Polyethylene compositions with high tracking resistance for wire and cable applications

Abstract

This invention relates to a crosslinkable polymer composition comprising (A) a high-density ethylene homopolymer or copolymer having a density of at least 930 kg / m³ as determined according to ISO 1183. 3 The invention relates to (A) a high-density ethylene homopolymer or copolymer, and (B) a copolymer of ethylene and a silane-containing comonomer, said copolymer having a content of no more than 4.0 wt% silane-containing comonomer, wherein the polymer composition passes an electrical tracking resistance test on a compression-molded plate prepared according to ISO 11357 at 4.5 kV for 1 h and 4.75 kV for 1 h according to IEC 60587 (2007) Method 2A. The invention also relates to an electrical tracking resistant wire or cable, preferably a power cable or optical cable comprising at least one layer of the above polymer composition, or to the use of the polymer composition in wires or cables for increasing electrical tracking resistance, and / or for increasing flame retardancy along the length of the wire or cable. The invention also relates to a method of manufacturing the above polymer composition, comprising the step of compounding or dry-blending the high-density ethylene homopolymer or copolymer (A) and the copolymer of ethylene and a silane-containing comonomer (B).

Description

Technical Field

[0001] This invention relates to a polymer composition for improving tracking resistance, the polymer composition comprising an ethylene and hexene copolymer for use in wires and cables to increase tracking resistance, to tracking-resistant wires and cables comprising a layer of the polymer composition, and to a method for producing such polymer composition. Background Technology

[0002] Improvable tracking resistance materials are particularly needed in overhead (OH) power lines, which are susceptible to damage from fires, voltage drops causing power outages, and mechanical damage such as falling trees or contact with flying objects. On the other hand, overhead AC power lines offer several advantages over ground-laid AC cables due to the limitations imposed by cable capacitance on their length. The higher the voltage, the shorter the AC cable length. When the system voltage exceeds 12kV, the net length of AC cables is limited to 5km-10km. Therefore, long-distance power grids still primarily rely on overhead lines.

[0003] The spacing between phases covering the conductor can be very narrow, thus better able to withstand trees falling onto the line. Such power lines can be built closer to trees without sacrificing forested areas. Another problem in dusty areas is that tracking can degrade or damage the wiring outside the insulation, potentially causing it to break and fall to the ground.

[0004] The voltage drop in a line depends on the resistance of the conductors and the inductance between the lines. For overhead lines in rural areas, inductive voltage drop is likely to be the primary factor in the line.

[0005] The narrow spacing between conductors also reduces the inductance of overhead lines, thus reducing the inductive voltage drop by about 50% compared to bare wires. Longer cable lines with lower system voltages can be constructed, which provides easier network design and lower costs.

[0006] Covering conductors in cable lines is common and has been used for over 30 years. It has been found that over long-term use, sparks can develop on the cable surface, especially in areas where conductive dust and / or trees / branches come into contact with the cable. These surface sparks (also known as tracking) damage the cable insulation, causing the conductor to burn and ultimately leading to cable failure. Therefore, higher tracking resistance is a pressing requirement for network and power plant facilities.

[0007] Today, power grids need to improve tracking resistance on OH lines to greater than 3kV, even up to 5.75kV and above. Further expectations include increased flame retardancy so that fire cannot spread along the lines.

[0008] To improve the reliability of power distribution and transmission, non-metallic sheathed plastic-coated overhead conductors (PAS and BLL / BLX conductors) have been developed. These coated conductor systems also offer considerable space savings, requiring approximately 40% less space compared to standard bare wire. Considering their advantages over traditional bare wire structures, the construction cost of coated conductor (CC) lines is moderate.

[0009] The polymer compositions known to achieve tracking resistance of 4.5 kV mostly contain carbon black. However, these black components, when heated by sunlight, may exacerbate the aforementioned tracking problems and could even cause fires due to their low heat resistance.

[0010] Optical cables contain optical fibers for signal transmission for any form of communication, data exchange, or control purpose. For example, this type of optical cable is described in GB A2 2 193 583. In addition to the optical fibers, the optical cable also includes an outer sheath that protects these fibers. The outer sheath is typically based on a polymer material such as polyolefins, particularly copolymers of polyethylene or ethylene, where the ethylene monomer constitutes the majority of the total polymer mass. The cable sheath must meet requirements for ease of manufacture and good mechanical properties (such as tensile strength and elongation at break), especially at temperatures rising to or exceeding 100°C. Furthermore, the outer sheath should have low thermal deformation and good resistance to tracking.

[0011] In particular, good tracking resistance of the sheath is significant because, for practical reasons, optical cables must often be installed alongside power cables. These power cables, due to their high voltage (especially exceeding 130kV), generate strong electric fields, inducing voltage in the sheath area adjacent to the optical cable. This leads to creeping currents through tracking and further localized breakdown of the sheath, especially under humid conditions, a phenomenon known as dry band arcing. Tracking is defined as the process of creating a track under the influence of an electric arc. The arc accumulates sufficient electrical energy to create a track and for the track to grow. Failure occurs when the track extends far enough to cross the remaining distance between two electrodes or grounding connections, thus becoming a localized degradation path on the insulation surface. Tracking resistance was determined according to a slope tracking test. Details of the test procedures for applying this method are given in the Examples section.

[0012] EP 1267189A1 discloses an anti-tracking optical cable comprising at least one optical fiber and an outer sheath comprising a polymer material, preferably a bimodal ethylene-butene copolymer, characterized in that the polymer material forms a matrix for the sheath and is composed of a multimodal olefin polymer obtained by coordination catalytic polymerization, wherein the total composition of the sheath comprises 15%-40% by weight of magnesium hydroxide and / or aluminum hydroxide and 0.01%-0.9% by weight of carbon black.

[0013] WO 93 / 05424A1 discloses an electrical tracking resistant optical cable comprising at least one optical fiber and an outer sheath of polymer material, characterized in that the polymer material forms a matrix composed of linear polyethylene blended with 0 to a maximum of 20% (based on the weight of linear polyethylene) of branched LDPE, wherein the total composition of the sheath material contains 15%-30% (based on the weight of linear polyethylene) of magnesium hydroxide or aluminum hydroxide.

[0014] JP-2004-01086A discloses a tracking-resistant, water-crosslinkable polymer composition comprising 8 pbw to 50 pbw of magnesium hydroxide (B) and 0.2 pbw to 1.1 pbw of carbon black (C) added to 100 pbw of a vinyl polymer (A), said vinyl polymer (A) being primarily composed of an ethylene-α-olefin copolymer. The polymer composition further comprises 0.1 pbw to 10 pbw of an unsaturated alkoxysilane (D), 0.01 pbw to 1 pbw of an organic peroxide (E), and 0.001 pbw to 1 pbw of a silanol condensation catalyst (F).

[0015] Each of the aforementioned polymer compositions and cables suffers from low heat resistance, electrical safety issues, short circuits and damage, as well as mechanical problems such as insufficient tensile strength and elongation at break. Furthermore, there is a strong market demand for materials with improved tracking resistance.

[0016] The objective of this invention is to design a tracking-resistant polymer composition for wire and cable applications and its use in wire or cable layers, the polymer composition having improved tracking resistance, combined with good mechanical properties, UV resistance, heat resistance and / or flame retardancy. Summary of the Invention

[0017] This invention discovers that crosslinkable polymer compositions can achieve the above objectives, said compositions comprising:

[0018] (A) A high-density ethylene homopolymer or copolymer, said homopolymer or copolymer having a density of at least 930 kg / m³ as determined according to ISO 1183. 3 density, and

[0019] (B) A copolymer of ethylene and a silane-containing comonomer, wherein the copolymer contains a silane-containing comonomer content of not more than 4.0 wt%.

