NZ785580A - Cable jacket composition - Google Patents

Abstract

The present invention relates to a cable jacket composition comprising a multimodal olefin copolymer, wherein said olefin copolymer has a density of 0.935-0.960 g/cm3 and MFR2 of 1.5-10.0 g/10 min and comprises a bimodal polymer mixture of a low molecular weight homo- or copolymer and a high molecular weight copolymer wherein the composition has ESCR of at least 2000 hours and wherein the numerical values of cable wear index and composition MFR2 (g/10 min) follow the correlation: Wear index ≤ 15.500+0.900*composition MFR2 The invention further relates to the process for preparing said composition and its use as outer jacket layer for a cable, preferably a communication cable, most preferably a fiber optic cable

Description

CABLE JACKET COMPOSITION FIELD OF THE INVENTION The present invention relates to a cable jacket composition, to the process for preparing said composition and its use as outer jacket layer for a cable, preferably a communication cable.

BACKGROUND OF THE INVENTION Cables, which e power cables for high, medium or low voltage, and ication cables, such as fiber-optic, coaxial and twisted pair cables, generally comprise a core surrounded by a sheath consisting of one or more .

The outermost layer is often referred to as jacket or jacketing layer and is nowadays made of polymer material, preferably ethylene copolymer. The jacket material has to meet a number of properties requirements, which may vary ing on the intended application.

Important properties of cable ing compositions are good processability, i.e. it should be easy to process the material within a broad temperature range, low shrinkage, high mechanical strength, high surface finish as well as high environmental stress cracking resistance (ESCR).

Often, however, good properties in one respect are obtained at the cost of poorer properties in some other respects.

Fiber optic cable (FOC) functionality is especially sensitive to shrinkage. As smaller and smaller constructions are sought, the requirements for age become even more stringent.

A current high density FOC sold on the market is Borstar®HE6067, which is a bimodal high density polyethylene ing ition known for its low shrinkage and good mechanical properties. However, there is still a need to decrease the age further while maintaining reasonable hardness and ESCR. While increasing MFR2 of the itions and at the same time compensating for the loss in ESCR provides compositions with improved shrinkage, featuring high ESCR, there is still a need to r improve abrasion resistance. Namely, there is the need to provide jacketing compositions having improved abrasion resistance than Borstar®HE6067, while maintaining the same ESCR, and possibly having lower shrinkage.

SUMMARY OF THE INVENTION The present invention provides a cable jacket composition comprising a multimodal olefin copolymer, wherein said multimodal olefin copolymer has a y of 0.935- 0.960 g/cm3 and MFR2 of 1.5-10.0 g/10 min and comprises a bimodal r mixture of a low molecular weight homo- or copolymer and a high molecular weight copolymer wherein the composition has ESCR of at least 2000 hours and wherein the numerical values of cable wear index and composition MFR2 (g/10min) follow the correlation: Wear index ≤ 15.500+0.900*composition MFR2 Preferably, the multimodal olefin copolymer has MFR2 of 1.6-8.0 g/10 min, more preferably 2.5-8.0 g/10 min, and/or the MFR2 of the low molecular weight homo- or copolymer is 25.0- 200.0 g/10 min. ably, the multimodal olefin copolymer has Mw of 55000-105000, more preferably 55000-95000.

Even more preferably, the MFR2 of the low molecular weight homo- or copolymer is 40.0- 150.0 g/10min, more preferably 40.0-100 g/10 min.

The ition of the invention has preferably cable shrinkage of 0.70% or lower and/or cable extrusion pressure of 144 bar or lower.

Further, the composition preferably has Eta 300 of 500 Pa.s or lower.

The multimodal olefin copolymer in the composition is preferably a l polymer e of a low molecular weight ethylene homo- or copolymer and a high lar weight copolymer of ethylene and a comonomer selected from the list consisting of 1-butene, 4-methyl pentene, 1-hexene and 1-octene.

More conveniently, the odal olefin copolymer mixture is a bimodal r mixture of a low molecular weight ethylene homopolymer and a high molecular weight copolymer of ethylene and 1-butene.

According to one embodiment, the composition may further comprise conductive filler in an amount from 0.05 to 5 wt%, preferably from 0.05 to 3 wt% of the entire composition.

Conveniently, the conductive filler is carbon black.

According to another ment, the composition essentially consists of multimodal olefin copolymer.

The invention is also directed to a cable comprising the composition as described in the variants above, said cable having shrinkage of 0.70% or lower and cable wear index of 17.0 or below. Preferably, said cable is a fiber-optic cable.

The invention further pertains to a s for preparing the cable jacket composition as described above, wherein the polymerization of the multimodal olefin copolymer ses two main rization stages in the presence of a MgCl2 supported catalyst prepared according to a method comprising the steps of: a) providing solid carrier particles of MgCl2*mROH adduct; b) eating the solid carrier particles of step a) with a compound of Group 13 metal; c) treating the pre-treated solid carried particles of step b) with a transition metal compound of Group 4 to 6; d) recovering the solid st component; wherein the solid carrier les are ted with an internal organic compound of a (I) or isomers or mixtures therefrom before treating the solid carrier particles in step c) and wherein in the formula (I), R1 to R5 are the same or different and can be hydrogen, a linear or branched C1 to C8-alkyl group, or a C3-C8-alkylene group, or two or more of R1 to R5 can forma ring, the two oxygen-containing rings are individually saturated or partially unsaturated or unsaturated, and R in the adduct MgCl2*mROH is a linear or branched alkyl group with 1 to 12 C atoms, and m is 0 to 6.

