Ultraviolet light stable polymeric compositions

Abstract

The present invention relates to a polymer composition comprising 90 to 99 weight percent, based on the total weight of the polymer composition, of an ethylene-based polymer; 0.1 to 1 weight percent, based on the total weight of the polymer composition, of a hindered amine light stabilizer; and 0.1 to 5.0 weight percent, based on the total weight of the polymer composition, of at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2.

Description

BACKGROUND TECHNICAL FIELD

[0001] The present disclosure relates generally to polymer compositions, and more particularly to ultraviolet light stabilized polymer compositions.

[0002] Brief Description

[0003] Polymer jacketing materials are used as the outermost protective layer for various power and telecommunications cables. The jacket helps to protect the cable from physical damage that it can be subjected to during installation and / or use. The jacket can be colored to help visually distinguish one cable from another. Jackets installed on cables for outdoor use are subject to weathering due to ultraviolet light and other environmental factors.

[0004] During exposure to ultraviolet light ("UV") and environmental conditions, free radicals and acids are generated within the polymer jacket. The free radicals oxidize the polymer of the jacket, causing the mechanical properties of the jacket to decrease as the UV exposure increases. Oxidation of the polymer forms acids within the jacket. There are various UV weathering standards for cables that require the cable to retain a predetermined amount of its tensile strength and tensile elongation at break after a certain accelerated UV testing time period.

[0005] A conventional method to mitigate the effects of free radicals in outdoor or high UV light exposure environments is to include both carbon black and a hindered amine light stabilizer ("HALS"). Carbon black, while effective at absorbing ultraviolet light and preventing free radical generation, has a strong impact on the ability to impart the desired color to the jacket. In addition to carbon black, HALS are also used in polymer jackets to neutralize the generated free radicals. HALS are effective at neutralizing free radicals, but are deactivated by the acids present in the polymer jacket environment. Thus, attempts to make colorable cables to prevent jacket degradation by exclusively using HALS result in accelerated mechanical property degradation due to more free radical generation and deactivation of the HALS via the acids.

[0006] Attempts have been made to make UV resistant colorable jackets. For example, World Intellectual Property Organization Publication No. 2014 / 177153 Al discloses the use of calcium carbonate containing materials within a cable jacket to prevent the deactivation of HALS by environmental acids. Upon neutralization of the environmental acids in the calcium carbonate, the mechanical properties of the polymer jacket are expected to degrade over time.

[0007] In view of the above, it was unexpectedly discovered that a polymer composition that can be used as a jacket that is both colorable and can be used to make a cable that passes UV weathering standards. SUMMARY

[0008] The present disclosure provides a polymer composition useful as a jacket that can be both colored and used to manufacture a cable that passes UV weathering standards. Surprisingly, embodiments of the present invention provide a polymer composition useful as a jacket that can be both colored and used to manufacture a cable that exceeds the requirements of UV weathering standards.

[0009] The present invention is the result of the discovery that while metal carbonates are effective at neutralizing strong acids from the cable environment, metal oxides are more effective at neutralizing acids generated within the polymer jacket due to polymer oxidation. Metal oxides form metal hydroxide compounds in the presence of water. Metal hydroxide compounds exhibit greater proton affinity than metal carbonates. As a result, metal hydroxides exhibit greater efficacy than metal carbonates at neutralizing acids generated by polymer oxidation. Thus, the use of metal oxides preserves the activity of HALS for a longer period of time than metal carbonates, and the polymer jacket of the cable exhibits greater retention of mechanical properties after accelerated UV exposure. The greater efficacy of metal oxides and hydroxides allows the polymer composition to be carbon black free and thus, colorable.

[0010] The polymer composition of the present disclosure can be used in wire and cable applications.

[0011] According to a first feature of the present disclosure, the polymer composition comprises: 90 to 99 weight percent, based on the total weight of the polymer composition, of an ethylene-based polymer; 0.1 to 1 weight percent, based on the total weight of the polymer composition, of a hindered amine light stabilizer; and 0.1 to 5.0 weight percent, based on the total weight of the polymer composition, of at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2.

[0012] According to a second feature of the present disclosure, the polymer composition is free of carbon black.

[0013] According to a third feature of the present disclosure, the polymer composition further comprises a colorant.

[0014] According to a fourth feature of the present disclosure, the ethylene-based polymer comprises a low density polyethylene having a density of 0.917 g / cc to 0.926 g / cc, measured according to ASTM D792, and a high density polyethylene having a density of 0.940 g / cc to 0.970 g / cc, measured according to ASTM D792.