[0020] The polymer composition was tested for resistance to electrical tracking according to IEC 60587 (2007), Method 2A, at 4.5 kV for 1 h and 4.75 kV for 1 h on a compression-molded plate prepared according to ISO 11357, as described in the Examples section.

[0021] Preferably, the polymer composition passed the tracking resistance test, measured on a compression-molded plate prepared according to ISO 11357, according to IEC 60587 (2007) method 2A at 5.0 kV for 1 h and 5.25 kV for 1 h, and even at 5.75 kV for 1 h and 6 kV for 1 h, as described herein.

[0022] The objective can also be achieved by tracking-resistant wires or cables (preferably power cables or optical cables containing at least one layer of the polymer composition described above), or by using the polymer composition in the wires or cables to increase tracking resistance, and / or by increasing flame retardancy along the length of the wires or cables.

[0023] The present invention also relates to a method for manufacturing the above-described polymer composition, the method comprising the step of compounding or dry-blending the high-density ethylene homopolymer or copolymer (A) and a copolymer (B) of ethylene and a silane-containing comonomer. Invention Details

[0025] The crosslinkable polymer composition of the present invention comprises a high-density ethylene homopolymer or copolymer having a density of at least 930 kg / m³ as determined according to ISO 1183. 3 The density is preferably 930 kg / m³. 3 Up to 960kg / m 3 Within this range, or even more preferably 945 kg / m 3 Up to 955kg / m 3 .

[0026] Preferably, the polymer composition of the present invention comprises a multimodal copolymer of ethylene and hexene, having a content of 930 kg / m³. 3 Up to 970kg / m 3 The density and the melt flow rate MFR2, determined according to ISO 1133 at 190°C with a load of 2.16 kg, not exceeding 0.4 g / 10 min, more preferably not exceeding 0.2 g / 10 min, and even more preferably not exceeding 0.1 g / 10 min.

[0027] The high-density ethylene homopolymer or copolymer is preferably a copolymer of ethylene and hexene, more preferably a multimodal polyethylene containing at least two polymer components, each with a different weight-average molecular weight. The term "polymer morphology" refers to the form of the polymer's molecular weight distribution (MWD) curve, i.e., the appearance of a graph showing the polymer mass fraction as a function of its molecular weight. If the polymer is produced in a continuous process, for example by utilizing reactors coupled in series and using different conditions in each reactor, the different polymer components produced in different reactors will each have their own molecular weight distribution, which may differ significantly from each other. The resulting final polymer's molecular weight distribution curve can be viewed as a superposition of the molecular weight distribution curves of the polymer components, with the polymer curve correspondingly showing two or more distinct maxima, or at least significantly broadened, compared to the curve of a single component. Polymers exhibiting such a molecular weight distribution curve are called "multimodal." Multimodal polymers can be produced according to different processes as described in WO 92 / 12182. The production of multimodal (particularly bimodal or trimodal) olefin polymers (preferably ethylene polymers) in two or more reactors connected in series is well known. Examples thereof are described in EP 040992, EP 041796, EP 022376, EP 0887379 and WO 92 / 12182. According to the disclosures in these documents, each of the polymerization stages can be carried out in the liquid phase, slurry phase or gas phase.

[0028] Multimodal copolymers of ethylene and hexene are preferably bimodal copolymers. Such bimodal polymers comprise two polymeric components present in the polymer, each with a different weight-average molecular weight. These components are sometimes referred to below as component (A) and component (B), respectively.

[0029] In this respect, ethylene copolymers refer to polymers containing at least 50 wt% ethylene monomer units.

[0030] Component (A) can be an ethylene homopolymer or an ethylene copolymer with the lowest content of comonomers in the component. Preferably, component (A) is an ethylene homopolymer.

[0031] Therefore, ethylene homopolymers refer to polymers that are essentially composed of ethylene monomer units. Due to the requirements of large-scale polymerization, ethylene homopolymers may include a small amount of comonomer units, typically less than 0.1 mol% of ethylene homopolymer, preferably less than 0.05 mol% of ethylene homopolymer, and most preferably less than 0.01 mol% of ethylene homopolymer.

[0032] In a preferred embodiment of the invention, hereinafter sometimes referred to as Embodiment A, the copolymer of ethylene and hexene may be a bimodal copolymer consisting of polymer component (A) and component (B), optionally further comprising a prepolymer component in an amount of up to 10 wt.% of the total polymer, more preferably up to 7 wt.% of the total polymer, and most preferably up to 5 wt.% of the total polymer. Those skilled in the art will understand that the measurement of polymer properties requires the presence of a stabilizer.

[0033] In embodiment A, component (A) of the copolymer can be an ethylene homopolymer or copolymer. Component (A) preferably has a content of 960 kg / m³. 3 Up to 980kg / m 3 The density.

[0034] Furthermore, preferably, component (A) of the copolymer has an MFR2 of 150 g / 10 min to 600 g / 10 min as measured according to ISO 1133, more preferably 175 g / 10 min to 550 g / 10 min, and most preferably 200 g / 10 min to 550 g / 10 min.

[0035] Component (A) and / or component (B) may consist of a single polymer component prepared in one reactor, or may consist of two or more components prepared in different reactors.

[0036] Preferably, component (A) and / or component (B) consist of two partial components or a single component.

[0037] Most preferably, component (A) consists of a single component or two partial components, preferably produced in one or two loop reactors, and component (B) consists of a single component, preferably produced in a gas phase reactor.

[0038] If one or more components of the matrix resin consist of fractional components produced in different reactors, preferably, the selected reaction conditions result in substantially identical polymers. This means that if (for example and preferably) the matrix resin consists of component (A) and component (B), and component (A) is produced as two fractional components in two different loop reactors, under these conditions, the polymers produced are substantially the same or identical, the polymer will still be a bimodal resin because it consists of two components of different polymers.

[0039] Furthermore, in the polyethylene composition, the copolymer of ethylene and hexene preferably has a weight-average molecular weight Mw of 150,000 g / mol to 350,000 g / mol, more preferably 200,000 g / mol to 320,000 g / mol.

[0040] The copolymer of ethylene and hexene preferably has a molecular weight distribution of 20 to 35 Mw / Mn, more preferably 22 to 31.

[0041] Preferably, the copolymer of ethylene and hexene accounts for at least 10 wt.% of the polyethylene composition, more preferably at least 20 wt.% of the polyethylene composition, and even more preferably at least 40 wt.% of the polyethylene composition.

[0042] The polymer composition of the present invention further comprises a copolymer (B) of ethylene and a silane-containing comonomer, said copolymer (B) having a silane-containing comonomer content of not more than 5.0 wt%. Preferably, the copolymer (B) of ethylene and a silane-containing comonomer comprises an ethylene copolymer containing a hydrolyzable silane group and / or a monomer unit containing a (meth)acrylate group, or consists of an ethylene copolymer containing a hydrolyzable silane group and / or a monomer unit containing a (meth)acrylate group.

[0043] The copolymer (B) preferably has a content of no more than 5 wt.% of silane-containing comonomers, more preferably 3 wt.%, and even more preferably 2 wt.%. The content of the silane-containing copolymer is preferably at least 20 wt.%, more preferably at least 40 wt.%. The preferred range is 30 wt.% to 70 wt.%, more preferably 40 wt.% to 60 wt.%, all values ​​are based on the total weight of the copolymer (B) divided by the total weight of all polymer components.

[0044] The copolymer (B) of ethylene and silane-containing comonomer preferably has an MFR2 of no more than 10 g / 10 min, more preferably no more than 4 g / 10 min, and even more preferably no more than 1.5 g / 10 min.

[0045] The copolymer (B) of ethylene and silane-containing comonomer preferably has a content of at least 860 kg / m³. 3 The density is preferably at least 900 kg / m³. 3 Ideally, it should be at least 920 kg / m³. 3 .

