POLYMER COMPOSITION AND ARTICLE

Abstract

Polymer composition comprising, (A) a first polyolefin component, wherein the first polyolefin component comprises, preferably consists of, a multimodal polyolefin polymer; (B) a second polyolefin component; and (C) optionally a filler, wherein the first polyolefin component (A) is present in an amount of from 65 wt. % to 99 wt. % based on the total polymer composition and the second polyolefin component (B) is present in an amount of from 35 wt. % down to 1 wt. % based on the total polymer composition; and wherein the polymer composition has a SHI ( 1/100) of from 6 to 25, a G′ (5 kPa) of 3000 Pa or less, and an environmental stress crack resistance (ESCR) of 1500 h or more when determined according to IEC 60811-406:2012, procedure B (reagent is a solution of 10% solution (by volume) in water of Igepal CO-630 (Antarox CO-630)).

Claims

1. Polymer composition comprising (A) a first polyolefin component, wherein the first polyolefin component comprises a multimodal polyolefin polymer, (B) a second polyolefin component, and (C) optionally a filler, wherein the first polyolefin component (A) is present in an amount of from 65 wt. % to 99 wt. % based on the total polymer composition and the second polyolefin component (B) is present in an amount of from 35 wt. % down to 1 wt. % based on the total polymer composition; wherein the first polyolefin component (A) is a linear polyethylene homo- or copolymer having a density of 900 kg/m.sup.3 to 950 kg/m.sup.3 and the second polyolefin polymer (B) is a low density polyethylene homo- or copolymer having a density of 880 kg/m.sup.3 to 930 kg/m.sup.3; wherein the first polyolefin component (A) is produced by a Ziegler Natta catalyst; and wherein the polymer composition has a SHI.sub.(1/100) of from 6 to 25, a G′ (5 kPa) of 3000 Pa or less, and an environmental stress crack resistance (ESCR) of 1500 h or more when determined according to IEC 60811-406:2012, procedure B (reagent is a solution of 10% solution (by volume) in water of Igepal CO-630 (Antarox CO-630)).

2. The polymer composition according to claim 1, wherein the polymer composition has a SHI.sub.(1/100) of from 7 to 23; and/or wherein the polymer composition has a G′ (5 kPa) of from 1000 to 2900 Pa.

3. The polymer composition according to claim 1, wherein the multimodal polyolefin polymer of the first polyolefin component (A) is a bi- or multimodal polymer.

4. The polymer composition according to claim 1, wherein the polymer composition has one or more of the following properties, a tensile strength of 22 MPa or more measured according to ISO 527-2; and/or a tensile strength of 22 MPa or more after ageing 14 days at 110° C. according to IEC60811- 401; and/or a deformation (115° C./6 h) of less than 30%; and/or a shrinkage of 0.80% or less.

5. The polymer composition according to claim 1, wherein the polymer composition has an environmental stress crack resistance (ESCR) of 2000 h or more, when determined according to IEC 60811-406:2012, procedure B (reagent is a solution of 10% solution (by volume) in water of Igepal CO-630 (Antarox CO-630)).

6. The polymer composition according to claim 1, wherein the polymer composition has one or more of the following properties, strain at break (%) of 600% or more, when determined according to ISO 527-1:1993 using a pressed test specimen prepared according to ISO 527-2:19935A; and/or an absorption coefficient (at 375 nm) of 350 abs/m or more when measured according to ASTM D-3349-17.

7. The polymer composition according to claim 1, wherein the polymer composition has a density of 926 kg/m.sup.3 or more.

8. The polymer composition according to claim 1, wherein the polymer composition has a MFR2 (2.16 kg; 190° C.) of 0.1 to 10 g/10 min, measured according to ISO 1133.

9. The polymer composition according to claim 1, wherein the optional filler (C) is present in the polymer composition and the filler is carbon black; and/or wherein the filler (C) is present in an amount of 0.1 wt. % to 10 wt. % based on the total polymer composition.

