Polyethylene compositions for blow molding, comprising waste recovered polyethylene

Abstract

The present disclosure relates to a polyethylene composition particularly suited for blow molding, comprising: I) from 25% to 85% by weight of waste recovered polyethylene; II) from 15% to 75% by weight of polyethylene with an at least trimodal molecular weight distribution.

Description

POLYETHYLENE COMPOSITIONS FOR BLOW MOLDING, COMPRISING WASTERECOVERED POLYETHYLENEFIELD OF THE INVENTION

[0001] The present disclosure relates to polyethylene compositions containing waste recovered polyethylene, that can be advantageously used for the production of blow molded articles.BACKGROUND OF THE INVENTION

[0002] Polyolefins, including polyethylene, are increasingly consumed in large amounts for many applications, including packaging for food and other goods, automotive components, fibers, and a large variety of manufactured articles. However, the said massive use of polyolefins is creating a concern as regards the environmental impact of the waste materials generated after the first use.

[0003] In fact, large amounts of waste plastic materials are presently coming from differential recovery of municipal plastic waste, also called post-consumer waste (PCW) and mainly constituted of flexible packaging (cast films, blown films and bioriented films), rigid packaging, blow molded and injection molded containers. Usually, through a step of separation from other polymers, such as PVC, PET or PS, two main polyolefinic fractions are obtained, namely ethylene polymers (in particular HDPE LDPE, LLDPE) and propylene polymers (homopolymers, random copolymers, heterophasic copolymers).

[0004] However, the multicomponent nature of the recovered material generally results in low mechanical properties.

[0005] In an attempt to mitigate such degradation of mechanical properties, blending with virgin polymer has been proposed in the art. For example, according to WO2021064127 the impact strength of polyethylene mainly deriving from a waste stream is improved by blending it with virgin HDPE having MIP (melt index at 190°C with 5 kg load, ISO 1133) of 0.001 to 0.50 g / 10 min.

[0006] The examples report polymer blends where the virgin HDPE is prepared by sequential polymerization in a cascade of reactors.

[0007] However, in addition to having poor impact strength, waste recovered polyethylene generally lacks sufficient environmental stress cracking resistance (ESCR) and cannot be easily processed with conventional techniques into final articles having satisfactory properties.

[0008] In particular, the presence of propylene polymers as contaminants decreases the weld strength of the welding lines in blow molded articles.

[0009] Moreover, the optimal swell ratio values required in the blow molding process to obtain articles with controlled, uniform wall thickness, is not easily obtained with waste recovered polyethylene.

[0010] It has now unexpectedly been found that blow molded articles with valuable mechanical properties, in particular ESCR and weld strength, are easily obtained, using conventional blow molding techniques and conditions, from polyethylene compositions comprising waste recovered polyethylene and an at least trimodal polyethylene having properly selected features.SUMMARY OF THE INVENTION

[0011] Thus present disclosure provides a polyethylene composition comprising:I) from 25% to 85% by weight, preferably from 40% to 60% by weight of waste recovered polyethylene;II) from 15% to 75% by weight, preferably from 40% to 60% by weight of polyethylene with an at least trimodal molecular weight distribution, having:1) density from 0.950 to 0.960 g / cm3, preferably from 0.950 to 0.958 g / cm3, determined according to ISO 1183-1 :2012 at 23°C;2) MIF from 6 to 12 g / 10 min., preferably from 8 tol2 g / 10 min., where MIF is the melt flow index at 190°C with a load of21.60 kg, determined according to ISO 1133-1 2012- 03;3) MIPfrom 0.20 to 1.0 g / 10 min., preferably from 0.30 to 0.80 g / 10 min., more preferably from 0.35 to 0.80 g / 10 min., where MIP is the melt flow index at 190°C with a load of 5 kg, determined according to ISO 1133-1 2012-03; and4) a ratio MIF / MIP of from 12 to 30, preferably from 15 to 30, more preferably from 15 to 25; wherein the amounts by weight of components I) and II) are referred to the total weight of the sum of I) and II).