Preferably, the two main polymerization stages are a combination of loop reactor/gas phase reactor or gas phase reactor/gas phase reactor. The process may further include a prepolymerization stage.

The invention is also directed to the use of the MgCl2 supported catalyst prepared according to the method described above (also described in WO 2016097193), in the preparation of the cable jacket ition as described in the above variants.

ED DESCRIPTION OF THE ION The present ion provides a cable jacket composition comprising a multimodal olefin copolymer, n said multimodal olefin copolymer has a density of 0.935-0.960 g/cm3 and MFR2 of 1.5-10.0 g/10 min and comprises a l polymer mixture of a low molecular weight homo- or copolymer and a high molecular weight copolymer, wherein the composition has ESCR of at least 2000 hours and wherein the numerical values of cable wear index and composition MFR2 (g/10min) follow the ation: Wear index ≤ 15.500+0.900*composition MFR2.

Preferably, the multimodal olefin copolymer has a MFR2 of 2.2-10.0 g/10min, more preferably of 2.5-8.0 g/10 min.

The density is preferably not higher than 0.950 g/cm3.

Further, the multimodal olefin copolymer of the invention preferably has MFR5 of higher than 8.0-25.0 g/10min, preferably of 9.0-25.0 g/10min.

Still further, the multimodal olefin copolymer preferably has Mw of 95000, or even more preferably of 91000. ably, the multimodal olefin copolymer has Mn of 6500-11000 or advantageously of 7000-10500. Further, the multimodal olefin copolymer preferably has MWD of 7-12.

Preferably, the multimodal olefin copolymer of the invention has MFRs of 8.0- 25.0 g/10min, Mw of 55000-95000, Mn of 6500-11000 and MWD of 7-12.

Even more preferably, the multimodal olefin copolymer of the invention has MFR5 of 9.0-25.0 g/10min, Mw of 65000-91000, Mn of 7000-10500 and MWD of 7-12.

The multimodal olefin copolymer in the composition of the invention is preferably a bimodal polymer mixture of a low molecular weight homo- or copolymer, preferably a homopolymer, and a high molecular weight copolymer; wherein the low molecular weight ethylene homopolymer has lower lar weight than the high molecular weight copolymer. ably the low molecular weight homo- or copolymer is an ne homo- or copolymer, preferably an ne homopolymer and the high molecular weight mer is a copolymer of ethylene and a comonomer.

Commonly used mers are olefins having up to 12 carbon atoms, such as a-olefins having 3-12 carbon atoms, e.g. propene, butene, 4-methyl 1-pentene, hexene, octene, decene, etc. According to the present invention, the comonomer is selected from the list consisting of 1-butene, 4-methylpentene, 1-hexene and 1-octene.

More conveniently, the multimodal olefin copolymer of the invention is a bimodal polymer mixture of a low molecular weight ethylene homopolymer and a high molecular weight copolymer of ethylene and 1-butene. lf a polymer consists of only one kind of monomers then it is called a olymer, while a polymer which consists of more than one kind of monomers is called a copolymer. However, according to the invention, the term homopolymer encompasses polymers that mainly consist of one kind of monomer but may further contain comonomers in amounts of 0.09 mol% or lower.

Preferably, the low molecular weight homo- or copolymer has a MFR2 of 25.0-200.0, preferably of 40.0-100.0 g/10 min.

The density of the low molecular weight homo- or copolymer is conveniently of 0.930-0.975 g/cm3.

The high lar weight copolymer preferably has a density from 0.880-0.930 g/cm3 and a MFR2 from 0.001 - 1.0 g/10 min, preferably between 0.003 and 0.8 g/10 min.

Preferably, the multimodal olefin copolymer of the invention has MFR5 of 8.0-25.0 g/10 min; and the olefin copolymer is a bimodal polymer mixture of a low molecular weight homo -or mer, ably a homopolymer, and a high lar weight copolymer, wherein the low molecular weight homo- or copolymer has a density from 0.930-0.975 g/cm3 and a MFR5 of 25.0-200.0 g/10 min, preferably of 40.0-100.0 g/10min.

It is well known to a person skilled in the art how to produce multimodal, in particular bimodal olefin polymers, or multimodal ethylene polymers, in two or more reactors, preferably ted in series. Each and every one of the rization stages can be carried out in liquid phase, slurry or gas phase.

In the production of, say, a bimodal homo- or copolymer, usually a first polymer is produced in a first reactor under certain conditions with respect to monomer composition, hydrogen-gas pressure, temperature, pressure, and so forth. After the polymerization in the first reactor, the reaction mixture including the polymer produced is fed to a second reactor, where r polymerization takes place under other conditions.

Usually, a first r of high melt flow rate (low molecular ) and with a moderate or small addition of comonomer, or no such addition at all, is produced in the first reactor, whereas a second polymer of low melt flow rate (high molecular weight) and with a greater addition of comonomer is produced in the second reactor. The order of these stages may, however, be reversed. Further, an additional reactor may be used to produce either the low molecular weight or the high molecular weight polymer or both.

According to the t invention, the main rization stages are preferably carried out as a combination of slurry polymerization/gas-phase polymerization or gas-phase rization/gas-phase polymerization. The slurry polymerization is preferably performed in a so called loop reactor.

The composition is preferably produced in two or three main polymerization stages in a combination of loop and gas-phase reactors. It is especially preferred that the composition is produced in three main polymerization stages, in which case the first two stages are lymer is performed produced as slurry polymerization and the third stage in is loop reactors n performed as a gas-phase polymerization in a gas-phase reactor wherein a copolymer is produced.

The main polymerization stages may be preceded by a pre-polymerization, which may serve to polymerize a small amount of r onto the catalyst at a low ature and/or a low monomer concentration. By prepolymerisation it is possible to improve the performance of the catalyst in slurry and/or modify the properties of the final polymer.

