Polyethylene composition suitable for small volume containers

Abstract

The invention relates polyethylene composition, (a) ≥ 55.0 and ≤ 80.0 wt.%, of a low molecular weight component (A); and (b) ≥ 20.0 and ≤ 45.0, of a high molecular weight component (B); and wherein the polyethylene composition has:. a melt flow index (MFI5) of ≥ 0.7 and ≤ 2.0 dg / min, determined in accordance with ISO1133-1:2011 at 190 ºC and measured at 5.0 kg; and. a complex viscosity (η0.01) at a shear rate of 0.01 rad / s of ≥ 65.0 kPa.s and ≤ 120.0 k.Pa.s, determined in accordance with ISO 6721-10 at 190 ºC; and. a density of ≥ 955.0 and ≤ 970.0 kg / m3. The invention further relates to an article, preferably a container having a storage volume of > 0 litre and < 3.0 litre and comprising the polyethylene composition.

Description

POLYETHYLENE COMPOSITION SUITABLE FOR SMALL VOLUME CONTAINERSFIELD OF INVENTION

[0001] The invention relates to a polyethylene composition and to articles, for example small volume containers, that are prepared from such a polyethylene composition.BACKGROUND

[0002] Compositions comprising an ethylene copolymer are used in many application fields for example in the production of pipes and films as well as in blow-molding and injection molding applications. Blow molding and injection molding may be used to make a wide variety of articles. 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. Desirable 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 balance of strain hardening and flow properties. Particularly strain hardening, helps in making maintaining the structural integrity. The ethylene polymer should also have flow properties which allow easy processing during the blow molding process.

[0003] One such application of blow molding is in the manufacture of containers of small storage volume. Desired performance parameters by industry practitioners involved in the manufacture of small articles e.ge. containers with storage volume less than by blow molding include: good processability, 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.

[0005] High slow crack growth resistance and stiffness allow for down-gauging of material required for blow molding, making the process sustainable and resource efficient. Typically, polyethylene resins with high density and high melt index perform well for processability and stiffness, but show a poor ESCR and melt strength. On the other hand, polyethylene resins with low density and low melt index for small articles by blow molding applications, while providing a good 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 fillers may reduce the mechanical and processability properties of the polyethylene resin.

[0006] Therefore, there is a need for polyethylene resins for small articles by blow molding that show a better balance between ESCR, melt strength, processability and stiffness. Accordingly, it is an objective of the present invention to provide for a polyethylene composition, that is suitable for manufacturing small volume containers that shows an excellent balance between ESCR, melt strength, processability and stiffness even without the need of cross-linking or adding carbon black based additives.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) > 55.0 and < 80.0 wt.%, preferably > 60.0 and < 75.0 wt.%, preferably > 62.0 and < 68.0 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 < 45.0, preferably > 25.0 and < 40.0, preferably > 32.0 and < 38.0 wt.%, 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 > 500,000 g / mol and < 800,000 g / mol; andpreferably 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 wherein 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 (MFIs) of > 0.7 and < 2.0 dg / min, preferably > 0.7 and < 1.5 dg / min, preferably > 0.7 and < 1.15 dg / min, preferably > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 65.0 kPa.s and < 120.0 k.Pa.s, preferably > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183.

[0008] Preferably the polyethylene composition, comprises the ethylene polymer comprising or consisting of: a) > 60.0 and < 75.0 wt.%, preferably > 62.0 and < 68.0 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) > 25.0 and < 40.0, preferably > 32.0 and < 38.0 wt.%, 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 > 500,000 g / mol and < 800,000 g / mol; and wherein the low molecular weight component (A) is an ethylene homopolymer or an ethylene copolymer and wherein the high molecular weight component (B) is a copolymer of ethylene and a C3-C8 alpha olefin; and wherein the high molecular weight component (B) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 8.0; and / or wherein the low molecular weight component (A) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 17.0, preferably >8.0 and < 10.0; andwherein the polyethylene composition has:• a melt flow index (MFIs) of > 0.7 and < 1.5 dg / min, preferably > 0.7 and < 1.15 dg / min, preferably > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 65.0 kPa.s and < 120.0 k.Pa.s, preferably > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183.