[0015] According to a fifth feature of the present disclosure, the polymer composition comprises 80 to 95 weight percent, based on the total weight of the polymer composition, of a high density polyethylene.

[0016] According to a sixth feature of the present disclosure, the polymer composition includes 5 to 20 weight percent of a low density polyethylene, based on the total weight of the polymer composition.

[0017] According to a seventh feature of the present disclosure, the polymer composition includes 0.1 to 3 weight percent of at least one of ZnO and Zn(OH)2.

[0018] According to an eighth feature of the present disclosure, the polymer composition includes 1.0 to 2 weight percent of at least one of MgO and Mg(OH)2, based on the total weight of the polymer composition.

[0019] According to a ninth feature of the present disclosure, 1.4 to 1.8 weight percent of the polymer composition, based on the total weight of the polymer composition, is MgO and Mg(OH)2.

[0020] According to a tenth feature of the present disclosure, a coated conductor includes: a conductor; and a polymer composition disposed at least partially around the conductor. DETAILED DESCRIPTION

[0021] 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 employed by itself, or any combination of two or more of the listed items can be employed. 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.

[0022] Unless otherwise stated, all ranges include endpoints.

[0023] Test methods refer to the most recent test method as of the priority date of this document, unless the date is indicated as a two-digit number with a hyphen following the year for test methods. References to test methods include reference to both the test society and the test method number. Test method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly known as American Society for Testing and Materials); IEC refers to International Electrotechnical Commission; EN refers to European Standard; DIN refers to Deutsches Institut fur Normung; and ISO refers to International Organization for Standardization.

[0024] As used herein, unless otherwise indicated, the term weight percent (“wt%”) means the weight percent of a component to the total weight of the polymer composition.

[0025] The melt index (I2) values herein refer to values determined according to ASTM method D1238 at 190 degrees Celsius (°C) and 2.16 kilograms (Kg) mass and are provided in units of grams eluted per ten minutes (“g / 10 min”).

[0026] The density values herein refer to values determined according to ASTM D792 at 23 °C and are provided in units of grams per cubic centimeter (“g / cc”).

[0027] As used herein, Chemical Abstracts Service Registry Number (“CAS #”) refers to the unique numerical identifier assigned to a chemical compound by the Chemical Abstracts Service as of the priority date of this document.

[0028] Polymer Composition

[0029] The polymeric composition of the present invention comprises an ethylene-based polymer, a hindered amine light stabilizer, and at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2. The polymeric composition can be free of carbon black and, thus, can be colored by optional addition of a colorant.

[0030] Ethylene-based Polymer

[0031] As noted above, one component of the polymeric composition is an ethylene-based polymer. As used herein, an “ethylene-based” polymer is one in which greater than 50 weight percent of the monomers are ethylene, although other comonomers can also be used. “Polymer” means a macromolecular compound composed of a plurality of identical or different types of monomers bonded together and includes homopolymers and interpolymers. “Interpolymer” means a polymer that comprises at least two different monomer types that are bonded together. Interpolymers include copolymers (typically used to refer to polymers prepared from two different monomer types) and polymers prepared from more than two different monomer types (e.g., terpolymers (three different monomer types) and tetrapolymers (four different monomer types)). The ethylene-based polymer can be an ethylene homopolymer. As used herein, “homopolymer” denotes a polymer comprising repeat units derived from a single monomer type, but does not exclude residual amounts of other components used in the preparation of the homopolymer such as catalysts, initiators, solvents, and chain transfer agents.

[0032] The ethylene-based polymer 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., a blend of two or more ethylene-based polymers that differ from one another in 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.

[0033] The polymer composition may contain 90% or more by weight, or 91% or more by weight, or 92% or more by weight, or 93% or more by weight, or 94% or more by weight, or 95% or more by weight, or 96% or more by weight, or 97% or more by weight, or 98% or more by weight, while simultaneously containing 99% or less by weight, or 98% or less by weight, or 97% or less by weight, or 96% or less by weight, or 95% or less by weight, or 94% or less by weight, or 93% or less by weight, or 92% or less by weight, or 91% or less by weight of an ethylene-based polymer.

