WO2024186717A1

WO2024186717A1 - Filled moisture-crosslinkable polymeric compositions

Info

Publication number: WO2024186717A1
Application number: PCT/US2024/018288
Authority: WO
Inventors: Bharat I. Chaudhary; Qian GOU
Original assignee: Dow Global Technologies Llc
Priority date: 2023-03-09
Filing date: 2024-03-04
Publication date: 2024-09-12

Abstract

A polymeric composition including an ethylene-silane copolymer comprising units derived from an ethylene monomer and a silane monomer, wherein the ethylene-silane copolymer has a copolymerized silane content from 0.40 mol% to 1.00 mol% based on the total moles of the ethylene-silane copolymer; a Lewis acid catalyst; and a halogen-free flame retardant selected from the group consisting of a metal hydrate, silica and combinations thereof.

Description

FILLED MOISTURE-CROSSLINKABLE POLYMERIC COMPOSITIONS

BACKGROUND

Field of the disclosure

The present disclosure relates to polymeric compositions, and more specifically to filled moisture-crosslinkable polymeric compositions.

Introduction

Ethylene-silane copolymers are used in the formation of moisture-crosslinkable polymer compositions. Such polymeric compositions are used to fabricate wires and cables (i.e., coated conductors) including low-voltage cable constructions and may be utilized as either a jacket or electrical insulation in the cable construction. The silane comonomer that is copolymerized with ethylene to make the ethylene-silane copolymer facilitates the crosslinking of the polymeric composition. The crosslinking of the polymeric composition is as accomplished by “curing” of the coated conductor at humid conditions. The copolymerized silane content of the copolymer can be adjusted depending on the desired level of curing of the polymeric composition. For example, US Patent number 8,460,770 (“the ‘770 patent”) discloses that an ethylene-silane copolymer can include from 0.5 weight percent to 5 weight percent of silane comonomer.

The silane content of the copolymer (with a given silane) affects the curing rate in addition to the ultimate level of crosslinking the polymeric composition undergoes. While higher levels of copolymerized silane advantageously speed the curing rate of the polymeric composition, yield increased degree of ultimate cure (crosslinking) and improve mechanical properties such as peak tensile stress, other mechanical properties like tensile strain at break suffer with increasing copolymerized silane content. The use of ethylene-silane copolymers having a silane content of 0.4 mol% or greater leads to tensile strain at break values lower than those obtained with comparable ethylene-silane copolymers having a silane content of less than 0.4 mol%. Tensile strain at break of 20% or greater is measured, in the case of coated conductors, according to Underwriter’s Laboratory (“UL”) 2556, Section 3.5 at a displacement rate of 20 inch per minute. Tensile properties can also be measured of extruded tape or compression molded samples, in accordance with ASTM D638-14, at a displacement rate of 20 inch per minute (using Type IV dog bone-shaped specimens obtained from the tapes or compression molded samples). The inclusion of fillers in polymers is also known to have a deleterious effect on the tensile strain at break (also known as tensile elongation) of the polymeric composition. Figure 4 of Journal of Saudi Chemical Society, Volume 19, Issue 1, January 2015, Pages 88-91 illustrates this phenomenon clearly with polyethylene and various fillers (including calcium carbonate). In the case of wires and cables, representative fillers used to make the polymeric compositions include calcium carbonate, carbon black, halogenated flame retardants, and flame retardant synergists (e.g., antimony trioxide) which all typically reduce the tensile strain at break of the polymeric composition. The depressive effect of the filler on the tensile strain at break of the cable insulation or jacket can be managed by using an ethylene-silane copolymer of low copolymerized silane content (typically less than 0.4 mol% silane) to make the moisture- crosslinkable polymer composition, but the benefits of faster cure rate and increased level of curing are lost due to the decreased silane content.

As stated above, with a given silane, the silane content of an ethylene-silane copolymer affects the rate and level of curing the polymeric composition undergoes. A commonly used measure for the ultimate level of crosslinking of silane-functionalized polymers is to measure what percent hot creep a polymeric composition reaches after curing in a 90°C water bath for at least 4 hours and up to 72 hours (“Ultimate Cure”). This can be preceded or followed by conditioning at 23°C and 50% relative humidity for hours or days or weeks, from 0 hours up to 12 weeks. Hot creep is measured at a specified temperature (either 200°C or 150°C) under a fixed stress (e.g., 0.2 MPa) by the test method described ahead, based on Underwriter’s Laboratory (“UL”) 2556 Section 7.9 or Insulated Cable Engineers Association (ICEA) standard for power cable insulation materials, ICEA-T-28-562-2003. Ideally, a polymeric composition achieves a hot creep of 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003.

In view of the foregoing, it would be surprising to discover a filled moisture- crosslinkable polymeric composition that does not suffer a loss in tensile strain at break (or even exhibits increased tensile strain at break) in comparison to polymeric compositions using an ethylene-silane copolymer of less than 0.4 mol% copolymerized silane and which achieves a hot creep of 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003. SUMMARY OF THE DISCLOSURE

The inventors of the present disclosure have surprisingly discovered a filled moisture- crosslinkable polymeric composition that does not suffer a loss in tensile strain at break (or even exhibits increased tensile strain at break) in comparison to polymeric compositions using an ethylene-silane copolymer of less than 0.4 mol% copolymerized silane and which achieves a hot creep of 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003.

The invention is the result of discovering that unlike other filler materials, the inclusion of halogen-free flame retardant fillers comprising a metal hydrate into ethylene-silane copolymers having a copolymerized silane content from 0.40 mol% to 1.00 mol% surprisingly enhances the tensile strain at break of the polymeric composition. This result is surprising as other types of fillers have a depressive effect on mechanical properties observed. Without being bound by theory, it is believed that the hydroxide moieties of the metal hydrate filler aid in compatibilization of the ethylene-silane copolymer with the flame retardant filler thereby increasing the mechanical properties of the polymeric composition. Along with fillers that have hydroxide moieties, those such as silica that have hydroxyl groups on the surface are also in scope of the present invention. Such a feature is advantageous in providing flame retardancy to the polymeric composition while achieving the desired tensile strain at break. Additionally, the surprising effect of the metal hydrate filler on the mechanical properties of the polymeric composition means that ethylene-silane copolymers having a copolymerized silane content from 0.40 mol% to 1.00 mol% can be used which allow cables to achieve the target hot creep values faster and to a greater ultimate extent. Additionally, relatively greater amounts of polymers that are not silane functionalized (such as linear polyethylenes) can be incorporated in the formulations to enhance properties (if desired) while still maintaining the desired degree of crosslinking.

The present invention is particularly useful in the manufacture of wires and cables.

According to a first feature of the disclosure, a polymeric composition, comprises an ethylene-silane copolymer comprising units derived from an ethylene monomer and a silane monomer, wherein the ethylene-silane copolymer has a copolymerized silane content from 0.40 mol% to 1.00 mol% based on the total moles of the ethylene-silane copolymer; a Lewis acid catalyst; and a halogen-free flame retardant selected from the group consisting of a metal hydrate, silica and combinations thereof. According to a second feature of the disclosure, the Lewis acid catalyst is selected from the group consisting of dibutyl tin dilaurate, dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethyl hydroxy tin oleate, dioctyl tin maleate, di-n-butyl tin maleate, dibutyl tin diacetate, dibutyl tin dioctoate, stannous acetate, stannous octoate, lead naphthenate, zinc caprylate and cobalt naphthenate, and combinations thereof.

