Polyethylene compositions suitable for producing large volume containers

Abstract

The invention relates to a polyethylene composition, comprising an ethylene polymer, which comprises or consists of: a) a low molecular weight component (A); and b) a high molecular weight component (B); wherein the polyethylene composition has:. a melt flow index (MFI21.6) of ≥ 5.0 and ≤ 20.0 dg / min, determined in accordance with ISO1133-1:2011 at 190 ºC and measured at 21.6 kg; and. a density of ≥ 955.0 and ≤ 970.0 kg / m3determined in accordance with ISO 1183; and. a complex viscosity (η100) at a shear rate of 100 rad / s of ≥ 1800 and ≤ 2700 Pa.s, determined in accordance with ISO 6721-10 at 190 ºC. The invention further relates to an article, preferably a container having a storage volume of > 0 litre and < 100.0 litre, preferably > 5 litre and < 100.0 litre, comprising the polyethylene composition.

Description

POLYETHYLENE COMPOSITIONS SUITABLE FOR PRODUCING LARGE VOLUME CONTAINERSFIELD OF INVENTION

[0001] The invention relates to a polyethylene composition and to articles, for example large volume containers (e.g. >100 litre), that are prepared from such a polyethylene composition.BACKGROUND

[0002] Compositions comprising an ethylene copolymer are often used in many application fields for example in the production of pipes and films as well as in blow-molding and injection molding applications. Typically, blow molding is a molding process commonly used to produce, for example, household and industrial containers. In a blow molding process the polyethylene is melted and extruded into a mold and compressed air is used to inflate and shape the polymer into the desired form. Important properties of the polymer to be molded are its mechanical properties which, in turn, determine the properties of the final molded article. It is desirable for ethylene polymers for use in blow molding application to have a high strain hardening along with suitable flow properties.

[0003] One such application of blow molding is in the manufacture of containers of large storage volume. Desired performance parameters by industry practitioners involved in the manufacture of large volume articles e.ge. containers with storage volume of > 5.0 litre and < 100.0 litre by blow molding include: good processability, low sagging characteristics, good organoleptic, high melt strength, high stiffness and excellent slow crack growth resistance, and in particular a good combination of all these properties.

[0004] Processability is related to the ability of the material to flow and fill up completely all the cavities of the mold. The higher the flow rate, the higher the speed at which the blow molded articles can be produced and the shorter the processing the time. High Melt Strength is related to the resistance of the material to flow when it is melted at high temperature and the shear rate is low or close to zero. The higher the melt strength, the higher the dimensional homogeneity of the final blow molded part. For large volume containers, it is particularly desirable to use resins whichhave excellent melt strength given by the strain hardening property. A desired melt strength prevents sagging in the parison while manufacturing the article during the blow molding process.

[0005] High slow crack growth resistance and stiffness allow for down-gauging of material needs for the blow molded part, making the process more sustainable and resource efficient. Typically, polyethylene resins with high density and high melt index perform well in processability and stiffness, but show a poor environmental stress cracking resistance (ESCR) and melt strength. On the other hand, polyethylene resins with low density and low melt index while providing an excellent ESCR and melt strength, typically show a poor processability and poor stiffness. In the past techniques such as using peroxide cross-linking and large loading of carbon black based master batches have been used to impart the desired balance of these properties. However, such an approach may be capital intensive and also may not be resource efficient. In some instance high loading of carbon black may adversely the mechanical and processability properties of the polyethylene resin.

[0006] Therefore, there is a need for developing polyethylene resins for large volume containers manufactured that show improved balance of environmental stress cracking resistance (ESCR), melt strength, processability and stiffness, preferably without the need of using carbon black based fillers. Accordingly, it is an objective of the present invention to provide for a polyethylene composition, that is suitable for manufacturing large volume containers (e.g. > 20 liter) and show an excellent balance between ESCR, melt strength, processability and stiffness.DESCRIPTION

[0007] Accordingly, the one or more objectives of the present invention is achieved by a polyethylene composition, comprising an ethylene polymer comprising or consisting of :(a) > 60.0 and < 80.0 wt.%, preferably > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol, preferably wherein the weight average molecular weight (Mw) is determined in accordance with ASTM D6474-12; and(b) > 20.0 and < 40.0, preferably > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; preferably wherein the low molecular weight component (A) is an ethylene homopolymer or an ethylene copolymer and preferably wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer, preferably the high molecular weight component (B) is a copolymer of ethylene and a C3-C8 alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 5.0 and < 20.0 dg / min, preferably > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 963.0 kg / m3, preferably> 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 1800 and < 2700 Pa.s, preferably> 2000 and < 2500 Pa.s, preferably > 2050 and < 2400 Pa.s, preferably > 2050 and < 2300 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0008] Preferably, the polyethylene composition, comprising an ethylene polymer comprising or consisting of:(a) > 60.0 and < 80.0 wt.%, preferably > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol, preferably wherein the weight average molecular weight (Mw) is determined in accordance with ASTM D6474-12; and(b) > 20.0 and < 40.0, preferably > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; wherein the low molecular weight component (A) is an ethylene homopolymer and wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer,preferably the high molecular weight component (B) is a copolymer of ethylene and a Cs-Cs alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 5.0 and < 20.0 dg / min, preferably > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 963.0 kg / m3, preferably> 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 1800 and < 2700 Pa.s, preferably> 2000 and < 2500 Pa.s, preferably > 2050 and < 2400 Pa.s, preferably > 2050 and < 2300 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0009] Preferably, the polyethylene composition, comprising an ethylene polymer comprising or consisting of:(a) > 60.0 and < 80.0 wt.%, preferably > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol, preferably wherein the weight average molecular weight (Mw) is determined in accordance with ASTM D6474-12; and(b) > 20.0 and < 40.0, preferably > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; wherein the low molecular weight component (A) is an ethylene homopolymer and wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer, preferably the high molecular weight component (B) is a copolymer of ethylene and a C3-C8 alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 963.0 kg / m3, preferably> 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2050 and < 2400 Pa.s, preferably> 2050 and < 2300 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0010] The weight average molecular weight (Mw) for the high molecular weight component (B) may be measured using any known techniques using ISO and ASTM standards such as deconvolution technique based on ASTM D6474-12.