[0034] As measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy, ethylene-based polymers may contain 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 91 mol% or more, or 92 mol% or more, or 93 mol% or more, or 94 mol% or more, or 95 mol% or more, or 96 mol% or more, or 97 mol% or more, or 97.5 mol% or more, or 98 mol% or more. 1% or more, or 99 mol% or more, while simultaneously, 100 mol% or less, 99.5 mol% or less, or 99 mol% or less, or 98 mol% or less, or 97 mol% or less, or 96 mol% or less, or 95 mol% or less, or 94 mol% or less, or 93 mol% or less, or 92 mol% or less, or 91 mol% or less, or 90 mol% or less, or 85 mol% or less, or 80 mol% or less, or 70 mol% or less, or 60 mol% or less ethylene. Other units of the ethylene-based polymer may include C3α-olefins, or C4α-olefins, or C6α-olefins, or C8α-olefins, or C... 10 α-olefins, or C 12 α-olefins, or C 16 α-olefins, or C 18 α-olefins, or C 20 α-olefins, such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0035] Ethylene-based polymers may include high-density polyethylene (“HDPE”). HDPE is an ethylene-based polymer with a density of at least 0.940 g / cc, or at least 0.94 g / cc to 0.97 g / cc. The melt index of HDPE is from 0.1 g / 10 min to 25 g / 10 min. HDPE may include ethylene and one or more C3-C... 20Alpha-olefin comonomer. The comonomer can be linear or branched. Non-limiting examples of suitable comonomers include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. The HDPE can be made in a slurry reactor, a gas phase reactor, or a solution reactor with a Ziegler-Natta catalyst, a chromium-based catalyst, a constrained geometry catalyst, or a metallocene catalyst. The ethylene / C3-C 20 The alpha-olefin comonomer includes at least 50 wt% of ethylene polymerized therein, or at least 70 wt%, or at least 80 wt%, or at least 85 wt%, or at least 90 wt%, or at least 95 wt% of ethylene in polymerized form. In embodiments, the HDPE is an ethylene / alpha-olefin copolymer having a density of 0.9450 g / cc and a melt index of 0.80 g / 10 min.

[0036] The polymer composition can include 80 wt% or more, or 81 wt% or more, or 82 wt% or more, or 83 wt% or more, or 84 wt% or more, or 85 wt% or more, or 86 wt% or more, or 87 wt% or more, or 88 wt% or more, or 89 wt% or more, or 90 wt% or more, or 91 wt% or more, or 92 wt% or more, or 93 wt% or more, or 94 wt% or more, while at the same time, 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 89 wt% or less, or 88 wt% or less, or 87 wt% or less, 86 wt% or less, or 85 wt% or less, or 84 wt% or less, or 83 wt% or less, or 82 wt% or less, or 81 wt% or less of the HDPE, based on the total weight of the polymer composition.

[0037] The ethylene-based polymer can include a low density polyethylene (“LDPE”). LDPE resins are commercially available and can be made by any of a variety of methods including, but not limited to, solution, gas phase, or slurry phase Ziegler-Natta, metallocene, or constrained geometry catalyst (CGC), etc. The LDPE resin has a density of 0.910 g / cc to 0.926 g / cc. The LDPE can have a melt index of less than 20 g / 10 min, or in the range of 0.1 g / 10 min to 10 g / 10 min, or 2 g / 10 min to 8 g / 10 min, or 4 g / 10 min to 8 g / 10 min.

[0038] The polymer composition can comprise 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, or 18 wt% or more, or 19 wt% or more, while at the same time, 20 wt% or less, or 19 wt% or less, or 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 of LDPE, based on the total weight of the polymer composition.

[0039] HALS

[0040] The polymer composition comprises one or more hindered amine light stabilizers. HALS are chemical compounds containing amine functional groups that are used as stabilizers in plastics and polymers. These compounds can be derivatives of tetramethylpiperidine and are primarily used to protect polymers from free radical oxidation due to exposure to UV light.

[0041] HALS can include one or more of: poly(4-hydroxy-2,2,6,6-tetramethyl-1- piperidinylethanol-alt-1,4-succinic acid) (CAS# 65447-77-0); bis(2,2,6,6-tetramethyl-4- piperidyl) sebacate (CAS# 52829-07-9); di-(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(3,5- di-tert-butyl-4-hydroxybenzyl)propanediol (CAS# 63843-89-0); bis(1 -octyloxy-2,2,6,6-tetramethyl-4- piperidyl) sebacate (CAS# 129757-67-1 ); poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-s-triazine-2,4- diyl]-[(2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4- piperidyl)imino] (CAS# 71878-19-8); 1,3,5-triazine-2,4,6-triamine, N,N'-1,2-ethanediylbis[N-[3-[[4,6- bis[butyl(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-1,3,5-triazin-2-yl]amino]propyl]-N',N"- dibutyl-N',N"-bis(1,2,2,6,6-pentamethyl-4-piperidyl)]-(CAS# 106990-43-6); 1,6-hexanediamine, N,N'- bis(2,2,6,6-tetramethyl-4-piperidyl)-, polymer with 2,4,6-trichloro-1,3,5-triazine, reaction products with N-butyl-1 -butanamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine (CAS# 192268-64-7). Examples of HALS are commercially available under the trade designations TINUVIN™ 622 and CHIMASSORB™ 944 from BASF, Ludwigshafen, Germany.