[0046] The comonomer containing silane groups is preferably an unsaturated silane compound, represented by the following formula:

[0047] R 1 SiR 2 q Y 3-q (I)

[0048] in

[0049] R 1It is an olefinic unsaturated hydrocarbon group (hydrocarbyl), hydrocarbon oxygen group (hydrocarbyloxy), or (meth)acryloxy hydrocarbon group ((meth)acryloxy hydrocarbyl).

[0050] Each R 2 Each is an independent aliphatic saturated hydrocarbon group.

[0051] Y can be the same or different, and is a hydrolyzable organic group.

[0052] q can be 0, 1, or 2.

[0053] Specific examples of the unsaturated silane compounds are those in which R 1 Y is vinyl, allyl, isopropenyl, butenyl, cyclohexyl, or gamma-(meth)acryloxypropyl; Y is methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, or alkyl or arylamino; and R is... 2 (If present) is methyl, ethyl, propyl, decyl, or phenyl.

[0054] Other suitable silane compounds are, for example, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, and vinyltriacetoxysilane, or combinations of two or more thereof.

[0055] Preferred unsaturated silane compounds are represented by the following formula:

[0056] CH2=CHSi(OA)3(II)

[0057] Each A is an independent hydrocarbon group having 1-8 carbon atoms, preferably 1-4 carbon atoms.

[0058] Preferred compounds are vinyltrimethoxysilane, vinyldimethoxyethoxysilane, or vinyltriethoxysilane.

[0059] Crosslinking polyolefins via additives is known because it can improve the properties of polyolefins (e.g., mechanical strength and chemical heat resistance). Crosslinking can be achieved by the condensation of silanol groups contained in the composition, which can be obtained by the hydrolysis of silane groups. Silane-containing compounds can be introduced as crosslinkable groups, for example by grafting silane compounds onto polyolefins, i.e., by chemically modifying the polymer primarily through the addition of silane groups in a free radical reaction, or by copolymerizing olefin monomers with monomers containing silane groups. Such techniques are included herein and are known, for example from US 4413066, US 4297310, US 4351876, US 4397981, US 4446283, US 4456704, EP1824926A1, and EP 2508558A1. If grafted polymers are used, they can be produced by any of the techniques described in US 3646155 and US4117195, respectively.

[0060] The crosslinkable polymer composition according to the present invention may further comprise polyolefins, preferably linear low-density ethylene polymers or copolymers grafted or copolymerized with unsaturated carboxylic acids or their derivatives, and / or elastomeric ethylene copolymers.

[0061] The unsaturated carboxylic acid may be selected from maleic acid or its anhydride. Based on the total weight of the copolymer, the content of the unsaturated carboxylic acid (preferably maleic acid or its anhydride) may range from 0.1 wt.% to 10 wt.%.

[0062] The elastomeric ethylene copolymer can be, for example, a very low-density copolymer, preferably a copolymer of ethylene and 1-octene. It preferably has a density not exceeding 910 kg / m³. 3 The density, or even better, is 860 kg / m³. 3 Up to 890kg / m 3 The range of MFR2 is 0.1 g / 10 min to 50 g / 10 min.

[0063] In addition to the polymer components, the polyethylene composition may contain commonly used additives for polyolefins, such as pigments (e.g., carbon black), stabilizers (e.g., antioxidants) and / or UV absorbers, antistatic agents, and utilization agents (e.g., processing aids). Preferably, the amount of these additives is 10 wt% or less of the composition, more preferably 8 wt% or less, and most preferably 5 wt% or less.

[0064] Preferably, based on the weight of the total composition, the composition contains less than 4 wt% carbon black, more preferably not more than 1 wt%, and even more preferably from 0.1 wt% to 0.8 wt%.

[0065] Furthermore, preferably, in the polyethylene composition containing carbon black, the copolymer of ethylene and hexene may have a content of 0.9 mol% to 1.45 mol% of units derived from hexene-1, more preferably 0.95 mol% to 1.30 mol%, even more preferably 1.0 mol% to 1.25 mol%, even more preferably 1.03 mol% to 1.24 mol%, and particularly preferably 1.04 mol% to 1.23 mol%.

[0066] Furthermore, it is preferred that in the polyethylene composition containing carbon black, the copolymer of ethylene and hexene may have a number average molecular weight of 9000 g / mol or higher, preferably 9300 g / mol or higher.

[0067] Preferably, in the polyethylene composition containing carbon black, the copolymer of ethylene and hexene has a total content of 0.50 mol% to 0.70 mol% of units derived from hexene-1, preferably 0.52 mol% to 0.69 mol%, more preferably 0.54 mol% to 0.67 mol%.

[0068] In a further embodiment of the invention, the polyethylene composition does not contain carbon black.

[0069] The crosslinkable polymer compositions of the present invention may further comprise fillers, preferably metal carbonates and / or metal hydroxides. A more preferred filler may be milled or precipitated magnesium hydroxide. Another preferred filler is calcium carbonate, which may be coated with stearic acid and has an average particle size of 0.5 μm to 10 μm. Based on the total weight of the composition, the filler is preferably contained in an amount of 10 wt.% to 65 wt.%, more preferably 20 wt.% to 40 wt.%, and even more preferably at least 25 wt.%. The above upper and lower limits can be combined with each other in each combination.

[0070] The crosslinkable polymer composition according to the invention may preferably further comprise a UV stabilizer and / or an antioxidant and / or a pigment.

[0071] The UV stabilizer may be a hindered amine light stabilizer (HALS), selected from... 944、 622、 770 and mixtures thereof. In addition, any UV stabilizer may be used, preferably the HALS compounds listed in EP 3622541A1. Two or more UV stabilizers may be combined. Any of the above-mentioned UV stabilizers may also be combined with one or more UV absorbers (such as benzotriazole, benzophenone, triazine, or phenolic compounds). Any UV absorber listed in EP 1919837.4 may be used.

[0072] Based on the total weight of the composition, the UV stabilizer may be present in an amount of 0.1 wt.% to 2 wt.%, more preferably 0.2 wt.% to 1.5 wt.%, and even more preferably 0.3 wt.% to 1 wt.%.

[0073] Antioxidants can be selected from, for example, sterically hindered phenols (e.g., Irganox 1010 (CAS No. 128-37-0), Irganox 1076 (CAS No. 2082-79-3), Irganox 1035 (CAS No. 41484-359)), sulfur-containing antioxidants (e.g., Irganox PS 802 (CAS No. 693-36-7), Irganox PS 800 (CAS No. 2500-88-1)), phosphites / phosphonates (e.g., Irgafos 168 (CAS No. 31570-04-4), Irgafos P-EPQ (CAS No. 38613-77-3)), and nitrogen-containing antioxidants (e.g., Naugard 445 (CAS No. 10081-67-1), Vulcanox HS / LG (CAS No. 26780-96-1)). Two or more can be used in combination.

[0074] Based on the total weight of the composition, the amount of the antioxidant may be 0.1 wt.% to 2 wt.%, more preferably 0.2 wt.% to 1 wt.%, and even more preferably 0.3 wt.% to 0.5 wt.%.

[0075] The pigment can be selected from, for example, blue, green, or orange pigments. A particularly preferred pigment is titanium dioxide. Preferably, the total amount of pigment other than carbon black present in the polyethylene composition can be up to 5 wt.% of the total composition, more preferably 3 wt.% to 5 wt.% of the total composition, even more preferably 1 wt.% or less of the total composition, or 0.001 wt.% to 2 wt.% of the total composition. A preferred pigment is carbon black. For carbon black, the amount of carbon black that may be included is 0.001 wt.% to 5 wt.%.