According to a third feature of the disclosure, the metal hydrate is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, Brucite, calcium hydroxide, zinc hydroxide, iron hydroxide, copper hydroxide, and combinations thereof.

According to a fourth feature of the disclosure, the polymeric composition comprises from 10 wt% to 80 wt% of the halogen-free flame retardant based on the total weight of the polymeric composition.

According to a fifth feature of the disclosure, the polymeric composition comprises from 10 wt% to 90 wt% of the ethylene-silane copolymer based on the total weight of the polymeric composition.

According to a sixth feature of the disclosure, the polymeric composition exhibits a Filler to Catalyst Weight Ratio from 75 to 1000.

According to a seventh feature of the disclosure, the ethylene-silane copolymer exhibits a crystallinity at 23°C of 40 wt% to 46 wt% as measured according to Crystallinity Testing.

According to an eighth feature of the disclosure, the ethylene-silane copolymer has a copolymerized silane content from 0.45 mol% to 0.85 mol%.

According to a nineth feature of the disclosure, the polymeric composition exhibits one or more of a hot creep of 175% or less after Ultimate Cure as measured according to ICEA-T- 28-562-2003 and a tensile strain at break of 20% or greater as measured according to ASTM D638-14.

According to a tenth feature of the disclosure, a coated conductor, comprises a conductor; and the polymeric composition.

According to an eleventh feature of the disclosure, the polymeric composition of the coated conductor exhibits one or more of a hot creep of 175% or less after Ultimate Cure as measured according to ICEA-T-28-562-2003 and a tensile strain at break of 20% or greater as measured according to UL 2556, Section 3.5. DETAILED DESCRIPTION

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.

All ranges include endpoints unless otherwise stated.

Test methods refer to the most recent test method as of the priority date of this document unless a date is indicated with the test method number as a hyphenated two-digit number. References to test methods contain both a reference to the testing 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); EN refers to European Norm; DIN refers to Deutsches Institut fur Normung; and ISO refers to International Organization for Standards.

“Polymer” means a polymeric material prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the terms homopolymer, interpolymer and copolymer.

“Ethylene polymer” means a polymer containing units derived from ethylene. An ethylene polymer typically comprises at least 50 wt% units derived from ethylene.

As used herein, the term weight percent (“wt%”) designates the percentage by weight a component is of a total weight of the polymeric composition unless otherwise indicated.

As used herein, a “CAS number” is the chemical services registry number assigned by the Chemical Abstracts Service.

The term "ambient conditions," as used herein, is an air atmosphere with a temperature from 5°C to 50°C and a relative humidity from 5% to 100%.

Polymeric composition

The present disclosure is directed to a polymeric composition. The polymeric composition comprises an ethylene-silane copolymer comprising units derived from an ethylene monomer and a silane monomer, a Lewis acid catalyst and a halogen-free flame retardant comprising a metal hydrate.

Ethylene-silane copolymer

The polymeric composition comprises the ethylene-silane copolymer (a form of silane functionalized ethylene polymer). The ethylene-silane copolymer comprises units derived from ethylene monomer and a silane monomer. A “copolymer” means a macromolecular compound prepared by reacting (i.e., polymerizing) two or more monomers of different types. The ethylene-silane copolymer is prepared by the copolymerization of ethylene and a silane monomer.

The polymeric composition may comprise 10 wt% or greater, or 15 wt% or greater, or 20 wt% or greater, or 25 wt% or greater, or 30 wt% or greater, or 35 wt% or greater, or 40 wt% or greater, or 45 wt% or greater, or 50 wt% or greater, or 55 wt% or greater, or 60 wt% or greater, or 65 wt% or greater, or 70 wt% or greater, or 75 wt% or greater, or 80 wt% or greater, or 85 wt% or greater, while at the same time, 90 wt% or less, or 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, 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, or 15 wt% or less of ethylene-silane copolymer based on the total weight of the polymeric composition.

The ethylene-silane copolymer has a density of 0.910 grams per cubic centimeter (“g/cc”) or greater, or 0.915 g/cc or greater, or 0.920 g/cc or greater, or 0.921 g/cc or greater, or 0.922 g/cc or greater, or 0.925 g/cc to 0.930 g/cc or greater, or 0.935 g/cc or greater, while at the same time, 0.940 g/cc or less, or 0.935 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 as measured by ASTM D792.

The ethylene-silane copolymer has a melt index as measured according to ASTM D1238 under the conditions of 190°C/2.16 kilogram (kg) weight and is reported in grams eluted per 10 minutes (g/10 min). The melt index of the ethylene-silane copolymer may be 0.5 g/10 min or greater, or 1.0 g/10 min or greater, or 1.5 g/10 min or greater, or 2.0 g/10 min or greater, or 2.5 g/10 min or greater, or 3.0 g/10 min or greater, or 3.5 g/10 min or greater, or 4.0 g/10 min or greater, or 4.5 g/10 min or greater, 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 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.

The ethylene-silane copolymer comprises 90 wt% or greater, or 91 wt% or greater, or

92 wt% or greater, or 93 wt% or greater, or 94 wt% or greater, or 95 wt% or greater, or 96 wt% or greater, or 96.5 wt% or greater, or 97 wt% or greater, or 97.5 wt% or greater, or 98 wt% or greater, or 99 wt% or greater, while at the same time, 99.5 wt% or less, or 99 wt% or less, or 98 wt% or less, or 97 wt% or less, or 96 wt% or less, or 95 wt% or less, or 94 wt% or less, or

93 wt% or less, or 92 wt% or less, or 91 wt% or less of alpha olefin (a-olefin) as measured using Fourier-Transform Infrared (FTIR) Spectroscopy. The a-olefin may include C2, or C3 to C4, or Ce, or Cs, or C10, or C12, or Ci6, or Cis, or C20 a-olefins, such as ethylene, propylene, 1- butene, 1 -hexene, 4-methyl-l -pentene, and 1 -octene. Other units of the ethylene-silane copolymer may be derived from one or more polymerizable monomers including, but not limited to, unsaturated esters (that is, the term “ethylene-silane copolymer” used herein also encompasses ethylene-silane-unsaturated ester terpolymers). The unsaturated esters may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have from 1 to 8 carbon atoms, or from 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8 carbon atoms, or from 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n- butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate.