10. The polymer composition according to claim 1, wherein the first polyolefin component (A) has a MFR2 (2.16 kg; 190° C.) of 0.05 to 10 g/10 min measured according to ISO 1133; and/or wherein the second polymer component (B) has a MFR2 (2.16 kg; 190° C.) of 0.05 to 15 g/10 min measured according to ISO 1133.

11. The polymer composition according to claim 1, wherein the first polyolefin polymer (A) is a linear polyethylene copolymer having a density of 910 kg/m.sup.3 to 950 kg/m.sup.3 and the second polyolefin polymer (B) is a low density polyethylene homo- or copolymer having a density of 900 kg/m.sup.3 to 930 kg/m.sup.3.

12. The polymer composition according to claim 11, wherein the first polyolefin component (A) comprises from 40 to 60 wt. %, based on the combined amount of components (1) and (2), of a low molecular weight (LMW) ethylene polymer (1) selected from ethylene homopolymer or a copolymer of ethylene and one or more alpha-olefins having from 3 to 10 carbon atoms, and having an MFR2 of from 4.0 to 1000 g/10 min; and from 40 to 60 wt. %, based on the combined amount of components (1) and (2), of a high molecular weight (HMW) copolymer (2) of ethylene with one or more alpha-olefin comonomer(s) having from 3 to 10 carbon atoms and having an MFR2 of said (HMW) ethylene copolymer (2) of less than 1.0 g/10 min; and wherein the LMW ethylene polymer (1) has a density which is greater than the density of the HMW ethylene copolymer (2).

13. The polymer composition according to claim 1, wherein the first polyolefin component (A) is present in an amount of from 70 to 98 wt. % based on the total polymer composition and the second polyolefin component (B) is present in an amount of from 2 to 30 wt. % based on the total polymer composition.

14. Article comprising a polymer composition according to claim 1, wherein the article is a wire or cable.

15. A process for producing an article comprising the polymer composition according to claim 1 wherein the article is a wire or cable.

16. Cable comprising at least one layer, which comprises the polymer composition according to claim 1.

17. A process for producing a cable comprising applying one or more layers on a conductor, wherein at least one layer comprises the polymer composition according to claim 1.

Description

DETERMINATION METHODS

[0171] Unless otherwise stated the following methods were used for determining the properties of the polymer composition or the components thereof as given in the description or in the experimental part and claims below. Unless otherwise stated, the samples used in the tests consist of the polymer composition or, respectively as specified, of the polymer component to be tested.

[0172] Cable Manufacturing

[0173] Cables are produced as follows:

[0174] 1 mm thick layer of the jacket has been extruded over a 3 mm thick Al-conductor. Extrusion has been done at line speed 75 m/min. Temperature profile: 170/175/180/190/190/210/210. Cooling water 23° C.

Shrinkage

[0175] The shrinkage (at 80° C./5 cycles) was measured on cable samples according to IEC60811-503:2012. The determination method of the shrinkage was performed in jacketing materials. The sample was placed in an air oven at determined temperature and time. This procedure was repeated at five cycles. The jacketing materials are designed and constructed according to EN 50290-2-24/A1, especially Table 1 and 2 of EN 50290-2-24/A1.

Deformation

[0176] Pressure test, inter alia the deformation test (115° C./6 h), at high temperature for insulation and sheathing materials was performed according to EN 60811-508: 2017. The cable sample was produced as described under cable manufacturing. The cable sample was placed in an air oven at a specified temperature with a constant load applied by means of a special indentation device. The percentage of indentation was measured after the specified test time using a digital gauge.

Absorption Coefficient (at 375 nm)

[0177] The absorption coefficient was determined according to ASTM D 3349-17. This test method measures the amount of light transmitted through a thin film of black pigmented polyethylene and then an absorption coefficient was calculated from the amount of transmitted light at wavelength of 375 nm and the film thickness.

