Flame retardant polymer composition

Abstract

A moisture-curable polymer composition includes from 10% to 99% by weight, based on the total weight of the moisture-curable polymer composition, of a silane-functionalized polyolefin and from 1% to 90% by weight, based on the total weight of the moisture-curable polymer composition, of an intumescent flame retardant mixture. The intumescent flame retardant mixture comprises piperazine pyrophosphate and 15 to 55 wt% of a phosphoric acid compound based on the total weight of the intumescent flame retardant mixture.

Description

BACKGROUND TECHNICAL FIELD

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

[0002] The jacketing and / or insulation layers of electrical wires and cables used in constructions often must exhibit certain threshold flame retardant properties. When high levels of halogen-free flame retardant ("HFFR") fillers are incorporated in such materials, thermoplastic vinyl polymers (also known as polyethylenes) are often used as the base polymer in the composition of such jacketing or insulation materials, however the thermoplastic compositions lack sufficient resistance to flow and deformation upon exposure to elevated temperatures. Crosslinked polyolefin compositions are used in various applications where such heat resistance and good mechanical properties are required. Crosslinking of polyolefins transforms the thermoplastic composition into a thermoset composition, which increases its resistance to deformation and flow at elevated temperatures, as the polymer chains are linked together unlike the case of thermoplastic compositions.

[0003] There are multiple methods to crosslink polymeric compositions, including vulcanization for peroxide-induced crosslinking, electron beam-based crosslinking, and wet-induced crosslinking by using silane-functionalized. Silane crosslinking of polymeric compositions utilizing silane-functionalized of the polymers often requires the use of silanol condensation catalysts, such as tin-based dibutyltin dilaurate and / or strong acids, such as sulfonic acids. The presence of moisture in such formulations is undesirable as it can lead to premature crosslinking during melt extrusion. Wet-induced crosslinking of the formulation occurs in subsequent steps after the manufacture of the article, by diffusion of water into the article.

[0004] Polymeric compositions are generally considered to be crosslinked if they exhibit a gel content of 10 wt% or greater as measured according to ASTM D2765. The level of flame retardancy required, if any, in a moisture-cured polymeric composition will depend on its intended application, with the UL-2556 Horizontal Flame Test being an example in the field of wire and cable applications. In general, a flame retardant moisture-cured polymeric composition should exhibit a peak tensile strength of 600 psi (4 megapascals, MPa) or greater, a tensile elongation at break of 50% or greater, a hot set of 175% (also known as hot set elongation) as measured according to ICEA Standard T-28-562, and for horizontal flame applications, should exhibit a char length of 100 mm or less, and no dripping or cotton ignition when tested according to the UL-2556 Horizontal Flame Test. <

[0005] ​Intumescent compounds can be used as halogen-free flame retardant ("HFFR") fillers in polymeric applications. Intumescent compounds operate by intumescing upon exposure to heat, thereby volumetrically diluting the available polymeric material that can be used for combustion. For example, U.S. Patent Application Publication No. 2003 / 0088000 Al discloses the use of intumescent compounds with polymeric systems such as polypropylene. Intumescent compounds have not previously been used in silane-crosslinking (moisture-curable) systems, possibly because they typically contain pentaerythritol (as a charring agent), which can undergo dehydration in the presence of an acid or acid source (such as ammonium polyphosphate, which is a typical component of intumescent compounds) to produce water, which in turn would cause premature crosslinking during melt extrusion of a composition containing a silane-functionalized polymer. Equation 1 of Applied Catalysis A: General, Vol. 253, 2003, pp. 29-32, depicts the production of water from acid-catalyzed dehydration of pentaerythritol.

[0006] In view of the foregoing, it was surprising to find a silane-crosslinking (moisture-curable) polymeric composition that includes an intumescent flame-retardant mixture that does not prematurely crosslink during melt extrusion and exhibits the above-mentioned peak tensile strength, tensile elongation at break, and passing of the horizontal burn test. SUMMARY

[0007] The inventors of the present disclosure have found a silane-crosslinking (moisture-curable) polymeric composition that includes an intumescent flame-retardant mixture that does not prematurely crosslink during melt extrusion and exhibits the above-mentioned peak tensile strength, tensile elongation at break, and passing of the horizontal burn test.

[0008] The present disclosure is the result of using an intumescent flame-retardant mixture that includes piperazine pyrophosphate and a phosphoric acid compound that does not undergo acid-catalyzed decomposition during melt extrusion to produce problematic water, evidence of which would be surface roughness due to premature crosslinking of the silane-functionalized polyolefin.

[0009] According to a first feature of the present disclosure, the moisture-curable polymeric composition includes from 10 wt% to 99 wt% of a silane-functionalized polyolefin based on the total weight of the moisture-curable polymeric composition; and from 1 wt% to 90 wt% of an intumescent flame-retardant mixture based on the total weight of the moisture-curable polymeric composition, wherein the intumescent flame-retardant mixture includes piperazine pyrophosphate and from 15 wt% to 55 wt% of a phosphoric acid compound based on the total weight of the intumescent flame-retardant mixture.

[0010] According to another feature of the present disclosure, the silane-functionalized polyolefin is a silane-functionalized ethylene-based polymer.

[0011] According to another feature of the disclosure, the polymer composition comprises 30 wt% or more silane-functionalized polyolefin, based on the total weight of the moisture-curable polymer composition.

[0012] According to another feature of the disclosure, the polymer composition comprises 15 wt% or more intumescent flame retardant mixture, based on the total weight of the moisture-curable polymer composition.

[0013] According to another feature of the disclosure, the intumescent flame retardant mixture comprises 25 wt% to 45 wt% phosphoric acid compound, based on the total weight of the intumescent flame retardant mixture.

[0014] According to another feature of the disclosure, the phosphoric acid compound is selected from the group consisting of melamine polyphosphate, ammonium polyphosphate, or a combination thereof.

[0015] According to another feature of the disclosure, the moisture-curable polymer composition exhibits a density of 1.70 g / cc or less, as measured according to ASTM D792.

[0016] According to another feature of the disclosure, the moisture-curable polymer composition is free of dibutyltin dilaurate and sulfonic acid.

[0017] According to another feature of the disclosure, the moisture-cured polymer composition prepared from the moisture-curable polymer composition exhibits one or more of the following properties: a peak tensile strength of 4 megapascals or more, as measured according to ASTM D638; a tensile elongation at break of 50% or more, as measured according to ASTM D638; and a hot creep of 175% or less, as measured according to UL 2556 Section 7.9.

[0018] According to another feature of the disclosure, the coated conductor comprises a conductor; and a moisture-cured polymer composition positioned around the conductor.

[0019] According to another feature of the disclosure, the coated conductor passes the UL-2556 horizontal flame test. DETAILED DESCRIPTION

[0020] 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.

[0021] All ranges include endpoints unless otherwise indicated.

[0022] Test methods refer to the latest test method as of the priority date of this document unless the date is indicated by the test method number as a two-digit number with a hyphen. A reference to a test method includes a reference to both the test society and the test method number. Test societies are referred to by one of the following abbreviations: ASTM refers to ASTM International (formerly known as American Society for Testing and Materials); EN refers to European Norm; DIN refers to Deutsches Institut fur Normung; and ISO refers to International Organization for Standardization. Moisture-curable polymer composition

[0023] The present disclosure generally relates to moisture-curable polymeric compositions. The moisture-curable polymeric compositions include a silane-functionalized polyolefin and an intumescent flame-retardant mixture. The moisture-curable polymeric compositions can exhibit a density of 1.70 g / cc or less as measured according to ASTM D792. For example, the moisture-curable polymeric compositions can exhibit a density of 1.70 g / cc or less, or 1.65 g / cc or less, or 1.60 g / cc or less, or 1.55 g / cc or less, or 1.50 g / cc or less, or 1.45 g / cc or less, or 1.40 g / cc or less, or 1.30 g / cc or less, or 1.20 g / cc or less, or 1.10 g / cc or less, or 1.00 g / cc or less, or 0.99 g / cc or less, or 0.98 g / cc or less, or 0.97 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, as measured according to ASTM D792. According to various examples, the moisture-curable polymeric compositions are free of dibutyltin dilaurate and sulfonic acid. Silane-functionalized polyolefins

[0024] A“silane-functionalized polyolefin” is a polymer containing silane and a major amount of polymerized alpha-olefins equal to or greater than 50 weight percent, based on the total weight of the silane-functionalized polyolefin. By“polymer” is meant a macromolecular compound prepared by reacting (i.e., polymerizing) monomers of the same or different type. As noted above, the moisture-curable polymeric compositions include a silane-functionalized polyolefin. The polyolefin includes polymerized alpha-olefins and optionally unsaturated esters.

[0025] Silane-functionalized polyolefins may include α-olefin and silane copolymers (i.e., α-olefin / silane copolymers), silane-grafted polyolefins, and / or combinations thereof. "α-olefin and silane copolymers" are formed by copolymerizing α-olefins (such as ethylene) and hydrolyzable silane monomers (such as vinylsilane monomers), such that the hydrolyzable silane monomers are incorporated into the polymer backbone, and then the polymer is incorporated into a moisture-curable polymer composition. "Silane-grafted polyolefins" or "Si-g-PO" can be formed via the Sioplas process, in which the hydrolyzable silane monomers are grafted onto the backbone of the base polyolefin via processes such as extrusion before the polymer is incorporated into the polymer composition.

