Polymer composition and coated conductor made therefrom

Abstract

A polymer composition comprises: 60 wt% to 85 wt%, based on the total weight of the polymer composition, of a first ethylene-based polymer, wherein the first ethylene-based polymer has a density of 0.93 g / cc to 0.97 g / cc as measured according to ASTM D792, and has a polydispersity index of 7 or greater as measured according to gel permeation chromatography, and has a shear viscosity v100 of 800 Pa.s or greater at 170°C as measured according to dynamic mechanical spectroscopy; 15 wt% to 40 wt%, based on the total weight of the polymer composition, of a second ethylene-based polymer, wherein the second ethylene-based polymer has a density of 0.916 g / cc to 0.930 g / cc as measured according to ASTM D792, and has a shear viscosity v100 of 800 Pa.s or greater at 170°C as measured according to dynamic mechanical spectroscopy; and 0.1 wt% to 2.0 wt%, based on the total weight of the polymer composition, of a blowing agent.

Description

Background Technology Technical Field

[0002] This disclosure relates to polymer compositions, and more particularly to polymer compositions that can be used to coat foamed insulators on conductors. Background Technology

[0003] The growth of cloud computing has increased the demand for data transmission within, between, and between data centers and users. This data transmission requires high-speed and high-frequency cables. High-category data cables (“CAT cables”) are designed to meet these requirements and provide excellent transmission characteristics over short distances. CAT cables are easier to install and therefore less expensive than fiber optic cables over similar distances.

[0004] CAT cables are typically constructed with three layers: a solid conductor, a foam insulation layer, and an outer protective layer. The insulation is foamed by injecting foaming gas into the polymer composition during cable manufacturing. The polymer composition requires certain rheological properties to achieve a fine and uniform closed-cell structure, thus exhibiting a low dissipation factor. For example, the polymer composition, in its unfoamed state, should exhibit a dissipation factor of less than 1.7E-04, as measured according to ASTM 1531 at 2.47 GHz. The polymer composition should also ensure that the insulation remains smooth and defect-free even at high extrusion rates. The smoothness of a CAT cable is expressed as the relative standard deviation (“RSD”) of its outer diameter (“OD”). Generally, a cable is considered sufficiently smooth if its RSD, as measured according to the smoothness test provided below, is 0.5% or less.

[0005] Numerous attempts have been made to improve the properties of CAT cables, but existing technologies have primarily focused on nucleating agents and foaming agents to improve foaming, as this is a relatively easier task than adjusting the resin structure. For example, U.S. Patent No. 10,858,492B2 (“'492 Patent”) provides a foamable composition comprising (A) 45% to 95% by weight of HDPE, (B) 4% to 54% by weight of LDPE, and (C) 0.01% to 2% by weight of a foaming agent comprising fluoropolymer and expandable polymer microspheres. The AXELERON used in the '492 Patent… ™ CX B - 1258 NT LDPE has a shear viscosity v100 of 408 Pa·s at 170 °C, as measured by dynamic mechanical spectroscopy.

[0006] Given the above, it is surprising to find a polymer composition that exhibits the aforementioned dissipation factor and RSD value at high extrusion rates. Summary of the Invention

[0007] The inventors of this application have discovered polymer compositions that exhibit the aforementioned dissipation factor and RSD value at high extrusion speeds.

[0008] This disclosure is a result of discovering that various characteristics of the resin must be considered to achieve the desired RSD and dissipation factor values. For example, it is believed that in a resin system comprising a relatively high-density ethylene-based resin and a relatively low-density ethylene-based resin, the high-density resin should exhibit a polydispersity index of 7 or greater, and both the high-density and low-density resins should exhibit a shear viscosity v100 of 800 Pa·s or greater at 170 °C. Without being bound by theory, it is believed that a synergistic effect occurs between the resins to stabilize the bubbles generated during foaming, thereby delivering the desired electrical and smoothing properties despite high extrusion rates.

[0009] According to a first feature of this disclosure, a polymer composition comprises: 60% to 85% by weight of a first ethylene-based polymer, based on the total weight of the polymer composition, wherein the first ethylene-based polymer has a density of 0.93 g / cc to 0.97 g / cc as measured according to ASTM D792, and has a polydispersity index of 7 or greater as measured according to gel permeation chromatography, and has a shear viscosity v100 of 800 Pa·s or greater at 170°C as measured according to dynamic mechanical spectroscopy; 15% to 40% by weight of a second ethylene-based polymer, based on the total weight of the polymer composition, wherein the second ethylene-based polymer has a density of 0.916 g / cc to 0.930 g / cc as measured according to ASTM D792, and has a shear viscosity v100 of 800 Pa·s or greater at 170°C as measured according to dynamic mechanical spectroscopy; and 0.1% to 2.0% by weight of a foaming agent, based on the total weight of the polymer composition.

