Polyethylene composition for tapes

Abstract

A polyethylene composition for the preparation of tapes, comprising: A) from 70% to 98% by weight of an ethylene polymer component having a density D 3 of from 952 to 965 kg / m A ; a MIF value of from 10 to 35 g / 10 min.; and a polydispersity index PDI A of from 15 to 35 ; B) from 2% to 30% by weight of an ethylene polymer component having a density D 3 of from 949 to 965 kg / m B ; a MIE value of from 0.1 to 3 g / 10 min.; and a polydispersity index PDI B of from 6 to 25 ; wherein the value of PDI A is higher than the value of PDI B , both PDI A and PDI B being the ratio Mw / Mn of weight average molecular weight Mw and number average molecular weight Mn, and the amount of A) and the amount of B) being referred to the total weight of A) + B).

Description

Technical Field

[0001] This disclosure relates to a polyethylene composition for use in strips. Background Technology

[0002] Steel and plastic strapping is commonly used in the transportation and packaging industries, such as for securing goods (especially heavy goods) or as reinforcement for rigid or flexible packaging.

[0003] Besides steel strapping, the most commonly used plastic strapping is made of polypropylene or polyethylene terephthalate (PET), which is suitable for packaging items (e.g., palletized goods) due to its high rigidity, load-bearing capacity, and stability. Polyethylene (especially HDPE) strapping (as described, for example, in US3651196) is primarily used for packaging goods that do not require high load-bearing capacity due to its reduced rigidity compared to polypropylene and PET, and is particularly suitable for simpler manual applications.

[0004] Therefore, improvements to key mechanical properties are still needed for plastic strips.

[0005] It has now been discovered that strips with an unusual combination of elongation properties (especially elongation at break and breaking load) and stiffness (Young's modulus) can be obtained from polyethylene compositions containing two polyethylene components with specific rheological properties and molecular weight distribution values. Summary of the Invention

[0006] Therefore, this disclosure provides a polyethylene composition, hereinafter referred to as "polyethylene composition (I)", which comprises:

[0007] A) 70% to 98% by weight, preferably 75% to 97% by weight, of an ethylene polymer component having a strength of 952 to 965 kg / m³ at 23°C as determined according to ISO 1183-1:2012. 3 Preferably, the water content is 955 to 962 kg / m³. 3 density D A The MIF value is 10 to 35 g / 10 min, preferably 15 to 30 g / 10 min, where MIF is the melt flow index MI measured according to ISO 1133-1:2011 at 190 °C and 21.6 kg load; and the polydispersity index PDI is 15 to 35, preferably 18 to 30. A ;

[0008] B) 2% to 30% by weight, preferably 3% to 25% by weight, of an ethylene polymer component having a content of 949 to 965 kg / m³. 3 Preferably, the water content is 952 to 960 kg / m³.3 density D B The MIE value is 0.1 to 3 g / 10 min, preferably 0.5 to 2 g / 10 min, wherein the MIE is the melt flow index MI measured according to ISO 1133-1:2011 at 190 °C and 2.16 kg load; and the polydispersity index PDI is 6 to 25, preferably 8 to 20, more preferably 8 to 15. B ;

[0009] PDI A The value is higher than PDI B The value of PDI A and PDI B Both are the ratio of weight-average molecular weight Mw to number-average molecular weight Mn, measured by gel permeation chromatography (GPC), Mw / Mn, and the amounts of A) and B) are referenced to the total weight of A) + B).

[0010] This disclosure also provides a strip comprising the polyethylene composition (I) described above.

[0011] Since other polyolefin components and / or components different from polyolefins may be present in the strip, it should be understood that the polyethylene composition (I) of the present invention may constitute a total polymer composition present in the strip, or may be a part of such a polymer composition, and the total weight of the strip may be the sum of the polyethylene composition (I) and other components. Detailed Implementation

[0012] Both ethylene polymer components A) and B) may contain one or more ethylene polymers selected from ethylene homopolymers, ethylene copolymers and mixtures thereof.

[0013] As used herein, the term "copolymer" includes polymers containing one or more comonomers.

[0014] In ethylene copolymers, the comonomer is preferably selected from olefins having the formula CH2=CHR, wherein R is a straight-chain or branched alkyl or aryl group having 1 to 8 carbon atoms.

[0015] Specific examples are propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, and decene-1.