Melt Index

[0178] The melt flow rate (MFR) was determined according to ISO 1133-1 (method A) and is indicated in g/10 min. The MFR is an indication of the melt viscosity of the polymer. The MFR is determined at 190° C. for PE. The load under which the melt flow rate is determined is usually indicated as a subscript, for instance MFR.sub.2 is measured under 2.16 kg load (condition D). MFR.sub.21 is measured under 21.6 kg load.

[0179] Where one of the components is produced in the second polymerization step, its melt flow rate may be calculated by using the equation of Hagström

[00001]${\mathrm{MI}}_b={\left(w.Math.{\mathrm{MI}}_1^{\frac{w^{-b}}{a}}+\left(1-w\right).Math.{\mathrm{MI}}_2^{\frac{w^{-b}}{a}}\right)}^{-a.Math.w^b}$

where a=5.2 and b=0.7 for calculating MFR.sub.2 and a=10.4 and b=0.5 for calculating MFR.sub.21. Further, w is the weight fraction of the low molecular weight component in the blend and MI.sub.1 and MI.sub.2 are the respective MFR (MFR.sub.2 or MFR.sub.21) of the LMW and HMW components, respectively, and MI.sub.b is the respective MFR (MFR.sub.2 or MFR.sub.21) of the blend. Reference is made to Hagström, The Polymer Processing Society, Europe/Africa Region Meeting, Gothenburg, Sweden, Aug. 19-21, 1997.

Density

[0180] Density of the polymer was measured according to ISO 1183-1 (method A). For the purpose of this invention the density of the blend can be calculated from the densities of the components according to:

[00002]${\rho }_b=\underset{i}{.Math.}{w}_i.Math.{\rho }_i$

where ρ.sub.b is the density of the blend, [0181] w.sub.i is the weight fraction of component “i” in the blend and [0182] ρ.sub.i is the density of the component “i”.

Flexural Modulus

[0183] Flexural modulus was determined according to ISO 178:2010. The flexural properties of 3-point bending of PE material was determined by using a tensile testing machine. By using a climate chamber testing in different test temperatures can be performed. A test specimen of rectangular cross-section, resting on two supports, is deflected by means of a loading edge, acting on the specimen midway between the two supports. The test specimen is deflected in this way at constant rate at mid span until rupture occurs at the outer surface of the specimen or until a maximum strain of 5% is reached, whichever occurs first. During testing, the force applied to the specimen and the resulting deflection of the specimen at mid span are measured.

[0184] The test specimens were prepared from pellets of the test polymer composition pressed to a dimension of 80×10×4.0 mm (length×width×thickness). The length of the span between the supports was 64 mm, the test speed was 2 mm/min and the load cell was 100 N. The equipment used was an Alwetron TCT 25.

Tensile Properties

[0185] Mechanical tests of determining the tensile properties are performed according to EN60811-501 by using a specimen type 5A.

[0186] Stress at break and Strain at break are measured according to ISO 527-1:1993 using a sample prepared according ISO527-2: 1993 5A (pressed test specimen prepared from pellets of the test polymer composition).

[0187] Stress at break tensile tester Alwetron TCT10. Lorentzen & Wettre ABB

[0188] Draw speed: 50 mm/min

[0189] Effective sample length: 50 mm

[0190] The term “tensile strength” is used in the present text to denote the maximum tensile stress recorded in extending the test piece to breaking point. Thus, the terms “tensile stress at break” and “tensile strength” are used synonymously in the text.

ESCR (Environmental Stress Cracking)

[0191] The determination was carried out according to procedure described IEC 60811-406:2012, Chapter 8, “Resistance to environmental stress cracking”, procedure B. The reagent is a solution of 10% solution (by volume) in water of Igepal CO-630 (Antarox CO-630). The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The pressed test specimens were prepared from pellets of the test polymer composition.