[0010] According to a second feature of this disclosure, the foaming agent is selected from the group consisting of: polytetrafluoroethylene, azodicarbonamide, sodium bicarbonate, titanium hydride, ammonium carbonate, ammonium bicarbonate and calcium azide, expandable microspheres and combinations thereof.

[0011] According to a third feature of this disclosure, the polymer composition comprises 70% to 85% by weight of a first ethylene-based polymer based on the total weight of the polymer composition.

[0012] According to a fourth feature of this disclosure, the polymer composition comprises 75% to 85% by weight of a first ethylene-based polymer based on the total weight of the polymer composition, and the first ethylene-based polymer exhibits a melt flow rate of 70 or greater (I0). 21 / I2).

[0013] According to a fifth feature of this disclosure, the polymer composition comprises 15% to 25% by weight of a second ethylene-based polymer based on the total weight of the polymer composition.

[0014] According to the sixth feature of this disclosure, the second ethylene-based polymer has a shear viscosity v100 of 1000 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy.

[0015] According to the seventh feature of this disclosure, the first ethylene-based polymer has a shear viscosity v100 of 1000 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy.

[0016] According to the eighth feature of this disclosure, the polymer composition exhibits a polydispersity index of 10 or greater as measured by gel permeation chromatography.

[0017] According to the ninth feature of this disclosure, the polymer composition exhibits a polydispersity index of 11 or greater as measured by gel permeation chromatography.

[0018] According to a tenth feature of this disclosure, the coated conductor comprises: a conductor; and a polymer composition coupled to the conductor, wherein the polymer composition exhibits a relative standard deviation of its outer diameter of 0.5% or less as measured according to a smoothness test. Detailed Implementation

[0019] As used herein, the term “and / or” when used in a list of two or more items means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone; contain B alone; contain C alone; contain A and B in combination; contain A and C in combination; contain B and C in combination; or contain A, B, and C in combination.

[0020] Unless otherwise stated, all ranges include the endpoints.

[0021] A test method refers to the most recent test method as of the priority date of this document, unless the date is indicated by a hyphenated two-digit test method number. References to test methods include references to both the testing association and the test method number. Testing method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly known as the American Society for Testing and Materials); EN refers to European Standards; DIN refers to the German Institute for Standardization; and ISO refers to the International Organization for Standardization.

[0022] polymer composition

[0023] This disclosure relates to polymer compositions. The polymer compositions comprise a first ethylene-based polymer, a second ethylene-based polymer, and a blowing agent.

[0024] Polymer compositions in non-foamed or non-expanded form have a dissipation factor of 1.70E-04 or less, as measured at 2.47 GHz according to ASTM Method D1531. The dissipation factor is a measure of the energy loss rate of oscillating modes in a dissipative system. The dissipation factor can be 1.70E-04 or less, or 1.65E-04 or less, or 1.60E-04 or less, or 1.55E-04 or less, or 1.50E-04 or less, or 1.45E-04 or less, while simultaneously being 1.40E-04 or greater, or 1.45E-04 or greater, or 1.50E-04 or greater, or 1.55E-04 or greater, or 1.60E-04 or greater, or 1.65E-04 or greater, as measured at 2.47 GHz according to ASTM Method D1531.

[0025] The polymer composition may exhibit relaxation index values ​​of 30 to 90 as calculated by dynamic oscillatory shear testing, as explained in more detail below. For example, RSI values ​​may be 30 or greater, or 35 or greater, or 40 or greater, or 45 or greater, or 50 or greater, or 55 or greater, or 60 or greater, or 65 or greater, or 70 or greater, or 75 or greater, or 80 or greater, or 85 or greater, while simultaneously 90 or less, or 85 or less, or 80 or less, or 75 or less, or 70 or less, or 65 or less, or 60 or less, or 55 or less, or 50 or less, or 45 or less, or 40 or less, or 35 or less, as calculated by dynamic oscillatory shear testing.

[0026] Ethylene-based polymers

[0027] As used herein, "ethylene-based" polymers are polymers in which more than 50% by weight of the monomers are ethylene, but other comonomers may also be used. Ethylene-based polymers include ethylene and may include one or more C3-C... 20 α-olefin comonomers, such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene.

[0028] Ethylene-based polymers may contain 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, or 91% or more, or 92% or more, or 93% or more, or 94% or more, or 95% or more, or 96% or more, or 97% or more, or 97.5% or more, or 98% or more, or 99% or more, while simultaneously, 99.5% or more Less, or 99% by weight or less, or 98% by weight or less, or 97% by weight or less, or 96% by weight or less, or 95% by weight or less, or 94% by weight or less, or 93% by weight or less, or 92% by weight or less, or 91% by weight or less, or 90% by weight or less, or 85% by weight or less, or 80% by weight or less, or 70% by weight or less, or 60% by weight or less ethylene monomer, as measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy.