[0009] Advantageously, the polyethylene composition of the present invention has an excellent balance of processability indicated by the melt flow index, stiffness as indicated by the density. In an aspect of the invention, the invention relates to the 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 > 0 litre and < 3.0 litre, preferably > 0.1 litre and < 1.0 litre.

[0010] The weight average molecular weight (Mw) of the high molecular weight component (B) may for example be measured by any known standards for example by deconvolution technique based on ASTM D6474-12.

[0011] Preferably, the polyethylene composition has a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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.

[0012] Preferably, the polyethylene composition has at least one of: a) a yield stress of > 26.0 MPa and < 35.0 MPa, preferably > 26.0 MPa and < 32.0 MPa, preferably > 26.5 MPa and < 30.0 MPa as measured according to ISO 527-2 at 23 °C; and / orb) a tensile modulus value of > 1300 MPa, preferably > 1320 MPa and < 1550 MPa as measured according to ISO 527-2 at 23 °C; and / or c) a Bell Test resistance F50 of > 3000 hours, preferably > 4000 hours, preferably > 5000 hours, preferably > 8000 hours and < 100000 hours when determined in accordance with ASTM DI 693 Method B at 50 °C in 10% IGEPAL.

[0013] Preferably, the polyethylene composition has: a) a yield stress of > 26.0 MPa and < 35.0 MPa, preferably > 26.0 MPa and < 32.0 MPa, preferably > 26.5 MPa and < 30.0 MPa as measured according to ISO 527-2 at 23 °C; and b) a tensile modulus value of > 1300 MPa, preferably > 1320 MPa and < 1550 MPa as measured according to ISO 527-2 at 23 °C; and c) a Bell Test resistance F50 of > 3000 hours, preferably > 4000 hours, preferably > 5000 hours, preferably > 8000 hours and < 100000 hours, when determined in accordance with ASTM DI 693 Method B at 50 °C in 10% IGEPAL.

[0014] The polyethylene composition of the present invention demonstrates 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 especially for small volume article.

[0015] For example, the polyethylene composition has a complex viscosity (qioo) at a shear rate of 100 rad / s of > 1000 and < 1750 Pa.s, preferably > 1200 and < 1750 Pa.s, preferably > 1250 and < 1725 Pa.s, preferably > 1200 and < 1700 Pa.s, preferably > 1400 and < 1700 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0016] 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.

[0017] For example, the polyethylene composition has a shear thinning index (SHI) of > 36.0 and < 120.0, preferably > 55.0 and < 100.0, preferably > 60.0 and < 90.0, preferably > 62.0and < 80.0, 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 (r| 100) at a shear rate of 100 rad / s. The SHI values as shown for the polyethylene composition is indicative of the suitable processability while maintaining the desired melt strength.

[0018] 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, preferably > 30.0, preferably > 35.0, preferably > 25.0 MPa and < 50.0 MPa, preferably > 28.0 MPa and < 40.0 MPa as measured in accordance with ISO 18488.

[0019] As used herein, the term “ethylene polymer” is meant 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 for example a C3-C8 alpha olefin comonomer.

[0020] Preferably, the C3-C8 alpha olefin comonomer is selected from propylene, 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, more preferably the C3-C8 alpha olefin comonomer is 1 -hexene.

[0021] Preferably, the polyethylene composition has a total content of polymeric units derived from C3-C8 alpha olefin of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition.

[0022] Accordingly, the polyethylene composition has a total content of polymeric units derived from the ethylene of > 99.5 and < 99.8 mol.%, preferably > 99.55 and < 99.75 mol.%, with regard to the total moles of the polyethylene composition.

