Flame-retardant polymer composition

Abstract

The polymeric composition includes a first ethylene-based polymer having a density of 0.93 g / cc to 0.97 g / cc as measured in accordance with ASTM D792, and a second ethylene-based polymer having a density of 0.93 g / cc to 0.97 g / cc as measured in accordance with ASTM D792, wherein the second ethylene-based polymer has a melt index (I2) of 3.0 g / 10 min or greater as measured in accordance with ASTM D1238, and the combination of the first ethylene-based polymer and the second ethylene-based polymer has a relaxation spectrum index value of 10 to 25, a polydispersity index of 10 or greater as measured in accordance with gel permeation chromatography, and a dynamic oscillatory shear viscosity at 100 rad / sec of 500 Pa.S or less as measured in accordance with ASTM D4440-15. The polymeric composition also includes a compatibilizer and a flame-retardant filler.

Description

[Technical Field]

[0001] The present disclosure relates to polymer compositions, and more particularly to flame retardant polymer compositions. [Background technology]

[0002] Introduction Cables typically use polymer compositions around one or more conductors (i.e., photoconductors and / or conductors). In such cables, flame retardancy may not be an important property considered for a particular element of the cable, and thus, the incorporation of flame-retardant materials into the elements has been limited. However, recently, flame-retardant standards have been refocused to target properties for the cable as a whole, rather than individual components. This change has led to a new emphasis on the flame retardancy of cable components. For example, a buffer tube containing a conventional unfilled polyolefin or other buffer tube without flame-retardant additives could result in flame-retardant-related failure of the entire cable, even if other components, such as the jacket, are flame-retardant. Therefore, to meet the new standard, the polymer composition of the buffer tube must have a flame retardancy of 250 kilowatts per square meter ("kW / m") as measured in accordance with ASTM E1354. 2 The test material must exhibit a Peak Heat Release Rate (PHRR) from cone calorimetry of less than 1000 kJ / cm2.

[0003] Traditional methods for adding flame retardancy to polymer compositions involve selecting a flexible base polyolefin (i.e., one with a low flexural modulus) and a flame-retardant filler for incorporation into the polyolefin. Utilizing this approach in buffer tubes is challenging for several reasons. First, the tensile elongation and flexural modulus of the buffer tube are important, and incorporating polyolefins with the typical low flexural modulus (e.g., 100 MPa to 200 MPa) used in flame-retardant polyolefins results in a buffer tube with an inappropriately low flexural modulus. Typically, buffer tubes require a tensile elongation of greater than 20% and a flexural modulus of greater than 950 MPa. Second, buffer tubes must process well at high extrusion rates (i.e., without tube breakage or dimensional defects). However, halogen-free flame-retardant fillers ("HFFRs") are typically included at levels of 60% by weight or greater, which significantly increases melt viscosity, impairing processability and adversely affecting final mechanical properties. To extrude buffer tubes quickly enough to be commercially viable, the shear viscosity of the buffer tube material at relatively high shear rates—for example, the dynamic oscillatory shear viscosity measured at 100 rad / s, which indicates how easily the material can be extruded—should be 500 Pascal-seconds ("Pa.s") or less as measured in accordance with ASTM D4440-15. Third, simply incorporating a flame-retardant filler is not sufficient to impart flame retardancy. Without proper compatibilization and dispersion, the flame-retardant filler may agglomerate within the polymer composition, resulting in minimal flame retardancy and reduced mechanical properties. Furthermore, incomplete dispersion of HFFR within the polymer composition can lead to fracture or cracking of the polymer composition when subjected to a mandrel bend test. Such results suggest that buffer tubes constructed from the polymer composition may fracture or crack during use.

[0004] The combination of ionomers and maleic anhydride-grafted polymers is known in the art. For example, U.S. Patent No. 6,569,947 (B1) ("'947 Patent") discloses a maleic anhydride-modified ethylene polymer / ionomer / high-density polyethylene blend useful in high-impact materials. However, such blends are only believed to be beneficial for improving impact properties, and no effect on flame retardancy has been known.

[0005] Taking the above into consideration, 250 kW / m when measured according to ASTM E1354 2 It is surprising to find a polymer composition that exhibits a PHRR of less than 100 MPa when measured according to ASTM D638, an elongation of greater than 20% when measured according to ASTM D638, a flexural modulus of greater than 950 MPa when measured according to ASTM D790, a dynamic oscillatory shear viscosity at 100 rad / sec of less than or equal to 500 Pa.s when measured according to ASTM D4440-15, and does not fracture or crack when subjected to a mandrel bend test. Summary of the Invention

[0006] The present inventors have reported a power rating of 250 kW / m when measured according to ASTM E1354. 2 have discovered polymer compositions that exhibit a PHRR of less than 100 psi, an elongation of greater than 20% as measured in accordance with ASTM D638, a flexural modulus of greater than 950 MPa as measured in accordance with ASTM D790, a dynamic oscillatory shear viscosity at 100 rad / sec of less than or equal to 500 Pa.s as measured in accordance with ASTM D4440-15, and that do not fracture or crack when subjected to a mandrel bend test.

[0007] The present invention is the result of the discovery that a polymer composition comprising a blend of an ethylene-based polymer, a flame-retardant filler, and a compatibilizer can achieve the above-mentioned properties. Specifically, it has been discovered that these results can be achieved by utilizing a blend of high-density ethylene-based polymers. Specifically, the blend should include a first ethylene-based polymer having a broad molecular weight distribution and a low melt index, and a second ethylene-based polymer having a narrow molecular weight distribution but a high melt index, and the blend exhibits a relaxation spectrum index of 10 to 25, a polydispersity index of 10 or greater as measured according to gel permeation chromatography, and a dynamic oscillatory shear viscosity at 100 rad / s of 500 Pa.s or less as measured according to ASTM D4440-15. Without wishing to be bound by theory, it is believed that the low melt index of the first ethylene-based polymer provides sufficient viscous shear-induced stress to disperse the HFFR filler during melt mixing, thereby homogenizing the filler in the polymer matrix and thus achieving effective flame retardancy and mechanical properties. The high melt index of the second ethylene-based polymer is believed to help reduce the overall compound viscosity, thereby aiding in the processability of the polymer composition. Furthermore, the enhanced relaxation spectrum index (RSI) and polydispersity index improve the physical properties of the blend, allowing high-speed extrusion to be achieved despite high filler incorporation. By combining two ethylene-based polymers, a compatibilizer, and a silane-treated flame-retardant filler, the above properties can be achieved in the polymer composition. Furthermore, removal of undispersed particles larger than 140 μm by melt filtration during the compounding process reduces defects that may occur during high-speed extrusion of thin-walled buffer tubes.