[0042] The polymer composition can include 0.1 wt% to 1.0 wt% of a HALS, based on the total weight of the polymer composition. For example, the polymer composition can include 0.1 wt% or more, or 0.2 wt% or more, or 0.3 wt% or more, or 0.4 wt% or more, or 0.5 wt% or more, or 0.6 wt% or more, or 0.7 wt% or more, or 0.8 wt% or more, or 0.9 wt% or more, while at the same time, 1.0 wt% or less, or 0.9 wt% or less, or 0.8 wt% or less, or 0.7 wt% or less, or 0.6 wt% or less, or 0.5 wt% or less, or 0.4 wt% or less, or 0.3 wt% or less, or 0.2 wt% or less of a HALS, based on the total weight of the polymer composition.

[0043] Metal Oxides and Hydroxides

[0044] The polymer composition includes at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2. As explained above, it has been surprisingly discovered that the incorporation of certain metal oxides and hydroxides can effectively neutralize acids present in the polymer composition that would otherwise neutralize the HALS. By including at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2, the coated conductor can achieve greater retention of tensile strength and elongation at break after exposure to ultraviolet radiation by protecting the HALS from deactivation.

[0045] The polymer composition includes 0.1 wt% to 5.0 wt% of at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2, based on the total weight of the polymer composition. For example, the polymer composition can include 0.1 wt% or more, or 0.2 wt% or more, or 0.4 wt% or more, or 0.6 wt% or more, or 0.8 wt% or more, or 1.0 wt% or more, or 1.2 wt% or more, or 1.4 wt% or more, or 1.6 wt% or more, or 1.8 wt% or more, or 2.0 wt% or more, or 2.2 wt% or more, or 2.4 wt% or more, or 2.6 wt% or more, or 2.8 wt% or more, or 3.0 wt% or more, or 3.2 wt% or more, or 3.4 wt% or more, or 3.6 wt% or more, or 3.8 wt% or more, or 4.0 wt% or more, or 4.2 wt% or more, or 4.4 wt% or more, or 4.6 wt% or more, or 4.8 wt% or more, and at the same time, 5.0 wt% or less, or 4.8 wt% or less, or 4.6 wt% or less, or 4.4 wt% or less, or 4.2 wt% or less, or 4.0 wt% or less, or 3.8 wt% or less, or 3.6 wt% or less, or 3.4 wt% or less, or 3.2 wt% or less, or 3.0 wt% or less, or 2.8 wt% or less, or 2.6 wt% or less, or 2.4 wt% or less, or 2.2 wt% or less, or 2.0 wt% or less, or 1.8 wt% or less, or 1.6 wt% or less, or 1.4 wt% or less, or 1.2 wt% or less, or 1.0 wt% or less, or 0.8 wt% or less, or 0.6 wt% or less, or 0.4 wt% or less, or 0.2 wt% or less of at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2, based on the total weight of the polymer composition. The polymer composition can include 0.1 wt% to 3 wt% of at least one of ZnO and Zn(OH)2. The polymer composition can include 0.5 wt% to 2 wt% of at least one of MgO and Mg(OH)2, based on the total weight of the polymer composition. The polymer composition can include 1.4 wt% to 1.8 wt% of at least one of MgO and Mg(OH)2, based on the total weight of the polymer composition.

[0046] Additives

[0047] The polymer composition can include additional additives in the form of antioxidants, crosslinking co-agents, cure accelerators and scorch retarders, processing aids, coupling agents, ultraviolet light stabilizers including UV absorbers such as hydroxyphenyltriazines, antistatic agents, additional nucleating agents, slip agents, lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, extender oils, acid scavengers, flame retardants, and metal deactivators. The polymer composition can include from 0.01 wt% to 10 wt% of one or more additional additives.