[0012] The present composition provides final articles with valuable mechanical properties even when the waste recovered polyethylene (I) contains relatively high amounts of polypropylene.DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferably the present polyethylene composition has density from 0.945 to 0.962 g / cm3, more preferably from 0.950 to 0.960 g / cm3.

[0014] The MIF of the present polyethylene composition is preferably from 5 to 30 g / 10 min., more preferably from 10 to 25 g / 10 min.

[0015] The MIP of the present polyethylene composition is preferably from 0.3 to 5 g / 10 min., more preferably from 0.5 to 3 g / 10 min., most preferably from 0.5 to 1 g / 10 min.

[0016] The MIE of the present polyethylene composition is preferably from 0.05 to 5 g / 10 min., more preferably from 0.1 to 1 g / 10 min., most preferably from 0.1 to 0.5 g / 10 min.

[0017] As previously explained, the waste recovered polyethylene (I) is a polyethylene recovered from plastic waste.

[0018] The recovery process generally consists of a standard waste treatment, including collection, shredding, sorting and washing.

[0019] As a consequence, the waste recovered polyethylene (I) generally contains minor amounts of other polymeric and / or inorganic components. In particular, the waste recovered polyethylene (I) according to the present disclosure may contain propylene polymers in an amount from 1% to 15% by weight, preferably from 3% to 10% by weight, with respect to the total weight of the waste recovered polyethylene.

[0020] The waste recovered polyethylene (I) is preferably a PCW, i.e. a post-consumer waste, but it may also comprise pre-consumer waste (Pre-CW). The PCW is a waste material deriving from at least one use cycle. The Pre-CW is a plastic waste diverted from a manufacturing process which is not reutilized such as rework, regrind or scrap, and is not reincorporated in the same process that generated it.

[0021] Hence, in general terms, the waste recovered polyethylene (I) is a material deriving from an article manufacturing process.

[0022] Preferably, the waste recovered polyethylene (I) is a high density polyethylene (HDPE).

[0023] It has preferably a density of from 0.940 g / cm3to 0.965 g / cm3.

[0024] The MIF of the waste recovered polyethylene (I) is preferably from 1 to 100 g / 10 min., more preferably from 5 to 60 g / 10 min.

[0025] The MIP of the waste recovered polyethylene (I) is preferably from 0.5 to 10 g / 10 min., more preferably from 1 to 5 g / 10 min.

[0026] The MIE of the waste recovered polyethylene (I) is preferably from 0.1 to 10 g / 10 min., more preferably from 0.2 to 5 g / 10 min., where where MIE is the melt flow index at 190°C with a load of 2.16 kg, determined according to ISO 1133-1 2012-03.

[0027] The swell ratio of the waste recovered polyethylene (I) is preferably of from 130% to 190%.

[0028] The stress crack resistance, measured by FNCT 6 MPa / 50°C, ratio of the waste recovered polyethylene (I) is preferably equal to or higher than 2h, in particular from 2 to 15h.

[0029] The waste recovered polyethylene (I) is available on the market.

[0030] An example is represented by the grade sold by LyondellBasell Industries under the tradename CirculenRecover HD5603, Silver or Ivory.

[0031] The polyethylene component (II) is preferably a virgin polyethylene.

[0032] The expression “virgin polyethylene” means that it is a polymer which has not been subjected to any process for production of finished articles, for instance packaging films, pipes, bottles, containers, or semi-finished articles, like fibers or sheets for thermoforming.

[0033] Thus the virgin polyethylene has not been subjected to post-production working, except for possible pelletization, which is still considered part of the polymer production process.

[0034] Moreover the polyethylene component (II) has preferably at least one of the following additional features:- a MIE of 0.01 to 1 g / 10 min., more preferably from 0.05 to 0.5 g / 10 min.;- a stress crack resistance, measured by FNCT 6 MPa / 50°C, equal to or higher than 50h, in particular from 50 to 200h;- a swell ratio from 130% to 180%;- a Charpy aCN fracture toughness at -30°C from 5 to 20 kJ / m2.

[0035] The expression “at least trimodal molecular weight distribution” means that the polyethylene component (II) comprises at least three fractions with different molecular weights, in particular a first (A) low, second (B) high and third (C) ultra-high molecular weight fraction.

