Propylene-based terpolymer composition for pipes

Abstract

The invention relates to a polypropylene composition comprising a terpolymer containing propylene, ethylene and 1-hexene wherein the polypropylene composition (i) has a content of ethylene derived units of at least 1.5 wt %; (ii) has a content of 1-hexene derived units of at least 1.5 wt %; (iii) has a melt flow rate of 0.10 to 0.70 g/10 min determined by ISO 1133-1:2011 (230 C., 2.16 kg); and (iv) has a ratio of weight average molecular weight (Mw) to numeric average molecular (Mn) weight of the terpolymer of 7.0 to 20.0, wherein Mw and Mn are measured according to ASTM D6474-12.

Claims

1. A polypropylene composition comprising a terpolymer containing propylene, ethylene and 1-hexene, wherein the polypropylene composition (i) has a content of ethylene derived units of at least 1.5 wt %; (ii) has a content of 1-hexene derived units of at least 1.5 wt %; (iii) has a melt flow rate of 0.10 to 0.70 g/10 min determined by ISO 1133-1:2011 at 230 C. and 2.16 kg; and (iv) has a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) of the terpolymer of 8 to 16, wherein Mw and Mn are measured according to ASTM D6474-12.

2. The polypropylene composition according to claim 1, wherein the melt flow rate of the polypropylene composition determined by ISO 1133-1:2011 at 230 C. and 2.16 kg is 0.10 to 0.50 dg/min.

3. The polypropylene composition according to claim 1, wherein the melt flow rate of the polypropylene composition determined by ISO 1133-1:2011 at 230 C. and 2.16 kg is 0.10 to 0.30 dg/min.

4. The polypropylene composition according to claim 1, wherein the content of ethylene derived units in the polypropylene composition is 1.5 to 5.0 wt %.

5. The polypropylene composition according to claim 1, wherein the content of ethylene derived units in the polypropylene composition is 1.6 to 4.0 wt %.

6. The polypropylene composition according to claim 1, wherein the content of ethylene derived units in the polypropylene composition is 1.7 to 3.5 wt %.

7. The polypropylene composition according to claim 1, wherein the content of 1-hexene derived units in the polypropylene composition is 1.5 to 4.0 wt %.

8. The polypropylene composition according to claim 1, wherein the content of ethylene derived units in the polypropylene composition in wt % is larger than the content of 1-hexene derived units in the polypropylene composition in wt %-0.20 wt %.

9. The polypropylene composition according to claim 8, wherein the content of ethylene derived units in the polypropylene polypropylene composition in wt % is larger than the content of 1-hexene derived units in the polypropylene polypropylene composition in wt %-0.10 wt %.

10. The polypropylene composition according to claim 1, wherein a ratio of the content of ethylene derived units to the content of 1-hexene derived units in the polypropylene composition is at least 0.70.

11. The polypropylene composition of claim 10, wherein the ratio of the content of ethylene derived units to the content of 1-hexene derived units in the polypropylene composition is at most 3.0.

12. The polypropylene composition according to claim 1, wherein the polypropylene composition has <Gp>/Y of at least 7.0, wherein <Gp> is strain hardening modulus and Y is yield stress and <Gp>/Y is determined by: a) providing a specimen of the polypropylene composition by compression molding a sheet from the polypropylene composition according to ISO 1873-2 to a thickness of 0.3 mm0.025 mm and punching a specimen having a geometry of a test specimen described in ISO/DIS 18488 from the sheet, wherein the sheet is annealed after the compression molding and before the punching at a temperature of 100 C. for 1 hour and cooled down to room temperature, b) elongating the specimen at a constant traverse speed of 20 mm/min at 100 C., c) measuring a load sustained by the specimen during the elongating to obtain a stress-strain curve and measuring a yield stress Y, d) calculating true stress-true strain curve from the stress strain curve obtained by step c) and calculating a tensile strain hardening modulus <Gp> from the true stress-strain curve, according to the method as described in ISO/DIS 18488 and e) calculating a quotient of the tensile strain hardening modulus <Gp> divided by the yield stress Y.

13. The polypropylene composition according to claim 1, wherein the polypropylene composition further comprises additives and a sum of an amount of the terpolymer and the additives is 100 wt % based on the polypropylene composition.