[0048] The polymer composition can be free of carbon black. As used herein, the term "free of" is defined to mean that the formulation includes less than 0.5 wt% of carbon black, based on the total weight of the polymer composition. As highlighted above, carbon black is effective at absorbing ultraviolet light and preventing the production of free radicals, but has a strong influence on the ability to impart the desired color to the polymer composition. The inclusion of at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2extends the useful life of the HALS such that carbon black is not needed and, thus, can be removed from the polymer composition.

[0049] The polymer composition can include a colorant. As explained above, the absence of carbon black enables the polymer composition to be colored by a colorant. The colorant can include one or more of azo dyes, anthraquinone dyes, and phthalocyanine dyes. The polymer composition can include one or more of COLOUR INDEX™ generic name colorants such as Pigment Violet 32 (CAS# 12225-08-0), Pigment Orange 34 (CAS# 15793-73-4), Pigment Red 38 (CAS# 6358-87-8), Pigment Red 208 (CAS# 31778-10-6), Pigment Red 48:2 (CAS# 7023-61-2), Pigment Red 57:1 (CAS# 5281-04-9), Pigment Yellow 155 (CAS# 68516-73-4 / 77465-46-4), Pigment Yellow 151 (CAS# 31837-42-0), Pigment Green 7 (CAS# 1328-53-6), Pigment Red 122 (CAS# 980-26-7 / 16043-40-6), Pigment Red 214 (CAS# 40618-31-3), Pigment Violet 23 (CAS# 6358-30-1), and / or Pigment Yellow 191 (CAS# 129423-54-7).

[0050] The polymer composition can include one or more particulate fillers, such as glass fibers or various mineral fillers (including nanocomposites). Fillers, particularly those with elongated or platelet-shaped particles that provide a higher aspect ratio (length / thickness), can improve modulus and post-extrusion shrinkage properties. The median size or d50 of the filler can be less than 20 pm, less than 10 pm, or less than 5 pm. The filler can be surface treated to promote wetting or dispersion in the polymer composition. Specific examples of suitable fillers include, but are not limited to, calcium carbonate, silica, quartz, fused quartz, talc, mica, clay, kaolin, wollastonite, feldspar, aluminum hydroxide, and graphite. The filler can be included in the polymer composition in an amount ranging from 2 wt% to 30 wt% or 5 wt% to 30 wt%, based on the total weight of the polymer composition.

[0051] Processing aids can include metal salts of fluororesins, such as polytetrafluoroethylene or fluorinated ethylene propylene; carboxylic acids such as zinc stearate, calcium stearate, and the like; fatty acids such as stearic acid, oleic acid, or erucic acid; fatty amides such as stearamide, oleamide, erucamide, or N,N'-ethylene bis stearamide; polyethylene waxes; oxidized polyethylene waxes; polymers of ethylene oxide; copolymers of ethylene oxide and propylene oxide; vegetable waxes; petroleum waxes; non-ionic surfactants; silicone fluids and polysiloxanes.

[0052] Antioxidants can include hindered phenols such as tetrakis[methylene(3,5-di-tert-butyl-4- hydroxyhydrocinnamate)]methane; bis[(beta-(3,5-di-tert-butyl-4-hydroxybenzyl)methylcarbinol)]- 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; thio compounds such as dilaurylthiodipropionate, dimyristylthiodipropionate, and distearylthiodipropionate; various siloxanes; polymeric 2,2,4-trimethyl-1,2- dihydroquinoline, n,n'-bis(1,4-dimethylpentyl-p-phenylenediamine), alkylated diphenylamine, 4,4'- bis(alpha,alpha-dimethylbenzyl) diphenylamine, diphenyl-p-phenylenediamine, mixed diaryl-p- phenylenediamines, and other hindered amine anti-degradants or stabilizers.

[0053] Compounding

[0054] 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 first be prepared for blending with the other components. Melt blending can be carried out at a temperature above the highest melting polymer. The melt blended composition can then be conveyed into an extruder or injection molding machine, or shaped through a die into a desired article, or converted into pellets, tape, strips, or films or some other form for storage or preparation of material for feeding into the next shaping or processing step. Optionally, if shaped into pellets or some similar configuration, the pellets or the like can be coated with an anti-sticking agent to facilitate handling upon storage.

[0055] 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 as well as the operating conditions of the mixer will affect the properties of the composition, such as viscosity, volume resistivity, and surface smoothness of extrusion.