The polymerization in several sive polymerization reactors is preferably done with the aid of a catalyst as described in The catalyst is a MgCl2 supported catalyst prepared according to a method comprising the steps of a) providing solid carrier particles of MgCl2*mROH ; b) pre-treating the solid carrier particles of step a) with a compound of Group 13 metal; c) treating the pre-treated solid carried les of step b) with a transition metal compound of Group 4 to 6; d) recovering the solid catalyst component; n the solid r particles are contacted with an internal organic compound of formula (1) or isomers or mixtures therefrom before treating the solid carrier les in step c) and wherein in the formula (1), R1 to R5 are the same or different and can be hydrogen, a linear or branched C1 to C8-alkyl group, or a C3-C8-alkylene group, or two or more of R1 to R5 can form a ring, the two oxygen-containing rings are individually saturated or lly unsaturated or unsaturated, and R in the adductMgCl2*mROH is a linear or branched alkyl group with 1 to 12 C atoms, and m is 0 to 6.

Magnesium dihalide is normally used as a starting material for producing a carrier. The solid carrier used in this invention is a carrier where alcohol is coordinated with Mg dihalide, preferably MgCl2.The MgCl2 is mixed with an alcohol (ROH) and the solid r mROH is formed according to the well know methods. Spherical and granular MgCl2*mROH carrier materials are le to be used in the present invention. The alcohol is preferably l. In MgCl2*mROH, m is 0 to 6, more preferably 1 to 4, especially 2.7 to 3.3.

MgCl2*mROH is available from commercial sources or can be prepared by methods bed in the art. The solid carrier particles of the invention may t of MgCl2*mROH.

Group 13 metal compound, used in step b) is preferably an aluminum compound. red um compounds are dialkyl aluminum chlorides or trialkyl aluminum compounds, for example dimethyl aluminum chloride, diethyl aluminum chloride, di-isobutyl aluminum chloride, and triethylaluminum or mixtures there from. Most preferably the aluminum compound is a trialkyl aluminium compound, especially triethylaluminum compound.

The transition metal compound of Group 4 to 6 is preferably a Group 4 transition metal compound or a um compound and is more preferably a titanium compound. ularly preferably the titanium compound is a halogen- containing titanium compound. Suitable titanium compounds include trialkoxy titanium monochlorides, dialkoxy titanium dichloride, alkoxy titanium trichloride and titanium tetrachloride. Preferably, um tetrachloride is used.

In formula (I), examples of preferred linear or branched C1 to C8-alkyl groups are methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, tert-butyl, pentyl and hexyl groups. es for preferred C3-C8-alkylene groups are pentylene and butylene groups. The two R1 are preferably the same and are a linear C1 to C4-alkyl , more preferably methyl or ethyl. R2 to R5 are the same or different and are preferably H or a C1 to C2-alkyl groups, or two or more of R2 to R5 residues can form a ring. Most preferably R2 to R5 are all H.

Furthermore, both oxygen-containing rings are preferably saturated or partially unsaturated or unsaturated. More preferably both oxygen-containing rings are saturated. Examples of preferred internal organic compounds are 2,2-di(2-tetrahydrofuryl)propane, 2,2-di(2- furan)propane, and isomers or mixtures thereof. Most preferably, 2,2-di(2- ydrofuryl)propane (DTHFP) is used with the isomers thereof. DTHFP is typically a 1:1 mol/mol diastereomeric mixture of D,L-(rac)-DTHFP and meso-DTHFP.

The molar ratio of the internal organic compound of formula (I) / the adduct MgCl2*mROH added to the catalyst mixture is in the range of 0.02 to 0.20 mol/mol, preferably 0.05 to 0.15 mol/mol.

The Al nd can be added to the solid carrier before or after adding the internal organic compound or simultaneously with the internal organic compound to the r. Most preferably in any case, m is 2.7 to 3.3, ROH is ethanol, aluminum nd is an um trialkyl compound, such as triethylaluminum, internal donor is used 2,2-di(2-tetrahydrofuryl)propane, or and as 2,2-di-(2-furan)propane, especially 2,2-di(2-tetrahydrofuryl)propane or isomers or mixtures thereof.

The final solid catalyst component shall have Mg/Ti mol/mol ratio of 1 to 10, preferably 2 to 8, especially 3 to 7, Al/Ti mol/mol ratio 0.01 to 1, preferably 0.1 to 0.5 and Cl/Ti mol/mol ratio of to 20, preferably 10 to 17.

The resulting end product consists of an te mixture of the polymers from the reactors, the different molecular weight distribution curves of these rs er forming a molecular weight distribution curve having a broad m or two maxima, i.e. the end product is a bimodal polymer mixture.

According to the ion, it is preferred that the amount of olefin polymer having a high melt flow rate (low-molecular weight) makes up at least 30% by weight but no more than 65% by weight of the total polymer, preferably 35-62% by weight of the total polymer. Preferably, the amount of olefin polymer having a low melt flow rate molecular weight) makes up at least % by weight but no more than 70% by weight of the total polymer, preferably 38-65% by weight of the total polymer.

According to one embodiment, the composition may further comprise conductive filler in an amount up to 5 wt% or up to 3 wt% of the entire composition. The filler is conveniently carbon black. Preferably, the carbon black is added to the composition in a master-batch on a polymer carrier.

According to another embodiment, the ition essentially consists of the multimodal olefin copolymer. In that case, then the multimodal olefin copolymer represents at least 98 wt% of the entire composition.