[0036] The molecular weight distribution curve of the resulting final polymer, obtained by GPC (Gas Permeation Chromatography) analysis, can be looked at as the superposition of the molecular weight distribution curves of the said polymer fractions and will accordingly show three or more distinct maxima or will at least be distinctly broadened compared with the individual curves for the individual fractions.

[0037] Preferably, the polyethylene component (II) comprises from 40 to 50 % by weight of a low molecular weight ethylene homopolymer A), from 25 to 40 % by weight of a high molecular weight ethylene copolymer B), and from 15 to 28 % by weight of an ultrahigh molecular weight ethylene copolymer C).

[0038] All the said weight amounts are referred to the total weight of A)+B)+C).

[0039] Preferably, the ethylene homopolymer A) has a MIE1.2 from 30 to 120 g / 10 min., more preferably from 40 to 100 g / 10 min., where MIE1.2 is the melt flow index at 190°C with a load of 1.2 kg, determined according to ISO 1133-1 2012-03.

[0040] The density of the ethylene homopolymer A) is preferably equal to or higher than 0.962 g / cm3, more preferably equal to or higher than 0.965 g / cm3.

[0041] The ethylene copolymer B) has preferably a MIP from 2 to 15 g / 10 min., more preferably from 3 to 10 g / 10 min.

[0042] The density of the ethylene copolymer B) is preferably equal to or higher than 0.955 g / cm3, in particular from 0.955 to 0.960 g / cm3.

[0043] The ethylene copolymer C) has preferably a MIF from 0.1 to 5 g / 10 min., more preferably from 0.2 to 2 g / 10 min.

[0044] The density of the ethylene copolymer C) is preferably equal to or higher than 0.950 g / cm3, in particular from 0.950 to 0.954 g / cm3.

[0045] The comonomer or comonomers present in the ethylene copolymers are generally selected from olefins having formula CH2=CHR wherein R is an alkyl radical, linear or branched, having from 1 to 10 carbon atoms.

[0046] Specific examples are propylene, butene- 1, pentene- 1, 4-methylpentene-l, hexene- 1, octene- 1 and decene- 1. Particularly preferred comonomers are butene- 1 and hexene- 1.

[0047] Preferably the ethylene copolymer B) contains from 0.2% to 0.5% by weight of comonomer(s) with respect to the total weight of the copolymer.

[0048] Preferably the ethylene copolymer C) contains from 1% to 2% by weight of comonomer(s) with respect to the total weight of the copolymer.

[0049] It has been found that the polyethylene component (II) can be prepared by using in polymerization a Ziegler-Natta catalyst.

[0050] A Ziegler-Natta catalyst comprises the product of the reaction of an organometallic compound of group 1, 2 or 13 of the Periodic Table of elements with a transition metal compound of groups 4 to 10 of the Periodic Table of Elements (new notation). In particular, the transition metal compound can be selected among compounds of Ti, V, Zr, Cr and Hf and is preferably supported on MgCh.

[0051] Particularly preferred catalysts comprise the product of the reaction of said organometallic compound of group 1 , 2 or 13 of the Periodic Table of elements, with a solid catalyst component comprising a Ti compound supported on MgCh.

[0052] Preferred organometallic compounds are the organo-Al compounds.

[0053] Thus in a preferred embodiment, the polyethylene component (II) is obtainable by using a Ziegler-Natta polymerization catalyst, more preferably a Ziegler-Natta catalyst supported on MgCh, even more preferably a Ziegler-Natta catalyst comprising the product of reaction of: a) a solid catalyst component comprising a Ti compound and optionally an electron donor compound ED (internal electron donor) supported on MgCh; b) an organo-Al compound; and optionally c) an external electron donor compound EDext.

[0054] Preferably in component a) the ED / Ti molar ratio, when ED is present, ranges from 1.5 to 3.5 and the Mg / Ti molar ratio is higher than 5.5, in particular from 6 to 80.

[0055] Among suitable titanium compounds are the tetrahalides or the compounds of formula TiXn(OR1)4-n, where 0<n<3, X is halogen, preferably chlorine, and R1is Ci-Cio hydrocarbon group.