[0076] The present invention also relates to a method for producing a polyethylene composition according to any of the above embodiments, wherein the high-density ethylene homopolymer or copolymer (A) is produced in a multi-stage process and is compounded with a copolymer (B) of ethylene and a silane-containing comonomer.

[0077] Multistage polymerization refers to the process of producing a polymer comprising two or more components by polymerizing each of at least two polymer components in different reaction stages, typically with different reaction conditions in each stage containing a polymerization catalyst. A composite step is preferably followed by the polymerization.

[0078] Preferably, components (A), (B), and possibly another component (C) are polymerized in any order at different stages of a multi-stage process. Therefore, it is preferred that components (A), (B), and possibly (C) are polymerized in subsequent stages. Further components may also be generated in the copolymer.

[0079] Preferably, the high-density ethylene homopolymer or copolymer (A) in the polymer composition according to the invention is polymerized in at least one slurry reactor and at least one gas-phase reactor.

[0080] In a preferred embodiment, component (A) is polymerized in a slurry reactor, preferably a loop reactor, and component (B) is polymerized in a gas-phase reactor in any order. If a copolymer comprising components (A), (B), and (C) is to be produced, it is preferred that components (A) and (B) be polymerized in a slurry reactor, preferably a loop reactor, and that component (C) be polymerized in a gas-phase reactor. The multi-stage process may also preferably include a prepolymerization stage.

[0081] There is no preferred order for the subsequent polymerization stages of a multi-stage process that can be set in any order.

[0082] Optionally, the reaction phase carried out in the slurry reactor therefore precedes the prepolymerization phase. Detailed reaction conditions are described in EP 1655333A1.

[0083] The multi-stage process can also be carried out in two reaction stages in the slurry phase, preferably in a loop reactor, and then in a gas-phase reactor.

[0084] In a preferred embodiment of the process according to the invention, component (A) is polymerized in the first reaction stage.

[0085] Therefore, it is preferable that component (B) polymerizes in the second reaction stage in the presence of component (A).

[0086] If component (C) is present, polymerization is preferably carried out in the third reaction stage where components (A) and (B) are present.

[0087] The low molecular weight polymer (such as component (A)) can be prepared in the first polymerization step, and the high molecular weight polymer (such as component (B)) can be prepared in the second polymerization step. This can be referred to as the normal mode and is preferred.

[0088] Alternatively, the HMW copolymer portion (B) can be prepared in the first polymerization step, and the LMW polymer portion (A) can be prepared in the second polymerization step. This can be referred to as the reverse mode.

[0089] If the LMW component is produced in the first polymerization step, the melt flow rate of the first ethylene component (A) can be measured directly as described herein. If the LMW component is produced in the second polymerization step, the melt flow rate of the LMW ethylene component (A) can be calculated based on the weight ratio of the LMW component and the HMW component and the molecular weight of the total polyethylene composition.

[0090] Furthermore, when the composition of each polymer is known, subtracting the GPC curve can also determine the melt flow rate of the polymer produced in the second stage of a multi-stage polymerization process.

[0091] The slurry and gas phases can be carried out using any conventional reactor known in the art. For example, slurry polymerization can be carried out in a continuous stirred tank reactor, a batch stirred tank reactor, or a loop reactor. Preferably, slurry polymerization is carried out in a loop reactor. In such a reactor, the slurry is circulated at high speed along a closed pipe using a circulation pump. Loop reactors are well known in the art and several embodiments have been given, for example in US 4582816A, US 3405109A, US 3324093A, EP 479186A, and US 5391654A.

[0092] The term gas-phase reactor includes any mechanically mixed fluidized bed reactor, fast fluidized bed reactor, or settling bed reactor, or a gas-phase reactor having two distinct zones, such as a fluidized bed combined with a settling bed zone. Preferably, the gas-phase reactor used for the second polymerization step is a fluidized bed reactor.

[0093] As a catalyst system, any catalyst system and optional co-catalyst can be used for the polymerization of polyethylene resin. Ziegler-Natta catalyst systems are particularly suitable. In a preferred embodiment, the polymerization is carried out in the presence of a Ziegler-Natta catalyst. Suitable Ziegler-Natta catalysts preferably contain magnesium compounds, aluminum compounds, and titanium compounds supported on a particulate support.

[0094] A particularly preferred catalytic system is described in EP 1378528A1.

[0095] The copolymer (B) of ethylene and a silane-containing comonomer can be produced by a high-pressure copolymerization process, as described in EP2508566A1. The hydrolyzable silane group can be introduced into the polymer by copolymerizing ethylene with a silane-containing comonomer or by grafting a silane-containing compound into the polymer. Grafting is a chemical modification of the polymer, typically achieved by adding a silane-containing compound in a free radical reaction. Such silane-containing comonomers and compounds are well known in the art and are commercially available, for example. The hydrolyzable silane group is typically crosslinked in a manner known in the art, through hydrolysis and subsequent condensation, in the presence of a silanol condensation catalyst and water. Silane crosslinking techniques are known, for example, as described in US 4413066, US 4297310, US 4351876, US 4397981, US 4446283, US 4456704, EP1824926A1 and EP 2508558A1.

[0096] The crosslinkable polymer composition of the present invention can be used to increase the tracking resistance of wires or cables. Therefore, the present invention also relates to a tracking-resistant wire or cable, preferably a power cable or optical fiber, wherein the power cable or optical fiber comprises at least one layer containing the above-described crosslinkable polymer composition. Preferably, the at least one layer is an outer jacket, a sheath, or an insulation layer.

[0097] Further preferably, the ethylene polymer is present in the wire or cable in the highest possible amount, i.e., in addition to optional further components, such as the fillers, stabilizers and / or carbon black described above.

[0098] When producing wire or cable materials, the preferred sheath / outer jacket / insulation material has components (such as ethylene polymer, magnesium hydroxide and / or calcium carbonate, carbon black, and optional additives) that should be tightly mixed to obtain the most homogeneous composition possible for production. In a preferred embodiment, this is used to produce the outer sheath of an optical cable.

[0099] The sheath material is preferably compounded according to the method described in WO 98 / 15591. According to this method, the filler and carbon black are mixed into the polymer material in two or more separate steps by allowing the polymer to pass through viscosity cross-stages two or more times; each step implies a separate mixing operation in a mixer or extruder. The two components are added in the desired proportions in the form of a fine powder to achieve optimal results and to incorporate both components into the sheath material as uniformly as possible.

[0100] The mixing can also be carried out in a conventional mixing unit, such as a twin-screw mixer, as those typically supplied by Werner & Pfleiderer and Berstorf, Banbury mixers, Farrel Pominis FCM mixers, or Buss co-kneaders.

[0101] The powder should have the smallest possible size. Therefore, the filler (preferably magnesium hydroxide) can preferably have a median particle size d of 1 μm to 10 μm. 50 The particle size is preferably 1.5 μm to 6 μm. The carbon black preferably has a nominal particle size of 10 nm to 30 nm, more preferably 20 nm. The particle size can be determined according to the method described in the Examples section.

[0102] The crosslinkable polymer composition according to the invention preferably has a tensile strength of at least 12.5 MPa as determined according to ISO 527-2, more preferably at least 21.5 MPa.

[0103] The crosslinkable polymer composition according to the invention preferably has an elongation at break of at least 50%, more preferably at least 100%, and even more preferably at least 300%, as determined according to ISO 527-2.

[0104] According to NFC62-062-2, measured on a 1 mm plate, and determined by Sepap UV aging test, after 1000 hours of aging, the crosslinkable polymer composition according to the present invention preferably has a UV resistance of at least 50% in terms of elongation, more preferably at least 100%.