[0023] Preferably, the polyethylene composition has a total content of polymeric units derived from C3-C8 alpha olefin of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 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 Infra Red spectroscopy; and / or wherein the Cs-Cs alpha olefin comonomer is selected from propylene, 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, more preferably the Cs-Cs alpha olefin comonomer is 1 -hexene.

[0024] The comonomer content influences the degree of low chain branching which in turn influences the degree of processability. Preferably, the polyethylene composition has a Long Chain Branch Index of > 0.5 and < 1.5, wherein LCB index is determined by LCBIndex=e3 6296 in(Mw)-8 3439’ where r|o.oi is the viscosity of the polyethylene composition at 190 °C and at 0.01 rad / s expressed as Pa*s and Mw is the weight average molecular weight expressed in kg / mol.

[0025] Preferably, the polyethylene composition has a molecular weight distribution (Mw / Mn) ranging from > 15.0 and < 30.0, preferably > 16.0 and < 26.0, preferably > 17.0 and < 26.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12.

[0026] Preferably, the polyethylene composition has a molecular weight distribution (Mw / Mn) ranging from > 15.0 and < 30.0, preferably > 16.0 and < 26.0, preferably > 17.0 and < 26.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12.

[0027] Preferably, the polyethylene composition has a (Mz / Mw) ranging from > 5.5 and < 8, preferably > 6.0 and < 7.5, as determined in accordance with ASTM D6474-12, where Mz is the Z-average molecular weight and Mw is the weight average molecular weight determined in accordance with ASTM D6474-12.

[0028] Preferably, polyethylene composition has a Peak Ratio ranging from > 1.8 and < 10.0, preferably > 1.8 and < 8.0, wherein Peak Ratio is defined as:wherein:(dW / dLogMw)at MwPeak,LMWF is the value of the molecular weight distribution for the low molecular weight component (A) of the ethylene polymer at the maximum value of the molecular weight distribution as measured (Mw peak);(dW / dLogMw)at MwPeak,HMWF is the value of the molecular weight distribution for the high molecular weight component (B) of the ethylene polymer at the maximum value of the molecular weight distribution as measured (Mw peak);(PolymerSplit)LMWF is the weight fraction of the low molecular weight component (A) of the ethylene polymer with regard to the total weight of the ethylene polymer;(PolymerSplit)HMWF is the weight fraction of the high molecular weight component (B) of the ethylene polymer with regard to the total weight of the ethylene polymer.

[0029] This PEAK ratio may for example quantify the spread between the low and high molecular weight components of the ethylene polymer.Low molecular weight component (A) of the ethylene polymer

[0030] The low molecular weight component(A) is present invent in an amount of > 55.0 and < 80.0 wt.%, preferably > 60.0 and < 75.0 wt.%, preferably > 62.0 and < 68.0 wt.%, with regard to the total weight of the polyethylene composition.

[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.

[0032] The low molecular weight component (A) of the ethylene polymer may be an ethylene homopolymer or an ethylene copolymer, having a density of > 963.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3, preferably > 968.0 kg / m3and < 975.0 kg / m3determined in accordance with ISO 1183, preferably the low molecular weight componentis an ethylene homopolymer having a density of > 963.0 kg / m3and < 978.0 kg / m3, preferably > 963.0 kg / m3and < 975.0 kg / m3, preferably > 968.0 kg / m3and < 975.0 kg / m3determined in accordance with ISO 1183.

[0033] The low molecular weight component (A) has a ratio of Mw / Mn of > 5.0 and < 17.0, preferably > 8.0 and < 10.0, preferably > 7.0 and < 10.0, preferably > 6.0 and < 9.0. Most preferably, the low molecular weight component (A) has a ratio of Mw / Mn of > 7.0 and < 10.0, preferably > preferably >8.0 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.

