most 350,000 g / mol; even more preferably at most 320,000 g / mol; and most preferably at most 300,000 g / mol.

[0152] For example, when measured by gel permeation chromatography, the polyethylene composition has a z-average molecular weight (Mz) in the range from 180,000 to 370,000 g / mol, preferably in the range from 200,000 to 350,000 g / mol.

[0153] For example, when measured by gel permeation chromatography, the polyethylene composition has an Mz / Mw of at least 2.0; preferably at least 2.2; more preferably at least 2.5. For example, when measured by gel permeation chromatography, the polyethylene composition has an Mz / Mw of at most 5.0; preferably at most 4.5; most preferably at most 4.0; and even most preferably at most 3.5. For example, when measured by gel permeation chromatography, the polyethylene composition has an Mz / Mw ranging from 2.0 to 5.0; preferably ranging from 2.2 to 4.0.

[0154] For example, when measured according to ISO 11357-3:2018, the polyethylene composition has a main melting temperature peak Tm of at least 120 °C; preferably at least 122 °C, more preferably at least 124 °C.

[0155] The polyethylene composition according to the present disclosure may contain one or more additives, such as, by way of example, antioxidants, light stabilizers, acid scavengers, flame retardants, lubricants, antistatic additives, nucleating agents / clarifying agents, colorants, slip agents, antiblocking agents, processing aids, and any mixtures thereof. The production of the polyethylene composition may include blending the polyethylene with one or more additives to obtain the polyethylene composition.

[0156] For example, the polyethylene composition according to the present disclosure may contain one or more antioxidants, such as primary antioxidants and / or secondary antioxidants. It is believed that one or more antioxidants do not affect the tensile behavior nor the final film mechanical properties.

[0157] Typical commercial primary antioxidants are hindered phenols and secondary aromatic amines. The most common secondary antioxidants are trivalent phosphorus compounds (phosphites (salts)).

[0158] In a preferred embodiment, based on the total weight of the polyethylene composition, the polyethylene composition contains from 100 to 5000 ppm of one or more antioxidants. Preferably, the one or more antioxidants include at least one phenolic antioxidant and / or at least one organic phosphite or phosphite (salt) antioxidant.

[0159] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition contains at least 100 ppm; preferably at least 150 ppm, more preferably at least 200 ppm; even more preferably at least 250 ppm and most preferably at least 300 ppm of one or more antioxidants.

[0160] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises up to 5000 ppm; preferably up to 4000 ppm; more preferably up to 3000 ppm; even more preferably up to 2500 ppm and most preferably up to 2000 ppm of one or more antioxidants.

[0161] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises from 100 to 5000 ppm; preferably from 150 to 4000 ppm; more preferably from 200 to 3000 ppm; even more preferably from 250 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more antioxidants.

[0162] In a preferred embodiment, the one or more antioxidants are or comprise one or more phenolic antioxidants selected from octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 2082-79-3, Irganox® 1076) and / or pentaerythritol-tetra(3-(3’,5’-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS 6683-19-8, Irganox® 1010).

[0163] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises at least 100 ppm; preferably at least 150 ppm, more preferably at least 200 ppm; even more preferably at least 250 ppm and most preferably at least 300 ppm of one or more phenolic antioxidants.

[0164] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises up to 5000 ppm; preferably up to 4000 ppm, more preferably up to 3000 ppm; even more preferably up to 2500 ppm and most preferably up to 2000 ppm of one or more phenolic antioxidants.

[0165] Based on the total weight of the polyethylene composition, the polyethylene composition comprises from 100 to 5000 ppm; preferably from 150 to 4000 ppm; more preferably from 200 to 3000 ppm; even more preferably from 250 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more phenolic antioxidants selected from octadecyl 3-(3’,5’-di-tert-butyl-4-hydroxyphenyl)propionate and / or pentaerythritol-tetra(3-(3’,5’-di-tert-butyl-4-hydroxyphenyl)propionate).