[0016] Butene-1 and hexene-1 are particularly preferred.

[0017] The molecular weight distributions of ethylene polymer components A) and B) can be unimodal, bimodal, or multimodal. In this disclosure, a unimodal molecular weight distribution means that the molecular weight distribution, as determined by gel permeation chromatography (GPC), has a single maximum value. The molecular weight distribution curve of a GPC-multimodal polymer can be viewed as a superposition of the molecular weight distribution curves of two or more polymer subfractions, and will therefore show two or more distinct maximum values, or will be at least significantly broadened compared to the curves of the individual fractions.

[0018] Preferred polyethylene composition (I) is a polyethylene composition in which PDI A –PDI B That is, the difference between the PDI value of A) and the PDI value of B) is equal to or greater than 2, more preferably equal to or greater than 4, and most preferably equal to or greater than 5, especially:

[0019] -2 to 15, or

[0020] -4 to 15, or

[0021] -5 to 15, or

[0022] -2 to 13, or

[0023] -4 to 13, or

[0024] -5 to 13.

[0025] Independently or in combination with the above-mentioned PDI difference, the preferred polyethylene composition (I) is a polyethylene composition in which D A –D B That is, the difference between the density value of A) and the density value of B) is 1 to 6, more preferably 1.5 to 5 kg / m³. 3 .

[0026] Advantageously but not necessarily, the ethylene polymer component A) has a weight-average molecular weight Mw of 350,000 g / mol or less (specifically, 300,000 g / mol or less).

[0027] In some non-limiting cases, the ethylene polymer component A) has a Mw of 90,000 g / mol or higher (in particular, 120,000 g / mol or higher).

[0028] According to some non-limiting embodiments, the ethylene polymer component A) has a z-average molecular weight Mz of 800,000 g / mol or higher (particularly, 900,000 g / mol or higher); particularly, 2,500,000 g / mol or lower (more particularly, 2,000,000 g / mol or lower).

[0029] Advantageously but not necessarily, the ethylene polymer component B) has a weight-average molecular weight Mw of 170,000 g / mol or less (specifically, 160,000 g / mol or less).

[0030] In some non-limiting cases, the ethylene polymer component B) has a Mw of 90,000 g / mol or higher (specifically, 100,000 g / mol or higher).

[0031] According to some non-limiting embodiments, the ethylene polymer component B) has a z-average molecular weight Mz of less than 800,000 g / mol (particularly equal to or less than 750,000 g / mol); particularly equal to or greater than 200,000 g / mol (more particularly equal to or greater than 250,000 g / mol).

[0032] Advantageously, but not necessarily, the ethylene polymer component B) has a melt index (MIF) of 5 to 28 g / 10 min, more preferably 10 to 25 g / 10 min.

[0033] The preferred MIF / MIP values ​​for both ethylene polymer component A) and ethylene polymer component B) are 4 to 30, more preferably 5 to 25.

[0034] In particular, the preferred MIF / MIP value of the ethylene polymer component A) is 8 to 30, more preferably 10 to 25.

[0035] The particularly preferred MIF / MIP value of the ethylene polymer component B) is 4 to 20, more preferably 5 to 15.

[0036] The homopolymers and copolymers can be obtained by polymerization processes in the presence of a coordination catalyst. These processes and the homopolymers and copolymers obtained therefrom are extensively described in the art.

[0037] In particular, polymerization processes can be carried out in the presence of Ziegler-Natta catalysts or single-point catalysts.

[0038] As is well known, Ziegler-Natta catalysts comprise reaction products of organometallic compounds from Groups 1, 2, or 13 of the periodic table with transition metal compounds from Groups 4 to 10 (new numbering system) of the periodic table. Specifically, the transition metal compounds can be selected from compounds of Ti, V, Zr, Cr, and Hf, and are preferably supported on MgCl2.

[0039] Particularly preferred catalysts include reaction products of organometallic compounds of Group 1, Group 2 or Group 13 of the periodic table and solid catalyst components including Ti compounds supported on MgCl2.

[0040] The preferred organometallic compound is an organoaluminum compound.

[0041] Single-point catalysts are well known in the art and are typically selected from metallocene single-point catalysts and non-metallocene single-point catalysts.

