Flame retardant polymer composition

Abstract

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

Description

BACKGROUND OF THE INVENTION Technical Field

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

[0002] Introduction

[0003] Cables typically employ a polymer composition around one or more conductors (i.e., optical and / or electrical). In such cables, flame retardancy may not be a critical property considered for certain elements of the cable and, as a result, the incorporation of flame retardant materials in the elements is restricted. However, recently, flame retardancy standards have refocused the target property on the overall cable rather than on individual components. This change has new importance for the flame retardancy of those components of the cable. For example, buffer tubes including conventional unfilled polyolefins or other buffer tubes without flame retardant additives may cause the overall cable to fail in terms of flame retardancy even if other components such as the sheath are flame retardant. Accordingly, the polymer composition of the buffer tube should exhibit a peak heat release rate (“PHRR”) according to cone calorimetry of less than 250 kilowatts per square meter (“kW / m 2 ”) in order to meet the new standard.

[0004] Conventional methods of adding flame retardancy to polymer compositions include selecting a flexible base polyolefin (i.e., a polyolefin having a low flexural modulus) and a flame retardant filler for incorporation into the polyolefin. Due to various reasons, using this method in buffer tubes is a challenging task. First, the tensile elongation and flexural modulus of the buffer tube are important, and the incorporation of typical low flexural modulus (e.g., 100 MPa to 200 MPa) polyolefins used in flame retardant polyolefins will result in insufficient flexural modulus of the buffer tube. Generally, the buffer tube requires a tensile elongation greater than 20% and a flexural modulus greater than 950 MPa. Second, the buffer tube must be well processed at high extrusion speeds (i.e., without tube breakage or dimensional defects). However, halogen-free flame retardant fillers ("HFFR") are typically included at 60 wt% or more, which results in a significant increase in melt viscosity, thereby impairing processability and also negatively affecting the final mechanical properties. In order to extrude fast enough for the buffer tube to be commercially viable, the shear viscosity of the buffer tube material at a relatively high shear rate (e.g., the dynamic oscillatory shear viscosity measured at 100 radians / second, which indicates the ease with which the material can be extruded) should be 500 Pascal seconds ("Pa.s") or less as measured according to ASTM D4440-15. Third, simply incorporating a flame retardant filler is not sufficient to impart flame retardant properties. Without proper compatibilization and dispersion, the flame retardant filler may agglomerate within the polymer composition, thereby providing minimal flame retardant properties while also reducing mechanical properties. Additionally, incomplete dispersion of HFFR within the polymer composition may cause the polymer composition to break or rupture when subjected to a mandrel bend test. Such results indicate that a buffer tube composed of the polymer composition may break or rupture during use.

[0005] Combinations of ionomers and maleic anhydride grafted polymers are known in the art. For example, U.S. Patent No. 6,569,947 B1 ("the '947 patent") discloses a maleic anhydride modified ethylene polymer / ionomer / high density polyethylene blend that can be used in high impact materials. However, it is only considered that such blends are beneficial for improving impact properties, and any effect on flame retardancy is unknown.

[0006] In view of the above, it has surprisingly been found that a polymer composition exhibits a PHRR of less than 250 kW / m 2 as measured according to ASTM E1354, an elongation greater than 20% as measured according to ASTM D638, a flexural modulus greater than 950 MPa as measured according to ASTM D790, a dynamic oscillatory shear viscosity of 500 Pa.s or less at 100 radians / second as measured according to ASTM D4440-15, and does not break or rupture when subjected to a mandrel bend test. SUMMARY OF THE INVENTION

[0007] The inventors of the present application have discovered a polymer composition that exhibits a peak heat release rate (PHRR) of less than 250 kW / m as measured according to ASTM E1354, an elongation at break of greater than 20% as measured according to ASTM D638, a flexural modulus of greater than 950 MPa as measured according to ASTM D790, a dynamic oscillatory shear viscosity of 500 Pa·s or less at 100 radians per second as measured according to ASTM D4440-15, and does not break or rupture when subjected to a mandrel bend test. 2 The present invention is the result of discovering that a polymer composition comprising a blend of an ethylene-based polymer, a flame retardant filler, and a compatibilizer can achieve the above properties. Specifically, it has been found that by utilizing a blend of high-density ethylene-based polymers, these results can be achieved. Specifically, the blend should comprise 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 by gel permeation chromatography, and a dynamic oscillatory shear viscosity of 500 Pa·s or less at 100 radians per second as measured according to ASTM D4440-15. Without being 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 as well as mechanical properties. It is believed that the high melt index of the second ethylene-based polymer helps to reduce the total compound viscosity and thus contributes to the processability of the polymer composition. Additionally, the prominent relaxation spectrum index (RSI) and polydispersity index improve the physical properties of the blend such that high-speed extrusion can still be achieved despite the incorporation of a high level of filler. By combining these two ethylene-based polymers, a compatibilizer, and a silane-treated flame retardant filler in the polymer composition, the above properties can be achieved. Furthermore, removal of undispersed particles greater than 140 μm via melt filtration during the compounding manufacturing step reduces defects that may occur during high-speed extrusion of thin-wall buffer tubes.

[0008] According to a first aspect of the present disclosure, the polymer composition comprises a first ethylene-based polymer having a density of 0.93 g / cc to 0.97 g / cc as measured according to ASTM D792, wherein the first ethylene-based polymer has a melt index (I

[0009] 2) of 0.8 g / 10 minutes or less as measured according to ASTM D1238. 2); a second ethylene-based polymer having a density of 0.93 g / cc to 0.97 g / cc as measured by ASTM D792, wherein the second ethylene-based polymer has a melt index (I 2 ) of 3.0 g / 10 minutes or greater as measured by ASTM D1238, wherein 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 by gel permeation chromatography, and a dynamic oscillatory shear viscosity of 500 Pa·s or less at 100 radians / second as measured by ASTM D4440-15; a compatibilizer; and a flame retardant filler.

[0010] According to a second feature of the present disclosure, the compatibilizer is selected from maleic anhydride grafted polymers, acid copolymers, and ionomers.

[0011] According to a third feature 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.