[0056] Mechanical Properties

[0057] The polymer composition can exhibit a non-UV aged or UV aged maximum tensile strength of 20.0 megapascals (MPa) to 35.0 MPa, as measured according to ASTM D638. For example, the polymer composition can exhibit a maximum tensile strength of 20.0 MPa or greater, or 20.5 MPa or greater, or 21.0 MPa or greater, or 21.5 MPa or greater, or 22.0 MPa or greater, or 22.5 MPa or greater, or 23.0 MPa or greater, or 23.5 MPa or greater, or 24.0 MPa or greater, or 24.5 MPa or greater, or 25.0 MPa or greater, or 25.5 MPa or greater, or 26.0 MPa or greater, or 26.5 MPa or greater, or 27.0 MPa or greater, or 27.5 MPa or greater, or 28.0 MPa or greater, or 28.5 MPa or greater, or 29.0 MPa or greater, or 29.5 MPa or greater, or 30.0 MPa or greater, or 30.5 MPa or greater, or 31.0 MPa or greater, or 31.5 MPa or greater, or 32.0 MPa or greater, or 32.5 MPa or greater, or 33.0 MPa or greater, or 33.5 MPa or greater, or 34.0 MPa or greater, or 34.5 MPa or greater, while at the same time, 35.0 MPa or less, or 34.5 MPa or less, or 34.0 MPa or less, or 33.5 MPa or less, or 33.0 MPa or less, or 32.5 MPa or less, or 32.0 MPa or less, or 31.5 MPa or less, or 31.0 MPa or less, or 30.5 MPa or less, or 30.0 MPa or less, or 29.5 MPa or less, or 29.0 MPa or less, or 28.5 MPa or less, or 28.0 MPa or less, or 27.5 MPa or less, or 27.0 MPa or less, or 26.5 MPa or less, or 26.0 MPa or less, or 25.5 MPa or less, or 25.0 MPa or less, or 24.5 MPa or less, or 24.0 MPa or less, or 23.5 MPa or less, or 23.0 MPa or less, or 22.5 MPa or less, or 22.0 MPa or less, or 21.5 MPa or less, or 21.0 MPa or less, or 20.5 MPa or less.

[0058] The polymer composition can exhibit a non-UV aged or UV aged elongation at break of 550% to 1000% as measured according to ASTM D638. For example, the polymer composition can exhibit an elongation at break of 550% or greater, or 560% or greater, or 570% or greater, or 580% or greater, or 590% or greater, or 600% or greater, or 610% or greater, or 620% or greater, or 630% or greater, or 640% or greater, or 650% or greater, or 660% or greater, or 670% or greater, or 680% or greater, or 690% or greater, or 700% or greater, or 710% or greater, or 720% or greater, or 730% or greater, or 740% or greater, or 750% or greater, or 760% or greater, or 770% or greater, or 780% or greater, or 790% or greater, or 800% or greater, or 810% or greater, or 820% or greater, or 830% or greater, or 840% or greater, or 850% or greater, or 860% or greater, or 870% or greater, or 880% or greater, or 890% or greater, or 900% or greater, or 910% or greater, or 920% or greater, or 930% or greater, or 940% or greater, or 950% or greater, or 960% or greater, or 970% or greater, or 980% or greater, or 990% or greater, while at the same time, 1000% or less, or 990% or less, or 980% or less, or 970% or less, or 960% or less, or 950% or less, or 940% or less, or 930% or less, or 920% or less, or 910% or less, or 900% or less, or 890% or less, or 880% or less, or 870% or less, or 860% or less, or 850% or less, or 840% or less, or 830% or less, or 820% or less, or 810% or less, or 800% or less, or 790% or less, or 780% or less, or 770% or less, or 760% or less, or 750% or less, or 740% or less, or 730% or less, or 720% or less, or 710% or less, or 700% or less, or 690% or less, or 680% or less, or 670% or less, or 660% or less, or 650% or less, or 640% or less, or 630% or less, or 620% or less, or 610% or less, or 600% or less, or 590% or less, or 580% or less, or 570% or less, or 560% or less.

[0059] The polymer composition can have a retention of maximum tensile strength and / or a retention of elongation at break (both measured by the UV aged value divided by the non-UV aged value) of 65% or greater, or 70% or greater, or 75% or greater, or 80% or greater, or 85% or greater, or 90% or greater, or 95% or greater, while at the same time, 100% or less, or 95% or less, or 90% or less, or 85% or less, or 80% or less, or 75% or less, or 70% or less.