[0011] Preferably, the polyethylene composition, comprising the ethylene polymer comprises or consists of:(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; preferably wherein the low molecular weight component (A) is an ethylene homopolymer or an ethylene copolymer; and preferably wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer, preferably a copolymer of ethylene and a C3-C8 alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 963.0 kg / m3, preferably > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2000 and < 2500 Pa.s, preferably> 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0012] Preferably, the polyethylene composition has a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 450.0 kPa.s and < 1500.0 k.Pa.s, preferably > 500.0 kPa.s and < 1100.0k.Pa.s, preferably > 600.0 kPa.s and < 1100.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C.

[0013] Advantageously, the polyethylene composition of the present invention has an excellent balance of processability, stiffness and ESCR properties. Advantageously, in an aspect of the invention the polyethylene composition is free of cross-linking and carbon black based additives.

[0014] In an aspect of the invention, the invention relates to the use of the polyethylene composition of the present invention, for improving the processability of manufacturing an article while imparting the desired stiffness and ESCR properties to the article, preferably wherein the article is a container having a storage volume of > 20 liter and < 1000 liter, preferably > 100 liter and < 1000 liter.

[0015] Preferably, the polyethylene composition, comprising the ethylene polymer comprises or consists of:(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; preferably wherein the low molecular weight component (A) is an ethylene homopolymer or an ethylene copolymer; and preferably wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer, preferably a copolymer of ethylene and a C3-C8 alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 963.0 kg / m3, preferably > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2000 and < 2500 Pa.s, preferably > 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 100.0 and < 175.0, preferably > 110.0 and < 170.0, preferably > 125.0 and < 150.0, where melt flow ratio is the ratio of melt flow index measured according to ISO1133-1 :2011 at 190 °C and at 21.6 and at 5.0 kg respectively.

[0016] Preferably, the polyethylene composition has at least one of:(a) a Bell Test resistance F50 of > 1000 hours and < 6000 hours when determined in accordance with ASTM DI 693 Method B at 50 °C in 10% IGEPAL; and / or(b) a Yield stress of > 27.0 MPa and < 35.0 MPa, preferably > 28.0 MPa and < 32.0 MPa, as measured according to ISO 527-2 at 23 °C; and / or(c) a Tensile modulus value of > 1350 MPa and < 1600 MPa as measured according to ISO 527-2 at 23 °C.

[0017] Preferably, the polyethylene composition has(a) a Bell Test resistance F50 of > 1000 hours and < 6000 hours when determined in accordance with ASTM DI 693 Method B at 50 °C in 10% IGEPAL; and(b) a Yield stress of > 27.0 MPa and < 35.0 MPa, preferably > 28.0 MPa and < 32.0 MPa, as measured according to ISO 527-2 at 23 °C; and(c) a Tensile modulus value of > 1350 MPa and < 1600 MPa as measured according to ISO 527-2 at 23 °C.

[0018] The polyethylene composition of the present invention demonstrates a desired shear thinning behavior when subjected to high stress. The polyethylene composition according to the invention has a relatively low viscosity at a relatively high shear rate, which results in a good processability for blow molding.

[0019] The polyethylene composition has an excellent balance of melt strength as indicated by the viscosity at low shear rate and processability indicated by the low viscosity at high shear rate.

[0020] For example, the polyethylene composition has a shear thinning index (SHI) of > 167.0 and < 833.0, preferably > 200.0 and < 550.0, preferably > 300.0 and < 500.0, wherein shear thinning index (SHI) is defined as the ratio of complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s to complex viscosity (rpoo) at a shear rate of 100 rad / s.

[0021] The polyethylene composition has the desired melt strength as also indicated by the strain hardening value. Preferably, the polyethylene composition has a strain hardening modulus of > 25.0 MPa and < 50.0 MPa, preferably > 28.0 MPa and < 45.0 MPa as measured in accordance with ISO 18488.

[0022] The term ethylene polymer as used throughout this disclosure means a polymer, the majority by weight, of which is derived from ethylene monomer units. The ethylene polymer may be an ethylene homopolymer or a copolymer of ethylene and a C3-C20 comonomer.

[0023] The ethylene polymer may be bimodal or multimodal. Preferably, the ethylene polymer has bimodal distribution comprising the component (A) and component (B).

[0024] Preferably the polyethylene composition a total content of polymeric units derived from C3-C8 alpha olefin comonomer of > 0.05 and < 0.3 mol.%, preferably > 0.1 and < 0.16 mol.%, with regard to the total moles of the polyethylene composition, preferably wherein the mole content of the polymeric units in the polyethylene composition is determined using InfraRed spectroscopy. Preferably, the C3-C8 alpha olefin comonomer is selected from 1 -butene, 1 -hexene, 4-methyl 1 -pentene, 1 -octene, preferably the C3-C8 alpha olefin comonomer is any one of 1 -butene or 1 -hexene.

[0025] Preferably the polyethylene composition has a total content of polymeric units derived from ethylene of > 99.7 and < 99.95 mol.%, preferably > 99.84 and < 99.9 mol.%, with regard to the total moles of the polyethylene composition.

[0026] Preferably, the polyethylene composition has a melt flow ratio of > 100.0 and < 175.0, preferably > 110.0 and < 170.0, preferably > 125.0 and < 150.0, where melt flow ratio is the ratio of melt flow index measured according to ISO1133-1 :2011 at 190 °C and at 21.6 and 5.0 kg respectively.

[0027] Preferably, the polyethylene composition has a weight average molecular weight (Mw) of > 350 kg / mol and < 510 kg / mol, preferably > 370 kg / mol and < 500 kg / mol is determined in accordance with ASTM D6474-12; and / or wherein the polyethylene composition has a Z- average molecular weight of > 2300 kg / mol and < 3000 kg / mol, preferably > 2350 kg / mol and < 2950 kg / mol is determined in accordance with ASTM D6474-12.

[0028] Preferably, the polyethylene composition has a ratio of Z-average molecular weight to weight average molecular weight (Mz / Mw) of > 4.6 and < 8.6, where Mz and Mw are determined in accordance with ASTM D6474-12.

[0029] Preferably, the polyethylene composition has a molecular weight distribution (Mw / Mn) of > 40.0 and < 70.0, preferably >50.0 and < 68.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight each determined in accordance with ASTM D6474-12.Low molecular weight component (A) of the ethylene polymer

[0030] The low molecular weight component A) is present invent in an amount of > 60.0 and < 80.0 wt.%, preferably > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer.