[0029] Other units of ethylene-based polymers can be derived from one or more polymerizable monomers, including but not limited to polar monomers such as unsaturated esters. Unsaturated esters (i.e., polar monomers) can be alkyl acrylates, alkyl methacrylates, or vinyl carboxylate esters. Alkyl groups can have 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Carboxylate ester groups can have 2 to 8 carbon atoms, or 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, tert-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylate esters include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butyrate. Ethylene-based polymers may have a polar comonomer content of 40% or less, or 35% or less, or 30% or less, or 25% or less, or 20% or less, or 15% or 10% by weight, or 5% or less, or 3% or less, or 1% or less, or 0% by weight, as measured by nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy.

[0030] Ethylene-based polymers can have unimodal or multimodal molecular weight distributions and can be used alone or in combination with one or more other types of ethylene-based polymers (e.g., blends of two or more ethylene-based polymers that differ from each other in monomer composition and content, catalytic preparation method, molecular weight, molecular weight distribution, density, etc.). If blends of ethylene-based polymers are used, the polymers can be blended by any in-reactor or post-reactor method. The term "multimodal polymer" refers to a polymer characterized by having at least two distinct peaks in a gel permeation chromatography (GPC) chromatogram depicting the molecular weight distribution of the composition. Therefore, the general term multimodal polymer includes bimodal polymers having two main fractions: a first fraction, which may be a low molecular weight fraction and / or component; and a second fraction, which may be a high molecular weight fraction and / or component.

[0031] The first ethylene-based polymer

[0032] As noted above, the polymer composition may comprise a first ethylene-based polymer. The density of the first ethylene-based polymer is from 0.93 g / cc to 0.97 g / cc, as measured according to ASTM D792. For example, the density of the first ethylene-based polymer is 0.930 g / cc or greater, or 0.935 g / cc or greater, or 0.940 g / cc or greater, or 0.945 g / cc or greater, or 0.950 g / cc or greater, or 0.955 g / cc or greater, or 0.960 g / cc or greater, or 0.965 g / cc or greater, while simultaneously being 0.970 g / cc or less, or 0.965 g / cc or less, or 0.960 g / cc or less, or 0.955 g / cc or less, or 0.950 g / cc or less, or 0.945 g / cc or less, or 0.940 g / cc or less, or 0.935 g / cc or less, as measured according to ASTM D792. Typically, ethylene-based polymers with a density of 0.93 g / cc to 0.97 g / cc are referred to as "high-density polyethylene" or "HDPE".

[0033] The first ethylene-based polymer may have a polydispersity index of 7 or greater, as measured by gel permeation chromatography. For example, the polydispersity index of the first ethylene-based polymer may be 7 or greater, or 8 or greater, or 9 or greater, or 10 or greater, or 11 or greater, or 12 or greater, or 13 or greater, or 14 or greater, while simultaneously being 15 or less, or 14 or less, or 13 or less, or 12 or less, or 11 or less, or 10 or less, or 9 or less, or 8 or less, as measured by gel permeation chromatography.

[0034] The first ethylene-based polymer may have a melt index (I2) of 0.8 g / 10 min or less as measured according to ASTM D1238. For example, the first ethylene-based polymer may have a melt index (I2) of 0.8 g / 10 min or less, or 0.7 g / 10 min or less, or 0.6 g / 10 min or less, or 0.5 g / 10 min or less, or 0.4 g / 10 min or less, or 0.3 g / 10 min or less, or 0.2 g / 10 min or less, or 0.1 g / 10 min or less as measured according to ASTM D1238.

[0035] The first ethylene-based polymer can exhibit a melt flow rate ratio of 70 or greater as measured according to ASTM D1238 (I 21 / I2). For example, the melt flow of the first ethylene-based polymer may be 70 or greater, or 75 or greater, or 80 or greater, or 85 or greater, or 90 or greater, or 95 or greater, while simultaneously, 100 or less, or 95 or less, or 90 or less, or 85 or less, or 80 or less, or 75 or less, as measured according to ASTM D1238.

[0036] The first ethylene-based polymer may exhibit a shear viscosity v100 of 800 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy. For example, the first ethylene-based polymer may exhibit a shear viscosity v100 of 800 Pa·s or greater, or 850 Pa·s or greater, or 900 Pa·s or greater, or 950 Pa·s or greater, or 1000 Pa·s or greater, or 1050 Pa·s or greater, or 1100 Pa·s or greater, or 1150 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy, while simultaneously exhibiting a shear viscosity v100 of 1200 Pa·s or less, or 1150 Pa·s or less, or 1100 Pa·s or less, or 1050 Pa·s or less, or 1000 Pa·s or less, or 950 Pa·s or less, or 900 Pa·s or less, or 850 Pa·s or less.