Rheology, Dynamic (Viscosity, Shear Thinning Index):

[0192] Rheological parameters such as Shear Thinning Index SHI and Viscosity are determined by using a rheometer, preferably an Anton Paar Physica MCR 300 Rheometer on compression moulded samples under nitrogen atmosphere at 190° C. using 25 mm diameter plates and plate and plate geometry with a 1.8 mm gap according to ASTM 144095. The oscillatory shear experiments were done within the linear viscosity range of strain at frequencies from 0.05 to 300 rad/s (ISO 6721-1). Five measurement points per decade were made. The method is described in detail in WO 00/22040.

[0193] The values of storage modulus (G′), loss modulus (G″) complex modulus (G*) and complex viscosity (η*) were obtained as a function of frequency (ω).

tan(δ)(angular freq.)=G″/G′

Shear thinning index (SHI), which correlates with MWD and is independent of Mw, was calculated according to Heino (“Rheological characterization of polyethylene fractions” Heino, E. L., Lehtinen, A., Tanner J., Seppälä, J., Neste Oy, Porvoo, Finland, Theor. Appl. Rheol., Proc. Int. Congr. Rheol, 11th (1992), 1, 360-362, and “The influence of molecular structure on some rheological properties of polyethylene”, Heino, E. L., Borealis Polymers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995).

[0194] The SHI can be defined as the ratio between two complex shear viscosities (η*) determined at two specific complex shear modulus (G*), equation 1.

[00003]$\begin{array}{cc}\mathrm{SHI}\left(x/y\right)=\frac{{\eta }^{*}\mathrm{for}\left(G^{*}=x\mathrm{kPa}\right)}{{\eta }^{*}\mathrm{for}\left(G^{*}=y\mathrm{kPa}\right)}& \left(1\right)\end{array}$

[0195] For example, using the values of complex modulus of 1 kPa and 100 kPa, then η*(1 kPa) and η*(100 kPa) are obtained at a constant value of complex modulus of 1 kPa and 100 kPa, respectively. The shear thinning index SHI.sub.1/100 is then defined as the ratio of the two viscosities η*(1 kPa) and η*(100 kPa), i.e., η(1)/η(100).

[0196] The determination of parameters such as Shear Thinning Indexes (SHI), and Loss Tangent (tan δ) shall be done with specific Rheoplus Macro calculations, as provided by Rheometer Supplier.

[0197] The values needed for the calculation of the so-called SHI and EI are determined by means of a single point interpolation procedure, as defined by Rheoplus software. In situations for which a given G* value is not experimentally reached, the value is determined by means of an extrapolation, using the same procedure as before. In both cases (interpolation or extrapolation), the option from Rheoplus”—Interpolate y-values to x-values from parameter” and the “logarithmic interpolation type” should be applied.

OIT Measurement

[0198] The oxidation induction time (OIT) at 200° C. was determined with a TA Instrument Q20 according to ISO11357-6. Calibration of the instrument was performed according to ISO 11357-1. The oxidation induction time is the time interval between the initiation of oxygen flow and the onset of the oxidative reaction. Each presented data point is the average of three independent measurements.

Cold Blend

[0199] The Cold bend was measured according to IEC 60811-504. Test specimen were cables produced on the cable line.

Shore D

[0200] The Shore D is measured according to ISO 868.

Experimental Part

Polyolefin Components of the Inventive Examples (IE1 to IE10)

Polyolefin Component (A)

[0201] LLDPE or MDPE being a bi- or multimodal znLLDPE or znMDPE and having the properties as given in Table 1.

Polyolefin Component (B)

[0202] As LDPE a conventional low density polyethylene homopolymer, produced in a high pressure process, in an autoclave reactor was used in examples IE1 to IE7. The LDPE can also be recycled material, Ecoplast NAV102 (Ecoplast Kunststoffrecycling GmbH, Austria), which was used in examples IE8 to IE10. The applied LDPE has the properties as given in Table 1.