[0034] Preferably, the low molecular weight component (A) of the ethylene polymer has a melt flow index (MFI1.2) of > 15.0 and < 70.0 dg / min, preferably > 20.0 and < 60.0 dg / min, preferably > 20.0 and < 55.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg.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 < 45.0, preferably > 25.0 and < 40.0, preferably > 32.0 and < 38.0 wt.%, 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 > 5.0 and < 8.0. The weight average molecular weight (Mw) and the number average molecular (Mn) weight may be measured by any known standards for example by deconvolution technique based on ASTM D6474-12.

[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 ISO 1133-1 :2011 at 190 °C and 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 alpha-olefins, preferably C3-8 alpha-olefins such as propylene, 1-butene, 1-hexene and 1-octene. For example, the high molecular weight component (B) is a copolymer comprising polymeric units derived from ethylene and a C3-C8 alpha olefin comonomer.

[0040] 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. Preferably, the high molecular weight component (B) of the ethylene copolymer is a copolymer of ethylene and a C3-C8 alpha olefin comonomer.

[0041] Preferably, the high molecular weight component (B) is a copolymer of ethylene and 1-butene or ethylene and 1-hexene. Most preferably, high molecular weight component (B) is a copolymer of ethylene and 1-hexene.

[0042] Preferably, the high molecular weight component (B) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 8.0; and / or wherein the low molecular weight component (A) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 17.0, preferably >8.0 and < 10.0.

[0043] Preferably, the low molecular weight component (A) of the ethylene polymer has a melt flow index (MFI1.2) of > 15.0 and < 70.0 dg / min, preferably > 20.0 and < 60.0 dg / min, preferably > 20.0 and < 55.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg; 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 > 90.0 wt.% and < 100. wt.%, preferably > 92.0 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 > 0.0 wt.% and < 10.0 wt.%, preferably > 0.0 wt.% and < 8.0 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 wherein the additive is selected from antioxidants, carbon black, fillers, process stabilisers, anti-oxidants, light and / or heat stabilisers, crosslinking agents and combinations thereof.

[0045] In an aspect of the invention, the polyethylene composition is free of carbon black and cross-linking. Preferably, the additive is selected from the group consisting of anti-oxidants, fillers, process stabilisers, anti-oxidants, light and / or heat stabilisers, and combinations thereof

[0046] Preferably, the polyethylene composition, comprising the ethylene polymer comprising or consisting of : a) > 60.0 and < 75.0 wt.%, preferably > 62.0 and < 68.0 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) > 25.0 and < 40.0, preferably > 32.0 and < 38.0 wt.%, 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 polyethylene composition has:• a melt flow index (MFh) of > 0.7 and < 1.15 dg / min, preferably > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; 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; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0.

[0047] Preferably, the polyethylene composition, comprising the ethylene polymer that comprises or consists of: a) > 62.0 and < 68.0 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) > 32.0 and < 38.0 wt.%, 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; and wherein the polyethylene composition has:• a melt flow index (MFh) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and< 35.0, 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 density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0.

[0048] Preferably the polyethylene composition, comprising the ethylene polymer that comprises or consists of: a) > 62.0 and < 68.0 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) > 32.0 and < 38.0 wt.%, 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; and wherein the polyethylene composition has:• a melt flow index (MFh) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio (MF 21.6 / 5.0) of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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 kg respectively; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0.

[0049] Preferably, the polyethylene composition, comprising the ethylene polymer that comprises or consists of: a) > 62.0 and < 68.0 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) > 32.0 and < 38.0 wt.%, 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; and wherein the polyethylene composition has:• a melt flow index (MFh) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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 kg respectively; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0; 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.