The ethylene-silane copolymer may comprise 0.40 mol% to 1.00 mol% of copolymerized silane. For example, the ethylene-silane copolymer may comprise 0.40 mol% or greater, or 0.42 mol% or greater, or 0.44 mol% or greater, or 0.45 mol% or greater, or 0.46 mol% or greater, or 0.48 mol% or greater, or 0.50 mol% or greater, or 0.55 mol% or greater, or 0.60 mol% or greater, or 0.65 mol% or greater, or 0.70 mol% or greater, or 0.75 mol% or greater, or 0.80 mol% or greater, or 0.85 mol% or greater, or 0.90 mol% or greater, or 0.95 mol% or greater, while at the same time, 1.00 mol% or less, or 0.95 mol% or less, or 0.90 mol% or less, or 0.85 mol% or less, or 0.80 mol% or less, or 0.75 mol% or less, or 0.70 mol% or less, or 0.65 mol% or less, or 0.60 mol% or less, or 0.55 mol% or less, or 0.50 mol% or less, or 0.48 mol% or less, or 0.46 mol% or less, or 0.45 mol% or less, or 0.44 mol% or less, or 0.42 mol% or less of copolymerized silane based on the total moles of ethylene-silane copolymer. The content of copolymerized silane present in the ethylene-silane copolymer is determined through Silane Testing as explained in greater detail below. The silane comonomer used to make the ethylene-silane copolymer may be a hydrolyzable silane monomer. A “hydrolyzable silane monomer’- is a silane-containing monomer that will effectively copolymerize with an a-olefin (e.g., ethylene) to form an a- olefin/silane copolymer (such as an ethylene-silane copolymer). The hydrolyzable silane monomer has structure (I):

Structure (I) in which R¹ is a hydrogen atom or 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 R² independently is a hydrolyzable organic group such as an alkoxy group having from 1 to 12 carbon atoms (e.g., methoxy, ethoxy, butoxy), an aryloxy group (e.g., phenoxy), an araloxy group (e.g., benzyloxy), an aliphatic acyloxy group having from 1 to 12 carbon atoms (e.g., formyloxy, acetyloxy, propanoyloxy), an amino or substituted amino group (e.g., alkylamino, arylamino), or a lower-alkyl group having 1 to 6 carbon atoms, with the proviso that not more than one of the three R² groups is an alkyl. The hydrolyzable silane monomer may be copolymerized with an a-olefin (such as ethylene) in a reactor, such as a high-pressure process to form an a-olefin-silane reactor copolymer. In examples where the a- olefin is ethylene, such a copolymer is referred to herein as an ethylene-silane copolymer.

The hydrolyzable silane monomer may include silane monomers that comprise an ethylenically unsaturated hydrocarbyl group, such as a vinyl, allyl, isopropenyl, butenyl, cyclohexenyl or gamma (meth)acryloxy allyl group, and a hydrolyzable group, such as, for example, a hydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group. Hydrolyzable groups may include methoxy, ethoxy, formyloxy, acetoxy, proprionyloxy, and alkyl or arylamino groups. In a specific example, the hydrolyzable silane monomer is an unsaturated alkoxy silane, which can be grafted onto the polyolefin or copolymerized in-reactor with an a- olefin (such as ethylene). Examples of hydrolyzable silane monomers include vinyltrimethoxysilane (“VTMS”), vinyltriethoxysilane (“VTES”), vinyltriacetoxysilane, and gamma-(meth)acryloxy propyl trimethoxy silane. In context to Structure (I), for VTMS: x = 0; R¹ = hydrogen; and R² = methoxy; for VTES: x = 0; R¹ = hydrogen; and R² = ethoxy; and for vinyltriacetoxysilane: x = 0; R¹ = H; and R² = acetoxy.

The ethylene-silane copolymer may have a crystallinity at 23 °C from 40 wt% to 46 wt% as measured according to Crystallinity Testing as provided below. For example, the crystallinity at 23°C of the ethylene-silane copolymer may be 40.0 wt% or greater, or 40.5 wt% or greater, or 41.0 wt% or greater, or 41.5 wt% or greater, or 42.0 wt% or greater, or 42.5 wt% or greater, or 43.0 wt% or greater, or 43.5 wt% or greater, or 44.0 wt% or greater, or 44.5 wt% or greater, or 45.0 wt% or greater, or 45.5 wt% or greater, while at the same time, 46.0 wt% or less, or 45.5 wt% or less, or 45.0 wt% or less, or 44.5 wt% or less, or 44.0 wt% or less, or 43.5 wt% or less, or 43.0 wt% or less, or 42.5 wt% or less, or 42.0 wt% or less, or 41.5 wt% or less, or 41.0 wt% or less, or 40.5 wt% or less as measured according to Crystallinity Testing.

Ethylene polymer that is not silane functionalized

The polymeric composition may comprise one or more ethylene polymer that is not silane-functionalized. The ethylene polymer that is not silane-functionalized can include ethylene and one or more C3-C20 a-olefin comonomers such as propylene, 1 -butene, 1 pentene, 4-methyl-l -pentene, 1 -hexene, and 1 -octene. In an embodiment, the ethylene polymer that is not silane-functionalized is a homopolymer. In an embodiment, the ethylene polymer that is not silane-functionalized is an ethylene/a-olefin copolymer. In an embodiment, the ethylene polymer that is not silane-functionalized is an ethylene/unsaturated ester copolymer. The unsaturated esters may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have from 1 to 8 carbon atoms, or from 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8 carbon atoms, or from 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate. The ethylene polymer that is not silane-functionalized can have a unimodal or a multimodal molecular weight distribution and can be used alone or in combination with one or more other type of ethylene polymer (e.g., a blend of two or more ethylene polymers that differ from one another by monomer composition and content, catalytic method of preparation, molecular weight, molecular weight distributions, densities, etc.). If a blend of ethylene polymers is employed, the polymers can be blended by any in-reactor or postreactor process.

The ethylene polymer that is not silane-functionalized may comprise 50 wt% or greater, 60 wt% or greater, 70 wt% or greater, 80 wt% or greater, 85 wt% or greater, 90 wt% or greater, or 91 wt% or greater, or 92 wt% or greater, or 93 wt% or greater, or 94 wt% or greater, or 95 wt% or greater, or 96 wt% or greater, or 97 wt% or greater, or 97.5 wt% or greater, or 98 wt% or greater, or 99 wt% or greater, while at the same time, 100 wt% or less, or 99.5 wt% or less, or 99 wt% or less, or 98 wt% or less, or 97 wt% or less, or 96 wt% or less, or 95 wt% or less, or 94 wt% or less, or 93 wt% or less, or 92 wt% or less, or 91 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or 70 wt% or less, or 60 wt% or less of ethylene as measured using Nuclear Magnetic Resonance (NMR) or Fourier-Transform Infrared (FTIR) Spectroscopy. Other units of the ethylene-based polymer may include C3, or C4, or C , or Cs, or C10, or C12, or Ci6, or Cis, or C20 a-olefins, such as propylene, 1-butene, 1 -hexene, 4-methyl- 1 -pentene, and 1 -octene.

The polymeric composition may comprise from 0 wt% to 60 wt% of the ethylene polymer that is not silane-functionalized. For example, the polymeric composition comprises 0 wt% or greater, or 5 wt% or greater, or 10 wt% or greater, or 15 wt% or greater, or 20 wt% or greater, or 25 wt% or greater, or 30 wt% or greater, or 35 wt% or greater, or 40 wt% or greater, or 45 wt% or greater, or 50 wt% or greater, or 55 wt% or greater, while at the same time, 60 wt% or less, or 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, or 15 wt% or less, or 10 wt% or less, or 5 wt% or less of the ethylene polymer that is not silane- functionalized.