[0056] Titanium tetrachloride is the preferred compound.

[0057] The optional ED compound is generally selected from alcohol, ketones, amines, amides, nitriles, alkoxysilanes, aliphatic ethers, and esters of aliphatic carboxylic acids.

[0058] Excellent results have been obtained with the use of esters which are thus particularly preferred as ED compound. Specific examples of esters are the alkyl esters of C1-C20 aliphatic carboxylic acids and in particular C1-C8 alkyl esters of aliphatic mono carboxylic acids such as ethylacetate, methyl formiate, ethylformiate, methylacetate, propylacetate, i-propylacetate, n-butylacetate, i-butylacetate. Moreover, are also preferred the aliphatic ethers and particularly the C2-C20 aliphatic ethers, such as tetrahydrofurane (THF) or dioxane.

[0059] The external electron donor compound EDext optionally used to prepare the said Ziegler-Natta catalysts can be equal to or different from the ED used in the solid catalyst component a). Preferably it is selected from the group consisting of ethers, esters, amines, ketones, nitriles, silanes and their mixtures. In particular it can advantageously be selected from the C2-C20 aliphatic ethers and in particulars cyclic ethers preferably having 3-5 carbon atoms such as tetrahydrofurane and dioxane.

[0060] The polymerization, which can be continuous or batch, is carried out following known techniques and operating in liquid phase, in the presence or not of inert diluent, or in gas phase, or by mixed liquid-gas techniques.

[0061] In particular, for preparing the ethylene polymer fractions A), B) and C), the polymerization process can be carried out in three or more reactors connected in series, wherein said fractions are prepared in separate subsequent stages, operating in each stage, except for the first stage, in the presence of the polymer formed and the catalyst used in the preceding stage.

[0062] The catalyst can be added in the first reactor only, or in more than one reactor.

[0063] Reaction time, pressure and temperature relative to the polymerization steps are not critical, however it is best if the temperature is from 50 to 100°C. The pressure can be atmospheric or higher, in particular in the range of from 0.15 to 1 MPa.

[0064] The regulation of the molecular weight is carried out by using known regulators, hydrogen in particular.

[0065] More details can be found in W02004058876.

[0066] In alternative, even if less practical, it is possible to prepare the said ethylene polymer fractions A), B) and C) separately, operating in a single reactor under the above said conditions, followed by mechanical blending of said fractions together.

[0067] The present polyethylene composition may comprise conventional additives. Examples of these additives are heat stabilizers, antioxidants, UV absorbers, light stabilizers, metal deactivators, compounds which destroy peroxide, and basic co-stabilizers, preferably in amounts of from 0.05% to 10 % by weight, more preferably from 0.05% to 5% by weight, based on the total weight of the polyethylene composition.

[0068] The present polyethylene composition may also comprise fillers, reinforcing agents, plasticizers, lubricants, emulsifiers, pigments, optical brighteners, flame retardants, antistatic agents, blowing agents, or a combination of these, preferably in total amounts of from 1 to 50% by weight, based on the total weight of the polyethylene composition.

[0069] The present polyethylene composition is obtainable by melting and mixing the components, and the mixing is effected in a mixing apparatus at temperatures generally of from 160 to 250°C.

[0070] Any known apparatus and technology can be used for this purpose.

[0071] Useful melt-mixing apparatus in this context are in particular extruders or kneaders, and particular preference is given to twin-screw extruders. It is also possible to premix the components at room temperature in a mixing apparatus.

[0072] As previously said, the present polyethylene composition can be advantageously used for producing blow molded articles.

[0073] In particular, the present polyethylene composition has particularly good suitability for production of small blow moldings.

[0074] Preferred examples of small blow moldings are those having a capacity from 250 to 5000 ml, like small containers, canisters and bottles.

[0075] In fact it is preferably characterized by an environmental stress crack resistance, measured by FNCT 6 MPa / 50°C, equal to or higher than 15h, more preferably equal to or higher than 18h, in particular from 15 to 50h or from 18 to 50h.

[0076] The swell ratio of the present polyethylene composition is preferably from 130% to 180%.