[0037] The first ethylene-based polymer exhibits dissipation factors ranging from 5.0E-05 to 9.0E-05 as measured at 2.47 GHz according to ASTM 1531. For example, the dissipation factor can be 5.0E-05 or greater, or 5.5E-05 or greater, or 6.0E-05 or greater, or 6.5E-05 or greater, or 7.0E-05 or greater, or 7.5E-05 or greater, or 8.0E-05 or greater, or 8.5E-05 or greater, while at the same time, 9.0E-05 or less, or 8.5E-05 or less, or 8.0E-05 or less, or 7.5E-05 or less, or 7.0E-05 or less, or 6.5E-05 or less, or 6.0E-05 or less, or 5.5E-05 or less, as measured at 2.47 GHz according to ASTM 1531.

[0038] The polymer composition may comprise 60% to 85% by weight of a first ethylene-based polymer based on the total weight of the polymer composition. For example, the polymer composition may comprise 60% or more, or 65% or more, or 70% or more, or 75% or more, or 80% or more by weight of the polymer composition, while simultaneously comprising 85% or less, or 80% or less, or 75% or less, or 65% or less by weight of a first ethylene-based polymer based on the total weight of the polymer composition.

[0039] Second ethylene-based polymer

[0040] The polymer composition further comprises a second ethylene-based polymer. The density of the second ethylene-based polymer may be 0.916 g / cc or greater, or 0.919 g / cc or greater, or 0.920 g / cc or greater, or 0.921 g / cc or greater, or 0.922 g / cc or greater, or 0.925 g / cc or greater, or 0.926 g / cc or greater, while simultaneously being 0.930 g / cc or less, or 0.925 g / cc or less, or 0.920 g / cc or less, or 0.919 g / cc or less, or 0.917 g / cc or less, as measured according to ASTM D792.

[0041] The second ethylene-based polymer may exhibit a shear viscosity v100 of 800 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy. For example, the second ethylene-based polymer may exhibit a shear viscosity v100 of 800 Pa·s or greater, or 850 Pa·s or greater, or 900 Pa·s or greater, or 950 Pa·s or greater, or 1000 Pa·s or greater, or 1050 Pa·s or greater, or 1100 Pa·s or greater, or 1150 Pa·s or greater at 170 °C, as measured by dynamic mechanical spectroscopy, while simultaneously exhibiting a shear viscosity v100 of 1200 Pa·s or less, or 1150 Pa·s or less, or 1100 Pa·s or less, or 1050 Pa·s or less, or 1000 Pa·s or less, or 950 Pa·s or less, or 900 Pa·s or less, or 850 Pa·s or less.

[0042] The second ethylene-based polymer may have a polydispersity index of 5 or greater, as measured by gel permeation chromatography. For example, the polydispersity index of the second ethylene-based polymer may be 5 or greater, or 6 or greater, or 7 or greater, or 8 or greater, or 9 or greater, or 10 or greater, or 11 or greater, or 12 or greater, while simultaneously being 13 or less, or 12 or less, or 11 or less, or 10 or less, or 9 or less, or 8 or less, or 7 or less, as measured by gel permeation chromatography.

[0043] The polymer composition may contain 15% to 40% by weight of a second ethylene-based polymer based on the total weight of the polymer composition. For example, the polymer composition may contain 15% or more, or 20% or more, or 25% or more, or 30% or more, or 35% or more by weight of the polymer composition, while simultaneously containing 40% or less, or 35% or less, or 30% or less, or 25% or less, or 20% or less by weight of a second ethylene-based polymer.

[0044] The second ethylene-based polymer can exhibit dissipation factors of 5.0E-04 to 7.0E-04 as measured at 2.47 GHz according to ASTM 1531. For example, the dissipation factor can be 5.0E-04 or greater, or 5.2E-04 or greater, or 5.4E-04 or greater, or 5.6E-04 or greater, or 5.8E-04 or greater, or 6.0E-04 or greater, or 6.2E-04 or greater, or 6.4E-04 or greater, or 6.6E-04 or greater, or 6.8E-04 or greater, while simultaneously, 7.0E-04 or less, or 6.8E-04 or less, or 6.6E-04 or less, or 6.4E-04 or less, or 6.2E-04 or less, or 6.0E-04 or less, or 5.8E-04 or less, or 5.6E-04 or less, or 5.4E-04 or less, or 5.2E-04 or less, as measured at 2.47 GHz according to ASTM 1531.

[0045] foaming agent

[0046] The polymer composition contains a foaming agent. A foaming agent is also called a heat-generating agent. The foaming agent can be selected from the group consisting of: polytetrafluoroethylene, azodicarbonamide, sodium bicarbonate, titanium hydride, ammonium carbonate, ammonium bicarbonate and calcium azide, expandable microspheres, nitrogen, inert gases, and combinations thereof.