[0031] The low molecular weight component (A) of the ethylene polymer may be an ethylene homopolymer or an ethylene copolymer. Preferably, the low molecular weight component (A) of the ethylene polymer is an ethylene homopolymer. Preferably, the lowmolecular weight component (A) of the ethylene polymer may be an ethylene homopolymer or an ethylene copolymer having a density of > 960.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3, preferably the low molecular weight component is an ethylene homopolymer having a density of > 960.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3. The density may be determined in accordance with ISO 1183.

[0032] Preferably, the low molecular weight component (A) has a ratio of Mw / Mn of > 5.0 and < 11.0, preferably > 6.0 and < 10.0. The weight average molecular weight (Mw) and the number average molecular weight (Mn) for the low molecular weight component (A) may be determined in accordance with ASTM D6474-12.

[0033] Preferably, the low molecular weight component (A) has a melt flow index (MFI1.2) of > 5.0 and < 50.0 dg / min, preferably > 15.0 and < 40.0 dg / min, preferably > 20.0 and < 35.0 dg / min preferably > 20.0 and < 30.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg.

[0034] Preferably, the low molecular weight component (A) has a melt flow index (MFI1.2) of > 5.0 and < 50.0 dg / min, preferably > 15.0 and < 40.0 dg / min, preferably > 20.0 and < 35.0 dg / min, preferably > 20.0 and < 30.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg; and / or wherein the low molecular weight component (A) has a molecular weight distribution (Mw / Mn) of > 5.0 and < 11.0, preferably > 6.0 and < 10.0.High molecular weight component (B) of the ethylene polymer

[0035] The high molecular weight component (B) is present in an amount of > 20.0 and <0.0, preferably > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer.

[0036] The high molecular weight component (B) has a ratio of Mw / Mn of > 4.0 and < 8.0, preferably > 4.5 and <7.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12. The valuesof Mw and Mn for high molecular weight component (B) can be determined can for example by using ASTM D6474-12 and deconvolution technique.

[0037] The high molecular weight component (B) has a density of > 920 and < 950 kg / m3, preferably > 920 and < 946 kg / m3. The density may be determined in accordance with ISO 1183.

[0038] Preferably, the high molecular weight component (B) has a melt flow rate as measured according to IS01 133-1 :2011 at 190 °C and at 21.6 kg of > 0.05 and < 2.0 dg / min, preferably > 0.08 and < 1.0 dg / min, preferably > 0.10 and < 0.5 dg / min.

[0039] The high molecular weight component (B) of the ethylene copolymer may be a copolymer of ethylene and a C3-C20 comonomer. The C3-C20 comonomer is preferably selected from the group consisting of C3-C10, preferably C3-C8 alpha-olefins such as propylene, 1 -butene, 1 -hexene and 1 -octene.

[0040] Preferably, the high molecular weight component (B) is a copolymer of ethylene and 1 -butene or ethylene and 1 -hexene. For example, the high molecular weight component (B) is a copolymer comprising polymeric units derived from ethylene and a C3-C8 alpha olefin comonomer. Most preferably, high molecular weight component (B) is a copolymer of ethylene and 1 -butene.

[0041] The high molecular weight component (B) of the ethylene polymer may be a copolymer of ethylene and a C3-C20 comonomer, preferably a C3-C8 alpha olefin comonomer.

[0042] Preferably, the high molecular weight component (B) is a copolymer comprising polymeric units derived from of ethylene and a C3-C8 alpha olefin comonomer. Preferably the C3- Cs alpha olefin comonomer is selected from propylene, 1 -butene, 1 -hexene and 1 -octene. Preferably, the high molecular weight component (B) is a copolymer of ethylene and 1 -butene or a copolymer of ethylene and 1 -hexene.Low Molecular Weight component (A) and high molecular weight component (B)

[0043] Preferably, the low molecular weight component (A) is an ethylene homopolymer having a density of > 960.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3determined in accordance with ISO 1183; and / or wherein the high molecular weight component (B) is a copolymer of ethylene and 1 -butene or ethylene and 1 -hexene, preferably wherein, the high molecular weight component (B) is a copolymer of ethylene and 1 -hexene.

[0044] Preferably the polyethylene composition comprises > 80.0 wt.% and < 100.wt.%, preferably > 90.0 wt.% and < 100. wt.%, preferably > 95.0 wt.% and < 100.wt.%, preferably > 98.0 wt.% and < 100. wt.% of the ethylene polymer with regard to the total weight of the polyethylene composition; and wherein the polyethylene composition comprises > 0.0 wt.% and < 20.0 wt.%, preferably > 0.0 wt.% and < 10.0 wt.%, preferably > 0.0 wt.% and < 5.0 wt.%, preferably > 0.0 wt.% and < 2.0 wt.%, of additives with regard to the total weight of the polyethylene composition, preferably the additive is selected from anti-oxidants, carbon black, fillers, process stabilisers, antioxidants, light and / or heat stabilisers, cross-linking agents and combinations thereof.

[0045] Preferably the additive is selected from the group consisting of anti-oxidants, fillers, light stabilizers, heat stabilizers and combinations thereof.

[0046] Preferably, the polyethylene composition, comprising an ethylene polymer comprising or consisting of:(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A)having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 963.0 kg / m3, preferably > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2000 and < 2500 Pa.s, preferably> 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a total content of polymeric units derived from Cs-Cs alpha olefin comonomer of > 0.1 and < 0.16 mol.%, with regard to the total moles of the polyethylene composition; and• a shear thinning index (SHI) of > 200.0 and < 550.0, preferably > 300.0 and < 500.0, wherein shear thinning index (SHI) is defined as the ratio of complex viscosity (T]O.OI) at a shear rate of 0.01 rad / s to complex viscosity (r| 100) at a shear rate of 100 rad / s.

[0047] Preferably, the polyethylene composition, comprising an ethylene polymer comprising or consisting of :(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 963.0 kg / m3, preferably > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2000 and < 2500 Pa.s, preferably> 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a total content of polymeric units derived from C3-C8 alpha olefin comonomer of > 0.1 and < 0.16 mol.%, with regard to the total moles of the polyethylene composition; and• a shear thinning index (SHI) of preferably > 300.0 and < 500.0, wherein shear thinning index (SHI) is defined as the ratio of complex viscosity (T]O.OI) at a shear rate of 0.01 rad / s to complex viscosity (rpoo) at a shear rate of 100 rad / s; and• > 98.0 wt.% and < 100.wt.% of the ethylene polymer with regard to the total weight of the polyethylene composition and > 0.0 wt.% and < 2.0 wt.%, of additives with regard to the total weight of the polyethylene composition.