[0105] The crosslinkable polymer compositions of the present invention can be crosslinked in the presence of a crosslinking agent or in the presence of moisture and a condensation catalyst. Known wet curing techniques in the presence of a condensation catalyst are described in the references mentioned above. Detailed Implementation

[0106] Experimental Section

[0107] A. Testing Methods

[0108] Unless otherwise defined, the following definitions of terms and measurement methods apply to the above general description of the invention and the following embodiments.

[0109] (1) Melt Flow Rate (MFR)

[0110] MFR can be determined according to ISO 1133 (Davenport R-1293 from Daventest). MFR values ​​can be obtained at 190°C with three different loads of 2.16 kg (MFR). 2.16), 5kg (MFR5) and 21.6kg (MFR 21 ) was measured.

[0111] (2) Density

[0112] Density can be determined according to ISO 1183-1-Method A (2019). Sample preparation can be completed by compression molding according to ISO 1872-2:2007.

[0113] (3) Electrical Tracking Test

[0114] The tracking tests were conducted according to IEC 60587 (2007), with failure criterion A. IEC 60567 (2007) Method 2A, "Step Tracking Voltage," specifies that a voltage exceeding 60 mA should not occur before the third voltage step. Five plates were measured for all materials, and the pass rate was calculated based on the number of plates passing each kV level. With a current not exceeding 60 mA, the tests were conducted at 4.5 kV for 1 hour and 4.75 kV for 1 hour, at 5.0 kV for 1 hour and 5.25 kV for 1 hour, or at 5.75 kV for 1 hour and 6 kV for 1 hour.

[0115] Plates (6 x 150 x 180 mm) for tracking testing were prepared according to compression molding according to ISO 293 (Collin R 1358, version: 2 / 060510). Particles were pressed between two Mylar membrane sheets and placed in a steel frame with suitable shape and size (140 x 150 x 3 mm). A pressure of 20 bar was applied to the sample at 200 °C for 1 minute, followed by a pressure of 200 bar at the same temperature for 5 minutes. The remaining compression was carried out at the same high pressure with a cooling rate of 15 °C / min for 9 minutes. The amount of particles used per plate was calculated using a material density exceeding 10 wt.%.

[0116] To produce crosslinked sheets, the catalyst masterbatch and polymer compound (compositions determined in Tables 1 and 2 below) were dry-mixed and then extruded as a tape in a tape extruder. Therefore, it is important to dry the polymer compound and catalyst before extrusion to prevent premature crosslinking in the extruder, which could lead to scorching. Tape (40 mm wide, 1 mm thick) was produced on a Collin TeachLine E20T tape extruder equipped with a 4.2:1, 20 mm diameter 20D compression screw. The temperature profile for the polymer A composition was 150°C / 160°C / 170°C with a screw speed of 55 rpm. The temperature profile for the polymer B composition was 150°C / 180°C / 200°C with a screw speed of 55 rpm. The extruded tape was cut, stacked on top of each other in a frame, and compressed into a 200 x 200 mm sheet with a thickness of 6 mm. The sheet was then crosslinked in water at 90°C for 24 hours. Cut a plate for electrical tracking testing from the cross-linked board according to standard IEC60587 (2007), and drill holes according to standard dimensions for electrical tracking testing.

[0117] (4) Median particle size (d) 50 )

[0118] Median particle size d 50 The particle size can be determined by laser diffraction (ISO 13320), dynamic light scattering (ISO 22412), or sieve analysis (ASTM D1921-06). For the metal hydroxides used in the examples, the median particle size d was determined by laser diffraction according to ISO 13320. 50 The determination.

[0119] (5) Manufacturing of adhesive tapes for determining tensile strength, elongation at break, electrical tracking and UV aging.

[0120] To determine tensile strength and elongation at break, 1.8 mm tape was produced on a Collin TeachLine E20T tape extruder equipped with a 20D compression screw with a 4.2:1 ratio and a diameter of 20 mm. The temperature profile for polymer A was 150°C / 160°C / 170°C with a screw speed of 55 rpm. For polymer B, the temperature profile was 150°C / 180°C / 200°C with a screw speed of 55 rpm.

[0121] Prior to the thermosetting test, the tape was cross-linked in water at 90°C for 24 hours.

[0122] (6) Tensile test

[0123] Tensile tests were performed using an Alwetron TCT 10 tensile testing machine according to ISO 527-1 and ISO 527-2. Ten specimens were punched from a plate using ISO 527-2 / 5A specimens and placed in a climate chamber at 50 ± 5% relative humidity and 23°C for at least 16 hours prior to testing. The specimens were placed vertically between clamps spaced 50 ± 2 mm apart, elongation meter clamps spaced 20 mm apart, and a 1 kN pressure gauge. The accurate width and thickness of each specimen were measured and recorded before testing. Each specimen bar was subjected to tensile testing at a constant speed of 50 mm / min until fracture, with at least six approved parallel tests performed. In highly filled systems, results often vary considerably; therefore, the median value was used to extract individual values ​​for elongation at break (%) and tensile strength (MPa).

[0124] (7) UV aging

[0125] UV aging was performed on 1mm thick dumbbells according to NFC62-062-2. Therefore, UV aging was carried out in a Sepap (mercury vapor lamp) oven at 60°C.

[0126] (8) Flame retardant test

[0127] The overhead cable with the covered conductor is made of tracking-resistant IE5 blend (as shown in Table 2 below). The cable has undergone a single-wire vertical flame test according to EN60332-1 and UL 1581 single-wire flame test and meets the requirements of both standards.

[0128] Overhead cable with a conductor of 50mm 2 It consists of seven aluminum conductors with a diameter of 7.8 mm. The IE5 mixture forms the insulator, and the tracking-resistant layer has an average thickness of 6.8 mm. The cable diameter is 21.4 mm.

[0129] (9) Comonomer content of the polymer

[0130] Quantitative nuclear magnetic resonance (NMR) spectroscopy is used to quantify the comonomer content of polymers.

[0131] Hexene content

[0132] Using a Bruker Avance III 500 NMR spectrometer, 1 H and 13 For C, operations were performed at 500.13 MHz and 125.76 MHz, respectively, and quantitative measurements were recorded in the molten state. 13 C{ 1 ¹H NMR spectroscopy. Nitrogen gas is used for all pneumatic operations, and the operation is carried out at 150°C. 13A C-optimized 7mm magic angle rotation (MAS) probe was used to record all spectra. Approximately 200 mg of material was packed into a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification. (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382., Parkinson, M., Klimke, K., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128., Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50(2009)2373). Standard single-pulse excitation was used, with a transient NOE with a short cyclic delay of 3s (Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813., Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.) and RS-HEPT decoupling scheme. (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239, Griffin, JM, Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. in Chem. 2007 45, S1, S198). A total of 16384 (16k) transients were obtained for each spectrum. This device was chosen because of its high sensitivity to low comonomer content.

[0133] Quantitative analysis was performed using a custom-defined automated spectral analysis program. 13 C{ 1 The ¹H NMR spectra were processed, integrated, and quantitatively determined. All chemical shifts were intrinsically referenced to the main methylene group signal (δ+) at 30.00 ppm (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

[0134] Observe the characteristic signal corresponding to the incorporation of 1-octene (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.) and calculate the total content relative to all other monomers present in the polymer.

[0135] The characteristic signal generated by isolated 1-hexene incorporation, namely the EEHEE comonomer sequence, was observed. The incorporation of this isolated 1-hexene was quantified by integrating the signal at 38.29 ppm attributed to the *B4 site as a percentage of the number of reporter sites per comonomer.