14. A process for the preparation of the polypropylene composition according to claim 1, comprising a step of polymerizing propylene, ethylene and 1-hexene in the presence of a Ziegler-Natta catalyst system to obtain the terpolymer, wherein the Ziegler-Natta catalyst system comprises a procatalyst, a co-catalyst and optionally an external electron donor, wherein the procatalyst is obtained by a process comprising the steps of Step A) providing or preparing a compound R.sup.4.sub.zMgX.sup.4.sub.2-z wherein each occurrence of R.sup.4 is independently selected from a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contains one or more heteroatoms; each occurrence of X.sup.4 is independently selected from the group consisting of fluoride (F), chloride (Cl), bromide (Br) and iodide (I); z is larger than 0 and smaller than 2, being 0<z<2; Step B) contacting the compound R.sup.4.sub.zMgX.sup.4.sub.2-z with a silane compound Si(OR.sup.5).sub.4-n(R.sup.6).sub.n to give a first intermediate reaction product, being a solid Mg(OR.sup.5).sub.xX.sup.1.sub.2-x wherein R.sup.5 and R.sup.6 are each independently selected from a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contains one or more heteroatoms; each occurrence of X.sup.1 is independently selected from the group consisting of fluoride (F), chloride (Cl), bromide (Br) and iodide (I); n is 0 to 4; z is larger than 0 and smaller than 2, being 0<z<2; x is larger than 0 and smaller than 2, being 0<x<2; Step C) activating said first intermediate reaction product, comprising two sub steps: Step C1) a first activation step comprising contacting the first intermediate reaction product obtained in step B) with at least one first activating compound which is a metal alkoxide compound of formula M.sup.1(OR.sup.2).sub.v-w(OR.sup.3).sub.w or M.sup.2(OR.sup.2).sub.v-w(R.sup.3).sub.w to provide a partially activated solid support; wherein: M.sup.1 is a metal selected from the group consisting of Ti, Zr, Hf, Al and Si; M.sup.2 is Si; v is a valency of M.sup.1 or M.sup.2 and w is smaller than v; R.sup.2 and R.sup.3 are each a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contains one or more heteroatoms; and a second activating compound which is a first activating electron donor; and Step C2) a second activation step comprising contacting the partially activated solid support obtained in step C1) with second activating electron donor; to obtain a second intermediate reaction product; Step D) reacting the second intermediate reaction product obtained from step C2) with a halogen-containing Ti-compound, at least one internal electron donor, and optionally an activator to obtain said procatalyst.

15. An article comprising the polypropylene composition according to claim 1.

16. The article according to claim 15, wherein the article is a pipe.

17. A method for the preparation of a pipe comprising extruding the polypropylene composition of claim 1.

18. A polypropylene composition comprising a terpolymer containing propylene, ethylene and 1-hexane, wherein the polypropylene composition (i) has a content of ethylene derived units of at least 1.5 wt %; (ii) has a content of 1-hexane derived units of at least 1.5 wt %; (iii) has a melt flow rate of 0.10 to 0.70 g/10 min determined by ISO 1133-1:2011 at 230 C. and 2.16 kg; and (iv) has a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) of the terpolymer of 7.0 to 20.0, wherein Mw and Mn are measured according to ASTM D6474-12, wherein the polypropylene composition has a polydispersity index (PI) of at least 4.0.

19. The polypropylene composition according to claim 18, wherein the ratio of weight average molecular weight to number average molecular weight (Mw/Mn) of the terpolymer is 8.0 to 16.0.

20. A polypropylene composition comprising a terpolymer containing propylene, ethylene and 1-hexane, wherein the polypropylene composition (i) has a content of ethylene derived units of at least 1.5 wt %; (ii) has a content of 1-hexane derived units of at least 1.5 wt %; (iii) has a melt flow rate of 0.10 to 0.70 g/10 min determined by ISO 1133-1:2011 at 230 C. and 2.16 kg; and (iv) has a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) of the terpolymer of 7.0 to 20.0, wherein Mw and Mn are measured according to ASTM D6474-12, wherein a lowest temperature at which maximum 1 out of 10 pipes made from the polypropylene composition fails determined by DIN8078 is 0.0 C.