[0048] Preferably the ethylene polymer comprises or consists of :(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 30,000 g / mol and < 60,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 1,200,000 g / mol; and wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a melt flow ratio of > 125.0 and < 150.0, where melt flow ratio is the ratio of melt flow index measured according to ISO1133-1 :2011 at 190 °C and at 21.6 and 5.0 kg respectively; and• a complex viscosity (rpoo) at a shear rate of 100 rad / s of > 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 600.0 kPa. s and < 1100.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C.

[0049] Preferably, the polyethylene composition, comprising an ethylene polymer comprising or consisting of:(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; wherein the low molecular weight component (A) is an ethylene homopolymer and wherein the high molecular weight component (B) is a copolymer of ethylene and a Cs-Cs alpha olefin; and wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 963.0 kg / m3, preferably > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 2000 and < 2500 Pa.s, preferably > 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a total content of polymeric units derived from C3-C8 alpha olefin comonomer of > 0.1 and < 0.16 mol.%, with regard to the total moles of the polyethylene composition; and• a shear thinning index (SHI) of > 200.0 and < 550.0, preferably > 300.0 and < 500.0, wherein shear thinning index (SHI) is defined as the ratio of complex viscosity (T]O.OI) at a shear rate of 0.01 rad / s to complex viscosity (r| 100) at a shear rate of 100 rad / s; and• a weight average molecular weight (Mw) of > 350 kg / mol and < 510 kg / mol, determined in accordance with ASTM D6474-12; and• a Z-average molecular weight of > 2300 kg / mol and < 3000 kg / mol, determined in accordance with ASTM D6474-12; and• a molecular weight distribution (Mw / Mn) of > 40.0 and < 70.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight each determined in accordance with ASTM D6474-12.Preparing the ethylene polymer and the polyethylene composition

[0050] The ethylene polymer according to the invention may be prepared by a process comprising the steps of producing the low molecular weight component (A) and the high molecular weight component (B) as a bimodal ethylene polymer made by polymerizing the low molecular weight component (Component A) and subsequently polymerizing the high molecular weight component (Component B) in the presence of the low molecular weight component.

[0051] Accordingly, the invention provides a process for the preparation of the ethylene polymer according to the invention, wherein the process comprises the step of sequential polymerization process comprising at least two reactors connected in series, wherein the process comprises the steps of a) preparing the low molecular weight component (high molecular weight component) in a first reactor using the first set of conditions, b) transferring the low molecular weight component (high molecular weight component) and unreacted monomers of the first reactor to a second reactor, c) feeding monomers to the second reactor, d) preparing the high molecular weight component (low molecular weight component) in the second reactor in the presence of the low molecular weight component (high molecular weight component) to obtain the ethylene polymer.

[0052] Each of the ethylene polymer components A and B and the optional further ethylene polymer component(s) may be produced in the presence of known catalyst systems such as a Ziegler Natta catalyst system or a metallocene catalyst system, preferably a Ziegler Natta catalyst system. The polymerization can be carried out in the presence of an anti-static agent or anti fouling agent in an amount ranging between for example 1 and 500 ppm related to the total amount of reactor contents.

[0053] The multi-step slurry polymerization process may be carried out using cascaded reactors in the presence of a Ziegler Natta catalyst system.

[0054] Alternatively, the properties of the fractions produced in a higher stage of the multistage process may also be calculated, e.g. in accordance with B. Hagstrom, Conference on Polymer Processing (The Polymer Processing Society), Extended Abstracts and Final Programme, Gothenburg, August 19 to 21 , 1997, 4: 13. Thus, although not directly measurable on the multistage process products, the properties of the fractions produced in higher stages of such a multistage process can be determined by applying either or both of the above methods. The skilled person will be able to select the appropriate method.

[0055] Alternatively, the ethylene polymer according to the invention may be prepared by a process comprising melt-mixing or solution blending the low molecular weight component (A) and the high molecular weight component (B) made in different reactors to obtain the ethylene polymer. The melt-mixing or solution blending may be carried out in any conventional blending apparatus. The low molecular weight component and the high molecular weight component to be melt-mixed or solution blended may be produced by any known process.

[0056] The ethylene polymer once obtained may be compounded with additives such as carbon black, anti-oxidant, masterbatch, color pigments to obtain the polyethylene composition. The amount of additives may not exceed 10.0 wt.% with regard to the total weight of the polyethylene composition, preferably the amount of additive is not greater than 2.0 wt.% with regard to the total weight of the ethylene polymer.

[0057] In an aspect of the invention, the invention relates to an article comprising the polyethylene composition of the present invention. Preferably the article is selected from a container, a bottle, and a storage vessel, preferably the article is a container having a storage volume of > 20 liter and < 1000 liter, preferably the article is a container having a storage volume of > 100 liter and < 1000 liter.

[0058] In an aspect of the invention the invention is directed to a container having a storage volume of > 20 liter and < 1000 liter, preferably the article is a container having a storage volume of > 100 liter and < 1000 liter.

[0059] Preferably the article comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably 100 wt.%, with regard to the total weight of the article, of the polyethylene composition of the present invention.

[0060] The invention will now be demonstrated with the following non-limiting examples.EXAMPLES

[0061] Purpose: To evaluate the properties of sample specimen prepared from the polyethylene composition of the present invention.