Non-limiting examples of ethylene polymers that are not silane-functionalized are low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), ethylene vinylacetate (EVA) copolymers, ethylene ethylacrylate (EEA) copolymers, and various elastomers (such as ENGAGE™ and INFUSE™ resins available from the Dow Chemical Company).

Halosen Free Flame Retardant

The polymeric composition comprises the halogen-free flame retardant. The halogen- free flame retardant of the polymeric composition can inhibit, suppress, or delay the production of flames. As used herein, "halogen-free" and like terms indicate that the flame-retardant filler is without or substantially without halogen content, i.e., contains less than 10,000 mg of halogen per kg of flame-retardant filler as measured by ion chromatography (IC) or a similar analytical method. Halogen content of less than this amount is considered inconsequential to the efficacy of the flame-retardant filler as, for example, in a coated conductor. Examples of the halogen-free flame retardants suitable for use in the polymeric composition include, but are not limited to, metal hydrates (such as aluminum hydroxide, magnesium hydroxide), metal carbonates, red phosphorous, silica, alumina, Brucite (mineral form of magnesium hydroxide), titanium oxide, carbon nanotubes, talc, clay, organo-modified clay, calcium carbonate, zinc borate, antimony trioxide, wollastonite, mica, ammonium octamolybdate, frits, hollow glass microspheres, intumescent compounds, expanded graphite, and combinations thereof. In an embodiment, the halogen-free flame retardant is selected from fillers that have hydroxide moieties (such as metal hydrates) and/or hydroxyl groups (such as silica). In an embodiment, the metal hydrate of the 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 an embodiment, the halogen-free flame retardant is selected from the group consisting of a metal hydrate, silica, and combinations thereof. The halogen-free flame retardant can optionally be surface treated (coated) with a saturated or unsaturated carboxylic acid having 8 to 24 carbon atoms, or 12 to 18 carbon atoms, or a metal salt of the acid. 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 acid or salt can be merely added to the composition in like amounts rather than using the surface treatment procedure. Other surface treatments known in the art may also be used including silanes, titanates, phosphates and zirconates.

Commercially available examples of halogen-free flame retardants suitable for use in the polymeric composition include, but are not limited to, APYRAL™ 40CD aluminum hydroxide available from Nabaltec AG, MAGNIFIN™ H5 magnesium hydroxide available from Magnifin Magnesiaprodukte GmbH & Co KG, Microcarb 95T ultramicronized and treated calcium carbonate available from Reverte, and combinations thereof.

The polymeric composition may comprise halogen-free flame retardants in a concentration of 10 wt% or greater, or 12 wt% or greater, or 14 wt% or greater, or 16 wt% or greater, or 18% or greater, or 20 wt% or greater, or 22 wt% or greater, or 24 wt% or greater, or 26 wt% or greater, or 28% or greater, or 30 wt% or greater, or 32 wt% or greater, or 34 wt% or greater, or 36 wt% or greater, or 38% or greater, 40 wt% or greater, or 42 wt% or greater, or 44 wt% or greater, or 46 wt% or greater, or 48% or greater, or 50 wt% or greater, or 52 wt% or greater, or 54 wt% or greater, or 56 wt% or greater, or 58% or greater, or 60 wt% or greater, or 62 wt% or greater, or 64 wt% or greater, or 66 wt% or greater, or 68% or greater, or 70 wt% or greater, or 72 wt% or greater, or 74 wt% or greater, or 76 wt% or greater, or 78% or greater, while at the same time, 80 wt% or less, or 78 wt% or less, or 76 wt% or less, or 74 wt% or less, or 72 wt% or less, or 70 wt% or less, or 68 wt% or less, or 66 wt% or less, or 64 wt% or less, or 62 wt% or less, or 60 wt% or less, or 58 wt% or less, or 56 wt% or less, or 54 wt% or less, or 52 wt% or less, or 50 wt% or less, or 48 wt% or less, or 46 wt% or less, or 44 wt% or less, or 42 wt% or less, or 40 wt% or less, or 38 wt% or less, or 36 wt% or less, or 34 wt% or less, or 32 wt% or less, or 30 wt% or less, or 28 wt% or less, or 26 wt% or less, or 24 wt% or less, or 22 wt% or less, or 20 wt% or less, or 18 wt% or less, or 16 wt% or less, or 14 wt% or less, or 12 wt% or less based on the total weight of the polymeric composition.

The polymeric composition may exhibit a Filler to Catalyst Weight Ratio from 75 to

1000. For example, the Filler to Catalyst Weight Ratio may be 75 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or

150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, or 100 or greater, or 125 or greater, or 150 or greater, or 175 or greater, while at the same time, 1000 or less, or 975 or less, or 950 or less, or 925 or less, or 900 or less, or 875 or less, or 850 or less, or 825 or less, or 800 or less, or 775 or less, or 750 or less, or 725 or less, or 700 or less, or 675 or less, or 650 or less, or 625 or less, or 600 or less, or 575 or less, or 550 or less, or 525 or less, or 500 or less, or 475 or less, or 450 or less, or 425 or less, or 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. The Filler to Catalyst Weight Ratio is calculated by dividing the total wt% of all the combined fillers present in the polymeric composition by the total wt% of Lewis acid catalyst in the polymeric composition.

Additives

The polymeric composition may include one or more additives. Nonlimiting examples of suitable additives include antioxidants, moisture scavengers, colorants, corrosion inhibitors, lubricants, silanol condensation catalysts, ultraviolet (UV) absorbers or stabilizers, antiblocking agents, flame-retardants, coupling agents, compatibilizers, plasticizers, fillers, processing aids, propylene polymers (homopolymers and copolymers including polypropylene homopolymer, random copolymer polypropylene and impact copolymer polypropylene), and combinations thereof. Nonlimiting examples of suitable moisture scavengers include alkylalkoxysilanes, and combinations thereof. Nonlimiting examples of alkylalkoxysilanes include octyltriethoxysilane, octyltrimethoxysilane and hexadecyltrimethoxysilane. In an embodiment, the moisture scavenger is octyltriethoxysilane. The moisture scavenger is present in an amount from 0 wt%, or 0.01 wt% or greater, or 0.03 wt% or greater, or 0.05 wt% or greater, or 0.1 wt% or greater, or 0.3 wt% or greater, or 0.5 wt% to 1.0 wt%, or 1.0 wt% or greater, or 2.0 wt% or greater, or 3.0 wt% or greater, or 4.0 wt% or greater, or 5.0 wt% or gerater based upon the total weight of the polymeric composition. In a further embodiment, the moisture scavenger, is present in an amount from 0 wt%, or from 0.01 wt% to 5.0 wt%, or from 0.05 wt% to 3.0 wt%, or from 0.1 wt% to 2.0 wt% or from 0.3 wt% to 1.0 wt % based upon the total weight of the polymeric composition.