[0012] According to a fourth feature of the present disclosure, the polymer composition comprises 5 wt% to 30 wt% of the first ethylene-based polymer based on the total weight of the polymer composition.

[0013] According to a fifth feature of the present disclosure, the polymer composition comprises 1 wt% to 20 wt% of the second ethylene-based polymer based on the total weight of the polymer composition.

[0014] 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 1:1 to 3:1.

[0015] According to a seventh feature of the present disclosure, the first ethylene-based polymer has a melt index (I 2 ) of 0.5 g / 10 min or less as measured by ASTM D1238, and the second ethylene-based polymer has a melt index (I 2 ) of 6 g / 10 min or greater as measured by ASTM D1238.

[0016] According to an eighth feature of the present disclosure, the relaxation spectrum index value of the combined first ethylene-based polymer and second ethylene-based polymer is 15 to 21.

[0017] According to a ninth feature of the present disclosure, the polymer composition exhibits a PHHR of less than 250 kW / m 2 as measured by ASTM E1354, an elongation at break of greater than 20% as measured by ASTM D638, and a flexural modulus of greater than 950 MPa as measured by ASTM D790.

[0018] According to a tenth feature of the present disclosure, the cable includes: a conductor; and a buffer tube positioned around the conductor and containing a polymer composition. Detailed Description

[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 can be used alone 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; 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 endpoints.

[0021] The test method refers to the latest test method as of the priority date of this document, unless the date is expressed as a two-digit number with a hyphen in the test method number. A reference to a test method includes a reference to both the test society and the test method number. The test method organization is referred to by one of the following abbreviations: ASTM refers to ASTM International (formerly known as the American Society for Testing and Materials); IEC refers to the International Electrotechnical Commission; EN refers to European Standards; DIN refers to the German Institute for Standardization; and ISO refers to the International Organization for Standardization.

[0022] As used herein, unless otherwise stated, the term weight percentage ("wt%") represents the weight percentage of a component in the total weight of the polymer composition.

[0023] The melt index (I 2 ) value herein refers to the value determined according to ASTM method D1238 at 190 degrees Celsius (°C) and a mass of 2.16 kilograms (kg) and is provided in grams per ten minutes eluted ("g / 10min").

[0024] The density value herein refers to the value determined according to ASTM D792 at 23 °C and is provided in grams per cubic centimeter ("g / cc").

[0025] As used herein, the Chemical Abstracts Service Registry Number ("CAS#") refers to the unique numerical identifier most recently assigned by the Chemical Abstracts Service to a chemical compound since the priority date of this document.

[0026] Polymer Composition

[0027] The present disclosure relates to a polymer composition. The polymer composition includes a first ethylene-based polymer, a second ethylene-based polymer, a compatibilizer, and a silane-treated flame retardant filler.

[0028] Polymer compositions can exhibit a variety of properties. The polymer composition can exhibit a peak heat release rate (PHRR) of less than 250 kW / m 2 measured using cone calorimetry in accordance with ASTM E1354. For example, the polymer composition can exhibit a PHRR of less than 250 kW / m 2 or 240 kW / m 2 or less, or 230 kW / m 2 or less, or 220 kW / m 2 or less, or 210 kW / m 2 or less, or 200 kW / m 2 or less, or 190 kW / m 2 or less, or 180 kW / m 2 or less, or 170 kW / m 2 or less, or 160 kW / m 2 or less, or 150 kW / m 2 or less, or 140 kW / m 2 or less, or 130 kW / m 2 or less, or 120 kW / m 2 or less, or 110 kW / m 2 or less, or 100 kW / m 2 or less, or 90 kW / m 2 or less, or 80 kW / m 2 or less, or 70 kW / m 2 or less, or 60 kW / m 2 or less, or 50 kW / m 2 or less PHRR.

[0029] The polymer composition can exhibit an elongation at break of greater than 20% as measured according to ASTM D638. For example, the polymer composition can exhibit an elongation at break of 21% or greater, or 22% or greater, or 23% or greater, or 24% or greater, or 25% or greater, or 26% or greater, or 27% or greater, or 28% or greater, or 29% or greater, or 30% or greater, or 40% or greater, or 50% or greater, or 75% or greater, or 100% or greater, or 175% or greater, or 180% or greater, or 190% or greater, or 200% or greater, or 225% or greater, or 250% or greater, or 275% or greater, or 300% or greater, while being 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.

[0030] The polymer composition can exhibit a flexural modulus of 950 MPa or greater. For example, the polymer composition can exhibit 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 as measured according to ASTM D790, while being 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.

[0031] The polymer composition can exhibit a dynamic oscillatory shear viscosity of less than 46,000 Pa·s at 0.1 radian per second as measured according to ASTM D4440-15. For example, the polymer composition can exhibit a dynamic oscillatory shear viscosity 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 at 0.1 radian per second as measured according to ASTM D4440-15.

[0032] The polymer composition can exhibit a dynamic oscillatory shear viscosity of 500 Pa·s or less at 100 radian per second as measured according to ASTM D4440-15. For example, the polymer composition can exhibit a dynamic oscillatory shear viscosity of 1 Pa·s or greater, or 10 Pa·s or greater, or 50 Pa·s or greater, or 100 Pa·s or greater, or 150 Pa·s or greater, or 200 Pa·s or greater, or 250 Pa·s or greater, or 300 Pa·s or greater, or 350 Pa·s or greater, or 400 Pa·s or greater, or 450 Pa·s or greater at 100 radian per second as measured according to ASTM D4440-15, while being 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.

[0033] First Ethylene-Based Polymer

[0034] As described above, the composition can comprise a first ethylene-based polymer. As used herein, an "ethylene-based" polymer is a polymer in which greater than 50 weight percent of the monomers are ethylene, although other comonomers can also be used. Ethylene-based polymers include ethylene and one or more C 3 -C 20 α-olefin comonomers such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene.