[0077] The Charpy aCN fracture toughness at -30°C of the present polyethylene composition is preferably from 3 to 10 kJ / m2.

[0078] The details of the test methods are given in the examples.

[0079] The blow-molding process is generally carried out by first plastifying the polyethylene composition in an extruder at temperatures in the range from 180 to 250°C and then extruding it through a die into a blow mold, where it is cooled.EXAMPLES

[0080] The practice and advantages of the various embodiments, compositions and methods as provided herein are disclosed below in the following examples. These examples are illustrative only, and are not intended to limit the scope of the appended claims in any manner whatsoever.

[0081] The following analytical methods are used to characterize the polymer compositions.

[0082] Melt flow index

[0083] Determined according to to ISO 1133-1 2012-03 at 190°C with the specified load.

[0084] Density

[0085] Determined according to ISO 1183-1 :2012 at 23°C.

[0086] Swell ratio

[0087] The Swell-ratio of the studied polymers was measured utilizing a capillary rheometer, Gbttfert Rheotester2000 and Rheograph25, at T = 190°C, equipped with a commercial 30 / 2 / 2 / 20 die (total length 30 mm, Active length=2 mm, diameter = 2 mm, L / D=2 / 2 and 20° entrance angle) and an optical device (laser-diod from Gbttfert) for measuring the extruded strand thickness. Sample was molten in the capillary barrel atl90°C for 6 min and extruded with a piston velocity corresponding to a resulting shear-rate at the die of 1440 s'1.

[0088] The extrudate was cut (by an automatic cutting device from Gbttfert) at a distance of 150 mm from the die-exit, at the moment the piston reached a position of 96 mm from the dieinlet. The extrudate diameter was measured with the laser-diod at a distance of 78 mm from the die-exit, as a function of time. The maximum value corresponds to the Dextrudate. The swell-ratio is determined from the calculation:SR = (Dextrudate-Ddie)100% / Ddie where Ddie is the corresponding diameter at the die exit, measured with the laser-diod.

[0089] Environmental stress cracking resistance according to full notch creep test (FNCT)

[0090] The environmental stress cracking resistance of polymer samples was determined in accordance to international standard ISO 16770 (FNCT) in aqueous surfactant solution. From the polymer sample a compression moulded 10 mm thick sheet has been prepared. The bars with squared cross section (10x10x100 mm) were notched using a razor blade on four sides perpendicularly to the stress direction. A notching device described in M. Fleissner in Kunststoffe 77 (1987), pp. 45 was used for the sharp notch with a depth of 1.6 mm.

[0091] The load applied is calculated from tensile force divided by the initial ligament area. Ligament area is the remaining area = total cross-section area of specimen minus the notch area. For FNCT specimen: 10x10 mm2- 4 times of trapezoid notch area = 46.24 mm2(the remaining cross-section for the failure process / crack propagation). The test specimen was loaded with standard condition suggested by the ISO 16770 with constant load of 6 MPa at 50°C in a 2% (by weight) water solution of non-ionic surfactant ARKOPAL N100. Time until rupture of test specimen was detected.

[0092] Charpy aCN

[0093] Fracture toughness determination by an internal method on test bars measuring 10 x 10 x 80 mm which had been sawn out of a compression molded sheet with a thickness of 10 mm. Six of these test bars were notched in the center using a razor blade in the notching device mentioned above for FNCT. The notch depth was 1.6 mm. The measurement was carried out substantially in accordance with the Charpy measurement method in accordance with ISO 179-1, with modified test specimens and modified impact geometry (distance between supports). All test specimens were conditioned to the measurement temperature of -30°C over a period of from 2 to 3 hours. A test specimen was then placed without delay onto the support of a pendulum impact tester in accordance with ISO 179-1. The distance between the supports was 60 mm. The drop of the 2 J hammer was triggered, with the drop angle being set to 160°, the pendulum length to 225 mm and the impact velocity to 2.93 m / s. The fracture toughness value is expressed in kJ / m2and is given by the quotient of the impact energy consumed and the initial cross-sectional area at the notch, aCN. Only values for complete fracture and hinge fracture can be used here as the basis for a common meaning (see suggestion by ISO 179-1).