The polymeric composition may include an antioxidant. Nonlimiting examples of suitable antioxidants include phenolic antioxidants, thio-based antioxidants, phosphate-based antioxidants, and hydrazine-based metal deactivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenol, phenols having substituents with primary or secondary carbonyls, and multifunctional phenols such as sulfur and phosphorous-containing phenol. Representative hindered phenols include 1,3,5-trimethyl- 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene; pentaerythrityl 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-tert-butyl-phenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6- di-tertbutylphenol;

6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-l,3,5 triazine; di-n-octylthio)ethyl 3,5-di-tert- butyl-4-hydroxy-benzoate; and sorbitol hexa|3-(3,5-di-tert-butyl-4-hydroxy-phenyl)- propionate]. The polymeric composition may include pentaerythritol tetrakis(3-(3,5-di-tert- butyl-4-hydroxyphenyl)propionate), commercially available as Irganox™ 1010 from BASF. A nonlimiting example of a suitable methyl-substituted phenol is isobutylidenebis(4,6- dimethylphenol). A nonlimiting example of a suitable hydrazine-based metal deactivator is oxalyl bis(benzylidiene hydrazide). The polymeric composition may contain from 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% antioxidant, based on total weight of the polymeric composition.

The polymeric composition may include a silanol condensation catalyst, such as a Lewis acids. A "silanol condensation catalyst" promotes crosslinking of the silane functionalized polyolefin through hydrolysis and condensation reactions. Lewis acids are chemical species that can accept an electron pair from a Lewis base. Lewis bases are chemical species that can donate an electron pair to a Lewis acid. Nonlimiting examples of suitable Lewis acids include the tin carboxylates such as dibutyl tin dilaurate (DBTDL), dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethyl hydroxy tin oleate, dioctyl tin maleate, di-n-butyl tin maleate, dibutyl tin diacetate, dibutyl tin dioctoate, stannous acetate, stannous octoate, and various other organo-metal compounds such as lead naphthenate, zinc caprylate and cobalt naphthenate, and combinations thereof. The polymeric composition includes from 0 wt%, or 0.001 wt%, or 0.005 wt%, or 0.01 wt%, or 0.02 wt%, or 0.03 wt% to 0.05 wt%, or 0.1 wt%, or 0.2 wt%, or 0.5 wt%, or 1.0 wt%, or 3.0 wt%, or 5.0 wt% or 10 wt% silanol condensation catalyst, based on the total weight of the polymeric composition. The silanol condensation catalyst is typically added to the article manufacturing-extruder (such as during cable manufacture) so that it is present during the final melt extrusion process. As such, the silane functionalized polyolefin may experience some crosslinking before it leaves the extruder with the completion of the crosslinking after it has left the extruder, typically upon exposure to moisture (e.g., a sauna, hot water bath or a cooling bath) and/or the humidity present in the environment in which it is stored, transported or used.

The Lewis acid silanol condensation catalyst may be included in a catalyst masterbatch blend with the catalyst masterbatch being included in the composition. Nonlimiting examples of suitable silanol condensation catalyst masterbatches include those sold under the trade name SI-LINK™ from The Dow Chemical Company, including SI-LINK™ DFDB-5480 NT and SI- LINK™ DFDA-5481 NT. In an embodiment, the composition contains from 0 wt%, or 0.001 wt%, or 0.01 wt%, or 0.5 wt%, or 1.0 wt%, or 2.0 wt%, or 3.0 wt%, or 4.0 wt% to 5.0 wt%, or 6.0 wt%, or 7.0 wt%, or 8.0 wt%, or 9.0 wt%, or 10.0 wt%, or 15.0 wt%, or 20.0 wt% silanol condensation catalyst masterbatch, based on total weight of the composition.

The polymeric composition may include an ultraviolet (UV) absorber or stabilizer. A nonlimiting example of a suitable UV stabilizer is a hindered amine light stabilizer (HALS). A nonlimiting example of a suitable HALS is l,3,5-Triazine-2,4,6-triamine, N,N-1,2- ethanediylbisN-3-4,6-bisbutyl(l,2,2,6,6-pentamethyl-4-piperidinyl)amino-l,3,5-triazin-2- ylaminopropyl-N,N-dibutyl-N,N-bis(l,2,2,6,6-pentamethyl-4-piperidinyl)-l,5,8,12- tetrakis[4,6-bis(n-butyl-n-l,2,2,6,6-pentamethyI-4-piperidylamino)-l,3,5-triazin-2-yI]- 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 from 0 wt%, or 0.001 wt%, or 0.002 wt%, or 0.005 wt%, or 0.006 wt% to 0.007 wt%, or 0.008 wt%, or 0.009 wt%, or 0.01 wt%, or 0.2 wt %, or 0.3 wt %, or 0.4 wt%, or 0.5 wt%, 1.0 wt %, or 2.0 wt%, or 2.5 wt%, or 3.0 wt% UV absorber or stabilizer, based on total weight of the composition.

The composition may include a processing aid. Nonlimiting 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 contains from 0 wt%, or 0.01 wt%, or 0.02 wt%, or 0.05 wt%, or 0.07 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%, or 5.0 wt%, or 10.0 wt%, or 20.0 wt% processing aid, based on total weight of the composition.

The composition may contain from 0 wt% or greater, or 0.001 wt% or greater, or 0.002 wt% or greater, or 0.005 wt% or greater, or 0.006 wt% or greater, or 0.008 wt% or greater, or 0.009 wt% or greater, or 0.01 wt% or greater, or 0.2 wt% or greater, or 0.3 wt% or greater, or 0.4 wt% or greater, or 0.5 wt% or greater, or 1.0 wt% or greater, or 2.0 wt% or greater, or 3.0 wt% or greater, or 4.0 wt% or greater, or 5.0 wt% or greater, or 10.0 wt% or greater, or 15.0 wt% or greater, or 20.0 wt% or greater, or 30 wt% or greater, or 40 wt% or greater, or 50 wt% or greater additive, based on the total weight of the polymeric composition.

Masterbatch

One or more of the ethylene-silane copolymer, the halogen-free flame retardant, and additives may be combined as a pre-mixed masterbatch. Such masterbatches are commonly formed by dispersing the flame-retardant and additives into an inert plastic resin. Masterbatches are conveniently formed by melt compounding methods.

One or more of the components or masterbatches may be dried before compounding or extrusion, or a mixture of components or masterbatches is dried after compounding or extrusion, to reduce or eliminate potential scorch (i.e., premature crosslinking during compounding or extrusion) that may be caused from moisture present in or associated with the component, e.g., filler. The compositions may be prepared in the absence of a silanol condensation catalyst for extended shelf life, and the silanol condensation catalyst may be added as a final step in the preparation of a cable construction (coated conductor) by extrusion processes. Alternatively, the catalyst may be combined with one or more other components in the form of a masterbatch.

Coated Conductor

The present disclosure also provides a coated conductor. The coated conductor includes a conductor and a coating on the conductor, the coating including the polymeric composition. The polymeric composition is at least partially disposed around the conductor to produce the coated conductor. The conductor may comprise a conductive metal and/or an optical waveguide.

The process for producing a coated conductor includes mixing and heating the polymeric composition to at least the melting temperature of the ethylene-silane polymer in an extruder to form a polymeric melt blend, and then coating the polymeric melt blend onto the conductor. The term "onto" includes direct contact or indirect contact between the polymeric melt blend and the conductor. The polymeric melt blend is in an extrudable state.