[0008] According to a first aspect of the present disclosure, a polymer composition includes a first ethylene-based polymer having a density from 0.93 g / cc to 0.97 g / cc as measured in accordance with ASTM D792, the first ethylene-based polymer having a melt index (I2) of 0.8 g / 10 minutes or less as measured in accordance with ASTM D1238; and a second ethylene-based polymer having a density from 0.93 g / cc to 0.97 g / cc as measured in accordance with ASTM D792, the second ethylene-based polymer having a melt index (I2) of 3.0 g / 10 minutes or greater as measured in accordance with ASTM D1238, the combination of the first ethylene-based polymer and the second ethylene-based polymer having a relaxation spectrum index value of 10 to 25, a polydispersity index of 10 or greater as measured in accordance with Gel Permeation Chromatography, and a polydispersity index of 10 or greater as measured in accordance with ASTM D1238. a second ethylene-based polymer having a dynamic oscillatory shear viscosity at 100 radians / second of 500 Pa.S or less, as measured in accordance with D4440-15; a compatibilizer; and a flame-retardant filler.

[0009] According to a second aspect of the present disclosure, the compatibilizer is selected from the group consisting of maleic anhydride grafted polymers, acid copolymers, and ionomers.

[0010] According to a third aspect of the present disclosure, the flame-retardant filler is a silane-treated flame-retardant filler, and the polymer composition comprises 10 wt% to 80 wt% of the silane-treated flame-retardant filler, based on the total weight of the polymer composition.

[0011] According to a fourth aspect of the present disclosure, the polymer composition comprises 5% to 30% by weight of a first ethylene-based polymer, based on the total weight of the polymer composition.

[0012] According to a fifth aspect of the present disclosure, the polymer composition comprises 1 wt % to 20 wt % of a second ethylene-based polymer, based on the total weight of the polymer composition.

[0013] According to a sixth feature of the present disclosure, the weight ratio of the first ethylene-based polymer to the second ethylene-based polymer is from 1:1 to 3:1.

[0014] According to a seventh feature of the present disclosure, the first ethylene-based polymer has a melt index (I2) less than or equal to 0.5 g / 10 min, as measured in accordance with ASTM D1238, and the second ethylene-based polymer has a melt index (I2) greater than or equal to 6 g / 10 min, as measured in accordance with ASTM D1238.

[0015] According to an eighth feature of the present disclosure, the combined first and second ethylene-based polymers have a relaxation spectrum index value of 15-21.

[0016] According to a ninth aspect of the present disclosure, the polymer composition has a thermal conductivity of 250 kW / m when measured in accordance with ASTM E1354. 2 The composition exhibits a PHHR of less than 100 MPa, an elongation of greater than 20% when measured according to ASTM D638, and a flexural modulus of greater than 950 MPa when measured according to ASTM D790.

[0017] According to a tenth aspect of the present disclosure, a cable includes a conductor and a buffer tube positioned around the conductor, the buffer tube including a polymer composition. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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 can be used by itself, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0019] Unless otherwise stated, all ranges are inclusive of the endpoints.

[0020] Test methods refer to the most current test method as of the priority date of this document unless the test method number indicates a date with a two-digit hyphen. References to test methods include references to both the testing organization and the test method number. Test method organizations are referred to by one of the following abbreviations: ASTM refers to ASTM International (formerly the American Society for Testing and Materials), IEC refers to the International Electrotechnical Commission, EN refers to European Norm, DIN refers to the Deutsches Institut fur Normung, and ISO refers to the International Organization for Standards.

[0021] As used herein, the term weight percent ("wt. %") refers to the weight percentage that a component represents of the total weight of the polymer composition, unless otherwise specified.

[0022] As used herein, melt index (I2) values ​​refer to values ​​determined according to ASTM method D1238 at 190 degrees Celsius (°C) using a mass of 2.16 kilograms (Kg) and are provided in units of grams dissolved per 10 minutes ("g / 10 min").

[0023] Density values ​​herein refer to values ​​determined in accordance with ASTM D792 at 23° C. and are provided in units of grams per cubic centimeter ("g / cc").

[0024] As used herein, Chemical Abstract Services Registry Number ("CAS#") refers to the unique numeric identifier last assigned to a chemical compound by the Chemical Abstract Service as of the priority date of this document.

[0025] polymer composition The present disclosure relates to a polymer composition that includes a first ethylene-based polymer, a second ethylene-based polymer, a compatibilizer, and a silane-treated flame-retardant filler.

[0026] The polymer composition may exhibit a variety of properties. The polymer composition may exhibit a thermal conductivity of 250 kW / m as measured using cone calorimetry according to ASTM E1354. 2 For example, the polymer composition may exhibit a PHRR of less than 250 kW / m when measured according to ASTM E1354. 2 Less than or 240kW / m 2 or less than 230kW / m 2 or less, or 220kW / m 2 or less than 210kW / m 2 or less than 200kW / m 2 or less, or 190kW / m 2 or less, or 180kW / m 2 or less, or 170kW / m 2 or less than 160kW / m 2 or less, or 150kW / m 2 or less, or 140kW / m 2 or less, or 130kW / m 2 or less, or 120kW / m 2 or less than 110kW / m 2 or less than 100kW / m 2 or less, or 90kW / m 2 or less, or 80kW / m 2 or less than 70kW / m 2 or less than 60kW / m 2 or less than 50kW / m 2 The following PHRRs may be present:

[0027] The polymeric composition may exhibit an elongation at break of greater than 20% when measured according to ASTM D638. For example, the polymeric composition may exhibit an elongation at break of 21% or more, or 22% or more, or 23% or more, or 24% or more, or 25% or more, or 26% or more, or 27% or more, or 28% or more, or 29% or more, or 30% or more, or 40% or more, or 50% or more, or 75% or more, or 100% or more, or 175% or more, or 180% or more, or 190% or more, or 200% or more, or 225% or more, or 250% or more, or 275% or more, or 300% or more, while simultaneously 350% or less, or 300% or less, or 250% or less, or 200% or less, or 150% or less, or 100% or less, or 50% or less, or 30% or less, when measured according to ASTM D638.

[0028] The polymeric composition may exhibit a flexural modulus of 950 MPa or greater. For example, the polymeric composition may have a flexural modulus of 950 MPa or greater, or 1,000 MPa or greater, or 1,100 MPa or greater, or 1,200 MPa or greater, or 1,300 MPa or greater, or 1,400 MPa or greater, or 1,500 MPa or greater, or 1,600 MPa or greater, or 1,700 MPa or greater, or 1,800 MPa or greater, or 1,900 MPa or greater, or 2,000 MPa or greater, or 2,100 MPa or greater, or 2,200 MPa or greater, or 2,300 MPa or greater, or 2,400 MPa or greater, or 2,500 MPa or greater, or 2,600 MPa or greater, or 2,700 MPa or greater, or 2,800 MPa or greater, or 2,900 MPa or greater, when measured according to ASTM D790. and simultaneously exhibit a flexural modulus of 3,000 MPa or less, or 2,900 MPa or less, or 2,800 MPa or less, or 2,700 MPa or less, or 2,600 MPa or less, or 2,500 MPa or less, or 2,400 MPa or less, or 2,300 MPa or less, or 2,200 MPa or less, or 2,100 MPa or less, or 2,000 MPa or less, or 1,900 MPa or less, or 1,800 MPa or less, or 1,700 MPa or less, or 1,600 MPa or less, or 1,500 MPa or less, or 1,400 MPa or less, or 1,300 MPa or less, or 1,200 MPa or less, or 1,100 MPa or less, or 1,000 MPa or less.