[0042] Examples of metallocene single-point catalysts are zirconium and hafnium, such as cyclopentadienyl or indene complexes of zirconium or hafnium, like bis(cyclopentadienyl)zirconium dichloride; bis(indene)zirconium dichloride or bis(indene)hafnium dichloride.

[0043] An example of a nonmetallocene single-site catalyst is an iron complex preferably having a tripentate ligand.

[0044] Particularly suitable tridentate ligands are 2,6-bis[1-(phenylimino)ethyl]pyridine, and preferably the corresponding compounds in which both phenyl groups are substituted at the ortho position with halogen or tertiary alkyl substituents.

[0045] Specific examples are 2,6-bis[1-(2-tert-butylphenylimino)ethyl]pyridine iron(II) dichloride; 2,6-bis[1-(2-tert-butyl-6-chlorophenylimino)ethyl]pyridine iron(II) dichloride or 2,6-bis[1-(2,4-dichlorophenylimino)ethyl]pyridine iron(II) dichloride.

[0046] The metallocene single-site catalyst and the non-metallocene single-site catalyst can also be used in combination.

[0047] Preferably, the unit site catalyst reacts with an activating compound (co-catalyst), a preferred example of which is an aluminum oxane, such as monomethylaluminoxane (MAO).

[0048] The polymerization reaction can be continuous or intermittent, carried out in the presence of the catalyst, according to known techniques, and in the liquid phase, in the presence or absence of an inert diluent, or in the gas phase or by liquid-gas mixing techniques.

[0049] Compared to the polymerization step, reaction time, pressure, and temperature are not critical; however, a temperature of 50 to 100°C is optimal. The pressure can be atmospheric pressure or higher.

[0050] Molecular weight adjustment is achieved by using known modifiers, particularly hydrogen.

[0051] All of the ethylene homopolymers and copolymers described herein are commercially available. Specific commercial polymers suitable for producing the polymer blends of this invention are described in the examples.

[0052] The polyethylene composition (I) can be obtained by melting and mixing the components, and the mixing is carried out in a mixing device at a temperature of typically 180 to 310°C, preferably 190 to 280°C, and more preferably 200 to 250°C.

[0053] Any known device and technique can be used for this purpose.

[0054] The melt mixing apparatus useful in this paper is, in particular, an extruder or kneader, with a twin-screw extruder being especially preferred. These components can also be premixed at room temperature in the mixing apparatus.

[0055] During the preparation of the polyethylene composition (I), in addition to the main components A) and B) and other optional components, additives commonly used in the art may be introduced, such as stabilizers (heat resistant, light resistant, UV resistant), plasticizers, acid resistant agents, antistatic agents and waterproofing agents, pigments, and polymer processing aids.

[0056] Preferably, the strip of the present invention comprises at least 70% by weight of polyethylene composition (I) relative to the total weight of the strip, more preferably at least 80% by weight, particularly 90% or 95% by weight of polyethylene composition (I), and in all cases, up to 100% by weight.

[0057] Typically, the strips of this invention are characterized by angular (e.g., rectangular) cross-sections.

[0058] Preferably, the strip has a thickness of 3 to 10 mm and a width of 0.1 to 2 mm.

[0059] The strips of the present invention have a high breaking load value, preferably 130 to 250 MPa. The breaking load is enhanced by inducing the orientation of the polymer chains through a stretching step during the preparation of the strip.

[0060] Therefore, the strips of the present invention are preferably oriented by stretching.

[0061] The preferred draw ratio (for achieving orientation) is 9:1 to 13:1.

[0062] The strip needs to have appropriate stiffness and fracture toughness, while dimensional stability (section: width × height) is also a relevant property, which provides strips with suitable and consistent dimensions for winding into very regular rolls and then using them in automated packaging systems.

[0063] Preferably, the strip of the present invention has at least one of the following properties:

[0064] -150 to 220 MPa breaking load;

[0065] -8% to 25% elongation at break;

[0066] Young's modulus from -2300 to 4500 MPa.

[0067] Details of the testing methods are given in the embodiments.

[0068] In some embodiments, the composition has a breaking load of 150 to 200 MPa, an elongation at break of 15% to 25% and a Young's modulus of 2300 to 3200 MPa, wherein the breaking load, the elongation at break and the Young's modulus are measured on a sample having a width of 5 mm, a thickness of 0.32 to 0.45 mm and a draw ratio of 8:1.