[0026] In examples where the silane-functionalized polyolefin is an α-olefin / silane copolymer, the silane-functionalized polyolefin is prepared by copolymerization of at least one α-olefin and a hydrolyzable silane monomer. In examples where the silane-functionalized polyolefin is a silane-grafted polyolefin, the silane-functionalized polyolefin is prepared by grafting one or more hydrolyzable silane monomers onto the α-olefin backbone.

[0027] Based on the total weight of the silane-functionalized polyolefin, the silane-functionalized polyolefin comprises 90% or more, or 91% or more, or 92% or more, or 93% or more, or 94% or more, or 95% or more, or 96% or more, or 97% or more, or 97.5% or more, or 98% or more, or 98.5% or more, or 99% or more, while simultaneously comprising 99.5% or less, or 99% or less, or 98% or less, or 97% or less, or 96% or less, or 95% or less, or 94% or less, or 93% or less, or 92% or less, or 91% or less of α-olefin and optional unsaturated ester, as measured using Fourier transform infrared (FTIR) spectroscopy. The α-olefin may comprise C2 or C3 to C4, or C6, or C8, or C 10 or C 12 or C 16 or C 18 or C 20 α-Alkenes, such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Unsaturated esters can be alkyl acrylates, alkyl methacrylates, or vinyl carboxylate esters.

[0028] The silane-functionalized polyolefin can comprise 0.1 wt%, or 0.3 wt%, or 0.5 wt%, or 0.8 wt%, or 1.0 wt%, or 1.2 wt%, or 1.5 wt%, or 1.6 wt% to 1.8 wt%, or 2.0 wt%, or 2.3 wt%, or 2.5 wt%, or 3.0 wt%, or 3.5 wt%, or 4.0 wt%, or 4.5 wt%, while 5.0 wt% or less, or 4.5 wt% or less, or 4.0 wt% or less, or 3.5 wt% or less, or 3.0 wt% or less, or 2.5 wt% or less, or 2.4 wt% or less, or 2.3 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 0.6 wt% or less silane, as measured using FTIR spectroscopy, based on the total weight of the silane-functionalized polyolefin.

[0029] The silane-functionalized polyolefin has a density of 0.850 g / cc, or 0.860 g / cc, or 0.875 g / cc, or 0.880, or 0.890 g / cc to 0.900 g / cc, or 0.910 g / cc, or 0.915 g / cc, or 0.920 g / cc, or 0.930 g / cc, or 0.940 g / cc, or 0.950 g / cc, or 0.960 g / cc, or 0.965 g / cc, while 0.970 g / cc or less, or 0.960 g / cc or less, or 0.950 g / cc or less, or 0.940 g / cc or less, or 0.930 g / cc or less, or 0.920 g / cc or less, or 0.910 g / cc or less, or 0.900 g / cc or less, or 0.890 g / cc or less, or 0.880 g / cc or less, or 0.870 g / cc or less, or 0.860 g / cc or less, as measured by ASTM D792.

[0030] The silane-functionalized polyolefin can have a melt index as measured according to ASTM D1238 at 190 °C / 2.16 kilogram (kg) weight and reported in grams eluted per 10 minutes (g / 10 min). The silane-functionalized polyolefin can have a melt index of 0.5 g / 10 min or more, or 1.0 g / 10 min or more, or 1.5 g / 10 min or more, or 2.0 g / 10 min or more, or 2.5 g / 10 min or more, or 3.0 g / 10 min or more, or 3.5 g / 10 min or more, or 4.0 g / 10 min or more, or 4.5 g / 10 min or more, while at the same time 50.0 g / 10 min or less, or 45.0 g / 10 min or less, or 40.0 g / 10 min or less, or 35.0 g / 10 min or less, or 30.0 g / 10 min or less, or 25.0 g / 10 min or less, or 20.0 g / 10 min or less, or 15.0 g / 10 min or less, or 10.0 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, or 3.0 g / 10 min or less, or 2.5 g / 10 min or less, or 2.0 g / 10 min or less, or 1.5 g / 10 min or less, or 1.0 g / 10 min or less.

[0031] A "hydrolysable silane monomer" is a silane-containing monomer that will effectively copolymerize with an alpha-olefin (e.g., ethylene) to form an alpha-olefin / silane copolymer (such as an ethylene / silane copolymer), or graft to an alpha-olefin polymer (i.e., polyolefin) to form a Si-g-PO, thus enabling subsequent crosslinking of the silane-functionalized polyolefin. A representative, but non-limiting, example of a hydrolysable silane monomer has structure (I):

[0032]

[0033] where R 1 is a hydrogen atom or a methyl group; x is 0 or 1; n is an integer from 1 to 4, or 6, or 8, or 10, or 12; and each R 2 is independently an organic group capable of hydrolysis, such as an alkoxy group having from 1 to 12 carbon atoms (e.g., methoxy, ethoxy, butoxy), an aryloxy group (e.g., phenoxy), an aralkyloxy group (e.g., benzyloxy), an aliphatic acyloxy group having from 1 to 12 carbon atoms (e.g., formyloxy, acetyloxy, propionyloxy), an amino or substituted amino group (e.g., alkylamino, arylamino), or a lower alkyl group having from 1 to 6 carbon atoms, provided that three R 2No more than one of the groups is an alkyl group. The hydrolysable silane monomer can be copolymerized in a reactor with an alpha-olefin, such as ethylene, such as a high pressure process, to form an alpha-olefin-silane copolymer (“i.e., a reactor copolymer”). In the example where the alpha-olefin is ethylene, such a copolymer is referred to herein as an ethylene-silane copolymer. The hydrolysable silane monomer can also be grafted to a polyolefin, such as polyethylene, by using an organic peroxide, such as 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, to form a Si-g-PO or an in situ Si-g-PO. The in situ Si-g-PO is formed by, for example, MONOSIL ™ process formed during the extrusion of the composition of the present invention to form a coated conductor, as described, for example, in USP 4,574,133.

[0034] The hydrolysable silane monomer can include silane monomers that include an ethylenically unsaturated hydrocarbyl group, such as a vinyl, allyl, isopropenyl, butenyl, cyclohexenyl, or gamma (meth)acryloxyallyl group, and a hydrolysable group, such as, for example, a hydrocarbyloxy, hydrocarbyloxyacyl, or hydrocarbylamino group. The hydrolysable group can include a methoxy, ethoxy, formyloxy, acetyloxy, propionyloxy, and alkyl or aryl amino group. In one particular example, the hydrolysable silane monomer is an unsaturated alkoxy silane that can be grafted to a polyolefin or copolymerized within a reactor with an alpha-olefin, such as ethylene. Examples of hydrolysable silane monomers include vinyltrimethoxysilane (VTMS), vinyltriethoxysilane (VTES), vinyltriacetoxysilane, and gamma-(meth)acryloxypropyltrimethoxysilane. In the context of Structure (I), for VTMS: x = 0; R 1 = hydrogen; and R 2 = methoxy; for VTES: x = 0; R 1 = hydrogen; and R 2 = ethoxy; and for vinyltriacetoxysilane: x = 0; R 1 = H; and R 2 = acetoxy.

[0035] Examples of suitable ethylene-silane copolymers are commercially available as SI-LINK ™ DFDA-5451 NT and SI-LINK ™ ACDFDB-5451 NT, each of which is available from The Dow Chemical Company, Midland, Mich.

[0036] The moisture-curable polymeric composition can include 10 to 99 weight percent of the silane-functionalized polyolefin. For example, the moisture-curable polymeric composition includes 10 weight percent or more, or 15 weight percent or more, or 20 weight percent or more, or 25 weight percent or more, or 30 weight percent or more, or 35 weight percent or more, or 40 weight percent or more, or 45 weight percent or more, or 50 weight percent or more, or 55 weight percent or more, or 60 weight percent or more, or 65 weight percent or more, or 70 weight percent or more, or 75 weight percent or more, or 80 weight percent or more, or 85 weight percent or more, or 90 weight percent or more, or 95 weight percent or more, or 98 weight percent or more, while at the same time 99 weight percent or less, or 95 weight percent or less, or 93 weight percent or less, or 90 weight percent or less, 85 weight percent or less, or 80 weight percent or less, 75 weight percent or less, or 70 weight percent or less, 65 weight percent or less, or 60 weight percent or less, or 55 weight percent or less, or 50 weight percent or less, or 45 weight percent or less, or 40 weight percent or less, or 35 weight percent or less, or 30 weight percent or less, or 25 weight percent or less, or 20 weight percent or less of the silane-functionalized polyolefin, based on the total weight of the moisture-curable polymeric composition. Ethylene-based polymers

[0037] The polyolefin of the silane-functionalized polyolefin can be an ethylene-based polymer. Additionally, the ethylene-based polymer can not be silane-functionalized and it can be used as a blend component in the formulation. The ethylene-based polymer can be a non-polar or polar ethylene-based polymer. As used herein, the term "non-polar" when used in connection with a polymer means that it contains 0.1 wt% or less of polar monomers or comonomers as measured using nuclear magnetic resonance ("NMR") or Fourier transform infrared ("FTIR") spectroscopy or X-ray fluorescence (XRF) techniques. As used herein, an "ethylene-based" polymer is a polymer in which greater than 50 wt% of the monomers are ethylene, although other comonomers can also be used. A description of "ethylene-based" polymers (polar and non-polar) can be found in Patel, R., "Types and Basics of Polyethylene," in Handbook of Industrial Polyethylene and Technology, Mark A. Spalding and Ananda M. Chatterjee (eds.), Chapter 4, Scrivener, 2017, pp. 105-138. Polar ethylene-based polymers can include ethylene and one or more unsaturated esters such as alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. Non-polar ethylene-based polymers can include ethylene and one or more C3-C20 α-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. 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. The term "multimodal" refers to polymers 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 major fractions: a first fraction, which can be a low molecular weight fraction and / or component; and a second fraction, which can be a high molecular weight fraction and / or component. 20 α-olefin comonomers such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. 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. The term "multimodal" refers to polymers 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 major fractions: a first fraction, which can be a low molecular weight fraction and / or component; and a second fraction, which can be a high molecular weight fraction and / or component.