[0136] H = I *B4

[0137] When observing the characteristic signal generated by continuous 1-hexene incorporation, i.e., the EHHE comonomer sequence, the amount of continuous 1-hexene incorporation is quantified by integrating the signal at 40.46 ppm attributed to the aaB4B4 site relative to the number of reporter sites per comonomer:

[0138] HH=2*I ααB4B4

[0139] When observing the characteristic signal generated by discontinuous 1-hexene incorporation, i.e., the EHEHE comonomer sequence, this discontinuous 1-hexene incorporation is quantified by integrating the signal at 24.7 ppm attributed to the ββB4B4 site as a percentage of the number of reporter sites per comonomer:

[0140] HEH=2*I ββB4B4

[0141] Because the signals from the *B4 and *ββB4B4 sites of isolated (EEHEE) and discontinuously incorporated (EHEHE)1-hexene overlap, the total amount of isolated 1-hexene incorporation is corrected for the amount of discontinuous 1-hexene present:

[0142] H = I *B4 -2*I ββB4B4

[0143] In the absence of other signals indicating the sequence of other comonomers, i.e., 1-hexene chain initiation, the total content of observed 1-hexene comonomers is calculated solely based on the amounts of isolated (EEHEE), continuous (EHHE), and discontinuous (EHEHE) 1-hexene comonomer sequences:

[0144] H 总 =H+HH+HEH

[0145] Observe the characteristic signals generated by saturated end groups. Quantify the content of these saturated end groups by averaging the signal integrals at 22.8 ppm and 32.23 ppm, respectively, at the 2S and 3S sites.

[0146] S=(1 / 2)*(I 2S +I 3S )

[0147] The relative content of ethylene was quantified by integrating the main methylene group (δ+) signal at 30.00 ppm:

[0148] E = (1 / 2) * I δ+

[0149] The total ethylene content is calculated based on the main methylene group signal and taking into account the ethylene units present in other observed comonomer sequences or end groups:

[0150] E 总 =E+(2 / 2)*H+(1 / 4)*HH+(3 / 4)*HEH+(3 / 2)*S

[0151] The total mole fraction of 1-hexene in the polymer is then calculated as follows:

[0152] fH=(H 总 / (E 总 +H 总 )

[0153] The molar percentage of the total comonomer content of 1-octene was calculated using the conventional method:

[0154] H[mol%]=100*fH

[0155] Calculate the weight percentage of the total comonomer content of 1-hexene using the mole fraction method:

[0156] H[wt%]=100*(fH*84.16) / ((fH*84.16)+((1-fH)*28.05))

[0157] Butene content

[0158] Using a Bruker Avance III 500 NMR spectrometer, 1 H and 13 For C, operations were performed at 500.13 MHz and 125.76 MHz, respectively, and quantitative measurements were recorded in the molten state. 13 C{ 1 ¹H NMR spectroscopy. Nitrogen gas is used for all pneumatic operations, and the operation is carried out at 150°C. 13All spectra were recorded using a C-optimized 7mm magic angle rotation (MAS) probe. Approximately 200 mg of material was packed into a zirconia MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This setup was chosen primarily for the high sensitivity required for rapid identification and accurate quantification (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382., Parkinson, M., Klimke, K., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128., Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373). Standard single-pulse excitation was employed, utilizing a transient NOE with a short cyclic delay of 3 s (Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813., Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382.) and an RS-HEPT decoupling scheme. (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239, Griffin, JM, Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. in Chem. 2007 45, S1, S198). A total of 1024 (1k) transients were obtained for each spectrum. This device was chosen because of its high sensitivity to low comonomer content.

[0159] Quantitative analysis was performed using a custom-defined automated spectral analysis program. 13 C{ 1 The ¹H NMR spectra were processed, integrated, and quantitatively determined. All chemical shifts were intrinsically referenced to the main methylene group signal (δ+) at 30.00 ppm (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

[0160] Observe the characteristic signal corresponding to the incorporation of 1-butene (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.) and calculate the total content of all other monomers present in the polymer.

[0161] The characteristic signal generated by isolated 1-butene incorporation, namely the EEBEE comonomer sequence, was observed. This isolated 1-butene incorporation was quantified by integrating the signal at 39.84 ppm, attributed to the *B2 site, as a percentage of the number of reporter sites per comonomer.

[0162] B = I *B2

[0163] When observing the characteristic signal generated by continuous 1-butene incorporation, i.e., the EBBE comonomer sequence, the amount of continuous 1-butene incorporation is quantified by the integral of the signal at 39.4 ppm at the ααB2B2 site relative to the number of reporter sites per comonomer:

[0164] BB = 2 * I ααB2B2

[0165] When also observing the characteristic signal generated by discontinuous 1-butene incorporation, namely the EBEBE comonomer sequence, this discontinuous 1-butene incorporation was quantified by the integral of the signal at 24.7 ppm attributable to the ββB2B2 site relative to the number of reporter sites per comonomer:

[0166] BEB = 2 * I ββB2B2

[0167] Because the signals from the *B2 and *ββB2B2 sites of isolated (EEBEE) and discontinuously incorporated (EBEBE)1-butene overlap, the total amount of isolated 1-butene incorporation is corrected for the amount of discontinuous 1-butene present:

[0168] B = I *B2 -2*I ββB2B2

[0169] In the absence of other signals indicating other copolymer sequences, i.e., butene chain initiation, the total content of the observed 1-butene copolymers was calculated solely based on the amounts of isolated (EEBEE), continuous (EBBE), and discontinuous (EBEBE) 1-butene copolymer sequences:

[0170] B 总 =B+BB+BEB

[0171] Observe the characteristic signals generated by saturated end groups. Quantify the content of these saturated end groups by averaging the signal integrals at 22.84 ppm and 32.23 ppm, respectively, at the 2S and 3S sites.

[0172] S=(1 / 2)*(I 2S +I 3S )

[0173] The relative content of ethylene was quantified by integrating the main methylene group (δ+) signal at 30.00 ppm:

[0174] E = (1 / 2) * I δ+

[0175] The total content of ethylene comonomers is calculated based on the main methylene group signal and taking into account the ethylene units present in other observed comonomer sequences or end groups:

[0176] E 总 =E+(5 / 2)*B+(7 / 2)*BB+(9 / 2)*BEB+(3 / 2)*S

[0177] The total mole fraction of 1-butene in the polymer is then calculated as follows:

[0178] fB=(B 总 / (E 总 +B 总 )

[0179] The molar percentage of the total comonomer content of 1-butene was calculated using the conventional method:

[0180] B[mol%]=100*fB

[0181] Calculate the weight percentage of the total comonomer content of 1-butene using the mole fraction method:

[0182] B[wt%]=100*(fB*56.11) / ((fB*56.11)+((1-fB)*28.05))

[0183] B. Materials

[0184] polymer

[0185] Polymer A

[0186] Polymer A is natural bimodal high-density polyethylene produced according to Example 1 of EP 1327664B1. It has a melt flow rate (MFR2) of 0.45 g / 10 min, an MFR5 of 1.75 g / 10 min, and an MFR6 of 38 g / 10 min. 21The density is 942 kg / m³. 3 It is produced using 1-butene as a comonomer (2wt-%).

[0187] Polymer B

[0188] Polymer B is a natural bimodal high-density polyethylene. It has a melt flow rate (MFR2) of <0.1 g / 10 min, an MFR5 of 0.2 g / 10 min, and an MFR6 of 6.2 g / 10 min. 21 The density is 949 kg / m³. 3 It is produced using 1-hexene as a comonomer (1.4 wt%). The production of polymer B is described below.

[0189] Polymer D

[0190] Polymer D is a linear low-density polyethylene grafted with maleic anhydride (maleic anhydride content = 0.5 wt.-% to 1.0 wt.-%, MFR2 = 2.0 g / 10 min, density = 930 kg / m³). 3 It is available for purchase from HDC Hyundai EP Co., Ltd., and the product name is [product name missing]. GE300C.