[0069] In some embodiments, the composition has a breaking load of 150 to 200 MPa, an elongation at break of 10% to 22%, and a Young's modulus of 2400 to 3500 MPa, wherein the breaking load, the elongation at break, and the Young's modulus are measured on a sample having a width of 5 mm, a thickness of 0.32 to 0.45 mm, and a draw ratio of 9:1.

[0070] In some embodiments, the composition has a breaking load of 150 to 220 MPa, an elongation at break of 8% to 15%, and a Young's modulus of 3000 to 4500 MPa, wherein the breaking load, the elongation at break, and the Young's modulus are measured on a sample having a width of 5 mm, a thickness of 0.32 to 0.45 mm, and a draw ratio of 10:1.

[0071] As the draw ratio increases, the breaking load at a draw ratio of 9:1 increases by 1.5% to 8% compared to a draw ratio of 8:1.

[0072] As the draw ratio increases, the elongation at break decreases and the Young's modulus increases.

[0073] Due to the aforementioned advantageous properties, the strips of the present invention can be used to package palletized goods by using loads and shapes secured by polyethylene strips and wrapped with polyethylene film (which may be shrink film or stretch film), which can be easily collected together during unloading and sent to recycling processes.

[0074] The strips of this invention can be obtained using techniques well known in the art.

[0075] Generally, the process for preparing strips includes the following steps:

[0076] (a) Molten polyethylene composition (I) and other polymer components (where present);

[0077] (b) Extruding the precursor band;

[0078] (c) Stretching the anterior fasciculus;

[0079] (d) Optionally arrange the strips obtained from step (c).

[0080] The melting step (c) and the extrusion step (b) are typically carried out sequentially and continuously using a single-screw or twin-screw extruder equipped with a suitable extrusion head. Therefore, the melt-mixing step described earlier can also be carried out in the same extrusion apparatus.

[0081] The extrusion head is usually a flat die.

[0082] A typical finishing process for extruded strips is embossing, in which smooth strips are made to be regularly roughened (e.g., by using square or diamond-shaped surface roller tools under pressure), thereby increasing grip and making friction welding easier to achieve on the packaging line.

[0083] In addition, the annealing step is also very important, as it can improve the dimensional stability of the strip and minimize the accumulated implicit tension generated during the extrusion, cooling and stretching steps.

[0084] Typically, the melting step (a) and the extrusion step (b) are carried out at the same temperature as previously defined for the melt mixing step (i.e., 180 to 310°C, preferably 190 to 280°C, more preferably 200 to 250°C).

[0085] Typical extrusion conditions are:

[0086] - The temperature inside the extruder head is 200 to 300°C;

[0087] - Output values ​​range from 20 to 1000 kg / hour (on industrial equipment).

[0088] The precursor belt obtained in step (b) is typically cooled by, for example, using one or more cooling rollers or by immersion in water at a temperature of 15 to 45°C.

[0089] For the drawing process, the precursor belt is preheated at a temperature of 40 to 120-140°C. Heating can be achieved by using, for example, a hot air oven, heated rollers, hot plates, or by radiation or other known means.

[0090] Drafting can be achieved by conveying the precursor belt through a series of rollers with different rotational speeds. The preferred range of draft ratios thus obtained are those previously specified.

[0091] The draft ratio is the ratio of the high speed of the rollers in the drafting unit to the speed (main speed) of the rollers in the transfer unit. As previously mentioned, in the transfer unit, the belt moving at a low speed is heated before being drafted by applying a faster speed.

[0092] Example

[0093] The practice and advantages of the various embodiments, compositions, and methods provided herein are disclosed in the following examples. These examples are merely illustrative and are not intended to limit the scope of the appended claims in any way.

[0094] The following analytical methods are used to characterize polymer compositions and filaments.

[0095] density

[0096] Determined at 23°C according to ISO 1183-1:2012.

[0097] Melt Flow Index (MI)

[0098] According to ISO 1133-1:2011, measured at the specified temperature and load.