[0035] Based on measurements using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy, the ethylene-based polymer can contain 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, or 91 wt% or more, or 92 wt% or more, or 93 wt% or more, or 94 wt% or more, or 95 wt% or more, or 96 wt% or more, or 97 wt% or more, or 97.5 wt% or more, or 98 wt% or more, or 99 wt% or more, while 99.5 wt% or less, or 99 wt% or less, or 98 wt% or less, or 97 wt% or less, or 96 wt% or less, or 95 wt% or less, or 94 wt% or less, or 93 wt% or less, or 92 wt% or less, or 91 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or 70 wt% or less, or 60 wt% or less of ethylene monomers.

[0036] Other units of the ethylene-based polymer can be derived from one or more polymerizable monomers, which include but are not limited to polar monomers, such as unsaturated esters. The unsaturated ester (i.e., polar monomer) can be an alkyl acrylate, an alkyl methacrylate, or a vinyl carboxylate. The alkyl group can have 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The carboxylate group 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 carboxylates include but are not limited to vinyl acetate, vinyl propionate, and vinyl butyrate. Based on the total weight of the ethylene-based polymer, the ethylene-based polymer can have a polar comonomer content of 40 wt% or less, or 35 wt% or less, or 30 wt% or less, or 25 wt% or less, or 20 wt% or less, 15 wt%, or 10 wt%, or 5 wt% or less, or 3 wt% or less, or 1 wt% or less, or 0 wt% as measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy.

[0037] Ethylene-based polymers can have a unimodal or multimodal molecular weight distribution 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 terms of monomer composition and content, catalytic preparation method, molecular weight, molecular weight distribution, density, etc.). If a blend of ethylene-based polymers is employed, 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. Thus, the general term multimodal polymer includes bimodal polymers, which have two main fractions: a first fraction that can be a low molecular weight fraction and / or component; and a second fraction that can be a high molecular weight fraction and / or component.

[0038] The density of the first ethylene-based polymer, measured according to ASTM D792, is from 0.93 g / cc to 0.97 g / cc. For example, the density of the first ethylene-based polymer, measured according to ASTM D792, 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 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. Generally, ethylene-based polymers having a density of from 0.93 g / cc to 0.97 g / cc are referred to as "high density polyethylene" or "HDPE".

[0039] The first ethylene-based polymer has a melt index (I 2 ) of 0.8 g / 10 min or less, measured according to ASTM D1238. For example, the first ethylene-based polymer has a melt index (I 2 ) 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, measured according to ASTM D1238.

[0040] Based on the total weight of the polymer composition, the polymer composition can comprise from 5 wt% to 30 wt% of a first ethylene-based polymer. For example, based on the total weight of the polymer composition, the polymer composition can comprise 5 wt% or more, or 10 wt% or more, or 15 wt% or more, or 20 wt% or more, or 25 wt% or more, while at the same time 30 wt% or less, or 25 wt% or less, or 20 wt% or less, or 15 wt% or less, or 10 wt% or less of the first ethylene-based polymer.

[0041] Second Ethylene-Based Polymer

[0042] The polymer composition comprises a second ethylene-based polymer. The second ethylene-based polymer

[0043] The density of the second ethylene-based polymer, measured according to ASTM D792, is from 0.93 g / cc to 0.97 g / cc. For example, the density of the second ethylene-based polymer, measured according to ASTM D792, 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 at the same time 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.

[0044] The second ethylene-based polymer has a melt index (I measured according to ASTM D1238 of 3.0 or g / 10 min or greater 2)。For example, 3.0 g / 10 min or greater, or 3.5 g / 10 min or greater, or 4.0 g / 10 min or greater, or 4.5 g / 10 min or greater, or 5.0 g / 10 min or greater, or 5.5 g / 10 min or greater, or 6.0 g / 10 min or greater, or 6.5 g / 10 min or greater, or 7.0 g / 10 min or greater, or 7.5 g / 10 min or greater, or 8.0 g / 10 min or greater, or 8.5 g / 10 min or greater, or 9.0 g / 10 min or greater, or 9.5 g / 10 min or greater, as measured according to ASTM D1238, while at the same time 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 less, 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.

[0045] Based on the total weight of the polymer composition, the polymer composition can comprise from 1 wt% to 20 wt% of a second ethylene-based polymer. For example, based on the total weight of the polymer composition, 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 at the same time 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.

[0046] The polymer composition may have a weight ratio of a first ethylene-based polymer to a 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 percentage of the first ethylene-based polymer in the polymer composition based on the total weight of the polymer composition by the weight percentage 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 represent the weight ratio. The weight ratio of the first ethylene-based polymer to the second ethylene-based polymer is 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.

[0047] Combined First and Second Ethylene-Based Polymers

[0048] The combined first ethylene-based polymer and second ethylene-based polymer have a relaxation spectrum index value of from 10 to 25 as calculated by dynamic oscillatory shear testing, as explained in more detail below. For example, the RSI value 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 at the same time 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 calculated by dynamic oscillatory shear testing.

[0049] The combined first ethylene-based polymer and second ethylene-based polymer have a polydispersity index value greater than 10 as measured by gel permeation chromatography. 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 at the same time 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.

[0050] Compatibilizer

[0051] The polymer composition comprises a compatibilizer. The compatibilizer can be one or more of a maleic anhydride grafted polymer, an acid copolymer, and an ionomer.

[0052] Maleic Anhydride Functionalized Polyolefin

[0053] The polymer composition can comprise a maleic anhydride functionalized polyolefin. As used herein, the term "maleic anhydride functionalized" means a polyolefin that has been modified to incorporate maleic anhydride monomers. The maleic anhydride functionalized polyolefin can 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, maleic anhydride can be graft polymerized onto the polyolefin. The maleic anhydride functionalized polyolefin can be any of the previously discussed ethylene-based polymers.

[0054] The maleic anhydride functionalized polyolefin can have a density of 0.87 g / cc or greater, or 0.88 g / cc or greater, or 0.89 g / cc or greater, or 0.90 g / cc or greater, or 0.91 g / cc or greater, or 0.92 g / cc or greater, or 0.93 g / cc or greater, or 0.94 g / cc or greater, or 0.95 g / cc or greater, 0.96 g / cc or greater as measured by ASTM D792, while 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.