[0050] Preferably the polyethylene composition, comprising the ethylene polymer that comprises or consists of:a) > 62.0 and < 68.0 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) > 32.0 and < 38.0 wt.%, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 500,000 g / mol and < 800,000 g / mol; and wherein the low molecular weight component (A) is an ethylene homopolymer and wherein the high molecular weight component (B) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 8.0; and wherein the low molecular weight component (A) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of >8.0 and < 10.0; wherein the polyethylene composition has:• a melt flow index (MFh) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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 kg respectively; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0; and• a weight average molecular weight (Mw) of preferably > 200 kg / mol and < 250 kg / mol, determined in accordance with ASTM D6474-12; and• a Z-average molecular weight (Mz) of > 1300 kg / mol and < 1700 kg / mol as determined in accordance with ASTM D6474-12; and• a complex viscosity (r|ioo) at a shear rate of 100 rad / s of > 1200 and < 1700 Pa.s, preferably > 1400 and < 1700 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12.Preparing the ethylene polymer and the polyethylene composition

[0051] The ethylene polymer according to the invention may be prepared by a process comprising the steps of producing the low molecular weight component and the high molecular weight component as a bimodal ethylene polymer made by polymerizing the low molecular weight component (Component A) and subsequently polymerizing the high molecular weight component (low molecular weight component) in the presence of the low molecular weight component (Component B).

[0052] Accordingly, the invention provides a process for the preparation of the ethylene polymer according to the invention, wherein the process comprises a 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 in a first reactor using the first set of conditions, b) transferring the low 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 in the second reactor in the presence of the low molecular weight component to obtain the ethylene polymer.

[0053] 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 agentin an amount ranging between for example 1 and 500 ppm related to the total amount of reactor contents.

[0054] The multi-step slurry polymerization process may be carried out using cascaded reactors in the presence of a Ziegler Natta catalyst system.

[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 and the high molecular weight component 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 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 article comprising the polyethylene composition of the present invention. Preferably wherein the article is selected from a container, a bottle, a storage vessel, preferably the article is a container.

[0058] Preferably, the article is a container having a storage volume of > 0.1 litre and < 3.0 litre, preferably > 0.1 litre and < 1.0 litre.

[0059] In an aspect of the invention the invention is directed to a container having a storage volume of > 0.1 litre and < 3.0 litre, preferably > 0.1 litre and < 1.0 litre and wherein the container comprises the polyethylene composition of the present invention.

[0060] 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.

[0061] The invention will now be demonstrated with the following non-limiting examples.EXAMPLES

[0062] Purpose: To evaluate the properties of sample specimen prepared from the polyethylene composition of the present invention.

[0063] Catalyst preparation:

[0064] 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.

[0065] Preparation of the catalystIn 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 dichloride (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 content was 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%.

[0066] Catalyst 2 - 100 grams of granular Mg(OC2H5)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 with1480 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.

[0067] 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.

[0068] Catalyst analysis results: Ti 9.7 wt.% Mg 10.4 wt.% Al 4.6 wt.% Cl 49 wt.% OEt 9.0 wt% and OBu 12 wt.%.

[0069] Preparation of the ethylene polymer -

[0070] 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 11.3 barg total pressure. For producing a first polymer fraction, 700 g / h of ethylene and 1.3 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 total pressure 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.

[0071] 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.

[0072] The second CSTR reactor was operated at 82 °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 80 g / h and nitrogen in order to keep the total pressure constant at 4.8 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.

[0073] Inventive example 2 (IE2) - Inventive examples 2 was identical to inventive example 1 except the polymerization conditions and feeds which are shown in Table 1.

[0074] Inventive examples 3 (IE3 ) / Inventive example 4 (IE4) - was identical to inventive example 1 except catalyst used is Catalyst 2, a mixture of C6 alkanes is used as diluent instead of C7 alkanes, comonomer is 1 -butene and the polymerization conditions and feeds which are shown in Table 1.

[0075] Comparative examples 5 to 7 are commercial HDPE materials for small articles by blow molding. Comparative Example 5 (CEx5), is a commercially available bimodal resin made with Ziegler-Natta catalyst and 1 -butene from Lotte Chemicals, BL6200. Comparative Example 6 (CEx6), is a commercially available trimodal HDPE made with Ziegler-Natta catalyst and 1 -butene from SABIC, B5822. Comparative Example 7 (CEx7), is a commercially available monomodal HDPE made with Chromium catalyst and 1-hexene from Chevron Phillips, HHM5502BN.