Small amounts of antioxidants, and or acid scavengers, may be present in both the above mentioned embodiments, up to 2 wt%, ably, in total, from 0.01 to 1 wt% of the entire composition.

Suitable antioxidants may be N,N'-bis(3(3',5'-di-t-butyl4'-hydroxyphenyl)propionyl)hydrazine and 4,4'-thiobis(2-t-butylmethylphenol). red antioxidants are pentaerythrityltetrakis (3-(3',5'-di-t-butyl hydroxyphenyl)propionate and tris(2,4-di-t-butylphenyl)phosphate.

Suitable acid scavengers are the ones known to a person d in the art. A preferred acid scavenger is calcium stearate.

Preferably, the cable jacket composition of the invention has cable age of 0.70% or lower, preferably of 0.60 or lower. The shrinkage is usually of 0.40-0.70 % or preferably 0.40- 0.60 %.

The cable wear index is 17.0 or lower, usually of 14.5-17.0.

The composition preferably has cable extrusion pressure of 144 bar or lower, usually of 144- 100 bar.

The composition preferably has Eta 300 of 500 Pa.s or lower, usually of 500-250 Pa.s, ably of 480-300 Pa.s. ably, the cable jacket composition has ESCR of at least 2000 hours. The ESCR of the composition may have an upper limit of 20000 hours.

Preferably, the cable jacket composition of the invention comprises a multimodal olefin copolymer, which has a density of 0.935-0.960 g/cm3 and MFR2 of 1.5-10.0 g/10 min, wherein the MFR2 of the low molecular weight homo- or copolymer is of 25.0-200.0 g/10 min, and has cable wear index of 14.5-17.0. ably, the cable jacket composition has in addition cable shrinkage of 0.40-0.70%, preferably 0.40-25 0.60%. Even more preferably, it also has Eta 300 of 250-500 Pa.s and/or cable extrusion pressure of 100-144 bar.

Even more preferably, the cable jacket composition of the invention comprises a multimodal olefin mer, which has a density of 0.960 g/cm3 and MFR2 of 2.5-8.0 g/10 min, n the MFR2 of the low molecular weight homo- or copolymer is of 40.0-100.0 g/10 min, and has cable wear index of 14.5-17.0 and cable shrinkage of 0.40-0.70%, preferably 0.40- 0.60%. Preferably the composition also has Eta 300 of 250-500 Pa.s and/or cable extrusion pressure of 100-144 bar.

The use of multimodal olefin polymer es of the type described above results in inventive cable jacket compositions having superior properties than conventional cable jacket compositions, ally as regard to shrinkage, ESCR, processability and abrasion resistance. In particular, the reduced shrinkage of the inventive cable jacket composition in combination with the excellent ESCR, processability properties and abrasion resistance is a great advantage.

The cable jacket composition ing to the invention may be used for producing outer sheaths for cables, including power cables as well as communication cables. Amongst power cables, whose outer sheaths may advantageously be produced from the cable jacket composition according to the ion, mention may be made of high-voltage cables, mediumvoltage cables and low-voltage cables.

Amongst communication cables, whose outer sheaths may advantageously be made from the cable jacket ition according to the invention, mention may be made to twisted pair , coaxial cables and l cables, preferably fiber optic cables.

Test methods MFR The MFR of a polymer is determined in accordance with ISO 1133-1 at 190°C. The load under which the measurement is conducted is given as a subscript. Thus, the MFR under the load of 2.16 kg is denoted as MFR2. The melt flow rate MFR21 is correspondingly determined at 190°C under a load of 21.6 kg and MFR5 under a load of 5 kg. The melt flow rate, which is indicated in g/10 min, is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the ity of the polymer. lt should here be pointed out that in the production of two or more polymer ents in reactors connected in series, it is only in the case of the ent produced in the first reactor stage and in the case of the end product that the melt flow rate, the density and the other properties can be ed directly on the material removed. The corresponding ties of the polymer components ed in reactor stages following the first stage can only be indirectly determined on the basis of the corresponding values of the materials introduced into and discharged from the respective reactor stages.

The MFR2 of the low molecular component is the one measured on the component produced in the first loop reactor stage even when a pre-polymerization stage ispresent. In particular, with reference to the examples, A21 MFR2 is the MFR2 of A1+A21 polymer blend; A2 MFR2 is the MFR2 of A1+A21+A2 polymer blend.

The composition MFR2 is measured on the pellets obtained as described in the below "Compounding" paragraph.

Density of the polymer is ed according to ISO 1183-1:2004 Method A on compression moulded specimen prepared according to EN ISO 1872-2 (Feb 2007) and is given in kg/m3.

By the term ESCR (environmental stress cracking resistance) is meant the resistance of the polymer to crack formation under the action of mechanical stress and a t in the form of a surfactant. The ESCR is ined in accordance with IEC 60811-406, method B. The reagent employed is 10 weight-% Igepal CO 630 in water. The materials were prepared according to instructions for HOPE as follows: The materials were pressed at 165°C to a thickness of 1.75 - 2.00 mm. The notch was 0.30 - 0.40 mm deep.

Eta300 The characterization of r melts by dynamic shear measurements complies with ISO standards 6721-1 and 6721-10. The measurements are performed on an Anton Paar MCR501 stress controlled rotational rheometer, equipped with 25 mm parallel plate geometry.

Measurements are undertaken on compression molded plates, using en atmosphere and setting a strain within the linear viscoelastic regime. The oscillatory shear tests are done at a temperature of 190°C applying a frequency range between 0.01 and 628 rad/s and setting a gap of 1.3 mm.