[0094] Welding quality

[0095] 22 g blow molded bottles with an internal volume of 310 ml and average wall thickness 0.8 mm were prepared with a W. Muller molding machine, model Blowtec BFB 1 / 4.

[0096] The machine parameters were:- Processing temperature: 200 °C;- Mold temperature: 12 °C;- Molding cycle time: 15 sec;- Blow pressure: 5 bar;- Throughput: 7Kg / h.

[0097] A bottom weld sample was cut from each of the so obtained bottles, after deflashing. The bottom weld samples were then bent twice manually and manual tear off was tried. The samples were classified “good” if they did not break along the weld, “bad” if they broke.

[0098] Comonomer content

[0099] The comonomer content was determined by means of IR in accordance with ASTMD 6248 98, using an FT-IR spectrometer Tensor 27 from Bruker, calibrated with a chemometric model for determining ethyl- side-chains in PE for butene- 1 as comonomer. The result was compared to the estimated comonomer content derived from the mass-balance of the polymerization process and was found to be in agreement.

[0100] Polypropylene content

[0101] 13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cryoprobe, operating at 160.91 MHz in the Fourier transform mode at 120°C.

[0102] The peak of the CH2 ethylene was used as internal reference at 29.9 ppm. The samples were dissolved in l,l,2,2-tetrachloroethane-<72 at 120°C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, 15 seconds of delay between pulses and CPD to remove1H-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

[0103] Molar composition was obtained according to the following using peak areas (table 1):P = 100 A3 / SE = 0.5100 A2 / SWhere S = 0.5A2+A3

[0104] Molar content was transformed in weight using monomers molecular weight.Table 1 : Assignment of PP / PE mixtures

[0105] Example 1 and Comparative Example 1

[0106] The commercial grade CirculenRecover ® HD5603 Grey, sold by LyodellBasell Industries, was used as waste recovered polyethylene (I).

[0107] CirculenRecover ® HD5603 Grey is a PCW HDPE, containing around 9% by weight of propylene polymer(s) with respect to the total weight, having the properties reported in Table 1, where it is identified as QCP 5603.

[0108] The polyethylene composition of Example 1 was obtained by blending 50% by weight of Hostalen ® QCP 5603 Grey with 50% by weight of PE-1, which was a polyethylene with trimodal molecular weight distribution, having the properties reported in Table 1.

[0109] Said polyethylene PE-1, representing present component (II), was made of 45% by weight of a low molecular weight ethylene homopolymer A) with MI1.2 of 75 g / 10 min. and a density of about 0.968 g / cm3, 33% by weight of a high molecular weight ethylene / butene-1 copolymer B) with MIP of 7.5 g / 10 min. and density of 0.958 cm3and 22% by weight of an ultrahigh molecular weight ethylene / butene-1 copolymer C) with MIF of 0.65 g / 10 min. and density of 0.953 g / cm3.

[0110] Said weight amounts are referred to the total weight of A) + B) + C).

[0111] Said polyethylene PE-1 was prepared by analogy with Example 1 of W02004058876.

[0112] The polyethylene composition of Comparison Example 1 was obtained by blending 50% by weight of Hostalen ® QCP 5603 Grey with 50% by weight of Hostalen ® ACP 5831 D, used for comparison purpose, having the properties reported in Table 1, where it is identified as 5831 D.

[0113] Hostalen ® ACP 5831 D is a commercial polyethylene with trimodal molecular weight distribution, sold by LyodellBasell Industries.

[0114] The polyethylene compositions of the said examples were prepared by blending the said components in a twin-screw extruder Leistritz ZSE 27 MAXX 44D operating at 250 rpm, with temperatures of 230°C (first barrel) and 250 °C (second to 10thbarrel and die).