[0029] The polymer composition may exhibit a dynamic oscillatory shear viscosity at 0.1 radians / second of less than 46,000 Pa.s when measured in accordance with ASTM D4440-15. For example, the polymer composition may exhibit a dynamic oscillatory shear viscosity at 0.1 radians / second of less than 46,000 Pa.s, or 40,000 Pa.s or less, or 35,000 Pa.s or less, or 30,000 Pa.s or less, or 25,000 Pa.s or less, or 20,000 Pa.s or less, or 15,000 Pa.s or less, or 10,000 Pa.s or less when measured in accordance with ASTM D4440-15.

[0030] The polymer composition may exhibit a dynamic oscillatory shear viscosity at 100 radians / second of less than or equal to 500 Pa.s, as measured according to ASTM D4440-15. For example, the polymer composition may exhibit a dynamic oscillatory shear viscosity at 100 rad / sec of 1 Pa.s or more, or 10 Pa.s or more, or 50 Pa.s or more, or 100 Pa.s or more, or 150 Pa.s or more, or 200 Pa.s or more, or 250 Pa.s or more, or 300 Pa.s or more, or 350 Pa.s or more, or 400 Pa.s or more, or 450 Pa.s or more, while simultaneously 500 Pa.s or less, or 450 Pa.s or less, or 400 Pa.s or less, or 350 Pa.s or less, or 300 Pa.s or less, or 250 Pa.s or less, or 200 Pa.s or less, or 150 Pa.s or less, or 10 Pa.s or less, or 50 Pa.s or less, when measured according to ASTM D4440-15.

[0031] First ethylene-based polymer As noted above, the composition can include a first ethylene-based polymer. As used herein, an "ethylene-based" polymer is a polymer in which greater than 50% by weight of the monomers are ethylene, although other comonomers may be used. Ethylene-based polymers are polymers in which ethylene and one or more C3-C6 comonomers, such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene, are copolymers of these comonomers. 20 and an α-olefin comonomer.

[0032] The ethylene-based polymer has an OC value of 50% by weight or greater, 60% by weight or greater, 70% by weight or greater, 80% by weight or greater, 85% by weight or greater, 90% by weight or greater, or 91% by weight or greater, or 92% by weight or greater, or 93% by weight or greater, or 94% by weight or greater, or 95% by weight or greater, or 96% by weight or greater, or 97% by weight or greater, or 97.5% by weight or greater, or 98% by weight or greater, as measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy. % or more, or 99% or more by weight, while at the same time comprising 99.5% or less, or 99% or less, or 98% or less, or 97% or less, or 96% or less, or 95% or less, or 94% or less, or 93% or less, or 92% or less, or 91% or less, or 90% or less, or 85% or less, or 80% or less, or 70% or less, or 60% or less by weight of ethylene monomer.

[0033] Other units of the ethylene-based polymer may be derived from one or more polymerizable monomers, including, but not limited to, polar monomers such as unsaturated esters. The unsaturated esters (i.e., polar monomers) may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. The alkyl groups may have 1 to 8 carbon atoms or 1 to 4 carbon atoms. The carboxylate groups may 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, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate. The ethylene-based polymer can 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% or less, or 5% or less, or 3% or less, or 1% or less, or 0% by weight, based on the total weight of the ethylene-based polymer, as measured using Nuclear Magnetic Resonance (NMR) or Fourier-Transform Infrared (FTIR) spectroscopy.

[0034] 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 differing in monomer composition and content, catalyst preparation, molecular weight, molecular weight distribution, density, etc.). When a blend of ethylene-based polymers is used, the polymers can be blended by any in-reactor or post-reactor process. The term "multimodal polymer" refers to a polymer characterized by having at least two distinct peaks in a gel permeation chromatography (GPC) chromatogram indicative of the molecular weight distribution of the composition. Thus, the generic term multimodal polymer includes bimodal polymers having two major 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.

[0035] The first ethylene-based polymer has a density of 0.93 g / cc to 0.97 g / cc, as measured in accordance with ASTM D 792. For example, the first ethylene-based polymer has a density of 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 having a density of 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 in accordance with ASTM D 792. Generally, ethylene-based polymers having a density between 0.93 g / cc and 0.97 g / cc are referred to as "high density polyethylene" or "HDPE."

[0036] The first ethylene-based polymer has a melt index (I2) less than or equal to 0.8 g / 10 minutes, as measured according to ASTM D 1238. For example, the first ethylene-based polymer has a melt index (I2) less than or equal to 0.8 g / 10 minutes, or less than or equal to 0.7 g / 10 minutes, or less than or equal to 0.6 g / 10 minutes, or less than or equal to 0.5 g / 10 minutes, or less than or equal to 0.4 g / 10 minutes, or less than or equal to 0.3 g / 10 minutes, or less than or equal to 0.2 g / 10 minutes, or less than or equal to 0.1 g / 10 minutes, as measured according to ASTM D 1238.

[0037] The polymer composition can comprise from 5% to 30% by weight of the first ethylene-based polymer, based on the total weight of the polymer composition. For example, the polymer composition can comprise 5% or more, or 10% or more, or 15% or more, or 20% or more, or 25% or more by weight, while simultaneously comprising 30% or less, or 25% or less, or 20% or less, or 15% or less, or 10% or less by weight of the first ethylene-based polymer, based on the total weight of the polymer composition.

[0038] Second ethylene-based polymer The polymer composition includes a second ethylene-based polymer. The second ethylene-based polymer has a density of 0.93 g / cc to 0.97 g / cc, as measured in accordance with ASTM D 792. For example, the second ethylene-based polymer has a density of 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 having a density of 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 in accordance with ASTM D 792.

[0039] The second ethylene-based polymer has a melt index (I2) of 3.0 or more, or g / 10 minutes, as measured in accordance with ASTM D 1238. For example, 3.0 or more, or g / 10 minutes, or 3.5 or more, or 4.0 or more, or g / 10 minutes, or 4.5 or more, or 5.0 or more, or 5.5 or more, or 6.0 or more, or 6.5 or more, or 7.0 or more, or 7.5 or more, or 8.0 or more, or 8.5 or more, or 9 or more, as measured in accordance with ASTM D 1238. 0.0 or g / 10 min or more, or 9.5 or g / 10 min or more, while simultaneously being 10.0 g / 10 min or less, or 9.5 g / 10 min or less, or 9.0 g / 10 min or less, or 8.5 g / 10 min or less, or 8.0 g / 10 min or more, or 7.5 g / 10 min or less, or 7.0 g / 10 min or less, or 6.5 g / 10 min or less, or 6.0 g / 10 min or less, or 5.5 g / 10 min or less, or 5.0 g / 10 min or less, or 4.5 g / 10 min or less, or 4.0 g / 10 min or less, or 3.5 g / 10 min or less.

[0040] The polymer composition can comprise from 1 wt% to 20 wt% of the second ethylene-based polymer, based on the total weight of the polymer composition. For example, the polymer composition can comprise 1 wt% or more, or 2 wt% or more, or 4 wt% or more, or 6 wt% or more, or 8 wt% or more, or 10 wt% or more, or 12 wt% or more, or 14 wt% or more, or 16 wt% or more, or 18 wt% or more, while simultaneously comprising 20 wt% or less, or 18 wt% or less, or 16 wt% or less, or 14 wt% or less, or 12 wt% or less, or 10 wt% or less, or 8 wt% or less, or 6 wt% or less, or 4 wt% or less, or 2 wt% or less of the second ethylene-based polymer, based on the total weight of the polymer composition.