[0076] Processing parameters for the preparation of ethylene polymer -Table 1

[0077] 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.

[0078] The extrusion conditions are provided below:Table 2

[0079] Various properties of the pellets of the polyethylene composition of IE1 to IE4(inventive) and CEx3 to CEx5 (comparative) were measured as reported in Table 4.Table 3Table 4

[0080] It is concluded that the polyethylene composition according to the invention (IE1 to IE4) has a combination of excellent processability evidenced from the low viscosity values at 100 rad / s (rpoo), wide window of transformation given by the high shear rates at which melt fracture appears, 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), and very high stiffness, evidenced from the yield stress and tensile modulus values and density.

[0081] In comparison, polyethylene composition CEx4 has a similar or poorer processability as measured by the viscosity values at a shear rate of 100 rad / s, lower stiffness asgiven by the yield stress and tensile modulus, much lower ESCR resistance and melt strength. CEx5 shows much higher viscosity values at very high shear rate, much lower melt strength given by the value of viscosity at 0.01 rad / s, similar stiffness, but much lower ESCR resistance, given by the values of Bell test and Strain Hardening. CEx6 shows similar viscosity values at 100 rad / s and slightly lower melt strength resistance given by the viscosity value at 0.01 rad / s but significantly lower ESCR resistance given by the Bell test and the Strain Hardening values.Measurement methodology of various parameters:

[0082] 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.

[0083] Density - Density of polymer powder samples (ethylene polymer) 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 has 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 is determined in air (Analytical Balance XS104 Mettler Toledo). Subsequently, the test plaque is 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 is cooled down to room temperature. The density is 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.

[0084] Density of polymer pellet samples (polyethylene composition) was measured by following ISO 1183.

[0085] 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 was 1 minute, press time was 1 minute, press pressure was 2 tons and the spacer is an E-ring. Films are pressed in between PTFE foils.

[0086] 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.

[0087] 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 and Molecular weight Distribution (MWD)

[0088] Mw, Mn and Mz were measured in accordance with ASTM D6474-12 (Standard Test Method for Determining molecular weight distribution and molecular weight Averages of Polyolefins 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.

[0089] 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- methylphenol 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 therange 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).Deconvolution technique to calculate Mw / Mn for high molecular weight polymer component B using ASTM D 6474-12

[0090] The molecular weight distribution moments for the polymer component B (Mn andMw) 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.

[0091] 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: 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 themolecular 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 was 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 was 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 in the 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 rheometer 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:wherer| is the viscosity in Pa.s r|o 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] Environmental Stress Crack Resistance was measured according to ASTM D1639 Method B at 50 C in 10% Igepal (F50) using the Bell Test.Determination of Long Chain Branching

[0100] Long Chain Branching in polyethylene can be determined through the relationship between low or zero-shear viscosity and molecular weight as shown in J. Janzen, R.H. Colby, Journal of Molecular Structure, 485-489 (1999). The cited reference is included only for the purpose of establishing that that there is a relationship between the long chain branching in polyethylene and low or zero shear viscosity and the molecular weight. One such relationship that can be used for the purpose of the invention is as below [2]:

[0101] Long Chain Branching content in the polymers of the invention has been characterized by the following relationship:where:

[0102] LCBindex diagnoses the amount of Long Chain Branching present in the polymer T|o.oi is the viscosity of the polymer at 190 C and 0.01 rad / s in Pa*s measured according to the procedure described in the document. Mw is the weight average molecular weight of the polymer measured according to the procedure described in the document in kg / mol.

[0103] Yield stress was 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.

[0104] Strain hardening modulus was determined according to ISO18488.

[0105] 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.

[0106] 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.

[0107] For example, the extrudate may be visually inspected for determination of the onset of melt fracture. The onset of melt fracture is a measure of the 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.