[0062] Catalyst preparation:

[0063] Catalyst 1 - Preparation of a hydrocarbon solution comprising the organic oxygen containing magnesium compound and the organic oxygen containing titanium compound 100 grams of granular Mg(OC2Hs)2 and 150 millilitres of Ti(OC4H9)4 were brought in a 2 litre round bottomed flask equipped with a reflux condenser and stirrer. While gently stirring, the mixture was heated to 180°C and subsequently stirred for 1.5 hours. During this, a clear liquid was obtained. The mixture was cooled down to 120°C and subsequently diluted with 1480 ml of hexane. Upon addition of the hexane, the mixture cooled further down to 67°C. The mixture was kept at this temperature for 2 hours and subsequently cooled down to room temperature. The resulting clear solution was stored under nitrogen atmosphere and was used as obtained. Analyses on the solution showed a titanium concentration of 0.25 mol / 1.Preparation o f the catalyst

[0064] In a 0.8 liters glass reactor, equipped with baffles, reflux condenser and stirrer, 424 ml hexanes and 160 ml of the complex from Example I were dosed. The stirrer was set at 1200 RPM. In a separate flask, 100 ml of 50% ethyl aluminum di chloride (EADC) solution was added to 55 mL of hexanes. The resulting EADC solution was dosed into the reactor in 15 minutes using a peristaltic pump. Subsequently, the mixture was refluxed for 2 hours. After cooling down to ambient temperature, the obtained red / brown suspension was transferred to a glass P4 filter and the solids were separated. The solids were washed 3 times using 500 ml of hexanes. The solids were taken up in 0.5 L of hexanes and the resulting slurry was stored under nitrogen. The solid contentwas 64 g ml'1. Catalyst analysis results: Ti 10.8 wt%; Mg 11.2 wt%; Al 5.0 wt%; CI 65 wt%; OEt 3.2 wt% and OBu 2.6 wt%.

[0065] Catalyst 2 - 100 grams of granular Mg(OC2Hs)2 and 150 millilitres of Ti(OC4H9)4 were brought in a 2 litre round bottomed flask equipped with a reflux condenser and stirrer. While gently stirring, the mixture was heated to 180°C and subsequently stirred for 1.5 hours. During this, a clear liquid was obtained. The mixture was cooled down to 120°C and subsequently diluted with 1480 ml of hexane. Upon addition of the hexane, the mixture cooled further down to 67°C. The mixture was kept at this temperature for 2 hours and subsequently cooled down to room temperature. The resulting clear solution was stored under nitrogen atmosphere and was used as obtained. Analyses on the solution showed a titanium concentration of 0.25 mol / 1.

[0066] In a 1.0 liter glass reactor, equipped with baffles, reflux condenser and stirrer, 286 ml hexanes and 170 ml of the complex from obtained above were dosed. The stirrer was set at 1400 rpm. In a separate flask, 75 ml of 50% ethyl aluminium dichloride (EADC) solution was added to 43 ml of hexanes. The resulting EADC solution was dosed into the reactor in 15 minutes using a peristaltic pump. Subsequently, the mixture was refluxed for 2 hours. After cooling down to ambient temperature, the obtained red / brown suspension was transferred to a glass P4 filter and the solids were separated. The solids were washed 4 times using 500 ml of hexanes. The solids were taken up in 0.3 L of hexanes and the resulting slurry was stored under nitrogen. The solid content was 30 g / 1.

[0067] Catalyst analysis results: Ti 9.7 wt.% Mg 10.4 wt.% Al 4.6 wt.% Cl 49 wt.% OEt9.0 wt% and OBu 12 wt.%.

[0068] Preparation of the ethylene polymer -

[0069] Inventive Example 1 (IE1) - A Continuous Stirred Tank Reactor (CSTR) reactor with 20 liters total volume and 15 liters of operating volume was operated at 85 °C and 9.3 barg total pressure. For producing a first polymer fraction, 700 g / h of ethylene and 1.13 g / h of hydrogen were added to the polymerization reactor, along with 4200 g / h of linear and branched C7 alkanes mixtures. In addition, Catalyst 1 was introduced into the reactor at the rate needed to keep the totalpressure of the reactor constant, along with Tri-isobuyl-aluminium (TIBA) as cocatalyst. No additional comonomer was introduced into the reactor. The conditions in the reactor are shown in table 1. The polymer slurry was withdrawn from the reactor and transferred to an adiabatic flash vessel were pressure was manipulated in order to get the desired H2 / C2 gas phase ratio in the second reactor. After this flashing step, the polymer slurry was withdrawn from the flash vessel and transferred to a second CSTR reactor with same total and operating volumes as the first CSTR reactor.

[0070] The second CSTR reactor was operated at 60 °C and 4.9 barg total pressure. Into the reactor were introduced ethylene at a rate of 377 g / h, linear and branched C7 alkanes mixtures at a rate of 4950 g / h, 1 -hexene at a rate of 60 g / h and nitrogen in order to keep the total pressure constant at 4.9 barg. The conditions in the second CSTR reactor are shown in table 1. The slurry withdrawn from the second CSTR reactor was transferred into a centrifugal decanter where the polymer and diluent were separated.

[0071] Inventive example 2 (IE2) / Inventive examples 3 (IE3) - Inventive examples 2 was identical to inventive example 1 except catalyst used is Catalyst 2, a C6 alkane mixture was used as diluent instead of a C7 alkane mixture, comonomer is 1 -butene and the polymerization conditions and feeds which are shown in Table 1.

[0072] Comparative examples 4and 5 Comparative examples 4 and 5 are commercial HDPE materials for large and very large articles by blow molding. Comparative Example 4 (CEx4), is a commercially available trimodal resin made with Ziegler-Natta catalyst and 1 -butene from SABIC, B5403.

[0073] Comparative Example 5 (CEx5), is a commercially available monomodal HDPE made with Chromium catalyst and 1 -hexene from SABIC, ICP5602.

[0074] Processing parameters for the preparation of ethylene polymer -Table 1

[0075] The resulting ethylene polymer samples obtained from Table 1 were extruded under conditions below. The resulting ethylene polymer was then dried under vacuum at 60 °C overnight. The dry polymer was stabilized with 3000 ppm of a mixture of Calcium Stearate, Irgafos 168 and Irganox 1010 in weight ratio 50 / 37.5 / 12.5 respectively and then extruded into pellets in a Coperion ZSK-18 co-rotating twin screw extruder system, so that the extruder throughput was 1.8 kg / h to obtain the pellets of the polyethylene composition.

[0076] No additional carbon black or peroxides were added further to the polyethylene composition. The properties of the obtained polyethylene composition post extrusion / pelletization is reported under Table 3.Table 2Table 3Table 4

[0077] It can be understood that the polyethylene composition according to the invention (IE1 to IE3) has a combination of excellent processability due to the low viscosity values at 100 rad / s (rpoo), excellent melt fracture performance, with no melt fracture appearing up to 3200 s'1of shear rate, a superior ESCR, given the high values of Bell test and Strain Hardening, an excellent Melt Strength, given by the value of viscosity at 0.01 rad / s (r|o.oi), very high stiffness, given by the yield stress and tensile modulus values and an excellent impact resistance given by a ductile to brittle transition temperature measured according to Charpy Impact test below -20 deg C.