[0041] The polymer composition can have a weight ratio of the first ethylene-based polymer to the second ethylene-based polymer of from 1:1 to 3:1. The weight ratio of the first ethylene-based polymer to the second ethylene-based polymer is determined by dividing the weight percent of the first ethylene-based polymer in the polymer composition, based on the total weight of the polymer composition, by the weight percent of the second ethylene-based polymer in the polymer composition, based on the total weight of the polymer composition, and using the quotient as X in the expression "X:1" to express the weight ratio. The weight ratio of the first ethylene-based polymer to the second ethylene-based polymer is from 1:1 or greater, or 1.2:1 or greater, or 1.4:1 or greater, or 1.6:1 or greater, or 1.8:1 or greater, or 2.0:1 or greater, or 2.2:1 or greater, or 2.4:1 or greater, or 2.6:1 or greater, or 2.8:1 or greater, or 3:1.

[0042] Combined First Ethylene-Based Polymer and Second Ethylene-Based Polymer The combined first and second ethylene-based polymers have a relaxation spectrum index value, as calculated from dynamic oscillatory shear testing, described in more detail below, of 10 to 25. For example, the RSI value, as calculated from dynamic oscillatory shear testing, can be 10 or greater, or 11 or greater, or 12 or greater, or 13 or greater, or 14 or greater, or 15 or greater, or 16 or greater, or 17 or greater, or 18 or greater, or 19 or greater, or 20 or greater, or 21 or greater, or 22 or greater, or 23 or greater, or 24 or greater, while simultaneously being 25 or less, or 24 or less, or 23 or less, or 22 or less, or 21 or less, or 20 or less, or 19 or less, or 18 or less, or 17 or less, or 16 or less, or 15 or less, or 14 or less, or 13 or less, or 12 or less, or 11 or less.

[0043] The combined first ethylene-based polymer and second ethylene-based polymer have a polydispersity index value, as measured according to gel permeation chromatography, of greater than 10. For example, the polydispersity index value can be 10.1 or greater, or 11 or greater, or 12 or greater, or 13 or greater, or 14 or greater, or 15 or greater, or 16 or greater, or 17 or greater, or 18 or greater, or 19 or greater, or 20 or greater, or 21 or greater, or 22 or greater, or 23 or greater, or 24 or greater, while simultaneously being 25 or less, or 24 or less, or 23 or less, or 22 or less, or 21 or less, or 20 or less, or 19 or less, or 18 or less, or 17 or less, or 16 or less, or 15 or less, or 14 or less, or 13 or less, or 12 or less, or 11 or less, as measured according to gel permeation chromatography.

[0044] Compatibilizer The polymer composition includes a compatibilizer, which may be one or more of a maleic anhydride grafted polymer, an acid copolymer, and an ionomer.

[0045] Maleic Anhydride Functionalized Polyolefins The polymer composition may include a maleic anhydride-functionalized polyolefin. As used herein, the term "maleic anhydride-functionalized" refers to a polyolefin that has been modified to incorporate maleic anhydride monomers. The maleic anhydride-functionalized polyolefin may be formed by copolymerizing maleic anhydride monomers with ethylene and other monomers, if present, to prepare an interpolymer having maleic anhydride incorporated into the polymer backbone. Additionally or alternatively, the maleic anhydride may be graft-polymerized onto the polyolefin. The maleic anhydride-functionalized polyolefin may be any of the ethylene-based polymers described above.

[0046] The maleic anhydride functionalized polyolefin may have a density of 0.87 g / cc or more, or 0.88 g / cc or more, or 0.89 g / cc or more, or 0.90 g / cc or more, or 0.91 g / cc or more, or 0.92 g / cc or more, or 0.93 g / cc or more, or 0.94 g / cc or more, or 0.95 g / cc or more, 0.96 g / cc or more, while simultaneously 0.97 g / cc or less, or 0.965 g / cc or less, or 0.96 g / cc or less, or 0.95 g / cc or less, or 0.94 g / cc or less, or 0.93 g / cc or less, or 0.92 g / cc or less, or 0.91 g / cc or less, or 0.90 g / cc or less, or 0.89 g / cc or less, or 0.88 g / cc or less, or 0.87 g / cc or less, as measured by ASTM D792.

[0047] The maleic anhydride functionalized polyolefin has a viscosity of 1 g / 10 min or greater, or 2 g / 10 min or greater, or 3 g / 10 min or greater, or 4 g / 10 min or greater, or 5 g / 10 min or greater, or 6 g / 10 min or greater, or 7 g / 10 min or greater, or 8 g / 10 min or greater, or 9 g / 10 min or greater, or 10 g / 10 min or greater, or 11 g / 10 min or greater, or 12 g / 10 min or greater, or 13 g / 10 min or greater, or 14 g / 10 min or greater, or 15 g / 10 min or greater, or 16 g / 10 min or greater, or 17 g / 10 min or greater, or 18 g / 10 min or greater, or 19 g / 10 min or greater, while simultaneously being 20 g / 10 min or less, or has a melt flow index of 19 g / 10 min or less, or 18 g / 10 min or less, or 17 g / 10 min or less, or 16 g / 10 min or less, or 15 g / 10 min or less, or 14 g / 10 min or less, or 13 g / 10 min or less, or 12 g / 10 min or less, or 11 g / 10 min or less, or 10 g / 10 min or less, or 9 g / 10 min or less, or 8 g / 10 min or less, or 7 g / 10 min or less, or 6 g / 10 min or less, or 5 g / 10 min or less, or 4 g / 10 min or less, or 3 g / 10 min or less, or 2 g / 10 min or less. MFI is measured at 190°C and 2.16 kg according to ASTM D1238.

[0048] The maleic anhydride-functionalized polyolefin may have a maleic anhydride content of 0.25 wt% or more, or 0.50 wt% or more, or 0.75 wt% or more, or 1.00 wt% or more, or 1.25 wt% or more, or 1.50 wt% or more, or 1.75 wt% or more, or 2.00 wt% or more, or 2.25 wt% or more, or 2.50 wt% or more, or 2.75 wt% or more, while simultaneously being 3.00 wt% or less, 2.75 wt% or less, or 2.50 wt% or less, or 2.25 wt% or less, or 2.00 wt% or less, or 1.75 wt% or less, or 1.50 wt% or less, or 1.25 wt% or less, or 1.00 wt% or less, or 0.75 wt% or less, or 0.5 wt% or less, based on the total weight of the maleic anhydride-functionalized polyolefin. The maleic anhydride concentration is determined by titration analysis. Titration analysis is performed by utilizing the dried resin and titrating it with 0.02N KOH to determine the amount of maleic anhydride. The dried polymer is titrated by dissolving 0.3-0.5 grams of maleic anhydride-functionalized polyolefin in approximately 150 mL of refluxing xylene. After complete dissolution, deionized water (4 drops) is added to the solution, and the solution is refluxed for 1 hour. 1% thymol blue (a few drops) is then added to the solution, and the solution is titrated with 0.02N KOH in ethanol, as indicated by the formation of a purple color. The solution is then back-titrated with 0.05N HCl in isopropanol to a yellow endpoint.