The polymeric composition is disposed on and/or around the conductor to form a coating. The coating may be one or more inner layers such as an insulating layer. The coating may wholly or partially cover or otherwise surround or encase the conductor. The coating may be the sole component surrounding the conductor as an insulation or jacket. Alternatively, the coating may be one layer of a multilayer jacket or sheath encasing the conductor. The coating may directly contact the conductor. The coating may directly contact an insulation layer surrounding the conductor.

The resulting coated conductor is cured at humid conditions for a sufficient length of time such that the coating reaches a desired degree of crosslinking. The temperature during cure is generally above 0°C. In an embodiment, the curing is done for at least 4 hours in a 90°C water bath. In an embodiment, the curing is done for up to 200 days at ambient conditions comprising an air atmosphere, ambient temperature (e.g., 5°C to 50°C), and ambient relative humidity (e.g., 5 to 100 percent relative humidity (% RH)).

In an embodiment, the polymeric composition is coated at 1.524 mm thickness onto a 10 American wire gauge (“AWG”) conductor (diameter: 2.59 mm).

The polymeric composition of the coated conductor may exhibit a tensile strain at break of 20% or greater as measured according to UL 2556, Section 3.5. For example, the polymeric composition of the coated conductor may exhibit a tensile strain at break of 20% or greater, or 25% or greater, or 30% or greater, or 40% or greater, or 50% or greater, or 60% or greater, or 70% or greater, or 80% or greater, or 90% or greater, or 100% or greater, or 150% or greater, or 200% or greater, or 250% or greater, or 300% or greater, or 400% or greater, or 500% or greater, while at the same time, 600% or less, or 500% or less, or 400% or less, or 300% or less, or 250% or less, or 200% or less, or 150% or less, or 100% or less as measured according to UL 2556, Section 3.5. The polymeric composition of the coated conductor may exhibit a hot creep of 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003. For example, the polymeric composition of the coated conductor may exhibit a hot creep 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, or 10% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003.

Tensile strain at break of the polymeric composition made in the form of extruded tape or compression molded sample may be 20% or greater as measured in accordance with ASTM D638-14. For example, the extruded tape or compression molded sample made of the polymeric composition may exhibit a tensile strain at break of 20% or greater, or 25% or greater, or 30% or greater, or 40% or greater, or 50% or greater, or 60% or greater, or 70% or greater, or 80% or greater, or 90% or greater, or 100% or greater, or 150% or greater, or 200% or greater, or 250% or greater, or 300% or greater, or 400% or greater, or 500% or greater, while at the same time, 600% or less, or 500% or less, or 400% or less, or 300% or less, or 250% or less, or 200% or less, or 150% or less, or 100% or less as measured according to ASTM D638-14.

Hot creep of the polymeric composition made in the form of extruded tape or compression molded sample may be 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003. For example, the extruded tape or compression molded sample made of the polymeric composition may exhibit a hot creep 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, or 10% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003.

Examples

Test Methods

Density: Density is measured in accordance with ASTM D792, Method B. The result is recorded in grams (g) per cubic centimeter (g/cc).

Melt Index: Melt index (MI) is measured in accordance with ASTM D1238, Condition 190°C/2.16 kilogram (kg) weight and is reported in grams eluted per 10 minutes (g/10 min).

Silane Testing: Use x-ray fluorescence spectroscopy (“XRF”) to determine weight percent (wt%) of silicon atom (Si) content of, and then calculate silane comonomeric unit wt% in, test samples of the ethylene- silane copolymer. Using a Buehler SimpliMet 300 automatic mounting press that is preheated for 3 minutes at 115.6° C. (240 degrees Fahrenheit (° F.)), press a powdered form of test sample for 1 minute under 8.3 megapascals (MPa; 1,200 pounds per square inch (psi)) to form a plaque having a thickness of about 6 mm, and cool the plaque to 25° C. Analyze the Si atom content of the plaque by wavelength dispersive XRF using a wavelength dispersive X-ray fluorescence spectrometer from PANalytical Axios. Determine Si atom content by comparing its line intensity in the XRF spectrum to a calibration curve for Si atom content that is established using polymer standards of known Si atom concentrations as independently measured using Neutron Activation Analysis (NAA) or Inductively Coupled Plasma (ICP) methods. Use the XRF measured Si atom wt% value, and the molecular weight(s) of the at least one silane comonomer from which the hydrolyzable silyl groups were derived, to calculate hydrolyzable silyl group comonomeric unit wt% (i.e., wt% of the hydrolyzable silyl groups) in the ethylene-silane copolymer. For hydrolyzable silyl groups derived from vinyltrimethoxysilane (VTMS), use the VTMS molecular weight of 148.23 g/mol. To calculate hydrolyzable silyl group content of (wt% of hydrolyzable silyl group comonomeric units in) the ethylene-silane copolymer, use the XRF obtained Si atom wt% (“C”) and the following formula: p = C * (m/28.086)(l/10000ppmw), wherein * means multiplication, / means division, p is wt% hydrolyzable silyl groups in ethylene-silane copolymer, C is the Si atom amount (XFR) in weight parts per million (ppmw), m is the molecular weight in g/mol of the silane comonomer from which the hydrolysable silyl groups are derived, 28.086 is the atomic weight of a silicon atom, and 10000 ppmw is the number of weight parts per million in 1.00 wt%. For example, when XRF shows 379 ppmw of Si atom in 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% comonomeric content is 0.20 wt%. To calculate mol% of hydrolyzable silyl group comonomeric units in the ethylene-silane copolymer of the silane comonomer used, use the calculated wt% of the hydrolyzable silyl group comonomeric units in ethylene-silane copolymer and the following equation: G = 100 * (p/m)/|(p/m) + (100.00 wt% - p)/28.05 g/mol], wherein * means multiplication, G is mole percent (mol%) of hydrolyzable silyl groups in the ethylene-silane copolymer; p is wt% of hydrolyzable silyl groups in ethylene-silane copolymer, m is molecular weight in g/mol of the silane comonomer from which the hydrolyzable silyl groups are derived, and 28.05 g/mol is the molecular weight of monomer ethylene (H2C=CH2). For example, when comonomeric 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 comonomeric 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 ethylene-silane copolymer, the molecular weight used in the calculation of the total mol% of all hydrolyzable silyl groups in ethylene-silane copolymer is a weighted average molecular weight of the comonomers. The weighting may be determined by the proportion of the amounts of the comonomers fed into the reactor; alternatively by NMR spectroscopy on the ethylene-silane copolymer to determine the relative amounts of the different comonomeric units in the ethylene-silane copolymer when the respective hydrolyzable silyl groups are bonded to different types of carbon atoms (e.g., tertiary versus secondary carbon atoms); alternatively by Fourier Transform Infrared (FT-IR) spectroscopy calibrated to provide quantitation of the different types comonomers. Crystallinity Testing: determine melting peaks and percent (%) or weight percent (wt%) crystallinity of ethylene polymers at 23 °C using Differential Scanning Calorimeter (DSC) instrument DSC Q1000 (TA Instruments). (A) Baseline calibrate DSC instrument. Use software calibration wizard. Obtain a baseline by heating a cell from -80° to 280° C. without any sample in an aluminum DSC pan. Then use sapphire standards as instructed by the calibration wizard. Analyze 1 to 2 milligrams (mg) of a fresh indium sample by heating the standards sample to 180°C, cooling to 120°C at a cooling rate of 10°C/minute, then keeping the standards sample isothermally at 120°C for 1 minute, followed by heating the standards sample from 120°C to 180°C at a heating rate of 10°C/minute. Determine that indium standards sample has heat of fusion = 28.71 ± 0.50 Joules per gram (J/g) and onset of melting = 156.6° ± 0.5°C (B) Perform DSC measurements on test samples using the baseline calibrated DSC instrument. Press test sample of semi-crystalline ethylenic polymer into a thin film at a temperature of 160°C. Weigh 5 to 8 mg of test sample film in aluminum DSC pan. Crimp lid on pan to seal pan and ensure closed atmosphere. Place lid-sealed pan in DSC cell, equilibrate cell at 30°C, and then heat at a rate of about 100° C/minute to 190°C, keep sample at 190°C for 3 minutes, cool sample at a rate of 10°C/minute to -60°C to obtain a cool curve heat of fusion (Hf), and keep isothermally at -60°C for 3 minutes. Then heat sample again at a rate of 10°C/minute to 190°C to obtain a 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 of density greater than or equal to 0.90g/cm³) or -40°C (in the case of copolymers of ethylene and unsaturated esters, and ethylene alpha olefin copolymers of density less than 0.90g/cm³) to end of melting. Using the second heating curve, calculate the “room temperature” heat of fusion (J/g) from 23 °C (room temperature) to end of melting by dropping perpendicular at 23 °C. Measure and report “total crystallinity” (computed from “total” heat of fusion) as well as “Crystallinity at room temperature” (computed from 23 °C heat of fusion). Crystallinity is measured and reported as percent (%) or weight percent (wt%) crystallinity of the polymer from the test sample’s second heating curve heat of fusion (AHf) and its normalization to the heat of fusion of 100% crystalline polyethylene, where % crystallinity or wt% crystallinity = (AHf*100%)/292 J/g, wherein AHf is as defined above, * indicates mathematical multiplication, / indicates mathematical division, and 292 J/g is a literature value of heat of fusion (AHf) for a 100% crystalline polyethylene.