[0038] The ethylene-based polymer can comprise 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 98.5 wt% or more, or 99 wt% or more, or 99.5 wt% or more, while at the same time 100 wt% or less, or 99.5 wt% or less, or 99 wt% or less, or 98.5 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, as measured using NMR or FTIR spectroscopy or XRF, based on the total weight of the ethylene-based polymer. Other units of the ethylene-based polymer can include unsaturated esters (such as alkyl acrylates, alkyl methacrylates, or vinyl carboxylates) or alpha-olefins (C3, or C4, or C6, or C8, or C 10 12 16 18 20 alpha-olefins such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene).

[0039] ​​​​The ethylene-based polymer can have a density of 0.850 g / cc to 0.970 g / cc or less, as measured according to ASTM D792. For example, the ethylene-based polymer can have a density of 0.850 g / cc or more, 0.860 g / cc or more, or 0.870 g / cc or more, or 0.880 g / cc or more, or 0.890 g / cc or more, or 0.900 g / cc or more, or 0.910 g / cc or more, or 0.915 g / cc or more, or 0.920 g / cc or more, or 0.921 g / cc or more, or 0.922 g / cc or more, or 0.925 g / cc or more, or 0.928 g / cc or more, while at the same time 0.970 g / cc or less, or 0.960 g / cc or less, or 0.950 g / cc or less, or 0.940 g / cc or less, or 0.930 g / cc or less, or 0.925 g / cc or less, or 0.920 g / cc or less, or 0.915 g / cc or less, or 0.910 g / cc or less, or 0.900 g / cc or less, or 0.890 g / cc or less, or 0.880 g / cc or less, or 0.870 g / cc or less, or 0.865 g / cc or less, or 0.860 g / cc or less, or 0.855 g / cc or less, as measured by ASTM D792.

[0040] The ethylene-based polymer can have a melt index as measured according to ASTM D1238 at 190 °C / 2.16 kilogram (kg) weight and reported in grams eluted per 10 minutes (g / 10 min). The ethylene-based polymer can have a melt index of 0.3 g / 10 min or more, or 0.5 g / 10 min or more, or 1.0 g / 10 min or more, or 1.5 g / 10 min or more, or 2.0 g / 10 min or more, or 2.5 g / 10 min or more, or 3.0 g / 10 min or more, or 3.5 g / 10 min or more, or 4.0 g / 10 min or more, or 4.5 g / 10 min or more, or 5.0 g / 10 min or more, or 5.5 g / 10 min or more, or 6.0 g / 10 min or more, while at the same time 30.0 g / 10 min or less, or 25.0 g / 10 min or less, or 20.0 g / 10 min or less, or 15.0 g / 10 min or less, or 10.0 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, or 3.0 g / 10 min or less, or 2.5 g / 10 min or less, or 2.0 g / 10 min or less, or 1.5 g / 10 min or less, or 1.0 g / 10 min or less, or 0.5 g / 10 min or less.

[0041] The ethylene-based polymer can be a polar ethylene-based polymer. As used herein, the term “polar” when used in connection with a polymer means that it contains 0.1 wt% or more of a polar monomer or comonomer as measured using NMR or FTIR spectroscopy or XRF techniques. The units in the polar ethylene-based polymer other than ethylene can be derived from one or more polymerizable monomers including, but not limited to, acids and unsaturated esters. The acids can be acrylic acid and methacrylic acid. The unsaturated esters can be alkyl acrylates, alkyl methacrylates, or carboxylic acid vinyl esters. The alkyl groups can have 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The carboxylic acid ester groups can have 2 to 8 carbon atoms, or 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of carboxylic acid vinyl esters include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butyrate. Polar ethylene-based polymers typically have a high level of long chain branching.

[0042] The polar ethylene-based polymer can have a density of 0.925 g / cc to 0.985 g / cc, as measured according to ASTM D792. For example, the polar ethylene-based polymer can have a density of 0.925 g / cc or more, or 0.930 g / cc or more, or 0.935 g / cc or more, or 0.940 g / cc or more, 0.945 g / cc or more, or 0.950 g / cc or more, or 0.955 g / cc or more, or 0.960 g / cc or more, or 0.965 g / cc or more, or 0.970 g / cc or more, or 0.975 g / cc or more, or 0.980 g / cc or more, while at the same time 0.985 g / cc or less, or 0.980 g / cc or less, or 0.975 g / cc or less, or 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, or 0.930 g / cc or less, as measured according to ASTM D792.

[0043] The moisture-curable polymer composition can include 0 wt% to 40 wt% of a silane- unfunctionalized ethylene-based polymer. The silane-unfunctionalized ethylene-based polymer can be added individually and / or as part of a masterbatch of the intumescent flame- retardant mixture. For example, the moisture-curable polymer composition includes 0 wt% or more, or 1 wt% or more, or 5 wt% or more, 10 wt% or more, or 15 wt% or more, or 20 wt% or more, or 25 wt% or more, or 30 wt% or more, or 35 wt% or more, while at the same time 40 wt% or less, or 35 wt% or less, or 30 wt% or less, or 25 wt% or less, or 20 wt% or less, or 15 wt% or less, or 10 wt% or less, or 5 wt% or less of an ethylene-based polymer, based on the total weight of the moisture-curable polymer composition. Halogen-free flame retardant

[0044] The moisture-curable polymer composition can include a halogen-free flame retardant. The halogen-free flame retardant can suppress, retard, or delay flame generation. As used herein, "halogen-free" and like terms mean that the flame retardant filler has no or substantially no halogen content, i.e., less than 10,000 mg of halogen per kg of the flame retardant filler, as measured by ion chromatography (IC) or similar analytical method. Halogen content less than this amount is considered to be insignificant to the efficacy of the flame retardant filler, for example, in coated conductors (also known as insulated wires). Examples of halogen-free flame retardants suitable for use in the moisture-curable polymer composition include, but are not limited to, intumescent flame retardants and other halogen-free flame retardants, including metal hydrates (such as aluminum hydroxide, magnesium hydroxide), metal carbonates, red phosphorus, silicon dioxide, aluminum oxide, brucite (mineral form of magnesium hydroxide), metal oxides (such as zinc oxide, calcium oxide, magnesium oxide, titanium oxide), carbon nanotubes, talc, clay, organically modified clay, calcium carbonate, zinc borate, antimony trioxide, wollastonite, mica, ammonium octamolybdate, glass frit, hollow glass microspheres, intumescent materials or compounds, expanded graphite, and combinations thereof. In embodiments, the other halogen-free flame retardant is selected from fillers having hydroxide moieties (such as metal hydrates) and / or hydroxyl groups (such as silicon dioxide). In embodiments, the metal hydrate of the other halogen-free flame retardant can be selected from the group consisting of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, iron hydroxide, copper hydroxide, and combinations thereof. In embodiments, the other halogen-free flame retardant is selected from the group consisting of metal hydrates, metal oxides, silicon dioxide, and combinations thereof. The other halogen-free flame retardant can optionally be surface treated (coated) with a silane, or a saturated or unsaturated carboxylic acid having 8 to 24 carbon atoms or 12 to 18 carbon atoms, or a metal salt of the acid, or other materials. Exemplary surface treatments are described in US 4,255,303, US 5,034,442, US 7,514,489, US 2008 / 0251273, and WO 2013 / 116283. Alternatively, the silane or acid or salt can be added to the composition in similar amounts without using a surface treatment procedure. Other surface treatments known in the art, including titanates, phosphates, and zirconates, can also be used.

[0045] Examples of other halogen-free flame retardants suitable for use in the moisture-curable polymer composition that are commercially available include, but are not limited to, APYRAL ™ 40CD aluminum hydroxide, MAGNIFIN ™H5 magnesium hydroxide, Microcarb 95T ultrafine micronized and treated calcium carbonate available from Reverte, and combinations thereof.