[0049] The polymer composition may comprise 4 wt% or more, or 5 wt% or more, or 6 wt% or more, or 7 wt% or more, or 8 wt% or more, or 9 wt% or more, or 10 wt% or more, or 11 wt% or more, or 12 wt% or more, or 13 wt% or more, or 14 wt% or more, or 15 wt% or more, or 16 wt% or more, or 17 wt% or more, while simultaneously 18 wt% or less, or 17 wt% or less, or 16 wt% or less, or 15 wt% or less, or 14 wt% or less, or 13 wt% or less, or 12 wt% or less, or 11 wt% or less, or 10 wt% or less, or 9 wt% or less, or 8 wt% or less, or 7 wt% or less, or 6 wt% or less, or 5 wt% or less, or 4 wt% or less of maleic anhydride functionalized polyolefin, based on the total weight of the polymer composition.

[0050] An example of a suitable commercially available maleic anhydride functionalized polyolefin is AMPLIFY™ GR208, available from The Dow Chemical Company (Midland, MI, USA).

[0051] Acid Copolymers and Ionomers The polymer composition includes an acid copolymer and / or an ionomer. As used herein, the term "acid copolymer" refers to a copolymer including repeat units derived from ethylene and 1 wt % to 50 wt %, based on the total weight of the acid copolymer, of an acidic comonomer, such as acrylic acid, methacrylic acid, ethacrylic acid, or a combination thereof. As used herein, the term "ionomer" refers to a partially or fully neutralized acid copolymer.

[0052] The acid copolymer or ionomer may contain up to 35 wt. % of optional comonomers, based on the total weight of the ionomer. Potential comonomers include carbon monoxide, sulfur dioxide, acrylonitrile, maleic anhydride, maleic acid diesters, maleic acid, maleic acid monoesters, itaconic acid, fumaric acid, fumaric acid monoesters, salts of these acids, glycidyl acrylate, glycidyl methacrylate, and glycidyl vinyl ether, methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, pentyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, pentyl methacrylate, or combinations thereof, where the alkyl group may be linear or branched.

[0053] Ionomers can have a wide range of neutralization degrees. For example, the ionomers can be neutralized at 0.1% or more, or 1% or more, or 10% or more, or 15% by weight or more, or 20% or more, or 30% or more, or 40% or more, or 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more, while simultaneously at 100% or less, or 90% or less, or 80% or less, or 70% or less, or 60% or less, or 50% or less, or 40% or less, or 30% or less, or 20% or less, or 15% by weight or less, or 10% or less, or 5% or less, based on the total acid content. The ionomers can be neutralized using one or more metal ions. The metal ions can be monovalent, divalent, trivalent, polyvalent, or a combination thereof. Examples of suitable metal ions include Li, Na, Ag, Hg, Cu, Be, Mg, Ca, Sr, Ba, Cd, Sn, Pb, Fe, Co, Zn, Ni, Al, Sc, Hf, Ti, Zr, Ce, K, Na, and combinations thereof. When the metal ion is multivalent, complexing agents such as stearate, oleate, salicylate, and phenolate radicals may be included.

[0054] The ionomer may be a blend of an ionomer having greater than 20% neutralization with, for example, a second ethylene acid copolymer to achieve the desired degree of neutralization. For example, the ionomer may comprise 1% to 50% by weight of the acid copolymer disclosed above.

[0055] Examples of commercially available ionomers include SURLYN™ ionomers available from The Dow Chemical Company (Midland, MI, USA).

[0056] The polymer composition comprises 1 wt % to 10 wt % of the acid copolymer and / or ionomer, based on the total weight of the polymer composition. For example, the polymer composition comprises one or more of 1 wt % or more, or 2 wt % or more, or 3 wt % or more, or 4 wt % or more, or 5 wt % or more, or 6 wt % or more, or 7 wt % or more, or 8 wt % or more, or 9 wt % or more, while simultaneously comprising 10 wt % or less, or 9 wt % or less, or 8 wt % or less, or 7 wt % or less, or 6 wt % or less, or 5 wt % or less, or 4 wt % or less, or 3 wt % or less, or 2 wt % or less of the acid copolymer and / or ionomer, based on the total weight of the polymer composition.

[0057] Flame-retardant filler The polymer composition includes a flame-retardant filler. The flame retardant of the polymer composition can inhibit, suppress, or delay the onset of flame. Examples of flame retardants suitable for use in the polymer composition include, but are not limited to, metal hydroxides, metal carbonates, red phosphorus, silica, alumina, aluminum trihydroxide, magnesium hydroxide, titanium oxide, carbon nanotubes, talc, clay, organically modified clay, calcium carbonate, zinc borate, antimony trioxide, wollastonite, mica, ammonium octamolybdate, frit, hollow glass microspheres, expandable compounds, expandable graphite, and combinations thereof. Specifically, the halogen-free flame retardant may be selected from the group consisting of aluminum hydroxide, magnesium hydroxide, calcium carbonate, and combinations thereof. The flame-retardant filler may be silane-treated. The silane-treated flame-retardant filler is surface-treated with vinyl silane. In addition to the silane surface treatment, the flame retardant may optionally be surface treated (coated) with a saturated or unsaturated carboxylic acid having 8 to 24 carbon atoms or 12 to 18 carbon atoms, or a metal salt of such an acid. Exemplary surface treatments are described in U.S. Patent Nos. 4,255,303, 5,034,442, and 7,514,489, U.S. Patent Application Publication No. 2008 / 0251273, and WO 2013 / 116283.

[0058] Examples of commercially available flame retardants suitable for use in the polymer compositions include, but are not limited to, MAGNIFIN™ H5A magnesium hydroxide available from Magnifin Magnesiaprodukte GmbH & Co KG.

[0059] The polymer composition may include the flame retardant filler in a concentration of 10% to 80% by weight, based on the total weight of the polymer composition. For example, the polymer composition may comprise 10 wt. % or more, or 20 wt. % or more, or 22 wt. % or more, or 24 wt. % or more, or 26 wt. % or more, or 28 wt. % or more, or 30 wt. % or more, or 32 wt. % or more, or 34 wt. % or more, or 36 wt. % or more, or 38 wt. % or more, or 40 wt. % or more, or 42 wt. % or more, or 44 wt. % or more, or 46 wt. % or more, or 48 wt. % or more, or 50 wt. % or more, or 52 wt. % or more, or 54 wt. % or more, or 56 wt. % or more, or 58% or more, or 60 wt. % or more, or 62 wt. % or more, or 64 wt. % or more, or 66 wt. % or more, or 68% or more, or 70 wt. % or more, or 72 wt. % or more, or 74 wt. % or more, or 76 wt. % or more, or 78% or more, based on the weight of the polymer composition. or less, or 78% by weight or less, or 76% by weight or less, or 74% by weight or less, or 72% by weight or less, or 70% by weight or less, or 68% by weight or less, or 66% by weight or less, or 64% by weight or less, or 62% by weight or less, or 60% by weight or less, or 58% by weight or less, or 56% by weight or less, or 54% by weight or less, or 52% by weight or less, or 50% by weight or less, or 48% by weight or less, or 46% by weight or less, or 44% by weight or less, or 42% by weight or less, or 40% by weight or less, or 38% by weight or less, or 36% by weight or less, or 34% by weight or less, or 32% by weight or less, or 30% by weight or less, or 28% by weight or less, or 26% by weight or less, or 24% by weight or less, or 22% by weight or less, or 20% by weight or less.