Description

(1) The invention is now elucidated by way of the following examples, without however being limited thereto.

(2) Methods

(3) SEC: Mz, Mn, Mw

(4) Size Exclusion Chromatography (SEC) was performed on the granule samples and Mw, Mn and Mz were all 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 weight. Mz stands for the z-average molecular weight.

(5) In addition to the method specified by ASTM D6474-12, the method was performed using a configuration in which a Polymer Char IR5 infrared concentration detector and a Polymer Char online viscosity detector was used to gain absolute (and therefore more accurate) molar masses. Three columns of Polymer Laboratories 13 m PLgel Olexis, 3007.5 mm were used in series with 1,2,4-trichlorobenzene stabilized with 1 g/L butylhydroxytoluene (also known as 2,6-di-tert-butyl-4-methylphenol or BHT) as elution.

(6) The molar mass distribution and derived molar masses were determined based on a calibration using linear PE standards (narrow and broad (Mw/Mn=4 to 15)) in the range of 0.5-2800 kg/mol. Samples of polymer granules were mixed with Tris (2,4-di-tert-butylphenyl)phosphite (Irgafos 168) and 1,1,3-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl)butane (Topanol CA) in a weight ratio of sample:Irgafos:Topanol of 1:1:1, after which the mixture thus obtained was dissolved in 1,2,4-trichlorobenzene stabilized with 1 g/L BHT until the concentration of the mixture in 1,2,3-trichlorobenzene stabilized with 1 g/L BHT was 0.03 wt %.

(7) Xylene Solubles (XS)

(8) Powder samples were evaluated for XS, wt % xylene solubles, 1 gram of polymer and 100 ml of xylene are introduced in a glass flask equipped with a magnetic stirrer. The temperature is raised up to the boiling point of the solvent. The so obtained clear solution is then kept under reflux and stirring for further 15 min. Heating is stopped and the isolating plate between heating and flask is removed. Cooling takes place with stirring for 5 min. The closed flask is then kept for 30 min in a thermostatic water bath at 25 C. for 30 min. The so formed solid is filtered on filtering paper. 25 ml of the filtered liquid is poured in a previously weighed aluminium container, which is heated in a stove of 140 C. for at least 2 hours, under nitrogen flow and vacuum, to remove the solvent by evaporation. The container is then kept in an oven at 140 C. under vacuum until constant weight is obtained. The weight percentage of polymer soluble in xylene at room temperature is then calculated.

(9) 13C-NMR for C2, C6 Comonomer Content

(10) Approximately 150 mg of sample was dissolved at 135 C. in 3 ml of 1,1,2,2-tetrachloroethane-d2 (TCE-d2)/BHT stock solution using a 10 mm NMR tube. The stock solution was made by dissolving 5 mg on BHT in 25 ml of TCE-d2. Oxygen concentration in the tube was reduced by flushing the tube for 1 min with nitrogen before dissolution. The sample was periodically checked for homogeneity and manually mixed as necessary.

(11) All NMR experiments were carried out on a Bruker 500 Avance III HD spectrometer equipped with a 10 mm DUAL (proton and carbon) cryogenically cooled probe head operating at 125 C. The 13C NMR measurements were performed using a spectral width of 220 ppm, an acquisition time of 1.4 s and a relaxation delay of 20 s between each of the 512 transients. The spectra were calibrated by setting the central signal of TCE's triplet at 74.2 ppm.

(12) Commoner content is calculated as described in: F. F. N. Escher, G. B. Galland, J Polym Sci Part A: Polym Chem 42: 2474-2482, 2004

(13) Dynamic Mechanical Spectroscopy (DMS) Analysis for PI (Polydispersity Index)

(14) Compression moulding of the samples was done at 200 C. in consecutive steps; at 0 bar for 1 minute, at 5 bars for 1 minute, at 40 bars for 3 minutes and was completed by a cooling step at 40 bars. The rheological behavior of the samples was studied using a DHR2 torsional rheometer (TA Instruments) equipped with a parallel plate geometry (diameter=25 mm, gap=1000 m). The rheological profiles were obtained by conducting oscillation frequency sweep experiments. The measurements were performed with the following procedure: a) Conditioning step at 230 C. for 60 seconds b) Oscillation frequency sweep at 230 C.: frequency 600-0.01 rad/s, 1% strain, logarithmic sweep, 5 pts/decade.