[0191] Polymer E

[0192] Polymer E is an extremely low-density copolymer of polyethylene and 1-octene, with a density of 883 kg / m³. 3 With a density of 3.0 g / 10 min and an MFR2 of 3.0 g / 10 min, it is commercially available as Queo 8201 from Borealis AG (Austria).

[0193] Polymer F

[0194] Polymer F is an ethylene methacrylate copolymer (EMA) with a methacrylate content of 25 wt.%, an MFR of 0.4 g / 10 min, and a strength of 944 kg / m³. 3 The density is available from Borealis AG (Austria) OE2325.

[0195] Polymer preparation

[0196] Catalyst preparation for polymers A and B

[0197] Complex preparation

[0198] 87 kg of toluene was added to the reactor. Then, 45.5 kg of Bomag A in heptane was also added to the reactor. Then, 161 kg of 99.8% 2-ethyl-1-hexanol was introduced into the reactor at a flow rate of 24 kg / h-40 kg / h. The molar ratio of BOMAG-A to 2-ethyl-1-hexanol was 1:1.83.

[0199] Preparation of solid catalyst components

[0200] 275 kg of nitrogen-activated silica (Crossfield ES747JR, with an average particle size of 20 μm) was charged into a catalyst preparation reactor at 600 °C. Then, 411 kg of 20% EADC (2.0 mmol / g silica) diluted in 555 L pentane was added to the reactor over 1 hour at room temperature. The temperature was then increased to 35 °C while stirring the treated silica for 1 hour. The silica was dried at 50 °C for 8.5 hours. Then, 655 kg of the composite prepared as described above (2 mmol Mg / g silica) was added over 10 minutes at 23 °C. 86 kg of pentane was added to the reactor over 10 minutes at 22 °C. The slurry was stirred at 50 °C for 8 hours. Finally, 52 kg of TiCl4 was added over 0.5 hours at 45 °C. The slurry was stirred at 40 °C for 5 hours. The catalyst was then dried by purging with nitrogen.

[0201] Polymer A

[0202] Polymer A was produced according to Example 1 of EP 1327664B1.

[0203] Polymer B

[0204] Operating at 70°C and 57 bar pressure, with a volume of 50 dm³ 3 A loop reactor was used. Ethylene, propane diluent, and hydrogen were injected into the reactor. Solid Ziegler-Natta polymerization catalyst (Lynx 200) and triethylaluminum co-catalyst were introduced into the reactor to achieve an Al / Ti molar ratio of approximately 15. The estimated yield was 2 wt.%.

[0205] The slurry flow is continuously extracted and directed to a volume of 150 dm³ 3 A loop reactor was used, operating at 95°C and 55 bar. Additional ethylene, propane diluent, and hydrogen were added to the reactor to bring the ethylene concentration in the fluid mixture to 3.9% molar and the hydrogen-to-ethylene ratio to 390 mol / kmol. The estimated yield share was 16 wt.%. The ethylene homopolymer extracted from the reactor had an MFR2 of 280 g / 10 min.

[0206] The slurry flow from the reactor is intermittently extracted and directed to a 350 dm³ volume. 3 A loop reactor was used, operating at 95°C and 52 bar. Fresh propane, ethylene, and hydrogen were further added to the reactor to achieve an ethylene concentration of 3.7 mol-%, and a hydrogen-to-ethylene molar ratio of 370 mol / kmol. The ethylene homopolymer extracted from the reactor had an MFR2 of 282 g / 10 min. The estimated yield share was 27 wt.%.

[0207] The slurry was intermittently drawn from the loop reactor and directed to a flash evaporator operating at 50°C and 3 bar. From there, the polymer was directed to a fluidized bed gas-phase reactor operating at 20 bar and 85°C. Ethylene, 1-hexene comonomer, nitrogen as an inert gas, and hydrogen were added to achieve a hydrogen to ethylene molar ratio of 7 mol / kmol and a 1-hexene to ethylene molar ratio of 46 mol / kmol. The estimated yield share was 55 wt.%. The polymer had a melt flow rate (MFR5) of 0.22 g / 10 min and a flow rate of 949 kg / m³. 3 The density.

[0208] polymer additives

[0209] Silane-modified polymers

[0210] Ethylene vinyl silane copolymers were produced in a 660 m long segmented-feed high-pressure tubular reactor (Union Carbide A-1 type). The inner wall diameter was 32 mm. A chain transfer agent (propylene), an initiator (tert-butylperoxy-2-ethylhexanoate (Luperox 26 and air)), and a comonomer (vinyltrimethoxysilane (VTMS)) were added to the reactor system in a conventional manner. Polymerization was carried out at a maximum temperature of 310 °C and a pressure of 230 MPa. MFR was adjusted... 2.16 Propylene was used as a chain transfer agent. The VTMS feed was adjusted to produce copolymers containing the target VTMS level.

[0211] catalyst MB-1

[0212] The catalyst masterbatch was prepared by mixing the crosslinking catalyst dioctyltin dilaurate (3.5 wt.%) (Acima DOTL 99) with antioxidants Irganox 1010 (1.8 wt.%), Irganox MD 1024 (1.5 wt.%) and Lowinox TBM6P (1.1 wt.%) into ethylene ethyl acrylate copolymer (OE3515), which is commercially available from Borealis AG.

[0213] EVS-1 is a moisture-curable ethylene vinyl silane copolymer containing 1.35 wt.% VTMS and an MFR2 of 1 g / 10 min and 929 kg / m³. 3 The density.

[0214] EVS-2 is a moisture-curable ethylene vinyl silane copolymer with an MFR of 1 g / 10 min. 2.16 922.5 kg / m 3 The density, VTMS content of 1.90 wt.% based on the total weight of the polymer, and HDTMS content of 0.85 wt.% based on the total weight of the polymer.

[0215] EVS-3 is a moisture-curable ethylene vinyl silane copolymer containing 1.1 wt.% VTMS and an MFR of 1 g / 10 min and 922.5 kg / m³. 3 The density.

[0216] filler

[0217] MDH-1 It is a commercially available type of brucite (ground magnesium hydroxide) produced by Europiren BV (Netherlands). 3.5C), which has a d of 3.5μm 50 , at 7m 2 / g to 10m 2 The specific surface area is within the range of / g, and the surface is coated with 2wt.% stearic acid. The chemical composition is: Mg(OH)2 > 92.8wt.%, CaO < 2.3wt.%, SiO2 < 1.3wt.%, and Fe2O3 < 0.13wt.%.

[0218] MDH-2 This is a high-purity (99.8 wt.%) precipitated magnesium hydroxide produced by Martinswerk in Germany and commercially available under the trade name Magnifin H5HV. It has a dx in the range of 1.7 μm to 2.1 μm.50 and 5m 2 Specific surface area (BET) per g. It contains a polymer coating.

[0219] Ca-1 It is a calcium carbonate coated with stearic acid (1 wt.%), with an average particle size of 1.5 μm. It is commercially available from Omya AG in Switzerland under the name " EXH 1SP-OM.

[0220] additive

[0221] Chimassorb 944 (CAS No. 106990-43-6) is a hindered amine light stabilizer (HALS) available commercially from BASF.

[0222] Tinuvin 783 is a hindered amine light stabilizer (HALS) oligomer available from BASF under the name Tinuvin 783FDL.

[0223] Irganox 1010 (CAS No. 6683-19-8), Irgafos 168 (CAS No. 31570-04-4), and Irganox MD1024 (CAS No. 32687-78-8) are commercially available antioxidants from BASF.

[0224] Lowinox TBM-6P (CAS No. 96-65-5) is a commercially available antioxidant from SIGroup.

[0225] Acima DOTL 99 dioctyltin dilaurate is commercially available from Dow Chemical Company (CAS No. 3648-18-8).

[0226] The carbon black was Printex Alpha A, which was commercially available from Orion Engineered Carbon.