[0060] additives The polymer composition may contain additional additives in the form of antioxidants, crosslinking coagents, cure accelerators and char retarders, processing aids, coupling agents, ultraviolet stabilizers (including UV absorbers), antistatic agents, additional nucleating agents, slip agents, lubricants, viscosity modifiers, tackifiers, antiblocking agents, surfactants, extender oils, acid scavengers, anti-drip agents (e.g., ethylene vinyl acetate), and metal deactivators. The polymer composition may contain from 0.01% to 20% by weight of one or more of the additional additives.

[0061] UV light stabilizers can include hindered amine light stabilizers ("HALS") and UV light absorber ("UVA") additives. Exemplary UVA additives include benzotriazole types such as TINUVIN 326™ and TINUVIN 328™ light stabilizers available from Ciba, Inc. Blends of HAL's and UVA additives are also effective.

[0062] Antioxidants include hindered phenols such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydro-cinnamate)]methane; bis[(beta-(3,5-di-tert-butyl-4-hydroxybenzyl)methylcarboxyethyl)]-sulfide, 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiobis(2-tert-butyl-5-methylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), and thiodiethylenebis(3,5-di-tert-butyl-4-hydroxy)-hydrocinnamate; tris(2,4-di-tert-butylphenyl)phosphazene; thio compounds such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate; various siloxanes; polymeric 2,2,4-trimethyl-1,2-dihydroquinoline, n,n'-bis(1,4-dimethylpentyl-p-phenylenediamine), alkylated diphenylamines, 4,4'-bis(alpha,alpha-dimethylbenzyl)diphenylamine, diphenyl-p-phenylenediamine, mixed diaryl-p-phenylenediamines, and other hindered amine antidegradants or stabilizers.

[0063] Processing aids may include metal salts of carboxylic acids such as zinc stearate or calcium stearate; fatty acids such as stearic acid, oleic acid, or erucic acid; fatty amides such as stearamide, oleamide, erucamide, or N,N'-ethylenebis-stearamide; polyethylene wax; oxidized polyethylene wax; polymers of ethylene oxide; copolymers of ethylene oxide and propylene oxide; vegetable waxes; petroleum waxes; nonionic surfactants; silicone fluids, polysiloxanes, fluoropolymers, and / or fluoroelastomers.

[0064] combination The polymer composition can be added to a batch or continuous mixer for melt blending. The components can be added in any order, or one or more masterbatches can be prepared first to blend with other components. Melt blending can be performed at a temperature higher than the highest melting point polymer but lower than the maximum compounding temperature of 285°C. The melt-blended composition can then be delivered to an extruder or injection molding machine, passed through a die to form the desired article, or converted into pellets, tape, strip, film, or other forms for storage or preparation of the material for subsequent molding or processing steps. Optionally, if formed into pellets or some similar configuration, the pellets or the like can be coated with an anti-blocking agent to facilitate handling during storage.

[0065] Examples of compounding equipment that can be used include an internal batch mixer, a continuous single or twin screw mixer, or a kneading continuous extruder. The type of mixer utilized and the operating conditions of the mixer affect the properties of the composition, such as viscosity, volume resistivity, and extruded surface smoothness.

[0066] cable The polymer composition may be utilized in a cable. In some examples, the cable may be a coated conductor. In other examples, the cable may be a fiber optic cable. In the example of a coated conductor, the coated conductor includes a conductor and a coating on the conductor, the coating including the polymer composition. The polymer composition is at least partially disposed around the conductor to produce the coated conductor. The conductor may include a conductive metal or an optically transparent structure.

[0067] In the example of an optical fiber cable, the cable includes a conductor, and the polymer composition is disposed around the conductor. The polymer composition may be in the form of buffer tubes, one or more jacket layers on the cable, and / or other components in the cable. The conductor may include optical fibers or other transparent components. The optical fiber cable may be a "loose buffer tube" design, in which the buffer tubes are radially disposed around a central strength member, with the optical fibers rotating helically relative to the buffer tube along their axial length. One or more conductors may be disposed within the buffer tubes such that the buffer tubes are disposed around the conductors. The buffer tube may comprise, consist of, or consist essentially of the polymer composition. Thus, the buffer tube may be a polymer tube. The buffer tube is optionally filled with an optical cable grease or gel. Gel and grease compounds may include hydrocarbon-based greases incorporating hydrocarbon oils and / or polymer-based greases using low-viscosity polymers formulated with hydrocarbon oils. [Example]

[0068] material The following materials were used in the comparative examples ("CE") and inventive examples ("IE").

[0069] MDH is magnesium hydroxide having a density of 2.36 g / cc and is commercially available as MAGNIFIN™ H5 from Magnifin Magnesiaprodukte GmbH & Co KG (Austria).

[0070] SI-MDH is a vinylsilane-treated magnesium hydroxide having a density of 2.36 g / cc and is commercially available as MAGNIFIN™ H5A from Magnifin Magnesiaprodukte GmbH & Co KG (Austria).

[0071] HDPE1 is UNIPOL™ II bimodal polyethylene with hexene comonomer, density of 0.95 g / cc, and melt index (I2) of 0.5 g / 10 min at 190° C. manufactured by The Dow Chemical Company (Midland, MI, USA).

[0072] HDPE2 is a bimodal polyethylene having a density of 0.955 g / cc and a melt index (I2) of 0.3 g / 10 min at 190° C., commercially available as DGDA-1310NT from The Dow Chemical Company (Midland, MI, USA).

[0073] HDPE3 is a unimodal polyethylene having a density of 0.965 g / cc and a melt index (I2) of 8 g / 10 min at 190° C., commercially available as DGDA-6944NT from The Dow Chemical Company (Midland, MI, USA).

[0074] HDPE4 is a unimodal polyethylene with hexane comonomer, a density of 0.952 g / cc, and a melt index (I2) of 12 g / 10 min at 190°C, commercially available as DMDA-8810NT from The Dow Chemical Company (Midland, MI, USA).

[0075] HDPE5 is a bimodal polyethylene with hexane comonomer, a density of 0.955 g / cc, and a melt index (I2) of 1.5 g / 10 min at 190°C, commercially available as DMDC-1250NT from The Dow Chemical Company (Midland, MI, USA).

[0076] HDPE6 is a bimodal polyethylene with hexane comonomer, a density of 0.955 g / cc, and a melt index (I2) of 2.5 g / 10 min at 190°C, commercially available as DMDC-1270NT from The Dow Chemical Company (Midland, MI, USA).

[0077] MAH-g-LLDPE (1) is a maleic anhydride grafted plastomer commercially available from The Dow Chemical Company (Midland, MI, USA) with a density of 0.902 g / cc, a melt index of 3.3 g / 10 min, and a maleic anhydride content of 0.45 wt.%.