[0055] The maleic anhydride-functionalized polyolefin has a melt flow index of 1 g / 10 min or greater, or 2 g / 10 min or greater, 3 g / 10 min or greater, 4 g / 10 min or greater, 5 g / 10 min or greater, 6 g / 10 min or greater, 7 g / 10 min or greater, 8 g / 10 min or greater, 9 g / 10 min or greater, 10 g / 10 min or greater, or 11 g / 10 min or greater, or 12 g / 10 min or greater, 13 g / 10 min or greater, 14 g / 10 min or greater, 15 g / 10 min or greater, 16 g / 10 min or greater, 17 g / 10 min or greater, 18 g / 10 min or greater, 19 g / 10 min or greater, while 20 g / 10 min or less, or 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. The MFI is measured according to ASTM D1238 at 190 °C and 2.16 kg.

[0056] Based on the total weight of the maleic anhydride-functionalized polyolefin, the maleic anhydride-functionalized polyolefin can 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 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. The maleic anhydride concentration is determined by titration analysis. The titration analysis is carried out by using the dry resin and titrating with 0.02N KOH to determine the amount of maleic anhydride. The dry polymer is titrated by dissolving 0.3 g to 0.5 g of the maleic anhydride-functionalized polyolefin in about 150 mL of refluxing xylene. After complete dissolution, deionized water (four drops) is added to the solution, and the solution is refluxed for 1 hour. Next, 1% thymol blue (a few drops) is added to the solution, and the solution is over-titrated with an ethanol solution of 0.02N KOH as indicated by the formation of a purple color. Then the solution is back-titrated to a yellow end point with an isopropanol solution of 0.05N HCl.

[0057] Based on the total weight of the polymer composition, the polymer composition can contain 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 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 the maleic anhydride-functionalized polyolefin.

[0058] Examples of suitable commercially available maleic anhydride-functionalized polyolefins are AMPLIFY available from The Dow Chemical Company, Midland, MI, USA. TM GR208.

[0059] Acid Copolymer and Ionomer

[0060] The polymer composition comprises an acid copolymer and / or an ionomer. As used herein, the term "acid copolymer" means a copolymer comprising repeat units derived from ethylene and 1 wt% to 50 wt% of an acidic comonomer (such as acrylic acid, methacrylic acid, ethylacrylic acid, or combinations thereof) based on the total weight of the acid copolymer. As used herein, the term "ionomer" means an acid copolymer that has been partially or fully neutralized.

[0061] Based on the total weight of the ionomer, the acid copolymer or ionomer can comprise up to 35 wt% of optional comonomers. Potential comonomers include carbon monoxide, sulfur dioxide, acrylonitrile, maleic anhydride, maleic diesters, maleic acid, maleic monoesters, itaconic acid, fumaric acid, fumaric 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, butyl methacrylate, pentyl methacrylate, or combinations thereof, wherein the alkyl groups can be straight or branched.

[0062] The ionomer can have a wide degree of neutralization. For example, based on the total acid content, the ionomer can be neutralized at 0.1% or greater, or 1% or greater, or 10% or greater, or 15 wt% or greater, or 20% or greater, or 30% or greater, or 40% or greater, or 50% or greater, or 60% or greater, or 70% or greater, or 80% or greater, or 90% or greater, while 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 wt% or less, or 10% or less, or 5% or less. One or more metal ions can be used to neutralize the ionomer. The metal ions can be monovalent, divalent, trivalent, polyvalent, or combinations 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. If the metal ions are polyvalent, complexing agents such as stearate radicals, oleate radicals, salicylate radicals, and phenate radicals can be included.

[0063] The ionomer can be a blend of an ionomer having greater than 20% neutralization with, for example, a second vinyl acid copolymer to achieve the desired degree of neutralization. For example, the ionomer can comprise 1 wt% to 50 wt% of the acid copolymer disclosed above.

[0064] Examples of commercially available ionomers include SURLYN available from The Dow Chemical Company, Midland, Michigan, USA TM ionomers.

[0065] Based on the total weight of the polymer composition, the polymer composition comprises 1 wt% to 10 wt% of an acid copolymer and / or an ionomer. For example, based on the total weight of the polymer composition, the polymer composition comprises 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 at the same time 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 one or more of the acid copolymer and / or the ionomer.

[0066] Flame Retardant Filler

[0067] The polymer composition comprises a flame retardant filler. The flame retardant of the polymer composition can inhibit, contain or delay flame generation. Examples of flame retardants suitable for 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, intumescent compounds, expanded graphite and combinations thereof. Specifically, the halogen-free flame retardant can be selected from the group consisting of aluminum hydroxide, magnesium hydroxide, calcium carbonate and combinations thereof. The flame retardant filler can be silane-treated. The silane-treated flame retardant filler is surface-treated in vinyl silane. In addition to the silane surface treatment, the flame retardant can optionally be surface-treated (coated) with a saturated or unsaturated carboxylic acid or metal salt of an acid having 8 to 24 carbon atoms or 12 to 18 carbon atoms. Exemplary surface treatments are described in US 4,255,303, US 5,034,442, US 7,514,489, US2008 / 0251273 and WO 2013 / 116283.

[0068] Commercially available exemplary flame retardants suitable for the polymer composition include but are not limited to MAGNIFIN TM H5A magnesium hydroxide available from Magnifin Magnesiaprodukte GmbH&Co KG

[0069] Based on the total weight of the polymer composition, the polymer composition may comprise a flame retardant filler at a concentration of 10 wt% to 80 wt%. For example, based on the weight of the polymer composition, the polymer composition may comprise a flame retardant filler at a concentration of 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% or more, or 30 wt% or more, or 32 wt% or more, or 34 wt% or more, or 36 wt% or more, or 38% or more, or 40 wt% or more, or 42 wt% or more, or 44 wt% or more, or 46 wt% or more, or 48% or more, or 50 wt% or more, or 52 wt% or more, or 54 wt% or more, or 56 wt% or more, or 58 wt% or more, or 60 wt% or more, or 62 wt% or more, or 64 wt% or more, or 66 wt% or more, or 68 wt% or more, or 70 wt% or more, or 72 wt% or more, or 74 wt% or more, or 76 wt% or more, or 78 wt% or more, while being 80 wt% or less, or 78 wt% or less, or 76 wt% or less, or 74 wt% or less, or 72 wt% or less, or 70 wt% or less, or 68 wt% or less, or 66 wt% or less, or 64 wt% or less, or 62 wt% or less, or 60 wt% or less, or 58 wt% or less, or 56 wt% or less, or 54 wt% or less, or 52 wt% or less, or 50 wt% or less, or 48 wt% or less, or 46 wt% or less, or 44 wt% or less, or 42 wt% or less, or 40 wt% or less, or 38 wt% or less, or 36 wt% or less, or 34 wt% or less, or 32 wt% or less, or 30 wt% or less, or 28 wt% or less, or 26 wt% or less, or 24 wt% or less, or 22 wt% or less, or 20 wt% or less of a silane-treated flame retardant filler.