[0046] The moisture-curable polymeric composition can include other halogen-free flame retardants at a concentration of 0 wt%, or 0.1 wt% or greater, or 0.5 wt% or greater, or 1 wt% or greater, or 3 wt% or greater, or 5 wt% or greater, or 7 wt% or greater, or 10 wt% or greater, or 12 wt% or greater, or 14 wt% or greater, or 16 wt% or greater, or 18 wt% or greater, or 20 wt% or greater, or 22 wt% or greater, or 24 wt% or greater, or 26 wt% or greater, or 28 wt% or greater, or 30 wt% or greater, or 32 wt% or greater, or 34 wt% or greater, or 36 wt% or greater, or 38 wt% or greater, 40 wt% or greater, or 42 wt% or greater, or 44 wt% or greater, or 46 wt% or greater, or 48 wt% or greater, while at the same time 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, 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 7 wt% or less, or 5 wt% or less, or 3 wt% or less, or 1 wt% or less, or 0.5 wt% or less, based on the total weight of the moisture-curable polymeric composition. Intumescent flame retardant mixture

[0047] The moisture-curable polymeric composition includes an intumescent flame retardant mixture as the HFFR filler. The intumescent flame retardant mixture can include piperazine pyrophosphate and a phosphoric acid compound. The intumescent flame retardant mixture can include 45 wt% to 85 wt% piperazine pyrophosphate, based on the total weight of the intumescent flame retardant mixture. For example, the intumescent flame retardant mixture can include 45 wt% or more, or 50 wt% or more, or 55 wt% or more, or 60 wt% or more, or 65 wt% or more, or 70 wt% or more, or 75 wt% or more, or 80 wt% or more, while at the same time 85 wt% or less, or 80 wt% or less, or 75 wt% or less, or 70 wt% or less, or 65 wt% or less, or 60 wt% or less, or 55 wt% or less, or 50 wt% or less, or 45 wt% or less piperazine pyrophosphate, based on the total weight of the intumescent flame retardant mixture.

[0048] The intumescent flame retardant mixture can include 15 wt% to 55 wt% of the phosphoric acid compound, based on the total weight of the intumescent flame retardant mixture. For example, the intumescent flame retardant mixture includes 15 wt% or more, or 20 wt% or more, or 25 wt% or more, or 30 wt% or more, or 35 wt% or more, or 40 wt% or more, or 45 wt% or more, or 50 wt% or more, while at the same time 55 wt% or less, or 50 wt% or less, or 45 wt% or less, or 40 wt% or less, or 35 wt% or less, or 30 wt% or less, or 25 wt% or less, or 20 wt% or less phosphoric acid compound, based on the total weight of the intumescent flame retardant mixture.

[0049] The phosphoric acid compound can be made from one or more materials. The phosphoric acid compound can be a salt formed by the reaction of phosphoric acid or polyphosphoric acid with an amine. The phosphoric acid compound can be selected from one of melamine polyphosphate (a reaction product of melamine and polyphosphoric acid), ammonium polyphosphate (a reaction product of ammonia and polyphosphoric acid), or a combination thereof.

[0050] The intumescent flame retardant mixture can include 0 weight percent to 20 weight percent of a flame retardant synergist, based on the total weight of the intumescent flame retardant mixture. For example, the intumescent flame retardant mixture can include 0 weight percent or more, or 0.5 weight percent or more, or 1.0 weight percent or more, or 2 weight percent or more, or 3 weight percent or more, or 4 weight percent or more, or 5 weight percent or more, or 6 weight percent or more, or 7 weight percent or more, or 8 weight percent or more, or 9 weight percent or more, or 10 weight percent or more, while at the same time 20 weight percent or less, or 18 weight percent or less, or 16 weight percent or less, or 14 weight percent or less, or 13 weight percent or less, or 12 weight percent or less, or 11 weight percent or less, or 10 weight percent or less, or 9 weight percent or less, or 8 weight percent or less, or 7 weight percent or less, or 6 weight percent or less, or 5 weight percent or less, or 4 weight percent or less, or 3 weight percent or less, or 2 weight percent or less, or 1 weight percent or less, or 0.5 weight percent or less, or 0 weight percent of a flame retardant synergist, based on the total weight of the intumescent flame retardant mixture. The flame retardant synergist in the intumescent flame retardant mixture can be a silicone component, such as but not limited to a silicone gum. The flame retardant synergist in the intumescent flame retardant mixture can be a metal oxide. In embodiments, the flame retardant synergist in the intumescent flame retardant mixture is zinc oxide.

[0051] The moisture-curable polymer composition includes 1 weight percent to 90 weight percent of the intumescent flame retardant mixture as the HFFR filler, based on the total weight of the polymer composition. For example, the polymer composition includes 1 weight percent or more, or 5 weight percent or more, or 7 weight percent or more, or 10 weight percent or more, or 15 weight percent or more, or 20 weight percent or more, or 25 weight percent or more, or 30 weight percent or more, or 31 weight percent or more, or 35 weight percent or more, or 40 weight percent or more, or 45 weight percent or more, or 50 weight percent or more, or 55 weight percent or more, or 60 weight percent or more, or 65 weight percent or more, or 70 weight percent or more, or 75 weight percent or more, or 80 weight percent or more, or 85 weight percent or more, while at the same time 90 weight percent or less, or 85 weight percent or less, or 80 weight percent or less, or 75 weight percent or less, or 70 weight percent or less, or 65 weight percent or less, or 60 weight percent or less, or 55 weight percent or less, 50 weight percent or less, or 45 weight percent or less, or 40 weight percent or less, or 35 weight percent or less, or 31 weight percent or less, or 30 weight percent or less, or 25 weight percent or less, or 20 weight percent or less, or 15 weight percent or less, or 10 weight percent or less, or 5 weight percent or less of the intumescent flame retardant mixture, based on the total weight of the polymer composition. Additive

[0052] The moisture-curable polymeric composition can include one or more additives. Non-limiting examples of suitable additives include antioxidants, colorants, corrosion inhibitors, lubricants, ultraviolet (UV) absorbers or stabilizers, antiblocking agents, moisture scavengers (including hydrolysable silane monomers), silanol condensation catalysts, flame retardants, coupling agents, compatibilizers, plasticizers, fillers, processing aids, propylene polymers (homopolymers and copolymers, including polypropylene homopolymers, random copolymer polypropylenes, and impact copolymer polypropylenes), and combinations thereof. Compatibilizers include, but are not limited to, anhydride-modified ethylene-based polymers (such as anhydride-modified ethylene plastomers or elastomers).

[0053] The moisture-curable polymeric composition can include an antioxidant. Non-limiting examples of suitable antioxidants include phenolic antioxidants, sulfur-based antioxidants, phosphate-based antioxidants, and hydrazine-based metal deactivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenols, phenols having primary or secondary carbonyl substituents, and multifunctional phenols such as sulfur- and phosphorus-containing phenols. Representative hindered phenols include 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(2,6-di-tert-butyl-phenol); 4,4'-thiobis(6-tert-butyl-o-cresol) 2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-l,3,5-triazine; 3,5-di-tert-butyl-4-hydroxybenzoic acid (di-n-octylthio)ethyl ester; and hexa[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionic acid] sorbitol ester. The polymeric composition can include tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) pentaerythritol, which can be Irganox 1010 commercially available from BASF. Non-limiting examples of suitable methyl-substituted phenols are isobutylene bis(4,6-dimethylphenol). Non-limiting examples of suitable hydrazine-based metal deactivators are oxalyl bis(benzylidene hydrazide). The moisture-curable polymeric composition can include 0 wt%, or 0.001 wt%, or 0.01 wt%, or 0.02 wt%, or 0.05 wt%, or 0.1 wt%, or 0.2 wt%, or 0.3 wt%, or 0.4 wt% to 0.5 wt%, or 0.6 wt%, or 0.7 wt%, or 0.8 wt%, or 1.0 wt%, or 2.0 wt%, or 2.5 wt%, or 3.0 wt% of an antioxidant based on the total weight of the moisture-curable polymeric composition. ™ 1010 commercially available from BASF. Non-limiting examples of suitable methyl-substituted phenols are isobutylene bis(4,6-dimethylphenol). Non-limiting examples of suitable hydrazine-based metal deactivators are oxalyl bis(benzylidene hydrazide). The moisture-curable polymeric composition can include 0 wt%, or 0.001 wt%, or 0.01 wt%, or 0.02 wt%, or 0.05 wt%, or 0.1 wt%, or 0.2 wt%, or 0.3 wt%, or 0.4 wt% to 0.5 wt%, or 0.6 wt%, or 0.7 wt%, or 0.8 wt%, or 1.0 wt%, or 2.0 wt%, or 2.5 wt%, or 3.0 wt% of an antioxidant based on the total weight of the moisture-curable polymeric composition.