[0108] Peak ratio: A ratio of the value of the peak of the molecular weight distributions of the low molecular weight component (A) and the value of the peak of the high molecular weight component (B) was calculated as follows: The molecular weight distribution for the high molecular weight component (B) and the low molecular weight component (A) was resolved by deconvolution of the ethylene polymer molecular weight distribution. There after using known split values the value was determined using the equation -

[0109] 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.

Claims

CLAIMS1. A polyethylene composition, comprising an ethylene polymer comprising or consisting of : a) > 55.0 and < 80.0 wt.%, preferably > 60.0 and < 75.0 wt.%, preferably > 62.0 and < 68.0 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 < 45.0, preferably > 25.0 and < 40.0, preferably > 32.0 and < 38.0 wt.%, 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 > 500,000 g / mol and < 800,000 g / mol; and 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 wherein 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 (MFIs) of > 0.7 and < 2.0 dg / min, preferably > 0.7 and < 1.5 dg / min, preferably > 0.7 and < 1.15 dg / min, preferably > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 65.0 kPa.s and < 120.0 k.Pa.s, preferably > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a density of > 955.0 and < 970.0 kg / m3, preferably > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183.

2. The polyethylene composition of claim 1, wherein the polyethylene composition has a total content of polymeric units derived from C3-C8 alpha olefin of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition, preferably wherein the mole content of the polymeric units in thepolyethylene composition is determined using Infra Red spectroscopy; and / or wherein the Cs-Cs alpha olefin comonomer is selected from propylene, 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, more preferably the C3-C8 alpha olefin comonomer is 1 -hexene.

3. The polyethylene composition according to any one of claims 1-2, wherein the polyethylene composition has weight average molecular weight (Mw) of > 100 kg / mol and< 250 kg / mol, preferably > 150 kg / mol and < 250 kg / mol, preferably > 200 kg / mol and < 250 kg / mol, determined in accordance with ASTM D6474-12; and / or wherein the polyethylene composition has a Z-average molecular weight (Mz) of > 1200 kg / mol and < 2000 kg / mol, preferably > 1200 kg / mol and < 1800 kg / mol, preferably > 1300 kg / mol and< 1700 kg / mol as determined in accordance with ASTM D6474-12.

4. The polyethylene composition according to any one of claims 1-3, wherein the polyethylene composition has a complex viscosity (rpoo) at a shear rate of 100 rad / s of > 1000 and < 1750 Pa.s, preferably > 1200 and < 1750 Pa.s, preferably > 1250 and < 1725 Pa.s, preferably > 1200 and < 1700 Pa.s, preferably > 1400 and < 1700 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

5. The polyethylene composition according to any one of claims 1-4, wherein the polyethylene composition has a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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.

6. The polyethylene composition according to any one of claims 1-5, wherein the polyethylene composition has a shear thinning index (SHI) of > 36.0 and < 120.0, preferably > 55.0 and < 100.0, preferably > 60.0 and < 90.0, preferably > 62.0 and < 80.0, 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.

7. The polyethylene composition according to any one of claims 1-6, wherein the polyethylene composition has a molecular weight distribution (Mw / Mn) ranging from > 15.0 and < 30.0, preferably > 16.0 and < 26.0, preferably > 17.0 and < 26.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12.

8. The polyethylene composition according to any one of claims 1-7, wherein the polyethylene composition, comprising the ethylene polymer comprises or consists of: a) > 62.0 and < 68.0 wt.%, with regard to the total weight of the ethylene polymer, of the low molecular weight component (A) having a weight average molecular weight of > 10,000 g / mol and < 80,000 g / mol; and b) > 32.0 and < 38.0 wt.%, with regard to the total weight of the ethylene polymer, of the high molecular weight component (B) having a weight average molecular weight of > 100,000 g / mol and < 2,000,000 g / mol; and wherein the polyethylene composition has:• a melt flow index (MFh) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (r|o.oi) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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 density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0.

9. The polyethylene composition according to any one of claims 1-8, wherein the high molecular weight component (B) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 8.0; and / or wherein the low molecular weight component (A) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 17.0, preferably >8.0 and < 10.0.