In a dynamic shear experiment the probe is subjected to a neous ation at a idal varying shear strain or shear stress (strain and stress controlled mode, respectively). On a controlled strain experiment, the probe is subjected to a sinusoidal strain that can be expressed by γ(t) = Y0 sin(ωt) (1) lf the applied strain is within the linear viscoelastic regime, the resulting sinusoidal stress response can be given by σ(t) = σ0 sin(ωt + δ) (2) where σ0 and y0 are the stress and strain amplitudes, respectively, ω is the angular frequency, δ is the phase shift (loss angle between applied strain and stress response), t is the time.

Dynamic test s are typically expressed by means of several different rheological functions, namely the shear storage modulus G', the shear loss modulus, G", the complex shear modulus, G*, the complex shear viscosity, ƞ*, the dynamic shear viscosity, ƞ', the outof-phase component of the x shear viscosity ƞ" and the loss tangent, tan δ which can be sed as follows: The values of storage modulus (G'), loss s (G"), complex modulus (G*) and complex viscosity are obtained as a function of frequency (ω). Thereby, e.g. Eta0.05 is used as abbreviation for the complex viscosity at the frequency of 0.05 rad/s or Eta300 is used as abbreviation for the complex viscosity at the frequency of 300 rad/s.

Filler content The amount of carbon black is measured through combustion of the material in a tube furnace in nitrogen atmosphere. The sample is weighted before and after thecombustion. The combustion temperature is 550°C. The result is based on one measurement. The method is according to ASTM D1603.

Comonomer content Quantitative r-magnetic resonance (NMR) spectroscopy is used to quantify the comonomer content of the polymers.

Quantitative 13C{1H} NMR spectra are recorded in the -state using a Bruker Advance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for 1H and 13C respectively. All spectra are recorded using a ‘°C optimized 7 mm magic-angle spinning (MAS) probe-head at 150°C using en gas for all tics. Approximately 200 mg of al is packed into a 7 mm outer diameter ia MAS rotor and spun at 4 kHz. This setup is chosen primarily for the high sensitivity needed for rapid identification and accurate quantification (Klimke et al, Macromol. Chem. Phys. 2006; 207:382; Parkinson et al, Macromol. Chem. Phys. 2007; 208:2128; Castignolles et al, M., Polymer 50 (2009) 2373).

Standard single-pulse excitation is employed utilizing the transient NOE at short recycle delays of 3s (Pollard et al, Macromolecules 2004; 37:813; Klimke et al, Macromol. Chem. Phys. 2006; 2) and the RS-HEPT decoupling scheme (Filip et al, J. Mag. Resn. 2005, 176, 239; Griffin et al, Mag. Res. in Chem. 2007 45, S1, S198). A total of 1024 (1k) transients are acquired per spectrum. This setup is chosen due its high sensitivity towards low comonomer contents.

Quantitative 13C{1H} NMR spectra are processed, integrated and quantitative properties determined using custom al analysis automation programs. All chemical shifts are internally referenced to the bulk methylene signal (δ+) at 30.00 ppm (J. l, Macromol.

Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

Characteristic signals corresponding to the incorporation of 1-butene are ed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201) and all contents calculated with respect to all other monomers present in the polymer.

Characteristic signals resulting from ed 1-butene incorporation i.e. EEBEE comonomer sequences, are observed. ed 1-butene oration is quantified using the integral of the signal at 39.84 ppm assigned to the «B2 sites, accounting for the number of reporting sites per comonomer: B = I*B2 When characteristic signals resulting from utive 1-butene incorporation i.e. EBBE comonomer sequences are observed, such consecutive 1-butene incorporation is fied using the integral of the signal at 39.4 ppm assigned to the ααB2B2 sites ting for the number of reporting sites per comonomer: BB = 2*lααB2B2 When characteristic s resulting from non consecutive 1-butene incorporation i.e. EBEBE comonomer sequences are also observed, such non-consecutive 1-butene incorporation is quantified using the integral of the signal at 24.7 ppm assigned to the ββB2B2 sites accounting for the number of reporting sites per comonomer: BB = 2*lββB2B2 Due to the overlap of the *B2 and *βB2B2 sites of isolated (EEBEE) and non-consecutively incorporated ) 1-butene respectively the total amount of isolated 1-butene incorporation is corrected based on the amount of non-consecutive 1-butene t: B = I*B2 — 2B2 With no other signals indicative of other comonomer sequences, i.e. butene chain initiation, observed the total 1-butene comonomer content is calculated based solely on the amount of isolated (EEBEE), consecutive (EBBE) and non-consecutive (EBEBE) 1-butene comonomer Btotal = B+ BB + BEB Characteristic signals resulting from saturated end-groups are observed. The content of such saturated end-groups is quantified using the average of the integral of the signals at 22.84 and 32.23 ppm ed to the 2s and 3s sites respectively: S = (1/2)* (l2s + I3s) The relative content of ne is quantified using the integral of the bulk methylene (δ+) signals at 30.00 ppm: E = (1/2)*lδ+ The total ethylene comonomer content is calculated based the bulk methylene signals and accounting for ethylene units present in other observed comonomer sequences or end-groups: Etotal = E + (5/2)*B + (7/2)*BB + BEB + (3/2)*S The total mole fraction of 1-butene in the polymer is then ated as: fB = Btotal /(Etotal + Btotal) The total comonomer incorporation of 1-butene in mole percent is calculated from the mole fraction in the usual manner: B [mol%] = 100 * fB The total comonomer incorporation of 1-butene in weight percent is calculated from the mole on in the standard manner: B [wt%] = 100*(fB*56.11) / ((fB*56.11) + ((1-fB)*28.05)) Mw, Mn Molecular weight averages (Mw and Mn), Molecular weight distribution (MWD) and its broadness, described by polydispersity index, PDI= Mw/Mn (wherein Mn is the number average molecular weight and Mw is the weight average lar ) are determined by Gel Permeation Chromatography (GPC) according to ISO 16014-1:2003, ISO 2:2003, ISO 16014-4:2003 and ASTM D 2 using the following formulas: For a constant elution volume interval ΔVi, where Ai, and Mi are the chromatographic peak slice area and polyolefin molecular weight (MW), respectively associated with the elution volume, Vi, where N is equal to the number of data points obtained from the chromatogram between the integration .