[0166] In a preferred embodiment, the one or more antioxidants are or comprise at least one organic phosphite or phosphonite antioxidant selected from tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4, Irgafos® 168), bis(2,4-di-tert-butyl-6-methylphenyl)-ethyl-phosphite (CAS No. 145650-60-8, Irgafos® 38), trinonylphenyl phosphite (CAS No. 26523-78-4), tetra-(2,4-di-tert-butylphenyl)-4,4'-biphenyl-di-phosphonite (CAS No. 119345-01-6, Irgafos® P-EPQ), 2,4,6-tri-tert-butylphenyl 2-butyl-2-ethyl-1,3-propanediol phosphite (CAS No. 161717-32-4, Ultranox® 641), and any mixture thereof.

[0167] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises at least 100 ppm; preferably at least 150 ppm, more preferably at least 200 ppm; even more preferably at least 250 ppm and most preferably at least 300 ppm of one or more organic phosphite or phosphonite antioxidants.

[0168] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises at most 5000 ppm; preferably at most 4000 ppm, more preferably at most 3000 ppm; even more preferably at most 2500 ppm and most preferably at most 2000 ppm of one or more organic phosphite or phosphonite antioxidants.

[0169] Based on the total weight of the polyethylene composition, the polyethylene composition comprises from 100 to 5000 ppm; preferably from 150 to 4000 ppm; more preferably from 200 to 3000 ppm; even more preferably from 250 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more organic phosphite or phosphonate antioxidants selected from tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4, Irgafos® 168), bis(2,4-di-tert-butyl-6-methylphenyl)-ethyl-phosphite (CAS No. 145650-60-8, Irgafos® 38), trinonylphenyl phosphite (CAS No. 26523-78-4), tetra-(2,4-di-tert-butylphenyl)-4,4'-biphenyl-di-phosphonate (CAS No. 119345-01-6, Irgafos® P-EPQ), 2,4,6-tri-tert-butylphenyl 2-butyl-2-ethyl-1,3-propanediol phosphite (CAS No. 161717-32-4, Ultranox® 641), or mixtures thereof.

[0170] In one embodiment, the one or more antioxidants comprise one or more selected from pentaerythritol tetra[3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate]; tris(2,4-di-tert-butylphenyl) phosphite and / or octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0171] In one embodiment, the one or more antioxidants comprise at least two selected from pentaerythritol tetra[3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0172] Pentaerythritol tetra[3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate] is commercially available as Irganox® 1010 from BASF. Tris(2,4-di-tert-butylphenyl) phosphite is commercially available as Irgafos® 168 from BASF. Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is commercially available as Irganox® 1076 from BASF.

[0173] For example, the polyethylene composition according to the present disclosure may contain one or more acid scavengers. It is believed that the one or more acid scavengers do not affect the tensile behavior nor the mechanical properties of the final film.

[0174] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises from 10 to 5000 ppm; preferably from 50 to 4000 ppm; more preferably from 100 to 3000 ppm; even more preferably from 200 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more acid scavengers.

[0175] Preferably, the one or more acid scavengers are selected from calcium oxide, zinc oxide, calcium stearate, magnesium stearate, zinc stearate, sodium stearate, potassium stearate, hydrotalcite, and mixtures thereof, preferably selected from calcium stearate, magnesium stearate, zinc stearate, sodium stearate, potassium stearate, and mixtures thereof, more preferably selected from calcium stearate, calcium oxide, zinc oxide, and any mixture thereof. Preferably, the one or more acid scavengers are or comprise calcium stearate.