[0047] The polymer composition may contain a blowing agent in amounts from 0.1% to 2.0% by weight of the total polymer composition. For example, the polymer composition may contain 0.1% or more, or 0.2% or more, or 0.3% or more, or 0.4% or more, or 0.5% or more, or 0.6% or more, or 0.7% or more, or 0.8% or more, or 0.9% or more, or 1.0% or more, or 1.1% or more, or 1.2% or more, or 1.3% or more, or 1.4% or more, or 1.5% or more, or 1.6% or more, or 1.7% or more, or 1.8% or more, or 1.9% or more, while simultaneously containing 2.0% or less, or 1.5% or less, or 1.0% or less, or 0.5% or less, or 0.2% or less of a blowing agent based on the total weight of the polymer composition.

[0048] additive

[0049] The polymer composition may contain one or more additives. Non-limiting examples of suitable additives include antioxidants, colorants, corrosion inhibitors, lubricants, ultraviolet (UV) absorbers or stabilizers, anti-blocking agents, flame retardants, coupling agents, compatibilizers, plasticizers, fillers, processing aids, and combinations thereof. One or more additives may be combined with a polyethylene resin to form a masterbatch, such that some or all of the additives may be incorporated into the polymer composition in the form of one or more masterbatches.

[0050] The polymer composition may contain antioxidants. Non-limiting examples of suitable antioxidants include phenolic antioxidants, sulfur-based antioxidants, phosphate antioxidants, and hydrazine metal passivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenols, phenols having primary or secondary carbonyl substituents, and polyfunctional phenols such as sulfur- and phosphorus-containing phenols. Representative hindered phenols include 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; 4,4'-methylenebis(2,6-tert-butylphenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5-triazine; ethyl 3,5-di-tert-butyl-4-hydroxybenzoate (di-n-octylthio); and hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]sorbitol ester. The polymer composition may contain pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), which can be used with Irganox ™ 1010 is commercially available from BASF. A non-limiting example of a suitable methyl-substituted phenol is isobutylenebis(4,6-dimethylphenol). A non-limiting example of a suitable hydrazine-based metal passivator is oxaloylbis(benzylhydrazine). The polymer composition may contain 0% by weight, or 0.001% by weight, or 0.01% by weight, or 0.02% by weight, or 0.05% by weight, or 0.1% by weight, or 0.2% by weight, or 0.3% by weight, or 0.4% to 0.5% by weight, or 0.6% by weight, or 0.7% by weight, or 0.8% by weight, or 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight of an antioxidant based on the total weight of the polymer composition.

[0051] The composition may contain processing aids. Non-limiting examples of suitable processing aids include oils, organic acids (such as stearic acid), and metal salts of organic acids (such as zinc stearate). In embodiments, the composition contains 0% by weight, or 0.01% by weight, or 0.02% by weight, or 0.05% by weight, or 0.07% by weight, or 0.1% by weight, or 0.2% by weight, or 0.3% by weight, or 0.4% to 0.5% by weight, or 0.6% by weight, or 0.7% by weight, or 0.8% by weight, or 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight, or 5.0% by weight, or 10.0% by weight, or 20.0% by weight of processing aids.

[0052] The polymer composition may contain additives based on the total weight of the polymer composition of 0% or more, or 0.001% or more, or 0.002% or more, or 0.005% or more, or 0.006% or more, or 0.008% or more, or 0.009% or more, or 0.01% or more, or 0.2% or more, or 0.3% or more, or 0.4% or more, or 0.5% or more, or 1.0% or more, or 2.0% or more, or 3.0% or more, or 4.0% or more, or 5.0% or more, or 10.0% or more, or 15.0% or more, or 20.0% or more, or 30% or more, or 40% or more, or 50% or more.

[0053] Coated conductor

[0054] This disclosure also provides a coated conductor. The coated conductor includes a conductor and a coating on the conductor, the coating comprising a polymer composition. The polymer composition is at least partially disposed around the conductor to create the coated conductor. The conductor may include a conductive metal or an optically transparent structure.

[0055] A method for preparing a coated conductor includes mixing a polymer composition in an extruder and heating it to the melt temperature of at least the polymer components to form a polymer melt blend, and then coating the polymer melt blend onto a conductor. The term "on" includes direct or indirect contact between the polymer melt blend and the conductor. The polymer melt blend is in an extrudable state.

[0056] A polymer composition is coupled to and / or disposed around a conductor to form a coating. The coating may be one or more inner layers, such as an insulating layer. The coating may completely or partially cover or otherwise surround or encapsulate the conductor. The coating may be the only component surrounding the conductor. Alternatively, the coating may be a layer of a multi-layered sheath or outer layer encapsulating the conductor. The coating may be in direct contact with the conductor. The coating may be in direct contact with the insulating layer surrounding the conductor.

[0057] The polymer composition placed on the coated conductor may exhibit a relative standard deviation of its outer diameter of 0.5% or less, as measured by a smoothness test. For example, the relative standard deviation of the polymer composition may be 0.5% or less, or 0.4% or less, or 0.3% or less, or 0.2% or less, or 0.1% or less, as measured by a smoothness test.

[0058] Example

[0059] Test methods

[0060] Dissipation factor Dissipation factor was measured at 2.47 GHz according to ASTM 1531.