[0054] The moisture-curable polymeric composition can include a UV absorber or stabilizer. A non-limiting example of a suitable UV stabilizer is a hindered amine light stabilizer (HALS). A non-limiting example of a suitable HALS is 1,3,5-triaz-2,4,6-triamine, N,N-1,2-ethanediylbis-N-3-4,6-bisbutyl(l,2,2,6,6-pentamethyl-4-piperidyl)amino- 1,3,5-triazin-2-ylaminopropyl-N,N-dibutyl-N,N-bis(l,2,2,6,6-pentamethyl-4-piperidyl)- 1,5,8,12-tetra[4,6-bis(n-butyl-n-l,2,2,6,6-pentamethyl-4-piperidylamino)-l,3,5-triazin-2-yl]- 1,5,8,12-tetraazadodecane, which is commercially available as SABO STAB UV-119 from SABO S.p.A. of Levate, Italy. In an embodiment, the composition contains 0 weight %, or 0.001 weight %, or 0.002 weight %, or 0.005 weight %, or 0.006 weight %, or 0.007 weight %, or 0.008 weight %, or 0.009 weight %, or 0.01 weight %, or 0.2 weight %, or 0.3 weight %, or 0.4 weight %, or 0.5 weight %, 1.0 weight %, or 2.0 weight %, or 2.5 weight %, or 3.0 weight % of the UV absorber or stabilizer based on the total weight of the composition. ™ STAB UV-119 is commercially available from SABO S.p.A. of Levate, Italy. In an embodiment, the composition contains 0 weight %, or 0.001 weight %, or 0.002 weight %, or 0.005 weight %, or 0.006 weight %, or 0.007 weight %, or 0.008 weight %, or 0.009 weight %, or 0.01 weight %, or 0.2 weight %, or 0.3 weight %, or 0.4 weight %, or 0.5 weight %, 1.0 weight %, or 2.0 weight %, or 2.5 weight %, or 3.0 weight % of the UV absorber or stabilizer based on the total weight of the composition.

[0055] The moisture-curable polymeric composition can include a processing aid. Non-limiting examples of suitable processing aids include oils, organic acids such as stearic acid, and metal salts of organic acids such as zinc stearate. In an embodiment, the composition includes 0 weight %, or 0.01 weight %, or 0.02 weight %, or 0.05 weight %, or 0.07 weight %, or 0.1 weight %, or 0.2 weight %, or 0.3 weight %, or 0.4 weight % to 0.5 weight %, or 0.6 weight %, or 0.7 weight %, or 0.8 weight %, or 1.0 weight %, or 2.0 weight %, or 2.5 weight %, or 3.0 weight %, or 5.0 weight %, or 10.0 weight %, or 20.0 weight % of the processing aid based on the total weight of the composition.

[0056] The moisture-curable polymer composition can comprise 0% by weight or more, or 0.001% by weight or more, or 0.002% by weight or more, or 0.005% by weight or more, or 0.006% by weight or more, or 0.008% by weight or more, or 0.009% by weight or more, or 0.01% by weight or more, or 0.2% by weight or more, or 0.3% by weight or more, or 0.4% by weight or more, or 0.5% by weight or more, or 1.0% by weight or more, or 2.0% by weight or more, or 3.0% by weight or more, or 4.0% by weight or more, or 5.0% by weight or more, or 10.0% by weight or more, or 15.0% by weight or more, or 20.0% by weight or more, or 30% by weight or more, or 40% by weight or more, or 50% by weight or more of the additive, based on the total weight of the moisture-curable polymer composition. Crosslinkable moisture-curable polymer composition

[0057] The present disclosure also relates to a method of crosslinking a moisture-curable polymer composition to form a moisture-cured polymer composition. This method includes the steps of producing a moisture-curable polymer composition of a silane-functionalized polyolefin and an intumescent flame-retardant mixture, where the intumescent flame-retardant mixture comprises piperazine pyrophosphate and 15% to 55% by weight of a phosphoric acid compound, based on the total weight of the intumescent flame-retardant mixture. Once the moisture-curable polymer composition is produced, it can be crosslinked to form a moisture-cured polymer composition.

[0058] The moisture-curable polymer composition can be converted into a moisture-cured polymer composition by catalyzing the moisture-induced crosslinking reaction of the silane-functionalized polyolefin using the intumescent flame-retardant mixture to form the moisture-cured polymer composition. As used herein, the term “moisture-cured” means that the curing process is carried out in the presence of water, and water is an essential component in the curing process. For example, the step of catalyzing the moisture-induced crosslinking reaction can be carried out in a water bath at a temperature greater than 50°C or in a gaseous atmosphere at a temperature of 15°C or greater and a relative humidity of 10% or greater, as measured according to ASTM E337. The gaseous atmosphere can be air at room temperature and humidity, such as 23°C and 50% relative humidity.

[0059] The curing process is carried out by inducing a condensation reaction of the hydrolysable silane monomer of the silane-functionalized polyolefin. The condensation reaction of the hydrolysable silane monomer results in cross-linking of the polymer chains of the silane-functionalized polyolefin chains, thereby causing the silane-functionalized polyolefin to cure. While this reaction can also occur in the presence of water, practical manufacturing and engineering considerations in the manufacture of the moisture-curable polymer composition generally require the use of a catalyst to increase the speed of the condensation reaction and ultimately speed up the curing of the moisture-curable polymer composition. As explained above, it is believed that the acidic moisture-curing catalyst can be generated upon pyrolysis of the phosphoric acid compound, which results in an increase in the moisture-curing reaction speed. This feature is advantageous for various reasons. First, the fact that the intumescent flame-retardant mixture can also be used as a catalyst is advantageous because it eliminates compounding complexity of the moisture-curable polymer composition because fewer different ingredients are needed, thereby simplifying manufacturing. Second, because the intumescent flame-retardant mixture does not contain materials such as tin and other potentially concerning substances, the resulting moisture-cured polymer composition can face less regulatory pressure.

[0060] According to a feature of the present disclosure, a method of cross-linking a moisture-curable polymer composition, the method comprising the steps of: producing a moisture-curable polymer composition of a silane-functionalized polyolefin and an intumescent flame-retardant mixture, wherein the intumescent flame-retardant mixture comprises piperazine pyrophosphate and 15 to 55 weight percent of a phosphoric acid compound based on the total weight of the intumescent flame-retardant mixture; and catalyzing a moisture-induced cross-linking reaction of the silane-functionalized polyolefin using the intumescent flame-retardant mixture to form a moisture-cured polymer composition.

[0061] According to another feature of the present disclosure, the step of catalyzing the moisture-induced cross-linking reaction is carried out in a water bath having a temperature greater than 50 °C or in a gaseous atmosphere having a temperature of 15 °C or greater and a relative humidity of 10% or greater, as measured according to ASTM E337.

[0062] According to another feature of the present disclosure, the moisture-curable polymer composition comprises 10 to 99 weight percent of the silane-functionalized polyolefin based on the total weight of the moisture-curable polymer composition, and the silane-functionalized polyolefin is a silane-functionalized ethylene-based polymer.

[0063] According to another feature of the present disclosure, the silane-functionalized ethylene-based polymer comprises 0.1 to 5.0 weight percent of silane groups based on the total weight of the silane-functionalized ethylene-based polymer.

[0064] According to another feature of the present disclosure, the silane is vinyltrimethoxysilane.

[0065] According to another feature of the disclosure, the moisture-curable polymeric composition comprises 1 to 90 weight percent of the intumescent flame retardant mixture, based on the total weight of the moisture-curable polymeric composition.

[0066] According to another feature of the disclosure, the polymeric composition comprises 1 to 30 weight percent of the intumescent flame retardant mixture, based on the total weight of the moisture-curable polymeric composition.

[0067] According to another feature of the disclosure, the intumescent flame retardant mixture comprises 25 to 45 weight percent of the phosphoric acid compound, based on the total weight of the intumescent flame retardant mixture.

[0068] According to another feature of the disclosure, the phosphoric acid compound is selected from the group consisting of melamine polyphosphate, ammonium polyphosphate, or a combination thereof.

[0069] According to another feature of the disclosure, the moisture-curable polymeric composition is free of dibutyltin dilaurate and sulfonic acid. Moisture-cured polymer composition

[0070] The moisture-curable polymeric composition can be converted into a moisture-cured polymeric composition by catalyzing a moisture-induced crosslinking reaction of the silane- functionalized polyolefin using the intumescent flame retardant mixture to form the moisture-cured polymeric composition. Catalyzing the moisture-induced crosslinking reaction can be performed in a water bath at a temperature greater than 50 °C or in a gaseous atmosphere at a temperature of 15 °C or greater and a relative humidity of 10% or greater, as measured according to ASTM E337. The gaseous atmosphere can be air at room temperature and humidity, such as 23 °C and 50% relative humidity.

[0071] The moisture-cured polymer composition exhibits one or more of the following properties: a peak tensile strength of 4 megapascals (MPa) or greater as measured according to ASTM D638; an elongation at break tensile of 50% or greater as measured according to ASTM D638; a gel content of 10% by weight or greater as measured according to ASTM D2765; and a hot set of 175% or less as measured according to UL 2556 Section 7.9. The moisture-cured polymer composition can exhibit a peak tensile strength of 4 MPa or greater, or 6 MPa or greater, or 8 MPa or greater, or 10 MPa or greater, or 12 MPa or greater, or 14 MPa or greater, or 16 MPa or greater, or 18 MPa or greater, while at the same time 20 MPa or less, or 18 MPa or less, or 16 MPa or less, or 14 MPa or less, or 12 MPa or less, or 10 MPa or less, or 8 MPa or less, or 6 MPa or less, as measured according to ASTM D638. The moisture-cured polymer composition can exhibit an elongation at break tensile of 50% or greater, or 75% or greater, or 100% or greater, or 125% or greater, or 150% or greater, or 175% or greater, or 200% or greater, or 225% or greater, or 250% or greater, or 275% or greater, or 300% or greater, or 325% or greater, or 350% or greater, or 375% or greater, while at the same time 400% or less, or 375% or less, or 350% or less, or 325% or less, or 300% or less, or 275% or less, or 250% or less, or 225% or less, or 200% or less, or 175% or less, or 150% or less, or 125% or less, or 100% or less, or 75% or less, as measured according to ASTM D638. The moisture-cured polymer composition can exhibit a gel content of 10% 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, as measured according to ASTM D2765. The moisture-cured polymer composition can exhibit a hot set of 175% or less, or 150% or less, or 125% or less, or 100% or less, or 75% or less, or 50% or less, or 25% or less, as measured according to UL 2556 Section 7.9. Coated conductor

[0072] The present disclosure also provides a coated conductor. The coated conductor includes a conductor and a coating on the conductor, the coating comprising a moisture-cured polymer composition. The moisture-cured polymer composition is disposed at least partially around the conductor to produce the coated conductor. The conductor can include an electrically conductive metal and / or an optical waveguide. In other words, the coated conductor can be referred to as a wire, a fiber, a cable, or other connector.