Hol Creep-. Hot creep (also known as hot creep elongation) of polymeric compositions is measured after Ultimate Cure has been performed and is measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003 at a specified temperature (either 200°C or 150°C) under a fixed stress (0.2 MPa).

Tensile peak stress and tensile strain at break'. In the case of coated conductors, tensile peak stress (also known as tensile strength) and tensile strain at break (also known as tensile elongation) of polymeric compositions is measured according to Underwriter’s Laboratory (“UL”) 2556, Section 3.5 at a displacement rate of 20 inch per minute and at 23°C and 50% relative humidity. The averages of four or five measurements are determined. Each test specimen is prepared by removing the polymeric composition coating (insulation) from a coated conductor that has undergone Ultimate Cure, without damaging it. Tensile properties can also be measured of extruded tape or compression molded samples made of the polymeric compositions, in accordance with ASTM D638- 14, at a displacement rate of 20 inch per minute (using Type IV dog bone-shaped specimens obtained from the tapes or compression molded samples).

Char Length and Filler Weighted Char Length (FWCL) value: The FWCL value of a coated conductor is determined by first performing International Electrotechnical Commission test 60332-1-2:2004 that specifies the procedure for testing the resistance to vertical flame propagation for a single vertical coated conductor. Test 60332-1-2:2004 measures a length of char (“char length”) formed on the coated conductor during the test. The FWCL value is calculated by multiplying the char length in centimeters by the wt% of flame-retardant filler present in the polymeric composition that is used to form the coated conductor and dividing by 100.

Materials

The materials used in the inventive examples (“IE”) and comparative examples (“CE”) are provided below.

ESC1 is an ethylene-silane copolymer (“ESC”) characterized by a melt index (L) of 2.0 g/10 minutes, a density of 0.922 g/cc, a copolymerized VTMS content of 0.65 mol% and a crystallinity at 23°C of 44.58 wt%. ESC1 is available from The Dow Chemical Company, Midland, Michigan.

ESC2 is made by adding a moisture scavenger to ESC1. It has similar melt index (I2), density, copolymerized VTMS content and crystallinity at 23 °C as ESC1 (as the moisture scavenger does not affect these properties). ESC2 is available from The Dow Chemical Company, Midland, Michigan. ESC3 is characterized by melt index (I2) of 1.5 g/10 minutes, a density of 0.921 g/cc, a copolymerized VTMS content of 0.31 mol% and a crystallinity at 23°C of 46.83 wt%. ESC3 is available from The Dow Chemical Company, Midland, Michigan.

ESC4, ESC5, ESC6 and ESC7 are prepared as follows: Into a stirred autoclave reactor having a capacity of 545 milliliters (mL), charge a mixture of ethylene, VTMS, and propylene, which is used as a chain transfer agent. Add organic peroxide (tert-butyl peroxy acetate 75 wt% solution in aliphatic hydrocarbons) at a loading of 0.2 wt% based on total weight of ethylene, VTMS, propylene, and organic peroxide. Pressurize the reactor to 193 MPa and heat the reactor to 250°C. Continuously feed ethylene, VTMS, and propylene into the reactor, and remove made ESC from the reactor. Convert ESC into pellet form via melt extrusion. ESC4, ESC5 ESC6 and ESC7 are made under the effective process conditions shown in Table 1 and are characterized by the properties shown in Table 2.

Table 1: Exemplified effective process conditions used to make ESC4, ESC5, ESC6 and ESC7.

Table 2: Properties of ESC4, ESC5, ESC6 and ESC7.

ESC8 is made by adding a moisture scavenger to ESC3. It has similar melt index (I2), density, copolymerized VTMS content and crystallinity at 23°C as ESC3 (as the moisture scavenger does not affect these properties). ESC8 is available from The Dow Chemical Company, Midland, Michigan.

Si-g-POE is a silane-grafted polyolefin elastomer characterized by melt index (I2) of 21.9 g/10 minutes and a grafted VTMS content of 0.75 mol%. It is made from an ethylene polymer (copolymer of ethylene and 1-octene, with 5.6 mol% octene comonomer content) and has a melt index (b) of 30 g/10 minutes, a density of 0.902 g/cc and a crystallinity at 23°C of 35.7 wt%. The preparation of Si-g-POE is described in World Intellectual Property Organization Publication number WO/2021/252312 as the “Si-g-POE2” sample.

Si-g-LDPE is a silane-grafted low density polyethylene characterized by melt index (I2) of 1.9 g/10 minutes and a grafted VTMS content of 0.57 mol%. It is made from a low density polyethylene (LDPE) having a melt index (b) of 8 g/10 minutes, a density of 0.918 g/cc and a crystallinity at 23°C of 47.1 wt%. The preparation of Si-g-LDPE is described in World Intellectual Property Organization Publication number WO/2021/252312 as the “Si-g-LDPE” sample.

CAT1 MB is a silanol condensation catalyst masterbatch (blend of thermoplastic ethylenic polymers, antioxidants, and about 2 wt% of dibutyltin dilaurate) developed to be used in conjunction with moisture curable ethylene-silane copolymers and is commercially available as SI-LINK™ DFDB-5480 NT from The Dow Chemical Company, Midland, MI.