[0176] For example, the polyethylene composition may contain one or more slip agents. Any slip agent known to those skilled in the art can be added. Non-limiting examples of slip agents include primary amides having from about 12 to about 40 carbon atoms (e.g., erucamide, oleamide, stearamide, and behenamide); secondary amides having from about 18 to about 80 carbon atoms (e.g., stearyl erucamide, behenyl erucamide, methyl erucamide, and ethyl erucamide); secondary bis-amides having from about 18 to about 80 carbon atoms (e.g., ethylene-bis-stearamide and ethylene-bis-oleamide); and combinations thereof. For example, the one or more slip agents are selected from polydimethylsiloxane, erucamide, oleamide, stearamide, behenamide, stearyl erucamide, behenyl erucamide, methyl erucamide, ethyl erucamide, ethylene-bis-stearamide, ethylene-bis-oleamide, and any combination thereof. Non-limiting examples of commercially available slip agents have trade names such as ATMER ™ SA from Uniqema, Everberg, Belgium; ARMOSLIP® from Akzo Nobel Polymer Chemicals, Chicago, IL; KEMAMIDE® from Witco, Greenwich, CT; and CRODAMIDE® from Croda, Edison, NJ.

[0177] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises from 10 to 5000 ppm, preferably from 50 to 4000 ppm; more preferably from 100 to 3000 ppm; even more preferably from 200 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more slip agents.

[0178] For example, the polyethylene composition may contain one or more anti-blocking agents. The anti-blocking agent can be used to prevent unwanted adhesion between the contact layers of articles made from the polymer composition, particularly under medium pressure and heat during storage, manufacture, or use. Any anti-blocking agent known to those of ordinary skill in the art can be added to the polyethylene compositions disclosed herein. Non-limiting examples of anti-blocking agents include minerals (such as clay, chalk, and calcium carbonate), synthetic silica gels (such as SYLOBLOC® from Grace Davison, Columbia, MD), natural silica (such as SUPER FLOSS® from Celite Corporation, Santa Barbara, CA), talc (such as OPTIBLOC® from Luzenac, Centennial, CO), zeolites (such as SIPERNAT® from Degussa, Parsippany, NJ), aluminosilicates (such as SILTON® from Mizusawa Industrial Chemicals, Tokyo, Japan), limestone (such as CARBOREX® from Omya, Atlanta, GA), spherical polymer particles (such as EPOSTAR® poly(methyl methacrylate) particles from NipponShokubai, Tokyo, Japan and TOSPEARL® silicone particles from GE Silicones, Wilton, CT), waxes, amides (such as erucamide, oleamide, stearamide, behenamide, ethylene-bis-stearamide, ethylene-bis-oleamide, stearyl erucamide, and other slip agents), molecular sieves, and combinations thereof.

[0179] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises from 10 to 5000 ppm; preferably from 50 to 4000 ppm; more preferably from 100 to 3000 ppm; even more preferably from 200 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more anti-blocking agents.

[0180] For example, the polyethylene composition may contain one or more processing aids. For example, the one or more processing aids are selected from fluoroelastomers, waxes, tristearin, zinc stearate, calcium stearate, magnesium stearate, erucamide, oleamide, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, cetyltrimethylammonium bromide, polyethylene oxide, polysiloxane, oleylamide, stearamide, behenamide, oleyl palmitamide, ethylene bis-oleamide, ethylene bis(stearamide) (EBS), and any mixtures thereof.

[0181] Preferably, based on the total weight of the polyethylene composition, the polyethylene composition comprises from 10 to 5000 ppm; preferably from 50 to 4000 ppm; more preferably from 100 to 3000 ppm; even more preferably from 200 to 2500 ppm; and most preferably from 300 to 2000 ppm of one or more processing aids.

[0182] Test Methods

[0183] Of the polyethylene resin Melt flow index MI2 Is determined according to ISO 1133-2005 at 190 °C under a load of 2.16 kg.

[0184] Of the polyethylene resin HLMI Is determined according to ISO 1133-2005 at 190 °C under a load of 21.6 kg.