[0073] The moisture-cured 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 as an insulating material or sheath. Alternatively, the coating can be one layer of a multi-layer 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.

[0074] The coated conductor can pass the UL-2556 horizontal burn test. Examples Test methods

[0075] Melt Index: Melt Index (MI) values are measured according to ASTM D1238 at 190 °C or 150 °C and using a load of 2.16 kg or 21.6 kg.

[0076] Density is measured according to ASTM D792, Method B or calculated as follows: For a given formulation, the "mL / 100 grams" for each ingredient or component is obtained by dividing the "wt%" of that ingredient by its density (in g / cm 3 The individual values of "mL / 100 grams" for each ingredient are added to obtain a total value of "mL / 100 grams" for that particular formulation. Next, the number "100" (representing the total wt% of all ingredients in that formulation) is divided by the total value of "mL / 100 grams" to produce the "calculated density" for that particular formulation, in g / cm 3 The measured or calculated densities provide the same or similar results. For the measurements, samples are prepared according to ASTM D 1928. Samples are manufactured by compression molding as previously described. Density measurements are made using ASTM D792, Method B after the samples are pressed for 40 hours.

[0077] Peak Heat Release Rate (PHRR): PHRR data is collected using a cone calorimeter. Using the Standardized Cone Calorimeter Procedure (ASTM E-1354-11), PHRR is measured on a horizontally disposed square sample having dimensions of 100 mm x 100 mm x 3 mm with a grid, at 50 kW / m 2Cone Calorimetry was performed on a Fire Testing Technology Cone Calorimeter at a heat flux of 50 kW / m2and a distance of 25 mm between the top of the sample surface and the bottom of the heater. A more in-depth description of this test is given in the following publication: Cogen, J. M., Chaudhary, B. I., Ghosh-Dastidar, A., Sun, Y., and Wasserman, S. H., “Flame Retardant Aspects of Crosslinked Polyethylene,” in Jince Thomas, Sabu Thomas, and Zakiah Ahmad (eds.), Crosslinkable Polyethylene - Manufacture, Properties, Recycling and Applications, Chapter 9, Springer, 2021, pp. 211-245.

[0078] Limiting Oxygen Index (LOI) is measured according to ASTM D2863 and reflects the minimum oxygen concentration that will support the combustion of a polymer sample, expressed as a percentage. It is measured by passing a mixture of oxygen and nitrogen through a burning sample and adjusting the oxygen level until a critical level is reached.

[0079] Horizontal Burning Test of Coated Conductor is performed according to UL-2556. The test is performed by placing the coated conductor in a horizontal position. Cotton is placed underneath the coated conductor. The burner is set at a 20° angle relative to a horizontal sample of 14 American Wire Gauge (“AWG”) copper wire with a coating wall thickness of 30 mils (0.762 mm). A one-time flame is applied to the middle of the sample for 30 seconds. The sample is considered to fail if (i) the cotton ignites and / or (ii) the sample chars more than 100 mm. The char length is measured according to UL-1581, 1100.4.

[0080] Thermal Creep (also referred to as thermal creep elongation) of the polymer composition (i.e., the coating removed from the insulated wire, i.e., the coated conductor) is measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003 at a specified temperature (250°C or 200°C or 150°C) under a fixed stress (0.2 MPa). The lower the thermal creep measurement, the higher the degree of crosslinking.

[0081] In the case of coated conductors, the tensile peak stress (also known as tensile strength) and the tensile strain at break (also known as tensile elongation) of the polymer composition are measured according to Underwriters Laboratories (“UL”) 2556, Section 3.5, at a displacement rate of 20 inches (508 mm) per minute and at 23 °C and 50% relative humidity. The average of four or five measurements is determined. Each test sample is prepared by removing the polymer composition coating (insulation material) from the coated conductor without damaging it.

[0082] The tensile properties of extruded tapes or compression molded samples made from the polymer composition are also measured according to ASTM D638-14, at a displacement rate of 20 inches (508 mm) per minute (using Type IV dog-bone shaped samples obtained from tape or compression molded samples).

[0083] The gel content of the polymer composition (i.e., the coating removed from the insulated wire, i.e., the coated conductor) is determined according to ASTM D2765 by extraction with the solvent decalin (decahydronaphthalene) under boiling conditions for 6 hours. The higher the gel content, the higher the degree of crosslinking.

[0084] Silane Test: The weight percent (wt%) of silicon atoms (Si) content of silane comonomer units in a test sample of ethylene-silane copolymer is determined using X-ray fluorescence spectroscopy ("XRF"), and then the wt% of silane comonomer units in the test sample of ethylene-silane copolymer is calculated. The test sample in powder form is pressed at 8.3 megapascals (MPa; 1,200 pounds per square inch (psi)) for 1 minute using a Buehler SimpliMet 300 automated plaque press preheated at 115.6 °C (240 degrees Fahrenheit (°F.)) for 3 minutes to form a plaque having a thickness of about 6 mm, and the plaque is cooled to 25 °C. The Si atomic content of the plaque is analyzed by wavelength dispersive XRF using a wavelength dispersive X-ray fluorescence spectrometer from PANalytical Axios. The Si atomic content is determined by comparing its line intensity in the XRF spectrum to a calibration curve of Si atomic content established using polymer standards of known Si atomic concentration, as independently measured using neutron activation analysis (NAA) or inductively coupled plasma (ICP) methods. The Si atomic wt% value measured using XRF and the molecular weight of the at least one silane comonomer from which the hydrolyzable silyl group is derived are used to calculate the wt% of hydrolyzable silyl group comonomer units in the ethylene-silane copolymer (i.e., the wt% of hydrolyzable silyl groups). For hydrolyzable silyl groups derived from vinyltrimethoxysilane (VTMS), a VTMS molecular weight of 148.23 g / mol is used. To calculate the hydrolyzable silyl group content (wt%) of the hydrolyzable silyl group comonomer units in the ethylene-silane copolymer, the Si atomic wt% ("C") obtained using XRF and the following equation are used: where * indicates multiplication, / indicates division, p is the wt% of hydrolyzable silyl groups in the ethylene-silane copolymer, C is the Si atomic wt% (XFR) in parts per million by weight (ppmw), m is the molecular weight in g / mol of the silane comonomer from which the hydrolyzable silyl group is derived, 28.086 is the atomic weight of a silicon atom, and 10000 ppmw is the number of parts per million by weight in 1.00 wt%. For example, when XFR shows 379 ppmw of Si atoms in the ethylene-silane copolymer and the comonomer used to make the ethylene-silane copolymer is VTMS having a molecular weight of 148.23 g / mol, the wt% comonomer content is 0.20 wt%. To calculate the mol% of the silane comonomer used in the hydrolyzable silyl group comonomer units in the ethylene-silane copolymer, the wt% of the hydrolyzable silyl group comonomer units in the ethylene-silane copolymer calculated and the following equation are used: where * denotes multiplication, G is the mole percent (mol%) of hydrolyzable silyl groups in the ethylene-silane copolymer; p is the weight percent of hydrolyzable silyl groups in the ethylene-silane copolymer, m is the molecular weight in g / mol of the silane comonomer from which the hydrolyzable silyl group is derived, and 28.05 g / mol is the molecular weight of the monomer ethylene (H2C=CH2). For example, when the comonomer content is 2.0 wt% and the comonomer is VTMS, p = 2.0 wt% and m = 148.23 g / mol, and G = 0.38 mol%. When the comonomer content is 5.0 wt% and the comonomer is VTMS, p = 5.0 wt% and m = 148.23 g / mol, and G = 0.99 mol%. When two or more silane comonomers having different molecular weights are used to make the ethylene-silane copolymer, the molecular weight used to calculate the total mol% of all hydrolyzable silyl groups in the ethylene-silane copolymer is the weight average molecular weight of the comonomers. The weight can be determined by the proportion of the amount of comonomer fed to the reactor; or by NMR spectroscopy to determine the relative amount of different comonomer units in the ethylene-silane copolymer when each hydrolyzable silyl group is bonded to different types of carbon atoms (e.g., tertiary carbon atoms versus secondary carbon atoms); or by Fourier transform infrared (FT-IR) spectroscopy calibrated to provide quantification of different types of comonomers.