CB Component (C)

[0203] Carbon Black is furnace Carbon Black, Printex Alpha A (obtained from Orion Engineered Carbons GmbH).

Catalyst Preparation

Complex Preparation

[0204] 87 kg of toluene was added into the reactor. Then 45.5 kg BOMAG-A in heptane was also added in the reactor. 161 kg 99.8% 2-ethyl-1-hexanol was then introduced into the reactor at a flow rate of 24-40 kg/h. The molar ratio between BOMAG-A and 2-ethyl-1-hexanol was 1:1.83.

Solid Catalyst Component Preparation

[0205] 275 kg silica (ES747JR of Crossfleld, having average particle size of 20 μm) activated at 600° C. in nitrogen was charged into a catalyst preparation reactor. Then, 411 kg 20% EADC (2.0 mmol/g silica) diluted in 555 litres pentane was added into the reactor at ambient temperature during one hour. The temperature was then increased to 35° C. while stirring the treated silica for one hour. The silica was dried at 50° C. for 8.5 hours. Then 655 kg of the complex prepared as described above (2 mmol Mg/g silica) was added at 23° C. during ten minutes. 86 kg pentane was added into the reactor at 22° C. during ten minutes. The slurry was stirred for 8 hours at 50° C. Finally, 52 kg TiCl.sub.4 was added during 0.5 hours at 45° C. The slurry was stirred at 40° C. for five hours. The catalyst was then dried by purging with nitrogen.

Polymerisation

Inventive Example 1 (IE1)

[0206] A loop reactor having a volume of 50 dm.sup.3 was operated at a temperature of 70° C. and a pressure of 63 bar. Into the reactor were ethylene, 1-butene, propane diluent and hydrogen fed so that the feed rate of ethylene was 1.0 kg/h, hydrogen was 5.0 g/h, 1-butene was 80 g/h and propane was 50 kg/h. In addition, 11 g/h of a solid Ziegler polymerisation catalyst component was introduced into the reactor together with triethylaluminium cocatalyst so that the molar ratio of Al/Ti was about 15. The production rate was 1 kg/h.

[0207] A stream of slurry was continuously withdrawn and directed to a loop reactor having a volume of 150 dm.sup.3 and which was operated at a temperature of 85° C. and a pressure of 61 bar. Into the reactor were further fed additional ethylene, propane diluent. 1-butene comonomer and hydrogen so that the ethylene concentration in the fluid mixture was 4.5% by mole, the hydrogen to ethylene ratio was 240 mol/kmol, the 1-butene to ethylene ratio was 450 mol/kmol and the fresh propane feed was 41 kg/h. The ethylene copolymer withdrawn from the reactor had MFR.sub.2 of 280 g/10 min and density of 948 kg/m.sup.3. The production rate was 19 kg/h. A stream of slurry from the reactor was withdrawn intermittently and directed into a loop reactor having a volume of 350 dm.sup.3 and which was operated at 85° C. temperature and 54 bar pressure. Into the reactor was further added a fresh propane feed of 69 kg/h and ethylene, 1-butene and hydrogen so that the ethylene content in the reaction mixture was 4.0 mol-%, the molar ratio of 1-butene to ethylene was 580 mol/kmol and the molar ratio of hydrogen to ethylene was 270 mol/kmol. The ethylene copolymer withdrawn from the reactor had MFR.sub.2 of 300 g/10 min and density of 948 kg/m.sup.3. The production rate was 25 kg/h.