[0060] Coated Conductor

[0061] The present disclosure also provides 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 disposed at least partially around the conductor to produce the coated conductor. The conductor can include an electrically conductive metal or an optically transparent structure.

[0062] A method for making a coated conductor includes mixing and heating a polymer composition in an extruder to at least the melting temperature of the polymer components to form a polymer melt blend, and then coating the polymer melt blend onto a conductor. The term "onto" includes direct contact or indirect contact between the polymer melt blend and the conductor. The polymer melt blend is in an extrudable state.

[0063] The polymer composition is disposed on and / or around the conductor to form a coating. The coating can be one or more inner layers, such as an insulating layer. The coating can completely or partially cover or otherwise surround or encase the conductor. The coating can be the only component that surrounds the conductor. Alternatively, the coating can be one layer of a multi-layered sheath or skin that encases the conductor. The coating can directly contact the conductor. The coating can directly contact an insulating layer that surrounds the conductor.

[0064] Examples

[0065] Materials

[0066] The following materials were employed in the following examples.

[0067] HDPE is a high density polyethylene (HDPE) composed of ethylene / octene copolymer and having a density of 0.9450 g / cc and a melt index of 0.80 g / 10 min, available from The Dow Chemical Company, Midland, MI, USA.

[0068] LLDPE is a linear low density polyethylene having a density of 0.920 g / cc, a melt flow index of 0.55 to 0.75 g / 10 min, and is available from The Dow Chemical Company, Midland, MI, USA.

[0069] AO is a sterically hindered phenolic antioxidant with the chemical name tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) pentaerythritol and is commercially available as IRGANOX 1010™ from BASF, Ludwigshafen, Germany.

[0070] UVA is an ultraviolet light absorber with the chemical composition hydroxyphenyltriazine and is commercially available as TINUVIN™ 1577 from BASF, Ludwigshafen, Germany.

[0071] HALS1 is a hindered amine light stabilizer (CAS# 70624-18-9) with the chemical name poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6 hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino]] and is commercially available as CHIMASSORB™ 944 from BASF, Ludwigshafen, Germany.

[0072] HALS2 is an oligomeric hindered amine light stabilizer with the chemical composition poly(4-hydroxy-2,2,6,6-tetramethyl-1 -piperidinoethanol-alt-1,4-butanediol dicarboxylate) (CAS# 65447-77-0) and is commercially available as TINUVIN® 765™ from BASF, Ludwigshafen, Germany. TM 622 from BASF, Ludwigshafen, Germany.

[0073] MgO is magnesium oxide commercially available from Lanxess corporation, Pittsburgh, Pennsylvania, USA.

[0074] ZnO is zinc oxide commercially available from Sinopharm Chemical Reagent Co. Ltd., China.

[0075] Sample Preparation

[0076] The samples were prepared by mixing the components in a BRABENDER® compounder at 150 °C for 5 minutes. TMHDPE and LDPE were compounded in a mixer to prepare the samples. The rotor speed of the mixer was set to 30 revolutions per minute (“RPM”). The components other than the HDPE and LDPE were fed into the mixer. The rotor speed was increased to 80 RPM and the sample was mixed for an additional 5 minutes. The sample was then cooled and cut into small pieces.

[0077] Forty grams of the small pieces were sandwiched between two biaxially oriented polyethylene terephthalate (i.e., Mylar) sheets and placed into a mold having dimensions of 100 millimeters (“mm”) x 200 mm x 2 mm. The mold was placed in a KT-201-A hot press from Shanghai Great Instrument Co. Ltd and preheated at 170 °C for 10 minutes. The mold was vented 8 times. The mold was then held at 170 °C and 10 megaPascals (“MPa”) (as measured by the hot press) for an additional 5 minutes. Next, the mold was cooled to room temperature using internal water cooling at 10 MPa in 5 minutes to form a plaque.

[0078] The plaque was cut into a 5A dogbone according to ISO 527-2. The 5A dogbone was placed in a SUV-W161 ultraviolet (“UV”) weathering chamber from EYE Applied Optix for ultraviolet (“SUV”) aging. The exposure cycle consisted of a 1 hour light period followed by a 2 hour dark period with continuous water spray on the front face. The broadband irradiance (integral of spectral irradiance from 295 nm to 400 nm) was controlled at 1500 W / m 2 . The uninsulated black panel temperature (“BPT”) was 70 ± 3 °C when the light was on and 55 ± 3 °C when the light was off. The relative humidity was 70 ± 10% during the light period and greater than 95% during the dark period. The air temperature was not controlled throughout the operation. The samples (at least four replicates per sample) were aged for 4 weeks (total of 1200 MJ / m 2 ) or 8 weeks (total of 2400 MJ / m 2 ). The 1200 MJ / m 2 Broadband UV dose is equivalent to 5700 hours of xenon-arc aging / 10,000 hours of fluorescent aging as described in ASTM D1248 or 7600 hours of xenon-arc aging as described in IEC 60794.