[0185] Mn, Mw, Mz, Mw / Mn and Mz / Mw: Molecular weight M n (number average molecular weight), M w (weight average molecular weight) and molecular weight distribution D (Mw / Mn) are determined by size exclusion chromatography (SEC) and in particular by gel permeation chromatography (GPC). Briefly, use GPC-IR5 from Polymer Char: Dissolve 10 mg of the polyethylene sample in 10 mL of trichlorobenzene at 160 °C for 1 hour. Injection volume: about 400 µl, automatic sample preparation and injection temperature: 160 °C. Column temperature: 145 °C. Detector temperature: 160 °C. Use two Shodex AT-806MS (Showa Denko) and one Styragel HT6E (Waters) columns, with a flow rate of 1 ml / min. Detector: infrared detector (2800 - 3000 cm -1 ). Calibration: Narrow standards of polystyrene (PS) (commercially available). The molecular weight Mi of each fraction i of the eluted polyethylene is calculated based on the Mark-Houwink relationship (log 10 (M PE) = 0.965909 × log 10 (M PS ) - 0.28264) (cuts off at M PE = 1000 at the low molecular weight end).

[0186] The molecular weight averages used to establish molecular weight / property relationships are the number average molecular weight (M n ), the weight average molecular weight (M w ), and the z - average molecular weight (M z ). These averages are defined by the following expressions and are determined from the calculated M i :

[0187]

[0188]

[0189]

[0190] where N i and W i are the number and weight, respectively, of molecules having molecular weight Mi. The third representation (farthest right) in each case defines how these averages are obtained from the SEC chromatogram. h i is the height (from the baseline) of the SEC curve at the i - th elution fraction, and M i is the molecular weight of the material eluting in that increment.

[0191] Then Molecular weight distribution (MWD) is calculated as Mw / Mn.

[0192] 13 C-NMR analysisPerformed using a 400 MHz or 500 MHz Bruker NMR spectrometer under conditions such that the signal intensity in the spectrum is proportional to the total number of carbon atoms contributing in the sample. Such conditions are well known to those skilled in the art and include, for example, sufficient relaxation time, etc. In practice, the intensity of the signal is obtained from its integral (i.e., the corresponding area). The data was obtained as follows: using proton decoupling, using a 10 mm room temperature probe (10 mm room temperature through) 2000 to 4000 scans per spectrum or using a 10 mm cryoprobe 240 scans per spectrum, a 11-second pulse repetition delay, and a spectral width of 25000 Hz (+ / -3000 Hz). Samples were prepared by dissolving a sufficient amount of the polymer in 1,2,4-trichlorobenzene (TCB, 99%, spectroscopic grade) at 130 °C and occasionally stirring to homogenize the sample, followed by the addition of hexadeuterobenzene (C6D6, spectroscopic grade) and a small amount of hexamethyldisiloxane (HMDS, 99.5+%), where HMDS was used as an internal standard. For example, approximately 200 mg to 600 mg of the polymer was dissolved in 2.0 mL of TCB, followed by the addition of 0.5 mL of C6D6 and 2 to 3 drops of HMDS.

[0193] After data acquisition, the signal of the chemical shift reference internal standard HMDS, which was assigned a value of 2.03 ppm.

[0194] The comonomer content in polyethylene was determined by C-NMR analysis of pellets according to the method described by G.J. Ray et al. (Macromolecules, 1977, 10, (4), 773 - 778). 13 C-NMR analysis.

[0195] Crystallization temperature (Tc) and melting temperature (Tm) was determined on a DSC Q2000 instrument from TA Instruments according to ISO 11357-3:2018. To eliminate the thermal history, the sample was first heated to 220 °C and held at 220 °C for 3 minutes. Then the polymer was cooled to up to 20 °C at -20 °C / min and held at 20 °C for 3 minutes. The crystallization temperature was determined during this cooling step. The crystallization temperature Tc corresponds to the temperature of the extremum of the thermogram that presents the heat flux associated with the polymer as a function of the temperature during its cooling. Then the polymer was melted to up to 220 °C at 20 °C / min, and the melting temperature was determined during this heating step. The melting temperature corresponds to the temperature of the extremum of the thermogram that presents the heat flux associated with the polymer as a function of the temperature during its melting.

[0196] Measure at a temperature of 23 °C according to the method (immersion method) of standard ISO 1183-1:2012 Density .

[0197] Determine according to DIN ISO 4593:1993 Thickness of the film .

[0198] Determine the Mechanical properties of the film according to ASTM D 882, such as tensile strength at break, elongation at break and modulus of elasticity E.