(15) Distorted torque-displacement data points were determined for each sample. Using the Cox-Merz rule and the Trios software, the undistorted rheology data collected in oscillation mode were transformed to the ones in flow mode. The transformed rheological curves were fitted using Yasuda-Carreau model from which a zero-shear viscosity value was obtained. From these, the rheology polydispersity index (PI) of the blends was determined by dividing the cross-over modulus (which occurs when the storage (G) and loss (G) moduli are equal) into 105 Pa as per definition. This is a convenient measure of polydispersity that is often employed. The PI value could be determined for all polymer blends without the need of extrapolating the cross-over point. PI is calculated as follows:

(16) $\mathrm{PI}=\frac{{10}^{5}Pa}{G_c}\mathrm{where}{G}_c\mathrm{occurs}\mathrm{when}\left(G^{}\right)\mathrm{storage}\mathrm{modulus}=\left(G^{}\right)\mathrm{loss}\mathrm{modulus}$

(17) Melt Flow Rate (MFR)

(18) For purpose of the invention the melt flow rate is the melt flow rate as measured according to ISO1133 (2.16 kg/230 C.).

(19) <Gp>/Ys

(20) Strain hardening modulus divided by yield stress (<Gp>/Ys) were measured by the method described in WO2018/011177: a) providing a specimen of the composition by compression molding a sheet from the composition according to ISO 1873-2 to a thickness of 0.3 mm0,025 mm and punching a specimen having a geometry of the test specimen described in ISO/DIS 18488 from the sheet, wherein the sheet is annealed after the compression molding and before the punching at a temperature of 100 C. for 1 hour and cooled down to room temperature, b) elongating the specimen at a constant traverse speed of 20 mm/min at 100 C., c) measuring the load sustained by the specimen during the elongation to obtain a stress-strain curve and measuring the yield stress Y, d) calculating true stress-true strain curve from the stress strain curve obtained by step c) and calculating the tensile strain hardening modulus <G.sub.p> from the true stress-strain curve, according to the method as described in ISO/DIS 18488 and e) calculating a quotient of the tensile strain hardening modulus <G.sub.p> divided by the yield stress Y.

(21) Steps b) and c) were performed as follows: Measurement of the exact dimensions (with accuracy of 0.01 mm) of width (b) and (with an accuracy of 0.005 mm) of thickness (h) of each individual test specimen. Conditioning of the test specimens for a period of time, e.g. at least 30 minutes, in the temperature chamber set at a predetermined temperature of 100 C. prior to starting the test. Clamping of the test piece in the upper grip of the elongation device. The clamps are chosen to avoid damage and slippage of the test piece. Closure of the temperature chamber. After reaching said predetermined temperature, clamp the test piece with the lower grip. The sample shall remain between the clamps for a certain period, e.g. at least 1 minute, before the load is applied and measurement starts. Add a pre-stress e.g. of 0.4 MPa reached with a speed of e.g. 5 mm/min. During the test, the load sustained by the specimen and the elongation are measured. Extend the test specimen at a constant traverse speed of 20 mm/min until the test specimen breaks.

(22) For step d), the method of the calculations is described in ISO/DIS 18488, section 8 Data treatment.

(23) The draw ratio, , is calculated from the length, l, and the gauge length, l.sub.0, as shown by formula 1.

(24) $\begin{array}{cc}=\frac{l}{l_0}=1+\frac{l}{l_0}& \left(1\right)\end{array}$

(25) where

(26) l is the increase in the specimen length between the gauge marks.

(27) The true stress, .sub.true, is calculated according to formula 2, which is derived on the assumption of conservation of volume between the gauge marks:

(28) $\begin{array}{cc}{}_{\mathrm{true}}=.Math.\frac{F}{A}& \left(2\right)\end{array}$

(29) where

(30) F is the measured force (N).

(31) It is important that the initial cross section A shall be determined for each individual test bar.

(32) The Neo-Hookean constitutive model (formula 3, see Annex A of ISO/DIN 18488) is used to fit and extrapolate the data from which <Gp> (MPa) for 8<<12 is calculated.