A high temperature GPC instrument, equipped with either infrared (IR) detector (IR4 or IR5 from PolymerChar (Valencia, Spain) or differential refractometer (RI) from Agilent Technologies, equipped with 3 x Agilent-Plgel Olexis and 1x Agilent-Plgel Olexis Guard columns is used. As the solvent and mobile phase 1,2,4-trichlorobenzene (TCB) stabilized with 250 mg/L 2,6-Di tert butylmethyl- phenol) is used. The chromatographic system is operated at 160°C and at a constant flow rate of 1 ml/min. 200 µL of sample on is injected per analysis. Data collection is performed using either Agilent Cirrus software version 3.3 or PolymerChar GPC-IR control software.

The column set is calibrated using universal calibration ding to ISO 16014-2:2003) with 19 narrow MWD polystyrene (PS) standards in the range of 0,5 kg/mol to 11 500 kg/mol. The PS standards are dissolved at room temperature over several hours. The conversion of the polystyrene peak molecular weight to polyolefin molecular weights is accomplished by using the Mark Houwink equation and the following Mark Houwink constants: A third order polynomial fit is used to fit the calibration data.

All s are prepared in the concentration range of 0,5 -1 mg/ml and dissolved at 160°C for 2.5 hours for PP or 3 hours for PE under uous gentle shaking.

As it is known in the art, the weight average molecular weight of a blend can be calculated if the molecular weights of its ents are known according to: where Mwb is the weight average molecular weight of the blend, wi is the weight fraction of component "i" in the blend and Mwi is the weight average molecular weight of the component The number average molecular weight can be calculated using the mixing rule: where Mnb is the number average molecular weight of the blend, wi is the weight fraction of component "i" in the blend and Mni is the number average molecular weight of the component Flexural modulus The flexural test is carried out according to the method of ISO 178 by using ssion molded test ens produced according to EN ISO 1872-2. Flexural modulus is determined at a cross-head speed of 2 mm/min.

Tensile strength and Tensile strain e test is measured according to ISO 527. Crosshead speed for testing the tensile strength and elongations is 50 mm/min. Test specimen produced as described in EN ISO 1872- 2, specimen type: 5A to ISO 527-2 are used.

Shore D Shore D (1s) is determined according to ISO0868 on moulded specimen with a thickness of 4 mm. The shore hardness is ined after 1 sec after the pressure foot is in firm contact with the test specimen. The specimen is moulded according to EN ISO 1872-2.

Cable ion The cable extrusion is done on a Maillefer cable line. The extruder has five temperature zones with temperatures of 170/175/180/190/190°C and the extruder head has three zones with temperatures of 210/210/210°C. The er screw is a barrier screw of the design Elise.

The die is a semi-tube on type with 5.9 mm diameter and the outer diameter of the cable is 5 mm. The compound is extruded on a 3 mm in diameter, solid aluminum conductor to investigate the extrusion properties. Linespeed is 75 m/min. The pressure at the screen and the current consumption of the extruder is recorded for each material.

Cable Shrinkage The shrinkage of the composition is determined with the cable samples obtained from the cable ion. The cables are conditioned in the constant room at least 24 hours before the g of the samples. The conditions in the constant room are 23±2°C and 50±5% humidity. Samples are cut to 400 mm at least 2 m away from the cable ends. They are further conditioned in the constant room for 24 hours after which they are place in an oven on a talcum bed at 100°C for 24 hours. After removal of the sample from the oven they are allowed to cool down to room temperature and then measured. The shrinkage is calculated according to formula below: [(LBefore - LAfter) / LBefore] x 100 %, wherein L is length.

Wear Index The wear index is measured according to ASTM D 4060. The plaque thickness is 2 mm, abrasive wheel is CS-17 and the load is 1000 g. The result is reported after 5000 cycles.

Examples Comparative example 1 (CE1) is the commercial products Borstar@HE6067. It is ed using the catalyst (I) (Lynx 200), which is a commercially available Ziegler-Natta catalyst manufactured and supplied by BASF.

Comparative example 2 (CE2) is prepared according to the same s steps described in connection to comparative examples 3 to 6 (CE3-CE6) and inventive examples (IE1 and IE2) with the only exception that catalyst (Il) is used instead of st (Il).

Catalyst (Il) The catalyst, referred as catalyst (Il), is described in according to the ing steps: ation of pre-treated support material A jacketed 160 dm3 stainless steel reactor equipped with a helical mixing element is pressurized with N2 to 2.0 barg and depressurized down to 0.2 barg until the Oz level is less than 3 ppm. The vessel is then charged with e (20.5 kg) and 2,2- di(tetrahydrofuryl)propane (0.512 kg; 2.81 mol; . The obtained mixture is stirred for min at 40 rpm. The MgCl2*3EtOH carrier (6.5 kg; DITHFP/Mg = 0.1 mol/mol; 27.5 mol of Mg; Mg 10.18 wt%, d10 = 9.5 um, d50 = 17.3 um and d90 = 28.5 um, granular shaped) is added to the reactor with stirring. This suspension is cooled to approximately -20°C and the 33 wt% solution of triethylaluminum (29.4 kg, 84.3 mol of Al; Al/EtOH = 1.0 mol/mol) in heptane is added in aliquots during 2.5 h time while keeping the temperature below 10°C. After the TEA addition, the on mixture is gradually heated to 80°C over a period of 2.4 h and kept at this temperature for additional 20 min at 40 rpm. The suspension is allowed to settle for 10 min, and the mother liquor is removed h a 10 µm filter net in the bottom of the reactor during 15 min. The vessel is charged with warm toluene (43 kg) and then stirred at 40 rpm for 38 min at 55-70°C. The sion is allowed to settle for 10 min at 50-55°C and the liquid d through a 10 µm filter net in the bottom of the reactor during 15 min.