10. The polyethylene composition according to any one of claims 1-9, wherein the low molecular weight component (A) of the ethylene polymer has a melt flow index (MFI1.2) of > 15.0 and < 70.0 dg / min, preferably > 20.0 and < 60.0 dg / min, preferably > 20.0 and < 55.0 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 1.2 kg; 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.

11. The polyethylene composition according to any one of claims 1-10, the polyethylene composition, comprising the ethylene polymer that comprises or consists of: a) > 62.0 and < 68.0 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) > 32.0 and < 38.0 wt.%, with regard to the total weight of the ethylene polymer, of a high molecular weight component (B) having a weight average molecular weight of > 500,000 g / mol and < 800,000 g / mol; and wherein the low molecular weight component (A) is an ethylene homopolymer and wherein the high molecular weight component (B) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of > 5.0 and < 8.0; and wherein the low molecular weight component (A) of the ethylene polymer has a molecular weight distribution (Mw / Mn) of >8.0 and < 10.0; wherein the polyethylene composition has:• a melt flow index (MFIs) of > 0.8 and < 1.15 dg / min, preferably > 0.8 and < 1.12 dg / min, determined in accordance with ISO1133-1 :2011 at 190 °C and measured at 5.0 kg; and• a complex viscosity (T|O.OI) at a shear rate of 0.01 rad / s of > 80.0 kPa.s and < 120.0 k.Pa.s determined in accordance with ISO 6721-10 at 190 °C; and• a melt flow ratio of > 20.0 and < 38.0, preferably > 22.0 and < 35.0, preferably > 25.0 and < 35.0, 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 kg respectively; and• a density of > 955.0 and < 960.0 kg / m3, preferably > 957.0 and < 959.0 kg / m3, determined in accordance with ISO 1183; and• a total content of polymeric units derived from 1 -hexene comonomer of > 0.2 and < 0.5 mol.%, preferably > 0.25 and < 0.45 mol.%, with regard to the total moles of the polyethylene composition; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0; and• a weight average molecular weight (Mw) of preferably > 200 kg / mol and < 250 kg / mol, determined in accordance with ASTM D6474-12; and• a Z-average molecular weight (Mz) of > 1300 kg / mol and < 1700 kg / mol as determined in accordance with ASTM D6474-12; and• a complex viscosity (rpoo) at a shear rate of 100 rad / s of > 1200 and < 1700 Pa.s, preferably > 1400 and < 1700 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and• a molecular weight distribution (Mw / Mn) ranging from > 16.0 and < 26.0, preferably > 17.0 and < 26.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight as determined in accordance with ASTM D6474-12.

12. The polyethylene composition according to any one of claims 1-11, wherein the polyethylene composition comprises > 90.0 wt.% and < 100.wt.%, preferably > 92.0 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 > 0.0 wt.% and < 10.0 wt.%, preferably > 0.0 wt.% and < 8.0 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 wherein theadditive is selected from anti-oxidants, carbon black, fillers, process stabilisers, antioxidants, light and / or heat stabilisers, cross-linking agents and combinations thereof.

13. The polyethylene composition according to any one of claims 1-12, wherein the polyethylene composition has a Strain Hardening modulus of > 25.0 MPa, preferably > 30.0, preferably > 35.0, preferably > 25.0 MPa and < 50.0 MPa, preferably > 28.0 MPa and < 40.0 MPa as measured in accordance with ISO 18488.

14. An article comprising the polyethylene composition as claimed in claims 1-13, preferably wherein the article is selected from a container, a bottle, a storage vessel, preferably wherein the article is a container; preferably wherein the article is a container having a storage volume of > 0.1 litre and < 3.0 litre, preferably > 0.1 litre and < 1.0 litre.

15. Use of the polyethylene composition as claimed in 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 > 0 litre and < 3.0 litre, preferably > 0.1 litre and < 1.0 litre.

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