[0208] The slurry was withdrawn from the loop reactor intermittently by using settling legs and directed to a flash vessel operated at a temperature of 50° C. and a pressure of 3 bar. From there the polymer was directed to a fluidized bed gas phase reactor (GPR) operated at a pressure of 20 bar and a temperature of 75° C. Additional ethylene, 1-butene comonomer, nitrogen as inert gas and hydrogen were added so that the ethylene content in the reaction mixture was 18 mol-%, the ratio of hydrogen to ethylene was 18 mol/kmol and the molar ratio of 1-butene to ethylene was 750 mol/kmol. The polymer production rate in the gas phase reactor was 55 kg/h and thus the total polymer withdrawal rate from the gas phase reactor was about 100 kg/h. The polymer had a melt flow rate MFR.sub.2 of 0.8 g/10 min and a density of 921 kg/m.sup.3. The production split (weight-% 1.sup.st stage component/weight-% 2.sup.nd stage component/weight-% 3.sup.rd stage component) was 20/25/55 (or 1/19/25/55 including the prepolymer material).

[0209] The polymer powder was mixed under nitrogen atmosphere with LDPE component, 2.6 wt. % carbon black. 1000 ppm of Ca-stearate and 3000 ppm of Irganox. Then it was compounded and extruded under nitrogen atmosphere to pellets by using a CIMP90 extruder so that the SEI was 200 kWh/ton and the melt temperature 230° C.

Inventive Examples 2 to 10 (IE2 to IE10)

[0210] The procedure of Example 1 was followed except that the operation conditions in the loop reactor and the gas phase reactor were modified as shown in Table 1. IE10 was carried out without carbon black addition in the extrusion step.

Comparative Example 1 (CE 1)

[0211] A commercially available reference grade of a unimodal linear low density polyethylene (LLDPE) used in cable jacketing layers and comprising 78 wt. % of a conventional LLDPE reference copolymer produced in the presence of a conventional Cr-catalyst in a low pressure process and 19 wt. % of a conventional LDPE copolymer (tubular LDPE having MFR2=2 g/10 min), 2.6 wt. % of a CB component (C) and 0.4 wt. % of additives were blended (mixed and pelletised using a twin screw extruder). The CB component is the same as CB (C) given above for inventive compositions. The properties are listed in Table 2.

[0212] The properties and experimental data of the inventive examples 1 to 10 (IE 1 to IE 10), comparative example 1 (CE 1) and of the inventive examples 5 to 7 (IE 5 to IE 7) of polymer compositions are shown in Tables 2 and 3. The inventive examples 1 to 9 (IE 1 to IE 9) and comparative example 2 contain 2.4 to 2.8 wt. % carbon black. Inventive example 10 (IE 10) does not contain carbon black.