[0061] Dynamic mechanical spectrometry Dynamic mechanical spectroscopy allows for the measurement of frequency-dependent viscoelastic properties of polymer compositions. An ARES-G2 from TA Instruments was used. ™ Rotational rheometers are used for dynamic mechanical spectrometry with a parallel plate geometry having a diameter of 25 mm and a gap of 1.5 mm.

[0062] Smoothness test Smoothness testing is performed by taking a random 1cm length of a cable sample manufactured according to the sample preparation description provided below. The outer diameter of the cable sample is measured at 10 randomly selected points using a microscope. The standard deviation of the 10 data points is divided by the average of the 10 data points, and then the result is multiplied by 100 to obtain the RSD. Generally, the smaller the RSD, the smoother the cable surface.

[0063] Dynamic oscillation shear test Unless otherwise stated, all dynamic viscosities (η*) disclosed herein are calculated using dynamic oscillatory shear (DOS) and reported in Pascal-seconds (Pa·s).

[0064] The sample was compressed and molded into a circular sheet 1.3 mm thick × 25 mm in air at 25,000 psi for five minutes at 180 °C. The sample was then removed from the press and allowed to cool.

[0065] Isothermal frequency scanning was performed under nitrogen purging using a TA Instruments Advanced Rheological Extension System (ARES) equipped with a 25 mm (diameter) parallel plate. The sample was placed on the plate and allowed to melt at 190 °C for five minutes. The plate was then brought close together to a 2 mm gap, and the sample was trimmed (removing any excess sample extending beyond the perimeter of the 25 mm diameter plate), and then testing began. This method includes an additional five-minute delay to allow for temperature equilibration. Testing was conducted at 190 °C over a frequency range of 0.1 rad / s to 100 rad / s at a constant strain of 0.25%. IRIS was used. ™ A commercial software package uses the values ​​obtained from measurements of G' and G'' (dynamic storage modulus and loss modulus, respectively) relative to frequency to calculate the relaxation spectrum. The corresponding value of the relaxation spectral index (“RSI”) is then calculated from the relaxation spectrum.

[0066] The RSI is determined by first subjecting the combined first and second ethylene-based polymers (“polymers”) to low-shear deformation and then measuring their response to deformation using a rheometer. As is known in the art, based on the polymer’s response and the mechanical and geometrical characteristics of the rheometer used, the relaxation modulus G(t) or dynamic modulus G’(ω) and G’’(ω) can be determined as functions of time t or frequency ω, respectively (see J.M.Dealy and K.F. Wissbrun, Melt Rheology and Its Role in Plastics Processing, Van Nostrand Reinhold, 1990, pp. 269–297). The mathematical relationship between the dynamic modulus and the storage modulus is a Fourier transform integral relationship, but a set of data can also be calculated from another set of data using the well-known relaxation spectrum (see S.H. Wasserman, Journal of Rheology, Vol. 39, pp. 601–625 (1995)). Using the classic Maxwell's mechanics model, a discrete relaxation spectrum can be defined consisting of a series of relaxations or "modes," each with a characteristic intensity or "weight" and a relaxation time. Using such a spectrum, the modulus is re-expressed as:

[0067]

[0068] Where N is the number of relaxation modes, and g i and λ iThese represent the weights and time for each mode (see JD Ferry, *Viscoelastic Properties of Polymers*, John Wiley & Sons, 1980, pp. 224-263). Once the mode distribution in the relaxation spectrum is calculated, the first moment M, similar to the molecular weight distribution, is calculated as follows. n Second moment and M w The first and second moments of the distribution:

[0069]

[0070] Where RSI is defined as g II / g I .

[0071] Gel permeation chromatography The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven chamber was set to 165°C, and the column chamber and detector were set to 155°C. The column used was a mixed-pore size column with 4 TOSOH TSKgel GMHHR-H (30) HT 30-micron particle size. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm of butylated hydroxytoluene (BHT). The solvent source was nitrogen injection. The injection volume used was 200 μL, and the flow rate was 1.0 mL / min.

[0072] The calibration of the GPC column was performed using 21 narrow molecular weight distribution polystyrene standards ranging from 580 g / mol to 8,400,000 g / mol, arranged in a mixture of six "mixtures" with at least ten-fold intervals between individual molecular weights. The standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 g of polystyrene standard was prepared in 50 mL of solvent; for molecular weights less than 1,000,000, 0.05 g of polystyrene standard was prepared in 50 mL of solvent. Separately prepared polystyrene standards (both from Agilent Technologies) at concentrations of 10,000,000 g / mol and 15,000,000 g / mol were also prepared at concentrations of 0.5 mg / mL and 0.3 mg / mL, respectively. The polystyrene standard was pre-dissolved at 80°C with gentle stirring for 30 minutes, then cooled, and the room temperature solution was transferred to an autosampler dissolution oven at 160°C and cooled for 30 minutes. The peak molecular weight of the polystyrene standard was converted to the molecular weight of polyethylene using Equation 1 (as described in Williams and Ward, *Journal of Polymer Science: Polymer Letters*, 6, 621 (1968)).