[0099] Molecular weight distribution determination

[0100] The average values ​​of Mw, Mn, and Mz, and the resulting Mw / Mn ratio, were determined by high-temperature gel permeation chromatography using the methods described in ISO 16014-1, ISO 16014-2, and ISO 16014-4, published in 2003. Details according to the mentioned ISO standards are as follows: solvent 1,2,4-trichlorobenzene (TCB); apparatus and solution temperature 145°C; and a PolymerChar (Valencia, Paterna 46980, Spain) IR-4 infrared detector compatible with TCB as the concentration detector. A WATERS Alliance 2000 system was used, equipped with the following pre-column SHODEX UT-G and separation columns SHODEX UT 806 M (3 columns) and SHODEX UT 807 (Showa Denko Europe GmbH, Konrad-Zuse-Platz 4, 81829 Muenchen, Germany) connected in tandem.

[0101] The solvent was vacuum distilled under nitrogen and stabilized with 0.025% by weight of 2,6-di-tert-butyl-4-methylphenol. The flow rate used was 1 ml / min, the injection volume was 500 µl, and the polymer concentration was in the range of 0.01% < concentration < 0.05% w / w. Molecular weight calibration was established using monodisperse polystyrene (PS) standards in the range of 580 g / mol to 11,600,000 g / mol from Polymer Laboratories (now Agilent Technologies, Herrenberger Str. 130, 71034 Boeblingen, Germany), with hexadecane also used.

[0102] The calibration curve was then adapted to polyethylene (PE) using a general calibration method (Benoit H., Rempp P., and Grubisic Z., *Journal of Polymer Science, Phys. Ed.*, 5, 753 (1967)). The Mark-Houwing parameters used here are as follows: for PS, k PS = 0.000121 dl / g, α PS = 0.706, and for PE, k PE = 0.000406 dl / g, α PE = 0.725, effective in TCB at 135℃. Data logging, calibration, and calculations were performed using NTGPC_Control_V6.02.03 and NTGPC_V6.4.24 (hs GmbH, Hauptstraße 36, D-55437 Ober-Hilbersheim, Germany), respectively.

[0103] Comonomer content

[0104] According to ASTM D 6248 98, the comonomer content was determined by IR using a Tensor 27 FT-IR spectrometer from Bruker. The Tensor 27 FT-IR spectrometer was calibrated with a chemometric model used to determine the ethyl side chain in PE (when butene-1 is used as a comonomer) and the butyl side chain in PE (when hexene-1 is used as a comonomer).

[0105] Fracture load, elongation at break and Young's modulus

[0106] Measurements were taken using a Lloyd LRX-Plus force gauge equipped with a 2500N cell, according to ASTM D882-18.

[0107] Young's modulus, also known as the elastic modulus, is equal to the longitudinal stress divided by the strain and is determined on the stress / strain curve.

[0108] Examples 1 and 2 and Comparative Example 1

[0109] The following materials are used to prepare polyethylene composition (I).

[0110] Ethylene polymer component A)

[0111] Ethylene copolymers prepared using Ziegler-Natta catalysts, exhibiting the properties reported in Table I below.

[0112] It is available on the market under the trademark Hostalen ACP 5831 D and sold by LyondellBasell.

[0113] Ethylene polymer component B)

[0114] Ethylene copolymers having the properties reported in Table I below.

[0115] It is available on the market under the trademark Luflexen hyPE 56P FA and sold by LyondellBasell.

[0116] Table I

[0117]

[0118] Preparation of polyethylene composition (I)

[0119] Components A) and B) were mixed with a typical stabilizing additive composition and blended together by extrusion under a nitrogen atmosphere in a twin-screw extruder, Berstorff ZE 25 (screw length / diameter ratio: 34), under the following conditions:

[0120] Speed: 250 rpm;

[0121] Extruder output: 15 kg / hour;

[0122] Melting temperature: 245℃.

[0123] The stabilizing additive composition is made from the following components:

[0124] - 0.1% Irganox® 1010 by weight;

[0125] - 0.1% Irgafos® 168 by weight;

[0126] - 0.2% calcium stearate by weight;

[0127] All percentages refer to the total weight of the polymer and stabilizing additive composition.

[0128] The Irganox® 1010 is 2,2-bis[3-[,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)-1-oxopropoxy]methyl]-1,3-propanediyl-3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl-propionate, while Irgafos® 168 is tris(2,4-di-tert-butylphenyl)phosphite.