TABLE-US-00001 TABLE 1 Polymerisation conditions and the product properties of the obtained polymer of inventive examples 1 to 10 Example IE 1 IE 2 IE 3 IE 4 IE 5 IE 6 IE 7 IE 8 IE 9 IE 10 1.sup.st loop C.sub.2 [mol-%] 4.5 4.5 4.5 4.5 4.6 4.5 4.8 4.5 4.8 4.8 H.sub.2/C.sub.2 [mol/kmol] 240 240 240 240 230 240 360 240 360 360 C.sub.4/C.sub.2 [mol/kmol] 450 450 450 450 480 450 0 450 0 0 MFR.sub.2 [g/10 min] 280 280 280 280 240 280 370 280 370 370 Density [kg/m.sup.3] 948 948 948 948 945 948 970 948 970 970 2.sup.nd loop C.sub.2 [mol-%] 4.0 4.0 4.0 4.0 4.2 4.0 4.7 4.0 4.7 4.7 H.sub.2/C.sub.2 [mol/kmol] 270 270 270 270 300 270 410 270 410 410 C.sub.4/C.sub.2 [mol/kmol] 580 580 580 580 590 580 0 580 0 0 MFR.sub.2 [g/10 min] 300 300 300 300 325 300 395 300 395 395 Density [kg/m.sup.3] 948 948 948 948 947 948 971 948 971 971 GPR (gas phase reactor) C.sub.2 [mol-%] 18 18 18 18 17 18 22 18 22 23 H.sub.2/C.sub.2 [mol/kmol] 18 18 18 18 19 18 26 18 26 22 C.sub.4/C.sub.2 [mol/kmol] 750 750 750 750 900 750 520 750 520 440 Polymer MFR.sub.2 [g/10 min] 0.8 0.8 0.8 0.8 0.9 0.8 0.6 0.8 0.6 0.5 Polymer MFR.sub.21 [g/10 min] 68 68 68 68 72 68 44 68 44 39 Polymer density [kg/m.sup.3] 921 921 921 921 919 921 935 921 935 940 Split .sup.1) 1/19/25/55 1/19/25/55 1/19/25/55 1/19/25/55 1/19/25/55 1/19/25/55 1/18/24/57 1/19/25/55 1/18/24/57 1/19/25/55 Final Amount of LDPE [wt. %] 19 24 19 19 22 4 4 24 .sup.2) 24 .sup.2) 35 .sup.2) MFR.sub.2 of LDPE [g/10 min] 0.25 0.25 2.1 7.5 2.1 2.1 2.1 0.5 0.5 0.5 MFR.sub.2 [g/10 min] 0.63 0.57 0.87 1.00 0.91 0.90 0.63 0.57 0.60 0.71 MFR.sub.21 [g/10 min] n.a. n.a. n.a. n.a. 73 69 44 n.a. n.a. n.a. Density [kg/m.sup.3] 933.7 932.8 933.7 933.5 931.9 934.7 948.4 935.7 950.1 935.5 .sup.1) Given as % prepoly material/% 1.sup.st loop material/% 2.sup.nd loop material/% gas phase reactor (GPR) material .sup.2) Recycled LDPE Ecoplast NAV102

TABLE-US-00002 TABLE 2 Properties and experimental data of the inventive examples 1 to 10 (IE 1 to IE 10) and comparative examples 1 and 2 (CE 1, CE 2) of polymer compositions IE 1 IE 2 IE 3 IE4 IE 5 IE 6 Component (A) Multimodal Multimodal Multimodal Multimodal Multimodal Multimodal LLDPE LLDPE LLDPE LLDPE LLDPE LLDPE Component (B); 19 24 19 19 22 4 LDPE [wt. %] LDPE MFR.sub.2 0.25 0.25 2.1 7.5 2.1 2.1 [g/10 min] MFR.sub.2 [g/10 min] 0.63 0.57 0.87 1.00 0.91 0.90 Density [kg/m.sup.3] 933.7 932.8 933.7 933.5 931.9 934.7 SHI.sub.(1/100) 15.4 16.8 12.8 14.1 15.2 11.9 G′ (5 kPa) [Pa] 2390 2490 2160 2270 2290 2120 tan(δ) (0.05 rad/s) 3.6 3.4 4.7 4.7 4.4 4.6 Tensile stress at 27.2 27.3 26.4 26.5 26.6 28.8 break [MPa] Stress at Yield 12.1 12.2 11.9 11.9 10.4 11.7 [MPa] ESCR [h] >2000 n.a. n.a. >2000 >2000 >2000 interrupted interrupted interrupted interrupted IE 7 IE8 IE 9 IE10 CE1 Component (A) Multimodal Multimodal Multimodal Multimodal Unimodal MDPE LLDPE MDPE MDPE LLDPE Component (B); 4 24 24 35 19 LDPE [wt. %] LDPE MFR.sub.2 2.1 0.5 0.5 0.5 2.1 [g/10 min] MFR.sub.2 [g/10 min] 0.63 0.86 0.57 0.60 0.71 Density [kg/m.sup.3] 948.4 935.7 950.1 935.7 932.8 SHI.sub.(1/100) 9.2 13.2 11.3 12.9 27.8 G′ (5 kPa) [Pa] 1930 2270 2150 2300 3250 tan(δ) (0.05 rad/s) 4.6 4.3 3.7 3.6 2.2 Tensile stress at 31.5 22.6 26.6 24.9 21.8 break [MPa] Stress at Yield 16.7 11.8 18.1 15.9 11.4 [MPa] ESCR [h] >2000 >5000 >5000 >5000 >2000 interrupted interrupted interrupted interrupted interrupted

[0213] From Table 2 can be derived that all inventive examples 1 to 10 (IE1 to 10) have a higher tensile strength than the comparative example 1. Besides, the shear thinning index, SHI.sub.(1/100), as well as the storage modulus, G′, are lower than comparative example 1.