[0078] MAH-g-LLDPE (2) is a maleic anhydride-grafted LLDPE commercially available from The Dow Chemical Company (Midland, MI, USA) with a density of 0.912 g / cc, a melt index of 2.1 g / 10 min, and a maleic anhydride content of 2.4 wt.%.

[0079] MAH-g-LLDPE (3) is a maleic anhydride-grafted LLDPE commercially available from The Dow Chemical Company (Midland, MI, USA) with a density of 0.925 g / cc, a melt index of 2.0 g / 10 min, and a maleic anhydride content of 1.8 wt.%.

[0080] MAA ionomer is a Zn-neutralized methacrylic acid-ethylene copolymer having 15 wt% methacrylic acid units, a density of 0.952 g / cc, and a melt index of 14 g / 10 min, commercially available from The Dow Chemical Company (Midland, MI, USA).

[0081] PDMS is a polydimethylsiloxane oil with a density of 0.977 g / cc, a viscosity of 60,000 centistokes, and is commercially available from The Dow Chemical Company (Midland, MI, USA).

[0082] AO1 is a sterically hindered phenolic antioxidant with the chemical name pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and is commercially available as IRGANOX 1010™ from BASF (Ludwigshafen, Germany).

[0083] DFDA is a halogen-free, flame retardant-filled polyolefin material with a density of 1.50 g / cc and is commercially available as UNIGARD™ DFDA-1638NT from The Dow Chemical Company (Midland, MI, USA).

[0084] Sample preparation of HFFR compounds Samples were prepared by melt blending in a BRABENDER™ mixer. All samples (except commercial samples) were mixed in a lab-scale, 250-gram BRABENDER™ mixing bowl with a 250 gm capacity using a BANBURY™-type mixing blade with the settings shown in Table 1. After melt mixing, the molten material was removed, placed between biaxially oriented polyethylene terephthalate sheets, and pressed into a sheet at 23°C using a WABASH™ compression molding press. The material was then cut into strips ready for pelletization using a BERLYN™ pelletizing unit.

[0085] Pellets from each sample were then used to make tape samples using a BRABENDER™ tape extruder under the conditions shown in Table 2. The tapes had dimensions of 1.58 mm thickness and approximately 51 mm width. Type 4a dogbone samples were die cut in the machine direction for tensile and elongation measurements according to ASTM D638.

[0086] [Table 1]

[0087] [Table 2]

[0088] Table 5. Resin Blend Sample Preparation Resin blends shown in Table 5 having two or more components were mixed in a lab-scale 250 gram BRABENDER™ mixing bowl with a 250 gm capacity using a BANBURY™ type mixing blade. The rotor speed was set at 40 RPM and the mixer temperature was set at 180°C.

[0089] The mixing process involved first adding the resin to a mixing bowl at a mixing speed of 15 RPM. Both heating zones were set to 180°C. After the resin began to melt, 0.4 wt% AO1 (IRGANOX™ 1010) was added and mixed at 40 RPM for 6 minutes. The molten material was then removed, placed between Mylar sheets, and pressed into a sheet at 23°C using a Wabash compression molding press. This material was then used to make plaques for rheology measurements.

[0090] Test Method Melt Index Melt index testing was performed on a Tinius Olsen MP-993 testing unit. Melt index was measured at 210°C using a 21.6 kg weight and followed ASTM D 1238 testing procedure. For each melt property test, the cylinder of the testing unit was filled with 6 grams of material and preheated for 6 minutes.

[0091] Tensile and elongation Five Type 4 dogbone specimens per sample were die cut in the machine direction from the tape samples. Tensile and elongation were completed on an INSTRON™ 4201 tensile tester using a 100 lb load cell at a strain rate of 2 in / min according to ASTM D638.

[0092] Flexural modulus Plaques for flexural modulus were compression molded in a 3.18 mm, 20 cm x 20 cm steel mold at 180°C. Samples were die cut to dimensions of approximately 3 cm x 1 cm. Testing was performed according to ASTM D790 at a crosshead speed of 1.27 mm / min and a support span of 51 mm.

[0093] Cone Calorimetry Samples for cone calorimetry testing were prepared by compression molding and then die cutting to a size of 100 mm x 100 mm x 3 mm. 2 Testing was completed in accordance with ASTM E1354 with the heat flux set at 1000 kJ / s. Samples were tested without a grid and values ​​reported are the average of 2-3 samples. Calorimetric results are expressed as Peak Heat Release Rate ("PHRR").

[0094] Extruded tape / mandrel flex test The tape sample was wrapped completely around a mandrel having a diameter of approximately 7.7 mm and held in that position for a minimum of 10 seconds. Any kinks or breaks were recorded for each sample.

[0095] Dynamic Oscillatory Shear Test Unless otherwise indicated, all dynamic viscosities (η * ) is calculated using Dynamic Oscillatory Shear (DOS) and is reported in Pascal seconds (Pa·s).

[0096] The samples were compression molded into 1.3 mm thick x 25 mm circular plaques in air at 25,000 psi for 5 minutes at 180° C. The samples were then removed from the press and allowed to cool.

[0097] Constant temperature frequency sweeps were performed using a TA Instruments Advanced Rheometric Expansion System (ARES) equipped with 25 mm (diameter) parallel plates under a nitrogen purge. The sample was placed on the plates and melted at 190 °C for 5 minutes. The plates were then closed to a 2 mm gap, the sample was trimmed (removing excess sample extending beyond the circumference of the 25 mm diameter plate), and the test was then initiated. The method incorporated an additional 5 minute delay to allow for temperature equilibration. Tests were performed at 190 °C over a frequency range of 0.1 radians per second (rad / s) to 100 rad / s at a constant strain of 0.25%. The resulting values ​​obtained from measurements of G' and G'' (dynamic storage modulus and dynamic loss modulus, respectively) versus frequency were used to calculate relaxation spectra using the IRIS™ commercially available software package. Respective values ​​of the relaxation spectrum index (RSI) were then calculated from the relaxation spectra.

[0098] The RSI is determined by first subjecting a combined first ethylene-based polymer and a second ethylene-based polymer ("polymer") to low shear deformation and measuring its response to deformation using a rheometer. As is known in the art, based on the polymer response and the setup and geometry of the rheometer used, the relaxation modulus G(t) or dynamic moduli G'(ω) and G''(ω) can be determined as a function of time t or frequency ω, respectively (see J.M. Dealy and K.W. Issbrun, Melt Rheology and Its Role in Plastics Processing, Van Nostrand Reinhold, 1990, pp. 269-297). The mathematical relationship between the dynamic and storage moduli is that of a Fourier transform integral, although one data set can also be calculated from the other using well-known relaxation spectra (see S.H. Wasserman, J. Rheology, Vol. 39, pp. 601-625 (1995)). Using the classical Maxwellian mechanical model, one can define a discrete relaxation spectrum consisting of a set of relaxations or "modes," each with a characteristic strength or "weight" and relaxation time. Using such a spectrum, the coefficients are re-expressed as:

[0099]

number

[0100]

number

[0101] Gel Permeation Chromatography The chromatography system consisted of a PolymerChar (Valencia, Spain) GPC-IR high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven compartment was set to 165 °C, and the column compartment and detector were set to 155 °C. The columns used were four TOSOH TSKgel GMHHR-H(30)HT 30-micron particle size, mixed-pore size columns. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters, and the flow rate was 1.0 milliliters / minute.