[0227] Preparation of polymer compositions

[0228] According to the embodiments (IE1 to IE5) and comparative examples (CE1 to CE5) of the invention, polymer compositions and catalyst MB-1 are produced by mixing these components together in a BUSS co-kneader (46 mm) at a screw speed of 225 rpm, at set temperatures of 40, 160, 180, and 200°C in the kneading section, and in a granulating extruder at 200°C. The mixer screw is heated to 120°C. The extruder screw temperature is 160°C, the barrel is heated to 170°C, and the rotation speed is 4 rpm. The filler is always added at port 2, while all other components are added at port 1. The contents of different components in the polymer compositions and the properties of the polymer compositions according to the embodiments and comparative examples of the invention are collected from Tables 1 and 2 below.

[0229] Table 1

[0230]

[0231]

[0232] Table 2

[0233]

[0234]

[0235] The above results show that none of the comparative examples passed the tracking test at 5.0 kV for 1 hour + 5.25 kV for 1 hour or at 5.75 kV for 1 hour + 6 kV for 1 hour. Only comparative example CE2 passed the tracking test at 4.5 kV for 1 hour + 4.75 kV for 1 hour. However, CE2 only passed under a high filler load of 25 wt.%, and it has the disadvantage of poor heat deformation resistance. The failure of the thermosetting tests in Table 1 shows the poor heat deformation resistance of CE2. However, heat deformation resistance is particularly important in high-temperature environments.

[0236] Surprisingly, the polymer compositions (IE1 to IE5) according to the present invention passed the tracking test of at least 5.0 kV for 1 h + 5.25 kV for 1 h, while IE2 to IE5, after adding magnesium hydroxide or calcium carbonate as fillers, even passed the tracking test of 5.75 kV for 1 h + 6 kV for 1 h, and also showed satisfactory mechanical properties and improved heat deformation resistance.

[0237] Example IE1 of the present invention shows that, even without filler, the composition surprisingly passed the tracking test at 5.0 kV for 1 hour, followed by 5.25 kV for 1 hour, and still exhibited good mechanical properties.

[0238] Furthermore, embodiments of the present invention demonstrate that the combination of multimodal high-density polyethylene and copolymers of ethylene with silane-containing comonomers unexpectedly yields excellent electrical tracking resistance while still achieving satisfactory or good mechanical properties. This is unexpected because ethylene vinyl silane copolymers are produced by high-pressure polymerization and have relatively low density.

[0239] The results also showed that the mechanical properties and electrotraceability were improved when the bimodal ethylene / hexene copolymer (polymer B) was replaced with a particularly preferred bimodal ethylene / hexene copolymer (CE1).

[0240] The results from IE3 to IE6 also showed that, at higher filler loadings (>25 wt.%), adding linear low-density polyethylene containing unsaturated carboxylic acids (polymer D) and / or very low-density polyethylene (polymer E) to polymer B of the present invention slightly improved the mechanical properties while maintaining excellent electro-tracking properties, and even increased the flexibility of the composition at the same time.

[0241] Flame retardancy testing was also conducted on IE5. The cover conductor containing the IE5 composition was tested according to the vertical flame test of EN60332-1 and the single-wire flame test of UL 1581. The cable meets the requirements of both standards. The filler-containing material composition in IE5 meets the fire resistance requirements of the cable and cover conductor and can inhibit or reduce the spread of fire. This effect is particularly evident at high filler loads of 40 wt.% or more (IE5).

[0242] Further addition of UV absorbers can not only achieve high tensile strength and elongation at break, but also satisfactory UV resistance, with an elongation of at least 50% after 1000 hours of aging (Sepap) (IE5 vs CE3-CE5).

[0243] Therefore, the multi-peak polymer composition of the present invention exhibits unexpectedly improved tracking resistance, combined with good mechanical properties, heat resistance and UV resistance, making it ideal for high-end wire and cable applications, especially optical cables or overhead power cables.

Claims

1. A crosslinkable polymer composition comprising (A) A high-density ethylene copolymer having a density of at least 930 kg / m³ as determined according to ISO 1183. 3 The density, of which, The high-density ethylene copolymer is a multimodal copolymer of ethylene and hexene, and (B) A copolymer of ethylene and a silane-containing comonomer, the copolymer having a content of not more than 5.0 wt% of the silane-containing comonomer. The polymer composition passed the tracking resistance test, which was performed on a compression-molded plate prepared according to ISO 11357, at 4.5 kV for 1 h and 4.75 kV for 1 h, according to IEC 60587 (2007) Method 2A.

2. The crosslinkable polymer composition according to claim 1, wherein, The polymer composition passed the tracking resistance test, which was performed on a compression-molded plate prepared according to ISO 11357, at 5.0 kV for 1 h and 5.25 kV for 1 h, according to IEC 60587 (2007) method 2A.

3. The crosslinkable polymer composition according to claim 1, wherein, The high-density ethylene copolymer (A) is a multimodal copolymer of ethylene and hexene, with a density of 930 kg / m³. 3 Up to 970 kg / m 3 The density and melt flow rate MFR2, determined according to ISO 1133 at a load of 2.16 kg and 190 °C, not exceeding 0.4 g / 10 min.

4. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein, In the copolymer (B) of ethylene and silane-containing comonomers, the silane-containing comonomers are selected from the group consisting of vinyltriethoxysilane (VTES), vinyltrimethoxysilane (VTMS), γ-methacryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltriethoxysilane.

5. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein the polymer composition further comprises a density not exceeding 890 kg / m³. 3 Very low density polyethylene.

6. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein, The polymer composition further comprises linear low-density polyethylene copolymerized or grafted with unsaturated carboxylic acids or their derivatives.

7. The crosslinkable polymer composition according to claim 6, wherein, The unsaturated carboxylic acid or its derivative is maleic anhydride.

8. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein, The polymer composition further comprises fillers that are metal carbonates and / or metal hydroxides.

9. The crosslinkable polymer composition according to claim 8, wherein, The filler is selected from the group consisting of calcium carbonate, ground and precipitated magnesium hydroxide.

10. The crosslinkable polymer composition according to claim 8, wherein, The filler content is at least 25 wt.% based on the total weight of the polymer composition.

11. The crosslinkable polymer composition according to any one of claims 1 to 3, further comprising a UV stabilizer and / or an antioxidant and / or a pigment, and / or It further comprises ethylene polymers or copolymers copolymerized or grafted with unsaturated carboxylic acids or their derivatives, and / or elastomeric ethylene copolymers.

12. The crosslinkable polymer composition according to any one of claims 1 to 3, having a tensile strength of at least 12.5 MPa as determined according to ISO 527-2, and / or having an elongation at break of at least 50% as determined according to ISO 527-1 and ISO 527-2.

13. The crosslinkable polymer composition according to any one of claims 1 to 3, measured on a 1 mm plate according to NFC62-062-2, and determined according to the Sepap UV aging test, has a UV resistance of at least 50% in terms of elongation after 1000 hours of aging.

14. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein it has been crosslinked in the presence of a crosslinking agent or in the presence of moisture and a condensation catalyst.

15. A tracking-resistant cable comprising at least one layer of a polymer composition according to any one of claims 1-14.

16. The tracking-resistant cable according to claim 15, wherein it is a power cable or an optical fiber, and / or The at least one layer is an outer shell layer, a sheath layer, or an insulating layer.

17. The use of the polymer composition according to any one of claims 1-14 in wires or cables for improving tracking resistance, and / or Used to improve the flame retardancy along the length of a wire or cable.

18. A method for manufacturing a polymer composition according to any one of claims 1-14, comprising the step of compounding or dry-blending the high-density ethylene copolymer (A) and a copolymer (B) of ethylene and a silane-containing comonomer.

Images