[0115] The properties of the final compositions so obtained are reported in Table 2.Table 1

Claims

CLAIMSWhat is claimed is:

1. A polyethylene composition comprising:I) from 25% to 85% by weight, preferably from 40% to 60% by weight of waste recovered polyethylene;II) from 15% to 75% by weight, preferably from 40% to 60% by weight of polyethylene with an at least trimodal molecular weight distribution, having:1) density from 0.950 to 0.960 g / cm3, preferably from 0.950 to 0.958 g / cm3, determined according to ISO 1183-1 :2012 at 23°C;2) MIF from 6 to 12 g / 10 min., preferably from 8 tol2 g / 10 min., where MIF is the melt flow index at 190°C with a load of 21.60 kg, determined according to ISO 1133-1 2012-03;3) MIP from 0.20 to 1.0 g / 10 min., preferably from 0.30 to 0.80 g / 10 min., more preferably from 0.35 to 0.80 g / 10 min., where MIP is the melt flow index at 190°C with a load of 5 kg, determined according to ISO 1133-1 2012-03; and4) a ratio MIF / MIP of from 12 to 30, preferably from 15 to 30, more preferably from 15 to 25; wherein the amounts by weight of components I) and II) are referred to the total weight of the sum of I) and II).

2. The polyethylene composition according to claim 1 , wherein the waste recovered polyethylene (I) is a PCW.

3. The polyethylene composition according to claim 1 or 2, wherein the waste recovered polyethylene (I) has a density from 0.940 g / cm3to 0.965 g / cm3.The polyethylene composition according to claim 1 or 2, wherein the waste recovered polyethylene (I) has a swell ratio from 130% to 190%. The polyethylene composition according to claim 1 or 2, wherein the polyethylene component (II) is a virgin polyethylene. The polyethylene composition according to claim 1 or 2, wherein the polyethylene component (II) is obtained by using a Ziegler-Natta polymerization catalyst. The polyethylene composition according to claim 1 or 2, wherein the polyethylene component (II) comprises from 40 to 50 % by weight of a low molecular weight ethylene homopolymer A), from 25 to 40 % by weight of a high molecular weight ethylene copolymer B), and from 15 to 28 % by weight of an ultrahigh molecular weight ethylene copolymer C). The polyethylene composition according to claim 7, wherein the ethylene homopolymer A) has a MIE1.2 from 30 to 120 g / 10 min., preferably from 40 to 100 g / 10 min., where MIE1.2 is the melt flow index at 190°C with a load of 1.2 kg, determined according to ISO 1133-1 2012-03, the ethylene copolymer B) has a MIP from 2 to 15 g / 10 min., preferably from 3 to 10 g / 10 min., the ethylene copolymer C) has a MIF from 0.1 to 5 g / 10 min., preferably from 0.2 to 2 g / 10 min. The polyethylene composition according to claim 7, wherein the ethylene homopolymer A) has a density equal to or higher than 0.962 g / cm3, preferably equal to or higher than 0.965 g / cm3, the ethylene copolymer B) has a density equal to or higher than 0.955 g / cm3, in particular from 0.955 to 0.960 g / cm3and the ethylene copolymer C) has a density equal to or higher than 0.950 g / cm3, in particular from 0.950 to 0.954 g / cm3. The polyethylene composition according to claim 1 or 2, wherein the polyethylene component (II) has at least one of the following additional features:- a MIE of 0.01 to 1 g / 10 min., preferably from 0.05 to 0.5 g / 10 min.;- a stress crack resistance, measured by FNCT 6 MPa / 50°C, equal to or higher than 50h, in particular from 50 to 200h;- a swell ratio from 130% to 180%;- a Charpy aCN fracture toughness at -30°C from 5 to 20 kJ / m2. The polyethylene composition according to claim 1 or 2, having density from 0.945 to 0.962 g / cm3, more preferably from 0.950 to 0.960 g / cm3. The polyethylene composition according to claim 1 or 2, having an environmental stress crack resistance, measured by FNCT 6 MPa / 50°C, equal to or higher than 15h, more preferably equal to or higher than 18h, in particular from 15 to 50h or from 18 to 50h. The polyethylene composition according to claim 1 or 2, having a swell ratio from 130% to 180%. Manufactured article comprising the polyethylene composition of claim 1. The manufactured article of claim 14, in form of a blow molded article, in particular a small blow molded article having a capacity from 250 to 5000 ml.

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