[0129] The polyethylene composition (I) thus obtained is processed on an extrusion line based on a 25mm diameter 27 L / D extruder, a gear pump, a screen, a head with one main die (with a rectangular opening of 22.0 x 1.3 mm), a quenching water bath, a dryer, low-speed rollers, a 2m drawing furnace with three channels, high-speed guide rollers, an embossing unit, a 2m annealing furnace, annealing speed guide rollers, and a winding unit.

[0130] The main operating conditions are:

[0131] -Extruder temperature setting: 190 / 225 / 235 / 255℃;

[0132] - Gear pump temperature setting: 265℃;

[0133] - Head / Die Head Temperature Setting: 275 / 285℃;

[0134] - Actual melting temperature: 273 + / - 3℃;

[0135] - Output: 1.9 kg / h;

[0136] - Main belt cooling water temperature: 25℃;

[0137] - Distance from free space / mold outlet to water: 10cm;

[0138] -Drawing furnace temperature: 132℃;

[0139] - Annealing furnace temperature: 110℃.

[0140] For all embodiments, the properties of the strips thus obtained are recorded in Table II.

[0141] Table II

[0142]

[0143] Note: Fracture means that the strip breaks at a specified draw ratio.

Claims

1. A polyethylene composition (I), said polyethylene composition (I) comprising: A) 70% to 98% by weight, preferably 75% to 97% by weight, of an ethylene polymer component, said ethylene polymer component having a content of 952 to 965 kg / m³ as determined according to ISO 1183-1:2012 at 23°C. 3 Preferably, the water content is 955 to 962 kg / m³. 3 density D A The MIF value is 10 to 35 g / 10 min, preferably 15 to 30 g / 10 min, where MIF is the melt flow index MI measured according to ISO 1133-1:2011 at 190 °C and 21.6 kg load; and the polydispersity index PDI is 15 to 35, preferably 18 to 30. A ; B) 2% to 30% by weight, preferably 3% to 25% by weight, of an ethylene polymer component having a content of 949 to 965 kg / m³. 3 Preferably, the water content is 952 to 960 kg / m³. 3 density D B The MIE value is 0.1 to 3 g / 10 min, preferably 0.5 to 2 g / 10 min, wherein the MIE is the melt flow index MI measured according to ISO 1133-1:2011 at 190 °C and 2.16 kg load; and the polydispersity index PDI is 6 to 25, preferably 8 to 20, more preferably 8 to 15. B ; PDI A The value is higher than PDI B The value of PDI A and PDI B Both are the ratio of weight-average molecular weight Mw to number-average molecular weight Mn, measured by gel permeation chromatography (GPC), Mw / Mn, and the amounts of A) and B) are referenced to the total weight of A) + B).

2. The polyethylene composition according to claim 1 or 2, wherein PDI A –PDI B That is, the difference between the PDI value of A) and the PDI value of B) is equal to or greater than 2, preferably equal to or greater than 4, and more preferably equal to or greater than 5.

3. The polyethylene composition according to claim 1 or 2, wherein D A –D B That is, the difference between the density value of A) and the density value of B) is 1 to 6, preferably 1.5 to 5 kg / m³. 3 .

4. The polyethylene composition according to claim 1 or 2, wherein the ethylene polymer component A) has a Mw of 90,000 g / mol or higher, preferably 120,000 g / mol or higher.

5. The polyethylene composition according to claim 1 or 2, wherein the ethylene polymer component A) has a z-average molecular weight Mz equal to or greater than 800,000 g / mol, preferably equal to or greater than 900,000 g / mol.

6. The polyethylene composition according to claim 1 or 2, wherein the ethylene polymer component B) has a Mw of 90,000 g / mol or higher, preferably 100,000 g / mol or higher.

7. The polyethylene composition according to claim 1 or 2, wherein the ethylene polymer component B) has a z-average molecular weight Mz of less than 800,000 g / mol, preferably equal to or less than 750,000 g / mol.

8. The polyethylene composition according to claim 1 or 2, wherein the ethylene polymer component B) has a melt index (MIF) of 5 to 28 g / 10 min, preferably 10 to 25 g / 10 min.

9. The polyethylene composition according to claim 1 or 2, wherein the MIF / MIP value of both the ethylene polymer component A) and the ethylene polymer component B) is 4 to 30, preferably 5 to 25.

10. A strip comprising the polyethylene composition (I) according to claim 1.

11. The strip according to claim 10, wherein the strip is drawn at a draw ratio of 9:1 to 13:1.

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