TABLE-US-00003 TABLE 3 Properties and experimental data of the inventive examples 5 to 7 (IE 5 to IE 7) and comparative example 2 (CE 2) of polymer compositions IE 5 IE 6 IE7 CE 1 Component (A) Multimodal Multimodal Multimodal Unimodal LLDPE LLDPE MDPE LLDPE Component (B); LDPE [wt. %] 22 4 4 19 MFR.sub.2 [g/10 min] 0.91 0.91 0.63 0.71 SHI.sub.(1/100) 15.2 11.9 9.2 27.8 G′ (5 kPa) [Pa] 2290 2120 1930 3250 tan(δ) (0.05 rad/s) 4.4 4.6 4.6 2.2 Density [kg/m.sup.3] 931.9 934.7 948.4 932.8 OIT (200 C.) [min] >65 >66 >65 >65 Absorption coefficient at 428 471 487 411 375 nm [abs/m] Cold bend pass pass pass pass Deformation (115° C./6 h) [%] 21 2 1 30 ESCR (cooling 5 C./h) [h] >2000 h, >2000 h, >2000 h, >2000 h, interr. interr. interr. interr. Flexural modulus (50 mm/min) 371 421 660 347 [MPa] Strain at break (50 mm/min) [%] 889 865 812 951 Tensile stress at break 26.6 28.9 31.5 21.4 (50 mm/min) [MPa] Tensile stress at break 25.2 26.7 27.3 20.1 (50 mm/min)* [MPa] Shrinkage (80° C./5 cycles) [%] 0.58 0.46 0.78 0.88 Shore D (1 sec) 53 55 60 53 *measured after ageing for 14 days at 110° C.

[0214] From Table 3 can be derived that apart of the advantageous rheological parameters the deformation and shrinkage are also better than comparative example 1.

[0215] Particularly IE5 to IE7 show the good balance between improved tensile strength even after ageing for 24 h and shrinkage as well as deformation over a broad density range.

Comparative Example 2

[0216] Multimodal znLLDPE polymer, which is similar to the polymer disclosed in EP 2 471 077 B1 inventive example 2, was prepared in pilot scale reactor system containing loop reactor and gas phase reactor. Product properties are shown in Table 4.

TABLE-US-00004 TABLE 4 Product properties of the obtained polymer used for comparative example 2 MFR.sub.2 of polymer produced in 290 loop reactor [g/10 min] Density of polymer produced 950 in loop reactor [kg/m.sup.3] Split, loop/gpr [wt. %/wt. %] 41/59 MFR.sub.2 of pelletised final polymer [g/10 min] 0.2 Density of pelletised final polymer [kg/m.sup.3] 923

[0217] This polymer was then melt homogenised and pelletised with conventional LOPE having MFR.sub.2=2 g/10 min and carbon black masterbatch on twin screw extruder. The properties of the final polymer composition of comparative example 2 (CE2) are shown in Table 5.

TABLE-US-00005 TABLE 5 Product properties of the polymer composition of comparative example 2 Multimodal LLDPE [wt. %] 38 LDPE [wt. %] 55 CBMB [wt. %] 7 MFR.sub.2 [g/10 min] 0.3 Density [kg/m.sup.3] 934 CB content [wt. %] 2.5 SHI.sub.(1/100) 33.2 SHI.sub.(2.7/210) 101 G′ (5 kPa) [Pa] 2942 Tan (d) 0.05 [rad/s] 2.4