[0079] Test Methods

[0080] The maximum tensile strength and the tensile elongation at break of the samples were performed according to ASTM D638 on a 5565 tensile testing machine from Instron Calibration Lab.

[0081] Table 1 provides the UV test related standards against which the samples were compared.

[0082] Table 1

[0083]

[0084] Results

[0085] Table 2 provides the composition of Inventive Examples ("IE") 1-12 as well as the mechanical properties at different accelerated UV aging periods, such as maximum tensile strength ("TS Max"), tensile elongation at break ("TE"), maximum tensile strength retention ("TS Retention"), and tensile elongation at break retention ("TE Retention").

[0086] Table 2

[0087]

[0088] With respect to the 4 week aging in Table 2, IE1-IE12 exhibited greater than 50% TS Retention and TE Retention for 4 weeks (1200 MJ / m 2 ) of SUV aging, which indicates that ZnO, MgO, Zn(OH)2, and Mg(OH)2, which are believed to form in the polymer composition due to moisture, are effective in allowing the polymer composition to pass ASTM D1248 aging despite the absence of carbon black. It should be noted that the total amount of UV energy to which IE1-IE12 were exposed (1200 MJ / m 2 ) far exceeds the requirements of ASTM D1248 (853 MJ / m 2 ). IE1, IE3, IE5, and IE8 all were able to pass the 80% TE Retention requirement of IEC 60794 despite receiving almost twice the UV exposure specified by IEC 60794 (633 MJ / m 2 ). Given these results, it is believed that IE1-IE12 will all pass ASTM D1248 and IEC 60794.

[0089] With respect to the 8 weeks aging in Table 2, it was surprisingly found that IE5 and IE7-IE12 all were able to pass the 50% or greater TE retention requirement of ASTM D1248, despite receiving nearly three times the UV energy specified by ASTM D1248. Even more surprisingly, IE8 was able to meet the 80% or greater TE retention requirement of IEC 60794, despite receiving almost four times the UV energy specified by IEC 60794. These results indicate that MgO and Mg(OH)2 produce surprising results from 1.00 wt% to 2.00 wt% and more specifically from 1.4 wt% to 1.8 wt% where the polymer composition can retain greater than 80% tensile elongation after 2400 MJ / m2 of UV exposure despite being free of carbon black.

Claims

1. A polymer composition comprising: 90 to 99 weight percent, based on the total weight of the polymer composition, an ethylene-based polymer; 0.1 to 1 weight percent, based on the total weight of the polymer composition, a hindered amine light stabilizer; and 0.1 to 5.0 weight percent, based on the total weight of the polymer composition, at least one of MgO, Mg(OH)2, ZnO, and Zn(OH)2; wherein the ethylene-based polymer comprises a low density polyethylene having a density of 0.917 g / cc to 0.926 g / cc as measured according to ASTM D792 and a high density polyethylene having a density of 0.940 g / cc to 0.970 g / cc as measured according to ASTM D792; wherein the polymer composition comprises 80 to 95 weight percent, based on the total weight of the polymer composition, of the high density polyethylene.

2. The polymer composition of claim 1, wherein the polymer composition is free of carbon black.

3. The polymer composition of claim 2, further comprising a colorant.

4. The polymer composition of claim 1, wherein the polymer composition comprises 5 to 20 weight percent, based on the total weight of the polymer composition, of the low density polyethylene.

5. The polymer composition of claim 1, wherein the polymer composition comprises 0.1 to 3 weight percent of at least one of ZnO and Zn(OH)2.

6. The polymer composition of claim 1, wherein the polymer composition comprises 1.0 to 2 weight percent, based on the total weight of the polymer composition, of at least one of MgO and Mg(OH)2.

7. The polymer composition of claim 6, wherein 1.4 to 1.8 weight percent, based on the total weight of the polymer composition, of the polymer composition is MgO and Mg(OH)2.

8. A coated conductor comprising: a conductor; and the polymer composition of any one of claims 1 to 7 disposed at least partially around the conductor.

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