(33) $\begin{array}{cc}{}_{\mathrm{true}}=\frac{<G_p>}{20}.Math.\left({}^2-\frac{1}{}\right)+C& \left(3\right)\end{array}$

(34) where

(35) C is a mathematical parameter of the constitutive model describing the yield stress extrapolated to =0.

(36) Accuracy of fit of data (R2) greater than 0.9 shall be achieved.

(37) The measurement of G.sub.p/Y was performed on test specimens made according to ISO1873-2 and ISO/DIS18488 at a constant traverse speed of 20 mm/min and a temperature of 100 C.

(38) Pipe Impact Measurements

(39) Pipe impact measurements are performed according to DIN 8078. The temperature shown is the lowest temperature at which at maximum 1 out of 10 pipes fails.

(40) Hydrostatic Pipe Testing

(41) For measuring the resistance to internal pressure, a pipe was prepared from the propylene copolymer composition according to ISO 1167-2:2006. According to ISO1167-1:2006, a run time without failure of the pipe was measured while a hoop stress of 4.9 MPa or 4.4 MPa measured according to ISO3213:2009 was applied to the pipe at a temperature of 95 C.

(42) Experiments

(43) The catalyst used for the polymerization was catalyst H (Ex. 8) of WO2018/059955. The composition of the solid catalyst H produced is given in Table 1.

(44) TABLE-US-00001 TABLE 1 Composition of solid catalyst H d50 Mg Ti ID Activator (EB) EtO Catalyst Example [m] [%] [%] [%] [%] [%] H 8 22.16 19.65 2.40 8.41 6.68 1.48

(45) Polymerization experiments of propylene terpolymers were performed on a bench-scale gas-phase reactor using above described catalyst.

(46) Polymerization experiments of propylene terpolymers were performed on gas phase fluidized bed polymerization reactor using above described catalyst. The reactor conditions and feed are described in table 2 below. Comparative example 1 is the propylene random copolymer P9421, which is commercially available from SABIC.

(47) TABLE-US-00002 TABLE 2 Process conditions. Exp Nr. Ex. 1 Ex. 2 Comp 1. Comp. 2 TEAL/SCA molar 2.1 3 ratio TEAI/Ti molar 110 110 110 ratio T C. 66 66 66 P Barg 26 26 26 H2/C3 mol/mol 0.0026 0.0029 0.0030 C2/C3 mol/mol 0.0140 0.0142 0.0110 C6/C3 mol/mol 0.0015 0.0010 0.02 XS powder M/M % 8.2 7.2 9.2 4.9 TC2 wt-% 2.2 2.2 3.7 1.4 TC6 wt-% 2 1.6 2.1 TC2 mol % 3.30 3.29 5.4 TC6 mol % 1.00 0.80 Mw/Mn 11.2 11.0 6.8 SCA = Selectivity Control Agent = ADT5500

(48) The powder was collected and granulate was prepared by melt-mixing the powders with the appropriate additives in a double screw extruder. The additives (antioxidants, acid scavengers) were used in an amount of 1.05 wt % based on the powder and mixed prior to dosing to the extruder. The temperature profile in the extruder was 20-79-190-230-230-230-230-230-230-235-235-240-240 C. at a throughput of 74 kg/h at 225 rpm.

(49) Preparation of the Pipe

(50) 203.4 mm pipes were extruded on a Reifenhauser S50 I with a barrier screw operated at 35 rpm. The die head temperature profile was set to 40/190/200/205/20500 and temperature profile of the extruder was set to 205/205/205/20500. The extruded pipes were cooled to a temperature of 2000. The pressure sensor to measure the melt pressure (indicated in the table below) was located in between the extruder and the die head.

(51) TABLE-US-00003 TABLE 3 Results Comp Comp. Exp Nr. Ex. 1 Ex. 2 1. 2 MFI 2.16 kg dg/min 0.17 0.189 0.3 0.14 MFI 5 kg dg/min 1.07 1 MFI 10 kg dg/min 5.6 5.43 Pl (gran) 5.6 5.6 3.4 <Gp>/Ys @100 C. 9.6 8.4 6.00 pipe impact C. 2 1 3 2 Pipe pressure hr >8900 1350 (D*) 25 (D*) 95 C., 4.9 Mpa Pipe pressure hr >8904 >8904 1827 (D*) 95 C., 4.4 Mpa *D = ductile failure

(52) It can be concluded from Table 3 that the time to failure is much longer for a pipe made from the composition according to the invention. A higher C2 content leads to a better pipe impact property. The pipe made from the composition according to the invention has a sufficient pipe impact property.