[0078] In comparison, polyethylene composition CEx4 has a poorer processability as measured by the viscosity values at a shear rate of 100 rad / s, much narrower window of transformation, with melt fracture already appearing at 200 s’1, lower stiffness as given by the yield stress and tensile modulus, and much lower ESCR resistance and melt strength. The polyethylene composition CEx5 shows much lower processability as measured by the viscosity values at a shear rate of 100 rad / s, much narrower window of transformation, with melt fracture already happening at 200 s’1, lower stiffness as given by the yield stress and tensile modulus, much lower ESCR resistance as shown by the Bell Test and Strain Hardening modulus, and significantly lower melt strength.Measurement methodology of various parameters:

[0079] MFI was measured according to ISO 1133-1 :2011 under a load of 1.2 kg (MH.2), 2.16 kg (MI5) or 21.6 kg (MI21.6) at 190°C. The term Melt Flow Index and Melt Flow Rate (MFR) may for example be used interchangeably for the purposes of the present invention.

[0080] Density - Density of the ethylene polymer powder samples was measured by preparing polymer test plaques of 40 x 40 x 1.6 mm, following ISO 17855-2 in a Fontyne press model TP200. The compression cycle had a temperature set at 180 C, with 10 minutes of contact pressure. Cooling was performed with an initial time of 30 seconds without pressure increase, followed by pressure increase until 200 kN and maintaining the pressure level during the time needed for the sample to reach 23 °C at a cooling rate of 15 ± 2 °C / min. Mass of the test plaque was determined in air (Analytical Balance XS 104 Mettler Toledo). Subsequently, the test plaquewas immersed in 4 liters of water at 100 °C (Automatic Densimeter D-H100 from Toyo Seiki equipped with a thermostatic bath MX7LR-20 from WMR) for 10 minutes after which the heat is turn off and the sample was cooled down to room temperature. The density was determined as follows:=- ms,air Pwater -+ Q 0Q27ms,air (ms+nc, watermnc, water ps= Density of the test plaque (g / cm3) ms,atr=Mass of the test plaque in air (g)Pwater=Density of demineralized water (g / cm3) at test temperature (23°C) ms+nc, water=Mass of the test plaque and sinker in water (g) mnc, water=Mass of the sinker clamp in water (g)Note: since density of polyethylene is lower than water, a sinker is used to keep the test plaque immersed.

[0081] Density of polymer pellet samples (polyethylene composition) was measured by following ISO 1183 A with the immersion method.

[0082] Comonomer content using Infrared method - Samples were pressed into 70 micron films using a Specac Atlas manual hydraulic press constant thickness film maker. Press temperature was set to 170 °C, preheat time is 1 minute, press time was 1 minute, press pressure was 2 tons and the spacer was an E-ring. Films are pressed in between PTFE foils.

[0083] Samples were subsequently measured via Infrared with a Perkin Elmer Spectrum 100 in transmission measurement mode. 9 scans are made in the scan rage 4400-400 cm’1with an spectral resolution of 4 cm’1with CO2 / H2O water correction active.

[0084] The infrared results are transformed into comonomer mol% by the use of 6 calibration (calibration type multivariate), and 3 validation sample standards in the comonomer range 0.25 to 1.75 mol%.Molecular weight Distribution (MWD) and molecular weight

[0085] Mw, Mn and Mz were measured in accordance with ASTM D6474-12 (Standard Test Method for Determining molecular weight distribution and molecular weight Averages ofPolyolefins by High Temperature Gel Permeation Chromatography). Mw stands for the weight average molecular weight and Mn stands for the number average molecular weight. Mz stands for the z-average molecular weight.

[0086] A high-temperature chromatograph Polymer Char GPC-IR system equipped with IR5 MCT detector and Polymer Char viscometer (Polymer Char S.A., Spain) was used at 160°C to determine the MWD and SCB as function of molecular weight. Three columns of Polymer Laboratories 13pm PLgel Olexis, 300 x 7.5mm, were used in series for GPC separation. 1,2,4- trichlorobenzene stabilized with Ig / L butylhydroxytoluene (also known as 2,6-di- / c / 7-butyl-4- m ethylphenol or BHT) was used as eluent at a flow rate of ImL / min. Sample concentration was around 0.7mg / mL and injection volume was 300pL. The molar mass was determined based on the Universal GPC-principle using a calibration made with PE narrow and broad standards (in the range of 0.5-2800kg / mol, Mw / Mn - 4 to 15) in combination with known Mark Houwink constants of PE-calibrant (alfa = 0.725 and log K = -3.721).

[0087] Then, the ratio value was calculated from the dW / dLogMw value at the peak molecular weight of the low molecular weight component multiplied by the corresponding molecular weight component.

[0088] Deconvolution technique to calculate Mw / Mn for the high molecular weight polymer component B using ASTM D 6474-12

[0089] The molecular weight distribution moments for the polymer component B (Mn and Mw) can be calculated by using a deconvolution technique employing the data obtained experimentally using the ASTM D 6474-12 standard for the low molecular weight component (Fraction A) and the final polyethylene composition. Such techniques for example has been described in WO99 / 14271.

[0090] For polymers manufactured using a Ziegler-Natta catalyst system such as the ones employed for the inventive examples of the invention, Catl and Cat2, the molecular weight distribution follows a log-normal distribution, defined by Equation [3]:Where:

[0091] wi is the weight component of polymer with molecular weight MiMo is the peak molecular weightP is a parameter which characterizes the width of the log-normal distribution

[0092] The MWD deconvolution technique involves a two parameter fit, Mo and P, as per equation [3], Both parameters values are fitted by minimizing the error defined by Eqn 4.

[0093] This is the error between the experimentally determined molecular weight distribution for the polyethylene composition (final product) obtained using ASTM D 6474- 12, and the fitted distribution obtained by the addition of fractions A and B of the final composition. The molecular weight distribution data for fraction A and for the final composition was obtained by using ASTM D 6474-12 on the collected inventive examples of Table 1, and molecular weight distribution data for fraction B was calculated from the molecular weight distribution data from final polyethylene composition and fraction A, as described below.