[0073] M 聚乙烯 = A × (M 聚苯乙烯 ) B (Equation 1)

[0074] Where M is the molecular weight, A has a value of 0.4122, and B equals 1.0.

[0075] A third-order polynomial is used to fit the corresponding polyethylene equivalent calibration point.

[0076] Total plate counts of the GPC column were performed using decane, which was introduced into the blank sample via a micropump controlled by a PolymerChar GPC-IR system. For a mixed pore size column with 4 TOSOH TSKgel GMHHR-H (30) HT 30 μm particle size, the plate count of the chromatographic system should be greater than 12,000.

[0077] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm BHT) was added to a pre-bubbled, septum-capped vial via a PolymerChar high-temperature autosampler. The sample was then dissolved at 160°C for 2 hours with "low-speed" shaking.

[0078] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph, according to Equations 2 to 4, the PolymerChar GPCOne was used. ™ The software calculates the Mn content based on the baseline-subtracted IR chromatograms at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) according to Equation 1. (GPC) Mw (GPC) and Mz (GPC) The calculation.

[0079] (Equation 2)

[0080] (Equation 3)

[0081] (Equation 3)

[0082] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (nominal flow rate) for each sample by comparing the RV of the corresponding decane peak in the sample (RV(FM sample)) with the RV of the decane peak within the narrow standard calibration (RV(FM calibrated)). It was then assumed that any variation in the decane marker peak time was linearly related to the flow rate (effective flow rate) throughout the run. After calibration based on the flow rate marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated according to Equation 5. Processing of the flow rate marker peaks was performed using PolymerCharGPCOne. ™ The software performed the adjustment. Acceptable flow correction ensures that the effective flow should be within + / - 0.5% of the nominal flow.

[0083] Flow rate (effective) = Flow rate (nominal) * (RV (FM calibration) / RV (FM sample)) (Equation 5)

[0084] Material

[0085] HDPE 1 is a unimodal polyethylene with a density of 0.965 g / cc, a melt index (I2) of 8 g / 10 min at 190 °C, and exhibits a dissipation factor of less than 6.31E-05 as measured according to ASTM 1531 at 2.47 GHz. HDPE 1 is commercially available from The Dow Chemical Company, Midland, MI, USA, as DGDA-6944NT.

[0086] LDPE 1 is a polyethylene with a density of 0.918 g / cc, a melt index (I2) of 2.3 g / 10 min at 190 °C, a shear viscosity (v100) of 483 Pa·s at 170 °C, and exhibits a dissipation factor of less than 5.5E-04 as measured according to ASTM 1531 at 2.47 GHz. LDPE 1 is commercially available from Dow Chemical Company, Midland, Michigan, USA, as LDPE 770G.

[0087] HDPE 2 is a monomodal polyethylene with a density of 0.945 g / cc, a melt index (I2) of 0.8 g / 10 min at 190°C, and a melt flow ratio (I) of 80. 21 The shear viscosity (v100) at 170°C is 1107 Pa·s, the polydispersity index is 11.68, and the dissipation factor at 2.47 GHz is 7.8E-05 as measured according to ASTM 1531. These are commercially available from Dow Chemical Company, Midland, Michigan, USA, DFH-4580.

[0088] LDPE 2 is a polyethylene with a density of 0.921 g / cc, a melt index (I2) of 0.25 g / 10 min at 190 °C, a shear viscosity (v100) of 1150 Pa·s at 170 °C, and exhibits a dissipation factor of less than 6.4E-04 as measured according to ASTM 1531 at 2.47 GHz. LDPE 2 is commercially available from Dow Chemical Company, Midland, Michigan, USA, as LDPE 150E.

[0089] MB1 is a masterbatch consisting of LDPE (density 0.919 g / cc, melt index (I2) 1.8 g / 10 min) and 10 wt% azodicarbonamide based on the total weight of MB1. MB1 can be AXELERON ™ CX A-0012 NT CPD was purchased from Dow Chemical Company in Midland, Michigan.

[0090] MB2 is a masterbatch of LDPE (density 0.918 g / cc, melt index (I2) 2.3 g / 10 min) and 2 wt% azodicarbonamide based on the total weight of MB2. MB2 is commercially available from Dow Chemical Company, Midland, Michigan, DFNK-0012 NT.

[0091] AO1 is a sterically hindered phenolic antioxidant, chemically named pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, which can be marketed under the name IRGANOX. ™ 1010 was purchased from BASF in Ludwigshafen, Germany.

[0092] AO2 is a phenolic antioxidant (CAS 32687-78-8) with a density of 1.11 g / cc and the chemical formula 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionylhydrazine, which is available under the trade name IRGANOX 1024 from BASF in Ludwigshafen, Germany.