Catalyst preparation The vessel containing the pre-treated support material is charged with toluene (43 kg) and then cooled to approximately 30°C. Neat TiCl4 (5.17 kg, 27.5 mol; Ti/Mg = 1.0 mol/mol) is added. The obtained suspension is heated to approximately 90 °C over a period of 2 h and kept at this temperature for additional 1 h with stirring at 40 rpm. The suspension is allowed to settle for 10 min at approximately 90°C and the mother liquor is removed through a 10 µm filter net in the bottom of the reactor during 15 min. The obtained solid material is washed twice with toluene (43 kg each) at ≈ 90°C and once with heptane (34 kg) at ~40°C. All three of these washing steps use the same ce of events: addition of preheated (90 or 40°C) solvent, then stirring at 40 rpm for 30 min, allowing the solid to settle for 10 min, and then removal of liquid through a 10 um filter net in the bottom of the reactor during 15 min.

The ed catalyst is mixed with 20 kg of white oil and dried 4 h at 40-50°C with en flow (2 kg/h) and vacuum (-1 barg). The catalyst is taken out from the reactor and reactor is flushed with another 20 kg of oil and taken out to the same drum. The dry catalyst yield is 3.60 kg (82.2 % based on Mg).

Polymerization In a polymerization plant consisting of a lymerization reactor, two loop reactors connected in series to a gas-phase r and involving using one of the catalyst as specified above, bimodal ethylene copolymers for ative examples CE2-CE4, and inventive example IE1 are obtained as follows: Pre-polymerization (A1) The main purpose of the pre-polymerization reactor is to ensure good logy of the final product. In the pre-polymerization reactor the catalyst is coated with a polymer which prevents the catalyst particle from breaking into smaller pieces when it enters the loop reactor. This minimizes the fines in the final product and ensures good morphology. It can also be used to moderate catalyst activity and optimize product properties.

First Loop Reactor (A21) In this reactor, a part of the ethylene lymer is produced by the polymerization of ethylene in the presence of hydrogen. Molar ratio of hydrogen to ethylene catalyst type and further process conditions are provided in Table 1. In the first loop reactor no copolymer is fed to the reactor. The minor copolymer amount which is indicated in the tables remains from the pre-polymerization.

Resulting ne homopolymers MFR2 values (A21 MFR2) are also provided in Table 1.

Second loop Reactor (A2) In this reactor, more ethylene homopolymer is produced by the polymerization of ethylene in the presence of hydrogen. Process conditions are ed in Table 1. In the second loop reactor no copolymer is fed to the reaction. The minor copolymer amount which is indicated in the tables remains from the pre- polymerization.

Resulting ethylene homopolymer MFRe2 values (A2 MFRz2) are also provided in Table 1.

Gas-Phase Reactor (A3) In this reactor, ethylene copolymers are produced by the polymerization of ne and 1- butene which is actively added to the reactor. Process ions are provided in the Table 1 as well as the weight ratio between the homopolymer and the copolymer. The resulting copolymer of ne and 1- butene is present in the form of an intimate e with the ethylene homopolymer from the loop reactors. Resulting ethylene copolymer density, MFR2, MFR5 values (A3 mixer y, MFR2 and MFR5) are provided in Table 1.

Compounding The r mixture is then compounded with carbon black, two antioxidants and one acid scavenger.

Carbon black is provided in the form of a master-batch, CB MB, which is a composition consisting of 60.39% of HDPE, 0.11% of pentaerythrityl-tetrakis(3- (3',5'-di-t-butyl hydroxyphenyl)propionate (antioxidant) and 39.5% carbon black.

Antioxidant 1 is pentaerythrityl-tetrakis(3-(3',5'-di-t-butylhydroxyphenyl)-propionate.

Antioxidant 2 is tris (2,4-di-t-butylphenyl)phosphate.

The acid scavenger is calcium stearate.

The amount of each component, which is ed in Table 1, is sed in wt% of the entire composition.

The polymer particles are mixed with additives and extruded to pellets as it is known in the art.

Preferably a counter-rotating twin screw er is used for the extrusion step. Such extruders are manufactured, for instance, by Kobe and Japan Steel Works. A suitable example of such extruders is disclosed in EP-A-1600276. Typically the specific energy input (SEl) is during the extrusion within the range of from 100 to 200 kWh/ton.

Results Table 2 shows many properties featured by the comparative and inventive compositions or by the corresponding cables. From comparing the tables, it is apparent that the cable jacket composition of the invention exhibit improved properties as regards age, and abrasion resistance in combination with other excellent mechanical properties. Also, the processability of the cable jacket itions of the invention, which can be deduced from the values of MFR2, MFR5, Eta300, cable extrusion pressure and current values, is improved.

In ular, the compositions of the present inventions have better processability and reduced shrinkage than the marketed product r®HE6067 (CE1). ical properties are maintained at able levels.