[0199] Determine the falling dart impact resistance according to ASTM D1709, Method A.

[0200] Determine the thermal shrinkage at a temperature of 100 °C during 5 minutes and a sample size of 100 mm x 100 mm.

[0201] Determine according to ASTM D 1003 Haze . Measure the haze on the final BOPE films: the thickness of these films is reported in Table 6.

[0202] Determine the heat sealability under the following conditions according to ASTM F1921 / Method B:

[0203] · Sample width: 15 mm

[0204] · Sealing time: 3 s

[0205] · Sealing pressure: 0.3 N / mm²

[0206] · Traction speed: 200 mm / s

[0207] TREF

[0208] Perform temperature rising elution fractionation analysis (TREF analysis) using a method similar to that described in Soares and Hamielec, Polymer, 36 (10), 1995 1639-1654 (which is incorporated herein by reference in its entirety). The TREF analysis is performed on a TREF model 200 TF series instrument equipped with an infrared detector from Polymer Char (Valencia, Spain). Dissolve the sample in 1,2-dichlorobenzene at 150 °C for 1 h. Use the following parameters as shown in the table below.

[0209]

[0210]

[0211] Examples

[0212] The following non-limiting examples illustrate the present disclosure.

[0213] Selection of components of the blend

[0214] - LLDPE1 for the examples of the present invention was prepared according to the process disclosed in WO2020078932. LLDPE1 is metallocene-catalyzed. The comonomer is hexene and is present at about 8 wt%.

[0215] - HDPE1 is lumicene® M5510EP (batch S106319328), commercially available from TotalEnergies.

[0216] - HDPE2 is HD6207CC (batch H008E00380), commercially available from TotalEnergies.

[0217] - HDPE3 is an experimental resin and is Ziegler-Natta catalyzed.

[0218] - HDPE4 is an experimental resin and is Ziegler-Natta catalyzed.

[0219] The properties of the components of the blends are provided in Table 1 below.

[0220] Table 1

[0221]

[0222] The composition of the blends and the properties of the blends are provided in Tables 2 to 4.

[0223] Table 2

[0224]

[0225] Prior to the BOPE pilot trial, blends 01 and 02 were melt-extruded / compounded to ensure optimal homogeneity of the mixture.

[0226] Table 3:

[0227]

[0228] (1) The blends have multiple temperature peaks, and the main melting temperature peak is reported herein.

[0229] Table 4: TREF results

[0230]

[0231] Multilayer film

[0232] A 5-layer BOPE film has been produced according to a sequential stretching process (tenter technology). All layers contain the same polyethylene composition.

[0233] In a first step, a cast sheet is extruded using several extruders, feeding 5 layers (“DBABC”) according to Table 5 below.

[0234] Table 5:

[0235]

[0236] At the die exit, the co-extruded sheet (about 1 mm thick) is cooled on a chill roll that is partially immersed in a water bath.

[0237] In a second step, the cast sheet passes through an MDO unit (Machine Direction Orientation), where it is stretched in the machine direction by a system of heated rolls. Then the MD-stretched film enters a tenter (or “TDO oven”), which is an oven-like device that uses chains to grip and stretch the film in the transverse direction on a turning track.

[0238] At the exit of the TD oven, the film reaches its final thickness (i.e., about 20 microns).

[0239] The properties of the BOPE film are reported in Table 6 as draw ratios in the machine direction (MDx) and in the transverse direction (TDx).

[0240] Compared to thicker, non-oriented PE blown films, these thin BOPE films are characterized by an improved balance of properties:

[0241] - Although the thickness is lower, the film stiffness and tensile strength at break are higher (based on a standard mPE with a density of 0.923 - 0.927, for a 40-micron blown film, the tensile strength at break is typically in the range of 50 to 60 MPa);

[0242] - Although the thickness is lower, the dart impact resistance is similar to higher (based on a standard mPE with a density of 0.923 - 0.927, for a 40-micron blown film, the dart is typically in the range of 200 to 310 grams);

[0243] - The transparency is similar to better (based on a standard mPE with a density of 0.923 - 0.927, for a 40-micron blown film, the haze is typically in the range of 5% to 8%).