[0094] The minimization error is expressed as:Where: wi, experimental is the weight fraction of polymer with a molecular weight Mi for the polymer composition of the invention. It is determined experimentally for the polyethylene composition following ASTM D 6474-12. wi, calculated is the weight fraction of polymer with a molecular weight Mi calculated for the polyethylene composition of the invention.

[0095] It is determined from the addition of the weight fraction of polymer with same molecular weight Mi for the fraction A, determined experimentally following ASTM D 6474- 12, times the weight component of polymer fraction A in the total polyethylene composition and the addition of the weight fraction of polymer with same molecular weight Mi for the fraction B, calculated with Equation [3], times the weight component of polymer fraction B inthe final polyethylene composition. The weight components of fractions A and B with respect to the total polyethylene composition can be found for each inventive example in Table 1. The error was minimized by using Solver Excel minimization algorithm iterating over the values of Mo and p.

[0096] Mn and Mw for the calculated molecular weight distribution of component B are calculated by the formulas described in ASTM D 6474-12.Dynamic Mechanical Properties (complex viscosity n):

[0097] The viscosity values at each shear rate are calculated by fitting flow curves generated by oscillatory reometer according to ISO 6721-10 between 0.01 and 100 rad / s at 190 C on parallel plates with 25 mm diameter and 1.2 mm gap with a modified Carreau- Yasuda model, which is represented by the following equation:where q is the viscosity in Pa.s ro is the zero shear viscosity (Pa.s) a is the rheological breadth parameter n is the power law constant, set to 0 in the present case (defines the slope of the high shear rate region) y is the shear rate (1 / s)X is the relaxation time (s) rpoo is the viscosity value in Pa.s at 190 °C and a shear rate of 100 rad / s as calculated by equation [1] previously fitted to the flow curve data generated by oscillatory rheometry between 0.01 and 100 rad / s at 190 C according to ISO 6721-10 on parallel plates with 25 mm diameter and 1.2 mm gap.

[0098] To facilitate model fitting, the power law constant is held at a constant value, in this case zero. Details of the significance and interpretation of the Carreau-Yasuda model and derived parameters may be found in: C.A. Hieber and H.H. Chiang, Rheol Acta, 28, 321 (1989); C.A. Hieber and H.H. Chiang, Polym. Eng. Sci., 32, 931 (1992); and R.B. Bird, R.C. Armstrong and O.Hasseger, Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2ndEdition, John Wiley & Sons (1987).

[0099] Yield Stress: Yield stress is measured following ISO527-1 at 1 mm / min for modulus and at 50 mm / min for the tensile test, on bars of type IB, with average results from 5 specimens at 23 °C.

[0100] Strain Hardening Modulus: Strain hardening modulus was determined according to ISO18488.

[0101] Environmental Stress Crack Resistance measured according to ASTM D1639 Method B at 50 C in 10% Igepal (F50).

[0102] Impact Resistance: Impact resistance was measured by Charpy method following ISO 179-1 / leA, non-instrumented test at -10 °C, 0 °C and 23 °C on specimens with dimensions 80 x 10 x 4 mm and a notch of type A. The result is the average of 5 specimens being tested. The direction of the blow is edgewise. Specimens are prepared by compression molding following ISO17855-2, at a compression molding temperature of 180 °C, with a compression molding cooling rate of 15 °C / min and a plaque thickness of 4 mm. Final specimens are prepared by machining from the compression molded plaque.

[0103] Melt Fracture performance - Capillary rheometry is a technique whereby a sample undergoes extrusion through a die of defined dimensions and the shear pressure drop across the die is recorded at different shear rates. The capillary extrusion experiment may be carried out using any suitable methodology. For example, in this invention the capillary extrusion experiment are carried out at 190 °C, using a CEAST Rheologic 1000 rheometer, equipped with a 1.0 mm die diameter with an L / D ratio of 10: 1 and an entry angle of 30 °. Extrudates are collected at different shear rates and evaluated optically by any suitable methodology to identify the onset of melt fracture of the extrudate.

[0104] For example, the extrudate may be visually inspected for determination of the onset of melt fracture. The onset of melt fracture is a polymer instability in the polymer composition that originates at the exit of a die during extrusion of melted resin through the die. Further definitions and examples can be found elsewhere, for example, Polymer Rheology: Fundamentals and Applications, chapter 2, pages 45-47, by T. Osswald and N. Rudoph, Hanser Publishers, ISBN 978- 1-56990-517-3 and Polymer Processing Instabilities: Control and Understanding, chapter 5 by K.B. Migler, edited by S.G Hatzikiriakos and K.B. Migler, Marcel Deker ISBN 824 75386, Dec. 2004.

Claims

CLAIMS1. A polyethylene composition, comprising an ethylene polymer comprising or consisting of:(a) > 60.0 and < 80.0 wt.%, preferably > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol, preferably wherein the weight average molecular weight (Mw) is determined in accordance with ASTM D6474-12; and(b) > 20.0 and < 40.0, preferably > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; preferably wherein the low molecular weight component (A) is an ethylene homopolymer or an ethylene copolymer and preferably wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C20 comonomer, preferably the high molecular weight component (B) is a copolymer of ethylene and a C3-C8 alpha olefin; wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 5.0 and < 20.0 dg / min, preferably > 8.0 and < 17.0 dg / min, preferably > 9.0 and < 15.0 dg / min, preferably > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 963.0 kg / m3, preferably> 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a complex viscosity (qioo) at a shear rate of 100 rad / s of > 1800 and < 2700 Pa.s, preferably> 2000 and < 2500 Pa.s, preferably > 2050 and < 2400 Pa.s, preferably > 2050 and < 2300 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

2. The polyethylene composition of claim 1, wherein the polyethylene composition has a complex viscosity (T]O.OI) at a shear rate of 0.01 rad / s of > 450.0 kPa.s and < 1500.0 k.Pa.s, preferably > 500.0 kPa.s and < 1100.0 k.Pa.s, preferably > 600.0 kPa.s and < 1100.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C.