[0070] Additive

[0071] The polymer composition may comprise additional additives in the form of antioxidants, crosslinking aids, curing accelerators and scorch inhibitors, processing aids, coupling agents, ultraviolet stabilizers (including UV absorbers), antistatic agents, additional nucleating agents, slip agents, lubricants, viscosity control agents, tackifiers, antiblocking agents, surfactants, extender oils, acid scavengers, anti-drip agents (e.g., ethylene vinyl acetate), and metal deactivators. The polymer composition may comprise 0.01 wt% to 20 wt% of one or more additional additives.

[0072] UV light stabilizers can include hindered amine light stabilizers (“HALS”) and UV light absorber (“UVA”) additives. Representative UVA additives include benzotriazole types such as TINUVIN 326 commercially available from Ciba, Inc. TM light stabilizers and TINUVIN 328 TM light stabilizers. Blends of HAL and UVA additives are also effective.

[0073] Antioxidants can include hindered phenols such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane; bis[(β-(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 thiodiethylene bis(3,5-di-tert-butyl-4-hydroxy)-hydrocinnamate; phosphites and phosphonites such as tris(2,4-di-tert-butylphenyl) phosphite and di-tert-butylphenyl-phosphite; sulfur 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 diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, diphenyl-p-phenylenediamine, mixed diaryl-p-phenylenediamine and other hindered amine anti-degradants or stabilizers.

[0074] Processing aids can 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'-ethylenebisstearamide; 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.

[0075] Compounding

[0076] The components of 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 for blending with other components. The melt blending can be carried out at a temperature above the highest melting polymer but below the maximum compounding temperature of 285 °C. The melt-blended composition can then be conveyed to an extruder or an injection molding machine, or formed through a die into a desired article, or converted into pellets, tapes, strips or films or some other form for storage or for preparing a material to be fed to the next forming or processing step. Optionally, if formed into pellets or some similar configuration, the pellets etc. can be coated with an anti-sticking agent to facilitate handling during storage.

[0077] Examples of compounding equipment that can be used include internal batch mixers, continuous single or twin screw mixers, or kneading continuous extruders. The type of mixer utilized and the operating conditions of the mixer will affect the properties of the composition, such as viscosity, volume resistivity and the surface smoothness of the extrusion.

[0078] Cable

[0079] The polymer composition can be used in cables. In some examples, the cable can be a coated conductor. In other examples, the cable can be an optical fiber cable. In the coated conductor example, the coated conductor includes a conductor and a coating located on the conductor, and the coating includes the polymer composition. The polymer composition is at least partially disposed around the conductor to produce the coated conductor. The conductor can include a conductive metal or an optically transparent structure.

[0080] In the optical fiber cable example, the cable includes a conductor, and the polymer composition is positioned around the conductor. The polymer composition can be in the form of a buffer tube, one or more sheath layers on the cable, and / or as other components in the cable. The conductor can include optical fibers or other transmission components. The optical fiber cable can be a "loose buffer tube" design, where the buffer tube is radially positioned around a central strength member, and the buffer tube spirally rotates along the axial length of the optical fiber cable. One or more conductors can be positioned within the buffer tube such that the buffer tube is positioned around the conductor. The buffer tube can contain, consist of or consist essentially of the polymer composition. Thus, the buffer tube can be a polymer tube. The buffer tube is optionally filled with optical cable grease or gel. The gel and grease compounds can include hydrocarbon-based greases incorporating hydrocarbon oils and / or polymer-based greases using low-viscosity polymers formulated with hydrocarbon oils.

[0081] Examples

[0082] Materials

[0083] The following materials are used for Comparative Examples ("CE") and Examples of the Invention ("IE").

[0084] MDH is magnesium hydroxide with a density of 2.36 g / cc and can be obtained commercially as MAGNIFIN TM H5 from Magnifin Magnesiaprodukte GmbH & Co KG, Austria.

[0085] SI-MDH is vinyl silane-treated magnesium hydroxide with a density of 2.36 g / cc and can be obtained commercially as MAGNIFIN TM H5A from Magnifin Magnesiaprodukte GmbH & Co KG, Austria.

[0086] HDPE1 is a UNIPOL 2 II bimodal polyethylene from The Dow Chemical Company, Midland, Michigan, USA, with a density of 0.95 g / cc, a melt index (I TM ) of 0.5 g / 10 min at 190 °C and having a hexene comonomer.

[0087] HDPE2 is a bimodal polyethylene with a density of 0.955 g / cc and a melt index (I 2 ) of 0.3 g / 10 min at 190 °C, which can be obtained commercially as DGDA-1310NT from The Dow Chemical Company, Midland, Michigan, USA.

[0088] HDPE3 is a unimodal polyethylene with a density of 0.965 g / cc and a melt index (I 2 ) of 8 g / 10 min at 190 °C, which can be obtained commercially as DGDA-6944NT from The Dow Chemical Company, Midland, Michigan, USA.

[0089] HDPE4 is a unimodal polyethylene with a hexene comonomer, a density of 0.952 g / cc and a melt index (I 2 ) of 12 g / 10 min at 190 °C, which can be obtained commercially as DMDA-8810NT from The Dow Chemical Company, Midland, Michigan, USA.