[0244] The sealing properties of some BOPE films were evaluated by hot tack sealing tests and compared with a 40 - micron thick PE blown film reference (either based on a commercially available metallocene LLDPE with a density of 0.923 or a commercially available LDPE with a density of 0.924). Regarding the initial sealing temperature (i.e., the lowest temperature at which a given sealing strength is achieved): Considering a threshold of 0.2 to 0.5 N / 15 mm, the BOPE films of the present invention exhibit higher or at least similar sealing forces compared to the reference blown films. It can also be seen that the BOPE films allow for a higher maximum sealing strength (above about 120 °C at 2.0 N / 15 mm) to be reached compared to the reference blown films, and although they are thinner, they have a relatively wide sealing window.

[0245] The hot tack sealing properties are provided in Figure 2 the

[0246] In summary, it can be considered that the BOPE films of the present invention exhibit an improved balance of (mechanical, optical, and sealing) properties compared to thicker, non - oriented PE blown films.

[0247]

Claims

1. Process for producing a polyethylene composition for a biaxially oriented polyethylene film or a uniaxially oriented polyethylene film, characterized in that, It includes: - Based on the total weight of the polyethylene composition, provide from 60 to 90% by weight of a linear low density polyethylene resin; wherein the linear low density polyethylene resin has: an MI2 in the range of from 0.9 to 4.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density in the range of from 0.910 to 0.930 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012; an Mw / Mn of 2.5 - 6.0 when measured by gel permeation chromatography; a z-average molecular weight (Mz) of at most 310,000 g / mol when measured by gel permeation chromatography; and the linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers, wherein based on the linear low density polyethylene resin, the one or more comonomers are present in an amount in the range of from 7.0 to 11.0% by weight; - Based on the total weight of the polyethylene composition, providing from 10 to 40% by weight of a high-density polyethylene resin; wherein the high-density polyethylene resin has: an MI2 ranging from 0.5 to 1.6 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; a density ranging from 0.950 to 0.965 g / cm 3 when measured at 23 °C according to ISO 1183-1:2012, wherein the high-density polyethylene resin is selected to have an MI2 that is less than or equal to the MI2 of the linear low-density polyethylene resin; and - melt-blending the linear low density polyethylene resin and the high density polyethylene resin to produce a polyethylene composition; wherein the polyethylene composition has: - an MI2 in the range from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; - Density ranging from 0.915 to 0.935 g / cm 3 when measured at 23 °C in accordance with ISO 1183-1:2012; - an Mw / Mn in the range from 3.0 to 6.0 when measured by gel permeation chromatography; - a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography; - in the TREF curve, a main elution peak below 82 °C and a secondary elution peak above 95 °C; and - When determined by 13 C-NMR analysis, a comonomer content in the range of from 4.2 to 9.1% by weight, based on the total weight of the polyethylene composition.

2. The process according to claim 1, characterized in that, when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the polyethylene composition has an MI2 in the range from 1.0 to 2.6 g / 10 min.

3. The process according to claim 1 or 2, characterized in that, When measured at 23 °C according to ISO 1183-1:2012, the polyethylene composition has a density in the range from 0.920 to 0.935 g / cm 3 3.

4. The process according to any one of claims 1 to 2, characterized in that, When determined by 13 C-NMR analysis, the polyethylene composition has a comonomer content in the range of from 4.9 to 8.5% by weight, based on the total weight of the polyethylene composition.

5. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the polyethylene composition has an Mw / Mn in the range from 3.2 to 5.

8.

6. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the polyethylene composition has an Mz / Mw in the range from 2.0 to 5.

0.

7. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the polyethylene composition has a z-average molecular weight (Mz) of at most 350,000 g / mol.

8. The process according to any one of claims 1 to 2, characterized in that, When measured according to ISO 11357-3:2018, the polyethylene composition has a main melting temperature peak Tm of at least 120 °C.