[0085] Crystallinity Test: A differential scanning calorimeter (DSC) instrument, DSC Q1000 (TA Instruments), is used to determine the melting peak and the percent (%) or weight percent (wt%) crystallinity at 23 °C of the ethylene polymer. (A) Baseline calibrate the DSC instrument. Use the software calibration wizard. Obtain the baseline by heating the cell from -80 °C to 280 °C in an aluminum DSC pan without any sample. Then use the calibration wizard indicated sapphire standard. Analyze a fresh indium sample of 1 milligram (mg) to 2 mg by heating the standard sample to 180 °C, cool to 120 °C at a cooling rate of 10 °C / minute, then isothermally hold the standard sample at 120 °C for 1 minute, then heat the standard sample from 120 °C to 180 °C at a heating rate of 10 °C / minute. Determine the heat of fusion of the indium standard sample = 28.71 ± 0.50 Joules / gram (J / g) and the melting onset = 156.6 °C ± 0.5 °C. (B) Perform a DSC measurement on the test sample using the baseline calibrated DSC instrument. Press the test sample of semi-crystalline ethylene-based polymer into a thin film at a temperature of 160 °C. Weigh 5 mg to 8 mg of the test sample film in an aluminum DSC pan. Press the lid onto the pan to seal the pan and ensure a closed atmosphere. Place the pan sealed with the lid into the DSC cell, equilibrate the cell at 30 °C, then heat to 190 °C at a rate of about 100 °C / minute, hold the sample at 190 °C for 3 minutes, cool the sample to -60 °C at a rate of 10 °C / minute to obtain the cooling curve heat of fusion (Hf), and isothermally hold at -60 °C for 3 minutes. Then heat the sample again to 190 °C at a rate of 10 °C / minute to obtain the second heating curve heat of fusion (AHf). Using the second heating curve, calculate the “total” heat of fusion (J / g) by integrating from -20 °C (in the case of ethylene homopolymers, copolymers of ethylene and hydrolysable silane monomers, and ethylene alpha-olefin copolymers having a density greater than or equal to 0.90 g / cm 3 ) or -40 °C (in the case of copolymers of ethylene and unsaturated esters, and ethylene alpha-olefin copolymers having a density less than 0.90 g / cm 3 ) to the melting end point. Using the second heating curve, calculate the “room temperature” heat of fusion (J / g) by falling vertically at 23 °C from 23 °C (room temperature) to the melting end point. Measure and report the “total crystallinity” (calculated from the “total” heat of fusion) as well as the “crystallinity at room temperature” (calculated from the 23 °C heat of fusion). Room temperature means 23 °C. The crystallinity is measured and reported as the percent (%) or weight percent (wt%) crystallinity of the polymer from the second heating curve heat of fusion (AHf) of the test sample and is normalized to the heat of fusion of 100% crystalline polyethylene, wherein, where ΔHf is as defined above, * denotes mathematical multiplication, / denotes mathematical division, and 292 J / g is the literature value for heat of fusion (ΔHf) of 100% crystalline polyethylene. Materials

[0086] The materials used in the examples (“IE”) and comparative examples (“CE”) of the present application are provided below.

[0087] ESC is an ethylene-silane copolymer containing a moisture scavenger and is characterized by a melt index (190°C; 2.16 kg) of 1.5 g / 10 min, a density of 0.922 g / cc, a copolymer VTMS content of 1.6 wt% (0.31 mol%), and a crystallinity at 23°C of 46.8 wt%. ESC is commercially available from The Dow Chemical Company, Midland, MI.

[0088] CAT MB is a silanol condensation catalyst masterbatch (blend of thermoplastic olefinic polymer, antioxidant, and about 3 wt% of dibutyltin dilaurate) developed for use in conjunction with moisture-curable ethylene-silane copolymers and is commercially available as SI-LINK ™ DFDA-5481 NT is commercially available from The Dow Chemical Company, Midland, MI.

[0089] POLAR is a polar ethylene ethyl acrylate copolymer (ethylene-based polymer) having a density of 0.930 g / cc, a melt index (190°C; 2.16 kg) of 1.3 g / 10 min, and an ethyl acrylate content of 15 wt%. POLAR is commercially available as AMPLIFY ™ EA 100 functional polymer is commercially available from The Dow Chemical Company, Midland, MI, USA.

[0090] NPEP1 is a non-polar linear low density polyethylene LLDPE (i.e., ethylene-based polymer) having a density of 0.920 g / cc and a melt index (190°C; 2.16 kg) of 3.5 g / 10 min and is commercially available as DOW ™ LLDPE 1648 is commercially available from The Dow Chemical Company, Midland, MI, USA.

[0091] NPEP2 is a non-polar polyolefin elastomer (i.e., ethylene-based polymer) having a density of 0.870 g / cc and a melt index (190°C; 2.16 kg) of 5 g / 10 min and is commercially available as ENGAGE ™ 8200 is commercially available from The Dow Chemical Company, Midland, MI, USA.

[0092] COMP is an anhydride-modified ethylene elastomer (ethylene-based polymer) compatibilizer and is commercially available as FUSABOND ™ N216 is commercially available from The Dow Chemical Company, Midland, MI.

[0093] HFFR1 is uncoated aluminum trihydroxide (ATH) and is commercially available as APYRAL ™ 40CD is commercially available from Nabeltec AG, Schwandorf, Germany.

[0094] HFFR2 is magnesium dihydroxide (MDH) treated with a maximum of 1 wt% stearic acid and is commercially available as ECOPIREN 3.5 LC from Europiren B. V., Rotterdam, NL.

[0095] IFRM is a halogen-free flame retardant (HFFR) which is an intumescent flame- retardant mixture of 65 wt% piperazine pyrophosphate and 35 wt% melamine polyphosphate with a nitrogen content > 19%, a phosphorus content > 17.0% and a water content < 0.2%. The density of piperazine pyrophosphate is 1.74 g / cc and the density of melamine polyphosphate is 1.85 g / cc, which means that the density of IFRM is 1.78 g / cc. IFRM is commercially available as JNP™-2-3 from CENTURY MULTECH, INC, Flushing, NY, United States.

[0096] GPS is a combination of ultra-high molecular weight silicone gum and fumed silica in pellet form and is commercially available as GENIOPLAST ™ Pellets S are commercially available from Wacker Chemie AG, Munich, Germany.

[0097] AO1 is pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate and is commercially available as IRGANOX™ 1010 from BASF, Ludwigshafen, Germany.

[0098] AO2 is distearyl thiodipropionate (C 42 H 82O4S) and is commercially available as MORSTILL® 18C DSTDP from Struktol, OH, United States.

[0099] MDAO is bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine, which acts as a metal deactivator and antioxidant. MDAO is commercially available as IRGANOX® 1010 from BASF Corporation, Florham Park, NJ, United States. ™ MD 1024 FF is commercially available from BASF Corporation, Florham Park, NJ, United States.

[0100] MD is FUTURECHEM® MD 1024 FF. ™ OABH (oxalyl bis(benzylidene) hydrazide), which acts as a metal deactivator. MD is commercially available from FutureFuel Chemical Company, Missouri, USA.

[0101] LSAO is CIBA® LSAO. 132 H 250 N 32 and is used as a hindered amine light stabilizer and antioxidant. LSAO is commercially available as CHIMASSORB® 944 from CIBA®. ™ 119 FL is commercially available from SABO Spa, Italy.

[0102] CAT is dibutyltin dilaurate and is used as a silanol condensation catalyst when used in combination with an alkoxy silane functionalized polymer. CAT has a CAS number of 77-58-7 and is commercially available as FASCAT® 4202 from PMC Organometallix, Mount Laurel, NJ, US. ™ 4202 is commercially available from PMC Organometallix, Mount Laurel, NJ, US.

[0103] OTS is octyltriethoxysilane, which is used as a moisture scavenger and is commercially available as PROSIL® 9202 from SiVance LLC, of Milliken & Co, USA. It can be used in combination with an alkoxy silane functionalized polymer. ™ 9202 is commercially available from SiVance LLC, of Milliken & Co, USA. It can be used in combination with an alkoxy silane functionalized polymer. Sample preparation

[0104] Sample preparation for Masterbatch 1 (MB1) in Table 1 was prepared using a Brabender mixer equipped with a cam rotor and produced a bowl volume of 420 mL at a rotor speed of 50 rpm and a set temperature of 125 °C while filling 70% of the bowl volume. The HFFR filler (IFRM) was dried in a vacuum oven at 60 °C for 16 hours prior to use. The ethylene-based polymer was melted in the mixing bowl for 5 minutes prior to adding the other ingredients. The order of addition was ethylene-based polymer, antioxidant, IFRM, and other additives. The mixing blade speed was reduced to about 20 rpm when adding the various solid ingredients. Mixing was continued for 5 minutes after all ingredients were added.

[0105] The procedure for sample preparation for Masterbatch 2 (MB2) was the same as for MB1 except: (a) a roller blade with a rotor speed of 40 rpm was used and the resulting bowl volume was 350 mL; (b) a set temperature of 150 °C was used; (c) mixing was continued for 10 minutes after all ingredients were added; and (d) the IFRM was not dried prior to use.

[0106] The procedure for sample preparation for Masterbatch 3 (MB3) was the same as for MB2 except the order of addition was as follows: ethylene-based polymer, COMP2, GPS, antioxidant, MD, HFFR4, HFFR5, IFRM, OTS, and CAT.