[0090] HDPE5 is a bimodal polyethylene with a hexene comonomer, a density of 0.955 g / cc and a melt index (I 2 ) of 1.5 g / 10 min at 190 °C, which can be obtained commercially as DMDC-1250NT from The Dow Chemical Company, Midland, Michigan, USA.

[0091] HDPE6 is a bimodal polyethylene with a hexene comonomer, a density of 0.955 g / cc and a melt index (I2 ) bimodal polyethylene, which can be obtained commercially as DMDC-1270NT from The Dow Chemical Company, Midland, Michigan, USA.

[0092] MAH-g-LLDPE(1) is a maleic anhydride-grafted plastomer having 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%, and it can be obtained commercially from The Dow Chemical Company, Midland, Michigan, USA.

[0093] MAH-g-LLDPE(2) is a maleic anhydride-grafted LLDPE having 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%, and it can be obtained commercially from The Dow Chemical Company, Midland, Michigan, USA.

[0094] MAH-g-LLDPE(3) is a maleic anhydride-grafted LLDPE having 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%, and it can be obtained commercially from The Dow Chemical Company, Midland, Michigan, USA.

[0095] MAA ionomer is a Zn-neutralized methacrylic acid-ethylene copolymer having a methacrylic acid unit content of 15 wt%, a density of 0.952 g / cc, and a melt index of 14 g / 10 min, and it can be obtained commercially from The Dow Chemical Company, Midland, Michigan, USA.

[0096] PDMS is a polydimethylsiloxane oil having a density of 0.977 g / cc and a viscosity of 60,000 cSt, and it can be obtained commercially from The Dow Chemical Company, Midland, Michigan, USA.

[0097] AO1 is a sterically hindered phenolic antioxidant with the chemical name pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), which can be obtained commercially as IRGANOX 1010 TM from BASF, Ludwigshafen, Germany.

[0098] DFDA is a halogen-free flame retardant-filled polyolefin material having a density of 1.50 g / cc, and it can be obtained commercially as UNIGARD TM DFDA-1638NT from The Dow Chemical Company, Midland, Michigan, USA.

[0099] Sample Preparation for HFFR Compounds

[0100] By using in BRABENDER TMSamples were prepared by melt blending in a mixer. Using a BANBURY type mixing blade with the settings shown in Table 1, all samples (excluding commercial samples) were mixed in a laboratory-scale 250-gram BRABENDER mixing bowl with a capacity of 250 gm. TM After melt mixing, the molten material was taken out and placed between biaxially oriented polyethylene terephthalate sheets, and pressed into sheets at 23 °C using a WABASH compression molding press. Then, the material was cut into strips so that it could be granulated using a BERLYN granulation unit. TM After melt mixing, the molten material was taken out and placed between biaxially oriented polyethylene terephthalate sheets, and pressed into sheets at 23 °C using a WABASH compression molding press. Then, the material was cut into strips so that it could be granulated using a BERLYN granulation unit. TM After melt mixing, the molten material was taken out and placed between biaxially oriented polyethylene terephthalate sheets, and pressed into sheets at 23 °C using a WABASH compression molding press. Then, the material was cut into strips so that it could be granulated using a BERLYN granulation unit. TM After melt mixing, the molten material was taken out and placed between biaxially oriented polyethylene terephthalate sheets, and pressed into sheets at 23 °C using a WABASH compression molding press. Then, the material was cut into strips so that it could be granulated using a BERLYN granulation unit.

[0101] Then, the pellets of each sample were used to produce tape samples using a BRABENDER tape extruder under the conditions shown in Table 2. The tape had dimensions of 1.58 mm thickness and approximately 51 mm width. Type 4a dogbone samples were die-cut in the machine direction according to ASTM D638 for tensile and elongation measurements. TM Then, the pellets of each sample were used to produce tape samples using a BRABENDER tape extruder under the conditions shown in Table 2. The tape had dimensions of 1.58 mm thickness and approximately 51 mm width. Type 4a dogbone samples were die-cut in the machine direction according to ASTM D638 for tensile and elongation measurements.

[0102] Table 1: BRABENDER TM Mixing parameters

[0103] Settings Units Intermediate Temperature C 191 Current Ampere 7 Final Temperature C 187 Speed RPM 55 Mixing Time Min 8

[0104] Table 2: BRABENDER TM Tape extrusion parameters

[0105] Settings Units Zone 1 C 160 Zone 2 C 170 Zone 3 C 180 Zone 4 C 180 Melt Temperature C 185 Extruder RPM RPM 60

[0106] Sample Preparation for Table 5 Resin Blends

[0107] Using a BANBURY type mixing blade, a resin blend with two or more components shown in Table 5 was mixed in a laboratory-scale 250-gram BRABENDER mixing bowl with a capacity of 250 gm. The rotor speed was set to 40 RPM, and the mixer temperature was set to 180 °C. TM Using a BANBURY type mixing blade, a resin blend with two or more components shown in Table 5 was mixed in a laboratory-scale 250-gram BRABENDER mixing bowl with a capacity of 250 gm. The rotor speed was set to 40 RPM, and the mixer temperature was set to 180 °C. TM Using a BANBURY type mixing blade, a resin blend with two or more components shown in Table 5 was mixed in a laboratory-scale 250-gram BRABENDER mixing bowl with a capacity of 250 gm. The rotor speed was set to 40 RPM, and the mixer temperature was set to 180 °C.

[0108] The mixing process involved first adding the resin to the mixing bowl at a mixing speed of 15 RPM. Both heating zones were set to 180 °C. After the resin started to melt, AO1 (IRGANOX 1010) (0.4 wt%) was added and mixed at 40 RPM for 6 minutes. Then the molten material was removed and placed between Mylar sheets, and then pressed into sheets at 23 °C using a Wabash compression molding press. Then the material was used to prepare thin sheets for rheological measurements. TM The mixing process involved first adding the resin to the mixing bowl at a mixing speed of 15 RPM. Both heating zones were set to 180 °C. After the resin started to melt, AO1 (IRGANOX 1010) (0.4 wt%) was added and mixed at 40 RPM for 6 minutes. Then the molten material was removed and placed between Mylar sheets, and then pressed into sheets at 23 °C using a Wabash compression molding press. Then the material was used to prepare thin sheets for rheological measurements.