[0102] Calibration of the GPC column set was performed using 21 narrow molecular weight distribution polystyrene standards ranging from 580 to 8,400,000 g / mol, arranged in six "cocktail" mixtures with at least one decade between individual molecular weights. The standards were purchased from Agilent Technologies. Polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights above 1,000,000 and 0.05 grams in 50 milliliters of solvent for molecular weights below 1,000,000. Individually prepared polystyrene standards of 10,000,000 g / mol and 15,000,000 g / mol, both from Agilent Technologies, were also prepared at 0.5 and 0.3 mg / mL, respectively. The polystyrene standards were predissolved at 80 °C with gentle agitation for 30 minutes, then cooled, and the room temperature solutions were transferred to an autosampler dissolving oven at 160 °C for 30 minutes to cool. The peak molecular weights of the polystyrene standards were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)), M ポリエチレン =A×(M ポリスチレン ) B (Formula 1) where M is the molecular weight, A has a value of 0.4122, and B is equal to 1.0.

[0103] A third order polynomial was used to fit each polyethylene equivalent calibration point.

[0104] The total plate count of the GPC column set was performed using decane as a blank sample introduced via a micropump controlled using a PolymerChar GPC-IR system. The plate count of the chromatography system should exceed 12,000 for four TOSOH TSKgel GMHHR-H(30)HT 30 micron particle size, mixed pore size columns.

[0105] Samples were prepared in a semi-automated fashion using PolymerChar's "Instrument Control" software, with a target sample weight of 2 mg / mL, and solvent (containing 200 ppm BHT) was added via a PolymerChar high-temperature autosampler to a pre-nitrogen-sparged, septum-capped vial. Samples were dissolved at 160°C for 2 hours under "slow" shaking.

[0106] Mn (GPC) , Mw (GPC) , and Mz (GPC) was calculated based on GPC results using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 2-4 using PolymerChar's GPCOne™ software, baseline-subtracted IR chromatograms at each equally spaced data collection point (i), and polyethylene equivalent molecular weights obtained from a narrow standard calibration curve for point (i) of Equation 1.

[0107]

number

[0108] 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 (Flow Rate (Apparent)) for each sample by RV matching the respective decane peak in the sample (RV (FM Sample)) with that of the decane peak in the narrow standard calibration (RV (FM Calibrated)). Any change in the time of the decane marker peak is then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the run. After calibrating the system based on the flow rate marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated as per Equation 5. Processing of the flow rate marker peak was performed via PolymerChar GPCOne™ software. An acceptable flow rate correction is one in which the effective flow rate is within ±0.5% of the apparent flow rate. Flow rate (effective) = Flow rate (nominal) * (RV(FM calibrated) / RV(FM sample)) (Equation 5)

[0109] result Table 3 provides the compositions of the inventive examples ("IE") and comparative examples ("CE"), and Table 4 provides relevant test properties of the examples. Table 5 provides relaxation spectral index and gel permeation chromatography data for the inventive examples and comparative examples.

[0110] [Table 3]

[0111] [Table 4]

[0112] [Table 5]

[0113] Referring now to Tables 3-5, CE1-CE7 are values ​​of 250 kW / m when measured in accordance with ASTM E1354. 2 It can be seen that the desired values ​​of PHRR less than 100%, elongation greater than 20% as measured according to ASTM D638, flexural modulus greater than 950 MPa as measured according to ASTM D790, and dynamic oscillatory shear viscosity at 0.1 rad / sec less than 46,000 Pa.s as measured according to ASTM D4440-15 cannot be achieved.

[0114] Unlike CE1-CE7, IE1-IE5 are able to achieve all of the desired properties. Table 5 shows that the inventive example HDPE blends (i.e., the combined first ethylene-based polymer and second ethylene-based polymer) all achieve relaxation spectrum index values ​​between 10 and 25, polydispersity indices of 10 or greater, and dynamic oscillatory shear viscosities at 100 rad / sec of 500 Pa s or less (as shown in Table 4), thereby enabling the polymer compositions to achieve the desired processing and mechanical property targets despite containing higher loadings of HFFR.

Claims

1. 1. A polymer composition comprising: A first ethylene-based polymer having a density from 0.93 g / cc to 0.97 g / cc, as measured in accordance with ASTM D792, wherein the first ethylene-based polymer has a melt index (I) less than or equal to 0.8 g / 10 minutes, as measured in accordance with ASTM D1238. ２ a first ethylene-based polymer having a a second ethylene-based polymer having a density from 0.93 g / cc to 0.97 g / cc, as measured in accordance with ASTM D792, wherein the second ethylene-based polymer has a melt index (I) greater than or equal to 3.0 g / 10 minutes, as measured in accordance with ASTM D1238; ２ ) the combination of the first ethylene-based polymer and the second ethylene-based polymer comprising: a second ethylene-based polymer having a relaxation spectrum index value of 10 to 25, a polydispersity index of 10 or greater, as measured according to gel permeation chromatography techniques, and a dynamic oscillatory shear viscosity at 100 rad / sec of 500 Pa.S or less, as measured according to ASTM D4440-15; a compatibilizer; and and a flame-retardant filler.

2. 10. The polymer composition of claim 1, wherein the compatibilizer is selected from the group consisting of maleic anhydride grafted polymers, acid copolymers, and ionomers.

3. 3. The polymer composition of claim 1, wherein the flame retardant filler is a silanized flame retardant filler, and the polymer composition comprises 10 wt% to 80 wt% of the silanized flame retardant filler, based on the total weight of the polymer composition.

4. The polymer composition of any one of claims 1 to 3, comprising 5 wt% to 30 wt% of the first ethylene-based polymer, based on the total weight of the polymer composition.

5. The polymer composition of any one of claims 1 to 4, comprising 1 wt% to 20 wt% of the second ethylene-based polymer, based on the total weight of the polymer composition.

6. 6. The polymer composition of any one of claims 1 to 5, wherein the weight ratio of the first ethylene-based polymer to the second ethylene-based polymer is from 1:1 to 3:

1.

7. The first ethylene-based polymer has a melt index (I) of 0.5 g / 10 min or less, as measured in accordance with ASTM D1238. ２ ), and the second ethylene-based polymer has a melt index (I ) greater than or equal to 6 g / 10 minutes, as measured in accordance with ASTM D1238. ２ The polymer composition according to any one of claims 1 to 6, wherein

8. 8. The polymer composition of any one of claims 1-7, wherein the first ethylene-based polymer and the second ethylene-based polymer combined have a relaxation spectral index value of 15-21.

9. The polymer composition has a thermal conductivity of 250 kW / m as measured in accordance with ASTM E1354 ２ 9. The polymer composition of any one of claims 1 to 8, exhibiting a PHHR of less than 100%, an elongation of more than 20% as measured according to ASTM D638, and a flexural modulus of more than 950 MPa as measured according to ASTM D790.

10. A cable, A conductor; a buffer tube disposed around the conductor and comprising the polymer composition of any one of claims 1 to 9.

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