[0107] Each of the melt blended compositions of MB1 to MB3 was removed from the mixing bowl and compression molded at 500 psi (3.4 MPa) pressure for 5 minutes into a 75 mil (1.905 mm) thick plaque / sheet which was subsequently cut into a strip using a guillotine, which was fed into a pelletizer to make “chips”. These “chips” were next introduced into a Brabender ¾” extruder equipped with a Maddock mixing screw with a 25:1 length to diameter (L / D) ratio operating at 40 rpm with a set temperature profile across Zone 1, Zone 2, Zone 3, and the head / die of 140 °C / 145 °C / 150 °C / 155 °C (using a 40 / 60 / 100 mesh screen pack assembly). The composition was made into a strand which was then converted into pellets using a pelletizer. The pellets were dried in a vacuum oven at 70 °C for 16 to 24 hours and then packaged in vacuum sealed foil bags until use. Where appropriate, 75 mil (1.905 mm) or 125 mil (3.175 mm) thick plaques were prepared for testing properties by compression molding at 500 psi (3.4 MPa) for 3 minutes at 150 °C followed by compression molding at 2500 psi (17.2 MPa) for 3 minutes at 150 °C followed by cooling to 30 °C under 2500 psi (17.2 MPa) pressure.

[0108] Sample preparations of IE1-IE11 and CE1 in Table 2 were used to make coated conductors. In the case of IE1-IE11, this was done by melt blending any of MB1 to MB3 with ESC (ethylene-silane copolymer) and in the case of IE2 also with CAT MB in the proportions shown in Table 2 using the following experimental procedure. CE1 was prepared by melt blending CAT MB with ESC in the proportions indicated in Table 2 using the experimental procedure presented below.

[0109] IE1 and IE2: Physical blends were made from pellets of ESC, MB1 and / or CAT MB (in plastic bags). The pellet blend was fed into a Brabender ¾” extruder equipped with a Maddock screw of 25:1 length to diameter (L / D) and melt extruded to apply a coating (insulation layer) of nominal 30 mil (0.762 mm) wall thickness to a 14 AWG solid copper conductor having the following dimensions: conductor nominal diameter: 0.064 inch (1.626 mm); and nominal outer diameter of the insulated wire: 0.124 inch (3.150 mm). The set temperature profile across the extruder zone was 165°C, 170°C, 175°C and 180°C at the head / die. A 40 / 40 mesh screen pack assembly was employed and the screw speed was 40 rpm with a haul off belt speed of 8 ft / min (2.4 m / min). In both cases, the resulting melt temperature was about 188°C-189°C.

[0110] IE3 to IE10 and CE1: Same as IE1 and IE2 except: (a) MB2 was used; (b) CE1 was prepared without any of MB1 to MB3; (c) the set temperature profile across the extruder zone was 145°C, 150°C, 155°C and 160°C at the head / die; (d) the screw speed was about 40 rpm-41 rpm with a haul off belt speed of about 8.5 ft / min (2.6 m / min); and (e) in all cases, the resulting melt temperature was about 165°C-166°C.

[0111] IE11: Same as IE3 to IE10 except: (a) MB3 was used; (b) the pellet blend was fed into a Brabender 1 ¼” extruder equipped with a Maddock screw of 20:1 length to diameter (L / D) and melt extruded to apply a coating (insulation layer) of nominal 55 mil (1.397 mm) wall thickness to a 4 mm 2(a) stranded tin-copper conductor: conductor nominal diameter: 0.090 inch (2.286 mm); and nominal outer diameter of the insulated wire: 0.200 inch (5.080 mm); (c) pull tape speed of about 9.5 ft / min (2.9 m / min); and (d) resulting melt temperature of about 169 °C. Results

[0112] Table 1 provides composition and performance property data for the masterbatch materials ("MB") used to form the inventive examples. Table 2 provides composition data related to IE1-IE11 and CE1. Table 3 provides performance data related to the wet-cured examples of IE1-IE11 and CE1. NA means that the sample was not measured for the identified data.

[0113]

[0114]

[0115]

[0116] For Table 3, the "wet-cured properties" of the insulated wire (i.e., coated conductor) that had been cured for 1 week at 23 °C, 50% relative humidity, then cured for 24 hours or 72 hours or 96 hours in a 90 °C water bath were determined. In all cases (IE1-IE11 and CE1), the hot creep measurements were made at a test temperature of 150 °C.

[0117] *: tested after curing for 6 months at 23 °C, 50% relative humidity, then curing for 24 hours in a 90 °C water bath.

[0118] **: tested after curing for 1 month at 23 °C, 50% relative humidity, then curing for 24 hours in a 90 °C water bath.

[0119] Referring now to Tables 2 and 3, CE1 represents a conventional formulation that requires a so-called moisture cure (silanol condensation) catalyst for crosslinking to achieve high gel content and thus exhibit satisfactory hot set properties (<175% hot set). In contrast to CE1, the compositions of IE1 and IE3 through IE10 are surprisingly able to achieve sufficiently high gel content and / or pass the hot set test after curing in a hot water bath even without the use of a catalyst. Moreover, the inventive compositions pass the hot set test even when the gel content, as measured by naphthalene extraction, is relatively low. After an initial cure of about 1 week at ambient conditions of 23°C and 50% relative humidity, the inventive examples containing a relatively high loading of IFRM require curing in a 90°C water bath for 24 hours to exceed the hot set pass requirement without the use of any catalyst. Extending the curing time in the hot water bath to 96 hours enables even those inventive formulations containing a relatively low amount of IFRM to robustly pass the hot set test. The surface of all of the insulated electrical wires of IE1 through IE11 is smooth, as is the surface of the coated conductor of CE1, indicating that premature crosslinking of the silane-functionalized polyolefin (during the melt blending by extrusion, i.e., melt extrusion) does not occur.

[0120] In addition, as seen in IE3-IE10, the coated conductors (insulated electrical wires) made from compositions containing 21 wt% or more of IFRM exhibit strong pass performance in the horizontal burn test. However, due to the presence of the IFRM, even the compositions of IE6 through IE8 will inherently have a level of flame retardancy that can be sufficient for other burn / flame tests. IE11, which has 8.6 wt% IFRM, 20.5 wt% HFFR1, and 20.5 wt% MFFR2 (the latter two being metal hydrate flame retardants), would also be expected to exhibit good flame retardancy. Note that IE11 was not subjected to the horizontal burn test because it was not in the required configuration for that test (i.e., a 14 AWG copper wire with a 30 mil (0.762 mm) coating wall thickness).

[0121] It is clear from the hot set data (IE2 and IE11) that the intumescent flame retardant mixture is compatible with a conventional moisture cure catalyst (such as dibutyltin dilaurate, a Lewis acid) that is used in such formulations to enable silane crosslinking of the resulting HFFR composition. Such a feature is advantageous because such conventional catalysts can be incorporated into the inventive formulations to significantly shorten the curing time.

Claims

1. A moisture-curable polymeric composition comprising: 10 to 99 weight percent of a silane-functionalized polyolefin, based on the total weight of the moisture-curable polymeric composition; and 1 to 90 weight percent of an intumescent flame-retardant mixture, based on the total weight of the moisture-curable polymeric composition, wherein the intumescent flame-retardant mixture comprises piperazine pyrophosphate and 15 to 55 weight percent of a phosphoric acid compound, based on the total weight of the intumescent flame-retardant mixture.

2. The moisture-curable polymeric composition of claim 1, wherein the silane- functionalized polyolefin is a silane-functionalized ethylene-based polymer.

3. The moisture-curable polymeric composition of either of claims 1 and 2, wherein the polymeric composition comprises 30 weight percent or more of the silane- functionalized polyolefin, based on the total weight of the moisture-curable polymeric composition.

4. The moisture-curable polymeric composition of any of claims 1 to 3, wherein the polymeric composition comprises 15 weight percent or more of the intumescent flame- retardant mixture, based on the total weight of the moisture-curable polymeric composition.

5. The moisture-curable polymeric composition of any of claims 1 to 4, wherein the intumescent flame-retardant mixture comprises 25 to 45 weight percent of the phosphoric acid compound, based on the total weight of the intumescent flame-retardant mixture.

6. The moisture-curable polymeric composition of any of claims 1 to 5, wherein the phosphoric acid compound is selected from the group consisting of melamine polyphosphate, ammonium polyphosphate, or a combination thereof.

7. The moisture-curable polymeric composition of any of claims 1 to 6, wherein the moisture-curable polymeric composition exhibits a density of 1.70 g / cc or less, as measured according to ASTM D792.

8. The moisture-curable polymeric composition of any of claims 1 to 8, wherein the moisture-curable polymeric composition is free of dibutyltin dilaurate and sulfonic acid.

9. A moisture-cured polymeric composition prepared from the moisture-curable polymeric composition of any of claims 1 to 8, wherein the moisture-cured polymeric composition exhibits one or more of the following properties: a peak tensile strength of 4 megapascals or more, as measured according to ASTM D638; a tensile elongation at break of 50 percent or more, as measured according to ASTM D638; and a hot set of 175 percent or less, as measured according to UL 2556 Section 7.

9.

10. A coated conductor comprising a conductor; and the moisture-cured polymeric composition of claim 9 positioned around the conductor.

11. The coated conductor of claim 10, wherein the coated conductor passes the UL- 2556 horizontal flame test.

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