(53) TABLE-US-00004 TABLE 4 pipe processing results Sample Melt RPM Throughput Uptake pressure Temperature () (min-1) (kg/h) (m/min.) (kp/cm.sup.2) ( C.) Comp 1 40 34.7 3.5 136 220 Ex. 2 60 42.1 4.3 136 224

(54) It can be concluded from Table 4 that pipe processing is improved for the compositions according to the invention, which can be attributed to a higher Mw/Mn and a higher PI.

(55) Polymerization experiments of propylene terpolymers Ex, 3, Ex. 4 and Comp. 3 were performed on a gas phase polymerization reactor different from the reactor used for the polymers of Ex. 1 and 2 using above described catalyst (catalyst H (Ex. 8) of WO2018/059955). The reactor conditions and feed are described in Table 5. Measured properties of the propylene terpolymers are described in Table 6.

(56) For the determination of the C2, C6 comonomer content for Ex. 3, Ex. 4 and Comp. 3, FT-IR calibrated by NMR was used as follows:

(57) 3.75 gram of powder was melt-pressed at 190 C. and 100 kN for 2 minutes into disc film with a diameter of 12.5 cm and a thickness of 0.3 mm. After melt-pressing, the sample was removed from the hot melt press into a cold melt press and kept under a pressure of 100 kN for 2 minutes at 23 C. All spectra were recorded in transmittance mode with a Perkin Elmer Spectrum One spectrometer equipped with a motor that rotates the sample films. For quantification of C2 and C6 the wavenumber range 760-680 cm-1 was taken. The peak at 732 cm-1 is due to C2 and the peak at 726 cm-1 to C6. These two bands show strong overlap, therefore a multivariate regression method was used for deconvolution of the spectral signals and subsequent modelling of the relationship between the spectral responses and the C2 and C6 concentration of the samples. NMR was used as reference method.

(58) Any deviations in the C2, C6 comonomer contents determined by this method and the C2, C6 comonomer contents determined by the method described in the section titled 13C-NMR for C2, C6 comonomer content are within experimental error.

(59) Other properties mentioned in Tables 5 and 6 were measured by the methods described above.

(60) TABLE-US-00005 TABLE 5 Process conditions. Exp Nr. Ex. 3 Ex. 4 Comp. 3 TEAL/SCA molar ratio 2 2 2 TEAI/Ti molar ratio 30 30 30 T C. 66 66 66 P Barg 20 20 20 H2/C3 mol/mol 0.0073 0.0061 0.0058 C2/C3 mol/mol 0.014 0.0148 0.0145 C6/C3 mol/mol 0.0141 0.0126 0.0105 XS powder M/M % 5.13 TC2 wt-% 2.25 2.1 2.1 TC6 wt-% 2.05 1.6 1.3 SCA = Selectivity Control Agent = Diisopropyldimethoxysilane

(61) The powder was collected and granulate was prepared by melt-mixing the powders with the appropriate additives in a double screw extruder. The additives (antioxidants, acid scavengers) were used in an amount of 1.05 wt % based on the powder and mixed prior to dosing to the extruder. Temperature profile of the extruder was: , 20, 20, 20, 100, 70, 200, 220-240 C., throughput of 1.1 kg/h at 223 rpm.

(62) TABLE-US-00006 TABLE 6 Results Exp Nr. Ex 3 Ex 4 Comp. 3 MFI 2.16 kg dg/min 0.24 0.18 0.2 <Gp>/Ys @100 C. 9 8.4 7.8

(63) The comparison between Ex. 4 and Comp. 3 shows that the difference in the higher content of 1-hexene derived units leads to a higher <Gp>Ys, which shows that the time to failure of a pipe made from the composition of Ex. 4 is much longer than that made from the composition of Comp. 3. Thus, a pipe made from the composition according to the invention having a relatively high content of 1-hexene derived units has a higher advantageously has a long time to failure.