[0093] Sample preparation

[0094] Solid flakes for dissipation factor testing were prepared using a mold with sample dimensions of 100 mm × 100 mm × 1 mm. Sixteen grams of sample flakes were weighed and sandwiched between two 2 mm polyethylene terephthalate (“PET”) films. The sample and PET films were placed into the mold. The mold was clamped between the upper and lower plates of a thermopressor and preheated at 140°C and 0 MPa for 5 minutes. After preheating and venting eight times, the pressure was increased to 10 MPa and the temperature to 170°C. The mold was held at the temperature and pressure for 5 minutes. The mold was then cooled to approximately 23°C over 10 minutes at 10 MPa. The flakes were then removed from the mold for further testing.

[0095] Samples used for RSD testing were formed on an extrusion line manufactured by Rosendahl LLC, equipped with three different sizes of extruders, with the aim of a three-layer co-extrusion process. The extruders were operated with the parameters provided in Table 1.

[0096] Table 1

[0097]

[0098] result

[0099] Referring now to Table 2, compositions of Comparative Example 1 (“CE1”) and Examples 1 to 3 of the present invention (“IE1 to IE3”) are provided, wherein “DF” means dissipation factor.

[0100] Table 2

[0101]

[0102] As can be seen in Table 2, CE1 does not exhibit the expected RSD or DF. For example, the DF of CE1 far exceeds the target of 1.70E-04, and the RSD of CE1 is more than twice the target of 0.5%. Without being bound by theory, it is believed that the relatively low shear viscosity v100 of CE1's LDPE at 483 Pa·s is insufficient to stabilize bubble formation, thus leading to the high RSD value. Furthermore, the RSI of CE1 is below 30, indicating that the rheological properties of CE1 are poor compared to IE1 to IE3. Regarding IE1 to IE3, it goes without saying that these embodiments achieve the target DF and RSD characteristics. The combination of the properties of HDPE2 and LDPE2 not only achieves the target DF value in the non-foamed sample but also produces a very smooth foamed sample.

Claims

1. A polymer composition comprising: Based on the total weight of the polymer composition, 60% to 85% by weight of a first ethylene-based polymer, wherein the first ethylene-based polymer has a density of 0.93 g / cc to 0.97 g / cc as measured according to ASTM D792, and a polydispersity index of 7 or greater as measured according to gel permeation chromatography, and a shear viscosity v100 of 800 Pa·s or greater at 170°C as measured according to dynamic mechanical spectroscopy. Based on the total weight of the polymer composition, 15% to 40% by weight of a second ethylene-based polymer, wherein the second ethylene-based polymer has a density of 0.916 g / cc to 0.930 g / cc as measured according to ASTM D792, and a shear viscosity v100 of 800 Pa·s or greater at 170°C as measured by dynamic mechanical spectroscopy; and Based on the total weight of the polymer composition, 0.1% to 2.0% by weight of a foaming agent.

2. The polymer composition according to claim 1, wherein the foaming agent is selected from the group consisting of: polytetrafluoroethylene, azodicarbonamide, sodium bicarbonate, titanium hydride, ammonium carbonate, ammonium bicarbonate and calcium azide, expandable microspheres and combinations thereof.

3. The polymer composition according to any one of claims 1 and 2, wherein the polymer composition comprises 70% to 85% by weight of the first ethylene-based polymer based on the total weight of the polymer composition.

4. The polymer composition according to any one of claims 1 to 3, wherein the polymer composition comprises 75% to 85% by weight of the first ethylene-based polymer based on the total weight of the polymer composition, and the first ethylene-based polymer exhibits a melt flow rate of 70 or greater (I0). 21 / I2).

5. The polymer composition according to any one of claims 1 to 4, wherein the polymer composition comprises 15% to 25% by weight of the second ethylene-based polymer based on the total weight of the polymer composition.

6. The polymer composition according to any one of claims 1 to 5, wherein the second ethylene-based polymer has a shear viscosity v100 of 1000 Pa·s or greater at 170°C as measured by dynamic mechanical spectroscopy.

7. The polymer composition of claim 7, wherein the first ethylene-based polymer has a shear viscosity v100 of 1000 Pa·s or greater at 170°C as measured by dynamic mechanical spectroscopy.

8. The polymer composition according to any one of claims 1 to 7, wherein the polymer composition exhibits a polydispersity index of 10 or greater as measured by gel permeation chromatography.

9. The polymer composition of claim 8, wherein the polymer composition exhibits a polydispersity index of 11 or greater as measured by gel permeation chromatography.

10. A coated conductor, the coated conductor comprising: conductor; and The polymer composition according to any one of claims 1 to 9, wherein the polymer composition is coupled to the conductor, and wherein the polymer composition exhibits a relative standard deviation of its outer diameter of 0.5% or less as measured according to a smoothness test.

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