3. The polyethylene composition according to any one of claims 1-2, wherein the polyethylene composition a total content of polymeric units derived from Cs-Cs alpha olefin comonomer of > 0.05 and < 0.3 mol.%, preferably > 0.1 and < 0.16 mol.%, with regard to the total moles of the polyethylene composition, preferably wherein the mole content of the polymeric units in the polyethylene composition is determined using InfraRed spectroscopy, preferably wherein the Cs-Cs alpha olefin comonomer is selected from 1 -butene, 1 -hexene, 4-methyl 1 -pentene, 1 -octene, preferably the Cs-Cs alpha olefin comonomer is any one of 1 -butene or 1 -hexene.

4. The polyethylene composition according to any one of claims 1-3, wherein the polyethylene composition has a weight average molecular weight (Mw) of > 350 kg / mol and < 510 kg / mol, preferably > 370 kg / mol and < 500 kg / mol determined in accordance with ASTM D6474-12; and / or wherein the polyethylene composition has a Z-average molecular weight of > 2300 kg / mol and <3000 kg / mol, preferably > 2350 kg / mol and < 2950 kg / mol determined in accordance with ASTM D6474-12; and / or the polyethylene composition has a ratio of Z-average molecular weight to weight average molecular weight (Mz / Mw) of > 4.6 and < 8.6, where Mz and Mw are determined in accordance with ASTM D6474-12.

5. The polyethylene composition according to any one of claims 1-4, wherein the polyethylene composition has a shear thinning index (SHI) of > 167.0 and < 833.0, preferably > 200.0 and < 550.0, preferably > 300.0 and < 500.0, wherein shear thinning index (SHI) is defined as the ratio of the complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s to the complex viscosity (rpoo) at a shear rate of 100 rad / s.

6. The polyethylene composition according to any one of claims 1-5, wherein the polyethylene composition comprises > 80.0 wt.% and < 100.wt.%, preferably > 90.0 wt.% and < 100. wt.%, preferably > 95.0 wt.% and < 100. wt.%, preferably > 98.0 wt.% and < 100. wt.% of the ethylene polymer with regard to the total weight of the polyethylenecomposition; and wherein the polyethylene composition comprises > 0.0 wt.% and < 20.0 wt.%, preferably > 0.0 wt.% and < 10.0 wt.%, preferably > 0.0 wt.% and < 5.0 wt.%, preferably > 0.0 wt.% and < 2.0 wt.%, of additives with regard to the total weight of the polyethylene composition, preferably the additive is selected from anti-oxidants, carbon black, fillers, process stabilisers, anti-oxidants, light and / or heat stabilisers, cross-linking agents and combinations thereof.

7. The polyethylene composition according to any one of claims 1-6, wherein the polyethylene composition has a Strain Hardening modulus of > 25.0 MPa and < 50.0 MPa, preferably > 28.0 MPa and < 45.0 MPa as measured in accordance with ISO 18488.

8. The polyethylene composition according to any one of claims 1-7, wherein the low molecular weight component (A) is an ethylene homopolymer having a density of > 960.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3determined in accordance with ISO 1183; and / or wherein the high molecular weight component (B) is a copolymer of ethylene and 1 -butene or ethylene and 1 -hexene, preferably wherein, the high molecular weight component (B) is a copolymer of ethylene and 1 -hexene.

9. The polyethylene composition according to any one of claims 1-8, wherein the low molecular weight component (A) has a melt flow index (MFI1.2) of > 5.0 and < 50.0 dg / min, preferably > 15.0 and < 40.0 dg / min, preferably > 20.0 and < 35.0 dg / min, preferably > 20.0 and < 30.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg; and / or wherein the low molecular weight component (A) has a molecular weight distribution (Mw / Mn) of > 5.0 and < 11.0, preferably > 6.0 and < 10.0.

10. The polyethylene composition according to any one of claims 1-9, wherein the polyethylene composition has a melt flow ratio of > 100.0 and < 175.0, preferably > 110.0 and < 170.0, preferably > 125.0 and < 150.0, where melt flow ratio is the ratio of melt flowindex measured according to ISO1133-1 :2011 at 190 °C and at 21.6 and at 5.0 kg respectively.

11. The polyethylene composition according to any one of claims 1-10, wherein the polyethylene composition has a molecular weight distribution (Mw / Mn) of > 40.0 and < 70.0, preferably >50.0 and < 68.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight, each determined in accordance with ASTM D6474-12.

12. The polyethylene composition according to any one of claims 1-11, wherein the ethylene polymer comprises or consists of:(a) > 62.0 and < 70.0 wt.%, with regard to the total weight of the ethylene polymer, of a low molecular weight component (A) having a weight average molecular weight of > 30,000 g / mol and < 60,000 g / mol; and(b) > 30.0 and < 38.0, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 1,200,000 g / mol; and wherein the polyethylene composition has:• a melt flow index (MFI21.6) of > 11.0 and < 15.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 21.6 kg; and• a density of > 957.0 and < 963.0 kg / m3, determined in accordance with ISO 1183; and• a melt flow ratio of > 125.0 and < 150.0, where melt flow ratio is the ratio of melt flow index measured according to ISO1133-1 :2011 at 190 °C and at 21.6 and 5.0 kg respectively; and• a complex viscosity (rpoo) at a shear rate of 100 rad / s of > 2050 and < 2400 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 600.0 kPa.s and < 1100 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C.

13. The polyethylene composition according to any one of claims 1-12, wherein the polyethylene composition has at least any one of:(a) a Bell Test resistance F50 of > 1000 hours and < 6000 hours when determined in accordance with ASTM DI 693 Method B at 50 °C in 10% IGEPAL; and / or(b) a Yield stress of > 27.0 MPa and < 35.0 MPa, preferably > 28.0 MPa and < 32.0 MPa, as measured according to ISO 527-2 at 23 °C; and / or(c) a Tensile modulus value of > 1350 MPa and < 1600 MPa as measured according to ISO 527-2 at 23 °C.

14. An article comprising the polyethylene composition as claimed in claims 1-13, preferably wherein the article is selected from a container, a bottle, and a storage vessel, preferably the article is a container having a storage volume of > 20 liter and < 1000 liter, preferably the article is a container having a storage volume of > 100 liter and < 1000 liter.

15. Use of the polyethylene composition as claimed in any one of claims 1-13 for improving the processability of manufacturing an article while imparting the desired stiffness and ESCR properties to the article, preferably wherein the article is a container having a storage volume of > 20 liter and < 1000 liter, preferably > 100 liter and < 1000 liter.

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