Since shrinkage and cable extrusion pressure for IE2 were measured at a different occasion, the sample CE3 and IE1 were rerun at that occasion as well. The values for these rerun values for CE3 and IE1 are given in parentheses in Table 2.

While increasing MFR2 of the compositions with respect to CE1 and CE2, and at the same time compensating for the loss in ESCR by using catalyst Il, has provided compositions (CE4- CE6) with improved shrinkage featuring high ESCR, the abrasion resistance may further be ed when the composition MFR2 satisfies the following correlation: Wear indexs ≤ 15.500+0.900*composition MFR2 Then, an advantageous combination of properties is demonstrated for the compositions of the invention. 24 24 Table 2 % 3038 NMR Cd i Tonsil. swan at brook Tons" SVOSS am § 3i =* "mum" escn "mum-— "WM "manna-l- —mm 979-28 m-1°°°°6 ms m Cableenmsionpmssummscmen bar 172 173050) mommmmmummmp m- —m--—l:n"m

Claims (15)

1. A cable jacket composition comprising a multimodal olefin copolymer, wherein said multimodal olefin copolymer has a density of 0.935-0.960 g/cm3 measured according to ISO 1183-1:2004 Method A on ssion moulded specimen ed according to EN ISO 1872-2 (Feb 2007) and MFRz2 of .0 g/10 min measured in accordance with ISO 1133-1 at 190°C and comprises a bimodal r mixture of a low molecular weight homo- or copolymer and a high molecular weight copolymer wherein the composition has ESCR of at least 2000 hours measured in accordance with IEC 60811- 406, method B and wherein the numerical values of cable wear index measured according to ASTM D 4060 and composition MFRe (g/10 min) follow the correlation: Wear index ≤ +0.900*composition MFR2

2. The composition of claim 1, wherein the copolymer has MFR2 of 1.6-8.0 g/10 min, preferably 2.5-8.0 g/10 min.

3. The composition of claim 1 or 2, wherein the MFR2 of the low molecular weight homoor copolymer is of 25.0-200.0 g/10 min, preferably 40.0-150.0 g/10 min, more preferably 40.0-100.0 g/10 min.

4. The composition according to any one of the ing claims, wherein the composition has cable shrinkage of 0.70% or lower measured ing to the method disclosed in chapter “Test methods”.

5. The composition ing to any one of the preceding claims, wherein the multimodal olefin copolymer has Mw of 55000-105000 g/mol.

6. The composition according to any one of the preceding claims, n the composition has a cable extrusion pressure of 144 bar or lower.

7. The composition according to any one of the preceding claims, wherein the composition has Eta 300 of 500 Pa.s or lower measured according to ISO standards 6721-1 and 6721-10.

8. A composition according to any one of the preceding claims, wherein the multimodal olefin mer is a bimodal polymer mixture of a low molecular weight ethylene homo- or copolymer and a high molecular weight copolymer of ethylene and a comonomer selected from the list consisting of 1-butene, 4-methylpentene, 1- hexene or 1-octene.

9. The composition according to claim 5, wherein the multimodal olefin copolymer e is a bimodal polymer mixture of a low molecular weight ethylenehomopolymer and a high molecular weight copolymer of ethylene and 1-butene.

10. The composition according to any one of the preceding claims, further comprising conductive filler in an amount of 0.05 to 5 wt%, preferably 0.05 to 3 wt% of the entire composition.

11. The composition according to any one of claims 1-9 essentially consisting of the multimodal olefin copolymer.

12. A cable comprising the ition of any one of the preceding claims, said cable having shrinkage of 0.70% or lower and/or a wear index of 17.0 or lower.

13. A cable according to claim 12, which is a fiber-optic cable.

14. A process for preparing the composition of any one of claims 1-9, n the polymerization of the multimodal olefin copolymer comprises two main polymerization stages in the presence of a MgCl2 supported catalyst prepared according to a method comprising the steps of: a) providing solid r particles of MgCl2*mROH ; b) pre-treating the solid carrier particles of step a) with a compound of Group 13 metal; c) treating the pre- treated solid carried particles of step b) with a transition metal nd of Group 4 to 6; d) recovering the solid catalyst component; wherein the solid carrier particles are contacted with an internal c compound of formula (I) or isomers or mixtures rom before treating the solid carrier particles in step c) and wherein in the formula (Il), R1 to R5 are the same or different and can be hydrogen, a linear or branched C1 to C8-alkyl group, or a C3-C8-alkylene group, or two or more of R1 to R5 can form a ring, the two oxygen- ning rings are individually saturated or partially unsaturated or unsaturated, and R in the adduct MgCl2*mROH is a inear or branched alkyl group with 1 to 12 C atoms, and mis 0 to 6.

15. The use in the preparation of the composition of any one of claims 1-9 of a MgCl2 supported catalyst prepared according to a method comprising the steps of: a) providing solid carrier les of MgCl2*mROH adduct; b) pre-treating the solid carrier particles of step a) with a nd of Group 13 metal; c) treating the pre- treated solid carried particles of step b) with a transition metal compound of Group 4 to 6; d) recovering the solid catalyst component; wherein the solid carrier particles are contacted with an internal organic compound of formula (I) or s or mixtures therefrom before treating the solid carrier particles in step c) and wherein in the formula (1), R1 to R5 are the same or different and can be en, a linear or branched C1 to C8-alkyl group, or a C3-C8-alkylene group, or two or more of R1 to R5 can form a ring, the two oxygen- containing rings are individually ted or lly unsaturated or unsaturated, and R in the adduct MgCl2*mROH is a inear or branched alkyl group with 1 to 12 C atoms, and m is 0 to 6.