9. The process according to any one of claims 1 to 2, characterized in that, The process includes: - providing from 65 to 85 wt% of the linear low density polyethylene resin based on the total weight of the polyethylene composition; and / or - providing from 15 to 35 wt% of the high density polyethylene resin based on the total weight of the polyethylene composition.

10. The process according to any one of claims 1 to 2, characterized in that, The linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers selected from 1-butene, 1-hexene, and 1-octene.

11. The process according to any one of claims 1 to 2, characterized in that, The linear low density polyethylene resin is a copolymer of ethylene and one or more comonomers, wherein based on the linear low density polyethylene resin, the one or more comonomers are present in an amount in the range from 7.5 to 9.5 wt%.

12. The process according to any one of claims 1 to 2, characterized in that, When measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the linear low density polyethylene resin has an MI2 in the range from 1.0 to 3.5 g / 10 min.

13. The process according to any one of claims 1 to 2, characterized in that, When measured at 23 °C in accordance with ISO 1183-1:2012, the linear low density polyethylene resin has a density in the range of from 0.912 to 0.928 g / cm 3 3.

14. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw / Mn in the range from 3.5 to 6.

0.

15. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the linear low density polyethylene resin has a z-average molecular weight (Mz) in the range from 180,000 to 280,000 g / mol.

16. The process according to any one of claims 1 to 2, characterized in that, When measured by gel permeation chromatography, the linear low density polyethylene resin has an Mw of at most 110,000 g / mol.

17. The process according to any one of claims 1 to 2, characterized in that, The linear low density polyethylene resin is metallocene-catalyzed; and / or has a bimodal molecular weight distribution.

18. The process according to any one of claims 1 to 2, characterized in that, When measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005, the high-density polyethylene resin has an MI2 in the range of from 0.6 to 1.5 g / 10 min.

19. The process according to any one of claims 1 to 2, characterized in that, When measured at 23 °C in accordance with ISO 1183-1:2012, the high density polyethylene resin has a density in the range of from 0.952 to 0.964 g / cm 3 3.

20. A polyethylene composition, characterized in that, It is produced by the process according to any one of claims 1 to 19.

21. A polyethylene composition, characterized in that, It has: - an MI2 in the range of from 0.9 to 3.0 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; - A density in the range from 0.915 to 0.935 g / cm³ when measured at 23 °C in accordance with ISO 1183-1:2012 3 ; - an Mw / Mn in the range of from 3.0 to 6.0 when measured by gel permeation chromatography; - a z-average molecular weight (Mz) of at most 370,000 g / mol when measured by gel permeation chromatography; - in the TREF curve, a main elution peak below 82 °C and a secondary elution peak above 95 °C; and - When determined by 13 C-NMR analysis, a comonomer content in the range of from 4.2 to 9.1% by weight, based on the total weight of the polyethylene composition.

22. The polyethylene composition according to claim 21, wherein It has: - an MI2 in the range of from 1.0 to 2.6 g / 10 min when measured at 190 °C under a load of 2.16 kg according to ISO 1133-2005; and / or - A density in the range from 0.920 to 0.935 g / cm3 when measured at 23 °C in accordance with ISO 1183-1:2012; and / or 3 and / or - When determined by 13 13C-NMR analysis, a comonomer content in the range from 4.9 to 8.5% by weight, based on the total weight of the polyethylene composition; and / or - a main melting temperature peak Tm of at least 120 °C when measured according to ISO 11357-3:2018.

23. The polyethylene composition according to claim 21 or 22, characterized in that, It has: - an Mw / Mn in the range of from 3.2 to 5.8 when measured by gel permeation chromatography; and / or - an Mz / Mw in the range of from 2.0 to 5.0 when measured by gel permeation chromatography; and / or - a z-average molecular weight (Mz) of at most 350,000 g / mol when measured by gel permeation chromatography.

24. A membrane, which is a single-layer membrane or a multi-layer membrane, characterized in that, At least one of the one or more layers is made of the polyethylene composition according to any one of claims 20 to 23; and the film is a biaxially oriented polyethylene film or a uniaxially oriented polyethylene film.

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