[0109] Test Methods

[0110] Melt Index

[0111] The melt index test was carried out on a Tinius Olsen MP-993 test unit. The melt index was measured at 210 °C with a 21.6 kg weight and the ASTM D 1238 test procedure was followed. For each melt property test, 6 grams of the material was loaded into the barrel of the test unit and preheated for 6 minutes.

[0112] Tensile and Elongation

[0113] Five Type 4 dog bone specimens of each sample were die cut from the tape sample in the machine direction. According to ASTM D638, tensile strength and elongation were completed on an INSTRON TM 4201 tensile testing machine using a 100 lb load cell at a strain rate of 2 in / min.

[0114] Flexural Modulus

[0115] The flexural modulus specimens were compression molded in a steel mold of 3.18 mm, 20 cm × 20 cm at 180 °C. The samples were die cut into approximately 3 cm × 1 cm sizes. The test was carried out according to ASTM D790 at a crosshead speed of 1.27 mm / min and a support span of 51 mm.

[0116] Cone Calorimetry

[0117] Samples for cone calorimetry testing were prepared by compression molding and then die cut into a size of 100 mm × 100 mm × 3 mm. According to ASTM E1354, the test was completed at a heat flux set to 50 kW / m 2 . The samples were tested without a grid and the reported values are the average of 2 to 3 samples. The calorimetry results are expressed as the peak heat release rate (“PHRR”).

[0118] Extruded Tape / Spindle Bending Test

[0119] The tape samples were wound one full turn around a mandrel with a diameter of approximately 7.7 mm and held in that position for at least 10 seconds. Any kinks or breaks in each sample were recorded.

[0120] Dynamic Oscillatory Shear Test

[0121] Unless otherwise specified, all dynamic viscosities (η*) disclosed herein are calculated using dynamic oscillatory shear (DOS) and reported in Pascal-seconds (Pa·s).

[0122] The sample was compression molded into a 1.3 mm thick × 25 mm circular sheet at 25,000 psi pressure, in air, at 180 °C for five minutes. Subsequently, the sample was removed from the press and allowed to cool.

[0123] Isothermal frequency sweeps were performed using a TA Instruments “Advanced Rheology Expansion System (ARES)” equipped with 25 mm (diameter) parallel plates under a nitrogen purge. The sample was placed on the plates and allowed to melt at 190 °C for five minutes. Then the plates were brought to a 2 mm gap, the sample was trimmed (removing extra sample extending beyond the perimeter of the 25 mm diameter plate), and then testing was started. The method additionally has a five-minute delay built in to allow for temperature equilibration. Testing was performed at 190 °C in the frequency range from 0.1 radian per second (rad / s) to 100 rad / s at a constant strain of 0.25%. Using IRIS TM commercial software package, the resulting values obtained from the measurements of G' and G” (dynamic storage modulus and loss modulus, respectively) as a function of frequency were used to calculate the relaxation spectrum. Then the corresponding value of the relaxation spectrum index (RSI) was calculated from the relaxation spectrum.

[0124] The RSI was determined by first subjecting the combined first ethylene-based polymer and second ethylene-based polymer (“polymer”) to low shear deformation and measuring its response to the deformation using a rheometer. As is known in the art, based on the response of the polymer and the mechanics and geometry of the rheometer used, the relaxation modulus G(t) or the dynamic moduli 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 connection between the dynamic modulus and the storage modulus is a Fourier transform integral relationship, but it is also possible to calculate one set of data from another set using a well-known relaxation spectrum (see S.H. Wasserman, J. Rheology, Vol. 39: pp. 601 - 625, 1995). Using the classical Maxwell mechanical model, a discrete relaxation spectrum consisting of a series of relaxations or “modes” can be defined, each relaxation or “mode” having a characteristic strength or “weight” and a relaxation time. Using such a spectrum, the modulus can be re-expressed as:

[0125]

[0126] where N is the number of relaxation modes, and g i and λ iThe weights and times for each mode respectively (see J.D. Ferry, Viscoelastic Properties of Polymers, John Wiley & Sons, 1980, pp. 224 - 263). Once the mode distribution in the relaxation spectrum is calculated, the first and second moments M n and M w of the distribution similar to the molecular weight distribution are calculated as follows:

[0127]

[0128]

[0129] where RSI is defined as g II / g I .

[0130] Gel Permeation Chromatography

[0131] The chromatographic system consists of a PolymerChar GPC - IR (Valencia, Spain) high - temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler oven chamber is set to 165 degrees Celsius, and the column chamber and detector are set to 155 degrees Celsius. The column used is a 4 TOSOH TSKgel GMHHR - H(30)HT 30 - micron particle size mixed - pore column. The chromatographic solvent used is 1,2,4 - trichlorobenzene and contains 200 ppm of butylated hydroxytoluene (BHT). The solvent source is nitrogen - sparged. The injection volume used is 200 microliters, and the flow rate is 1.0 mL / min.

[0132] Calibration of the GPC column set is performed with 21 narrow molecular weight distribution polystyrene standards having molecular weights in the range of 580 g / mol to 8,400,000 g / mol and arranged in the form of 6 “mixture” mixtures with at least a ten-fold interval between individual molecular weights. The standards are purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 grams of polystyrene standard is prepared in 50 ml of solvent, and for molecular weights less than 1,000,000, 0.05 grams of polystyrene standard is prepared in 50 ml of solvent. Separate preparations of polystyrene standards of 10,000,000 g / mol and 15,000,000 g / mol (both from Agilent Technologies) are also prepared at 0.5 mg / mL and 0.3 mg / mL, respectively. The polystyrene standards are pre-dissolved at 80 °C with gentle stirring for 30 minutes, then cooled, and the room temperature solution is transferred to a 160 °C autosampler dissolution oven and cooled for 30 minutes. The polystyrene standard peak molecular weight is converted to polyethylene molecular weight using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):

[0133] M 聚乙烯 = A × (M 聚苯乙烯 ) B (Equation 1)

[0134] where M is the molecular weight, A has a value of 0.4122, and B equals 1.0.

[0135] A third-order polynomial is used to fit the corresponding polyethylene equivalent calibration points.

[0136] The total plate count of the GPC column set is performed with decane, and decane is introduced into a blank sample via a micro pump controlled by a PolymerChar GPC-IR system. For a 4TOSOH TSKgel GMHHR-H(30)HT 30-micron particle size mixed pore size column, the plate count of the chromatographic system should be greater than 12,000.

[0137] Samples are prepared semi-automatically using PolymerChar “Instrument Control” software, where the target weight of the sample is set at 2 mg / ml and the solvent (containing 200 ppm BHT) is added to a septum-capped vial pre-bubbled with nitrogen via a PolymerChar high-temperature autosampler. The sample is dissolved at 160 degrees Celsius for 2 hours with shaking at “low speed”.

[0138] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph, according to Equation 2-4, using PolymerChar GPCOne TM software, the Mn is calculated from the baseline-subtracted IR chromatogram at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the calibration curve of the narrow standard at point (i) according to Equation 1 (GPC) 、Mw (GPC) and Mz (GPC) .

[0139]

[0140] To monitor the deviation over time, a flow rate marker (decane) is introduced into each sample via a micro pump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) is used to linearly correct the pump flow rate (flow rate (nominal)) of each sample by comparing the RV of the corresponding decane peak in the sample (RV(FM sample)) with the RV of the decane peak in the narrow standard calibration (RV(FM calibrated)). Then, any change in the decane marker peak time is assumed to be related to a linear change in the flow rate (flow rate (effective)) throughout the run. After calibrating the system based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated according to Equation 5. The processing of the flow marker peak is completed by PolymerChar GPCOne TM software. An acceptable flow rate correction results in the effective flow rate being within + / - 0.5% of the nominal flow rate.

[0141] Flow rate (effective) = Flow rate (nominal) × (RV(FM calibrated) / RV(FM sample)) (Equation 5)

[0142] Results

[0143] Table 3 provides the compositions of the examples of the present invention ("IE") and comparative examples ("CE"), and Table 4 provides the relevant test characteristics of the examples. Table 5 provides the relaxation spectrum index and gel permeation chromatography data for the examples and comparative examples of the present invention.

[0144] Table 3

[0145] Materials CE1 IE1 CE2 IE2 CE3 IE3 CE4 IE4 CE5 IE5 CE6 CE7 MDH 66 66 66 66 66 66 66 66 66 SI-MDH 66 60 60 HDPE1 19.8 HDPE5 25.8 HDPE2 19.35 12.9 19.35 12.9 23.85 12.9 15.9 12.9 HDPE3 6.45 12.9 6.45 7.95 12.9 HDPE4 25.8 12.9 15.9 HDPE6 12.9 25.8 MAH-g-LLDPE(1) 12 MAH-g-LLDPE(3) 6 6 6 6 6 6 6 6 MAH-g-LLDPE(2) 6 6 6 MAA 1 1 1 1 1 1 1 1 1 1 1 1 PDMS 1 1 1 1 1 1 1 1 1 1 1 1 AO1 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

[0146]

[0147]

[0148] Now referring to Tables 3 - 5, it can be seen that CE1 - CE7 failed to achieve one or more of the following desired values: a PHRR of less than 250 kW / m 2 measured according to ASTM E1354, an elongation at break of greater than 20% measured according to ASTM D638, a flexural modulus of greater than 950 MPa measured according to ASTM D790, and a dynamic oscillatory shear viscosity of less than 46,000 Pa·s at 0.1 radian / second measured according to ASTM D4440 - 15.

[0149] In contrast to CE1 - CE7, IE1 - IE5 were able to achieve all of the desired properties. As can be seen from Table 5, the HDPE blends of the embodiments of the present invention (i.e., the combined first ethylene - based polymer and second ethylene - based polymer) all achieved relaxation spectrum index values of 10 to 25, a polydispersity index of 10 or greater, and a dynamic oscillatory shear viscosity of 500 Pa·s or less at 100 radians / second (shown in Table 4), such that the polymer compositions were able to achieve the desired processing and mechanical property targets despite containing a higher loading of HFFR.

Claims

1. A polymer composition, the polymer composition comprising: A first ethylene-based polymer having a density, measured according to ASTM D792, of from 0.93 g / cc to 0.97 g / cc, wherein the first ethylene-based polymer has a melt index (I 2 ) of 0.8 g / 10 min or less, measured according to ASTM D1238; A second ethylene-based polymer having a density, measured according to ASTM D792, of from 0.93 g / cc to 0.97 g / cc, wherein the second ethylene-based polymer has a melt index (I 2 ) of 3.0 g / 10 minutes or greater, measured according to ASTM D1238 wherein 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 by gel permeation chromatography, and a dynamic oscillatory shear viscosity of 500 Pa·S or less at 100 radians / second as measured by ASTM D4440-15; a compatibilizer; and a flame retardant filler.

2. The polymer composition according to claim 1, wherein the compatibilizer is selected from maleic anhydride grafted polymers, acid copolymers, and ionomers.

3. The polymer composition according to any one of claims 1 and 2, wherein the flame retardant filler is a silane-treated flame retardant filler, and based on the total weight of the polymer composition, the polymer composition comprises 10% to 80% by weight of the silane-treated flame retardant filler.

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

5. The polymer composition according to any one of claims 1 to 4, wherein based on the total weight of the polymer composition, the polymer composition comprises 1% to 20% by weight of the second ethylene-based polymer.

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

1.

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

8. The polymer composition according to any one of claims 1 to 7, wherein the relaxation spectrum index value of the combined first ethylene-based polymer and second ethylene-based polymer is 15 to 21.

9. The polymer composition according to any one of claims 1 to 8, wherein the polymer composition exhibits a PHHR of less than 250 kW / m measured according to ASTM E1354, an elongation at break of greater than 20% measured according to ASTM D638, and a flexural modulus of greater than 950 MPa measured according to ASTM D790. 2 ​ 10. A cable, the cable comprising: a conductor; and a buffer tube positioned around the conductor and containing the polymer composition according to any one of claims 1 to 9.

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