CAT2 MB is a silanol condensation catalyst masterbatch (blend of thermoplastic ethylenic polymers, antioxidants, and about 3 wt% of dibutyltin dilaurate) developed to be used in conjunction with moisture curable ethylene-silane copolymers and is commercially available as SI- LINK™ DFDA-5481 NT from The Dow Chemical Company, Midland, MI.

OBC is an olefin block copolymer having a density of 0.877 g/cc and a melt index (I2) of 15 g/10 minute. OBC is commercially available as INFUSE™ 9817 from The Dow Chemical Company, Midland, MI.

Compatibilizer is a maleic anhydride grafted ethylene vinyl acetate copolymer and is commercially available as FUSABOND™ C250 from The Dow Chemical Company, Midland, MI.

Filler is magnesium hydroxide (HFFR) and is commercially available as FR-20-100 from

Israel Chemicals Ltd. of Tel Aviv-Yafo, Israel. A01 is a sterically hindered phenolic antioxidant having the chemical name pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), which is commercially available as IRGANOX™ 1010 from BASF, Ludwigshafen, Germany.

AO2 is distearyl thiodipropionate and is commercially available as NAUGARD™ DSTDP from Addivant, Danbury, CT.

OBH is Oxalyl bis (benzylidene) hydrazide and is commercially available from Sigma- Aldrich, St. Louis, MO.

Silicone is DOWS1L™ Si Powder Resin Modifier 4-7081 and is commercially available from The Dow Chemical Company, Midland, MI.

OTS is Octyltriethoxy silane and is commercially available as PROSIL™ 9202 from Si Vance LLC, of Milliken & Co.

Carbon black is Vulcan XC72 and is commercially available from Cabot Corporation, Alpharetta, GA.

Carbon black containing intermediate compound based on ESC1 is constituted of 70 wt% ESC1 and 30 wt% carbon black. Its preparation is described ahead (see CE6).

Carbon black containing intermediate compound based on ESC3 is constituted of 70 wt% ESC3 and 30 wt% carbon black. Its preparation is described ahead (see CE7).

FR MB is a flame retardant masterbatch that is a blend of a thermoplastic ethylenic polymer, an antioxidant, a hindered amine stabilizer, and 60 wt% filler (brominated flame retardant and antimony trioxide). FR MB is available from The Dow Chemical Company, Midland, Michigan.

CB MB is a carbon black masterbatch comprising a blend of a thermoplastic ethylenic polymer, an antioxidant, and about 40 wt% of carbon black (filler). CB MB is available from The Dow Chemical Company, Midland, Michigan.

CA MB is a catalyst masterbatch comprising a blend of thermoplastic ethylenic polymers, an antioxidant, and about 3 wt% of an arylsulfonic acid (a Brpnsted Acid). CA MB is available from The Dow Chemical Company, Midland, Michigan.

CC MB is a combined catalyst and carbon black masterbatch comprising a blend of thermoplastic ethylenic polymer, a moisture scavenger, an antioxidant, a stabilizer, about 31 wt% carbon black (filler), and about 1.5 wt% of an arylsulfonic acid (a Brpnsled Acid). CC MB is available from The Dow Chemical Company, Midland, Michigan.

HFFR Masterbatch is a halogen free flame-retardant masterbatch formed by combining the materials of Table 3. The HFFR MB was made by combining the magnesium hydroxide and other ingredients with the OBC in a BRABENDER™ mixer with cam blades at 40 revolutions per minute (“RPM”) rotor speed and 160°C jacket (mixing bowl set) temperature. The OBC was fluxed for 5 minutes before adding the solid additives and mixing for another 10 minutes. Liquid additives of the HFFR MB were added thereafter and mixing was done for additional 5 minutes. The HFFR MB mixture was removed, compression molded in a press to make a 75 mil (1.9 mm) plaque (120°C, 3.44 MPa, 5 minutes), cooled and cut into small pieces (“chips”). The chips were fed to a Brabender 19.05 mm single screw extruder (25:1 L/D) operated at 40 RPM with a dual stage mixing screw (of 3:1 compression ratio) and set temperature profile of 150°C /160°C /170°C /180°C profile across all zones as well as the head/die (using a 40/60/40 US mesh screen pack) and fabricated into a strand that in turn was converted to pellets using a pelletizer. The pellets were packaged in sealed foil bags.

Table 3: Composition of the HFFR MB

Sample Preparation and Results: IE1, 1E2, and CE1

Wires were prepared using the HFFR MB, a silanol condensation catalyst masterbatch (CAT1 MB) and an ethylene-silane copolymer (ESC). Before wire preparation, pellets of the HFFR MB and CAT1 MB were dried separately in a vacuum oven at 60°C for 48 hours or 70°C oven for 16-24 hours to remove moisture. Preparation of wires was done by physically blending the ESC pellets with pellets of HFFR MB and CAT 1 MB at the specific proportions shown in Table 4. The physical blend was then melt mixed during extrusion to make wire constructions on 10 American wire gauge (“AWG”) solid copper with a nominal 1.524 millimeters wall thickness. The wire-preparation unit included a BRABENDER™ 19.05 mm extruder with variable speed drive, a 25:1 L/D mixing screw, a BRABENDER™ cross-head wire die, lab water cooling trough with air wipe, a laser micrometer, and a variable speed wire puller. The wire samples were extruded at 40 RPM screw speed with a temperature profile of 140^oC/155°C/165^oC/165°C (across zone 1, zone 2, zone 3 and head/die) and a 40/40 US mesh screen pack.

The wires (coated conductors) were cured in a 90°C water bath for 72 hours days, to achieve ultimate cure. After further conditioning at 23°C and 50% relative humidity for several hours, the properties of cured coatings or the coated conductors were tested.

Compared with CE1, IE1 and IE2 exhibited desirably lower hot creep values (indicative of increased crosslinking), enhanced flame retardant properties (char length and FWCL values) and surprisingly improved tensile properties. The tensile property results are suggestive of enhanced compatibilization of the magnesium hydroxide filler with increased content of copolymerized VTMS in the ethylene-silane copolymer.

Table 4: Compositions and properties of IE1 to IE2 and CE1.

Sample Preparation and Results: IE3-IE6, and CE2-5

Wires were prepared using the HFFR MB of Table 3, a silanol condensation catalyst masterbatch (CAT1 MB) and either an ethylene-silane copolymer (ESC) or a silane-grafted polyolefin elastomer (Si-g-POE) or a silane-grafted low density polyethylene (Si-g-LDPE). Before wire preparation, pellets of the HFFR MB and CAT1 MB were dried separately in a vacuum oven at 60°C for 48 hours or 70°C oven for 16-24 hours to remove moisture. Pellets of ESC, Si-g-POE or Si-g-LDPE were physically blended with pellets of HFFR MB and CAT1 MB at the specific proportions shown in Table 5. The blend was then melt mixed during extrusion to make wire constructions on 10 AWG solid copper with a nominal 1.524 millimeters wall thickness. The wire-preparation unit included a BRABENDER™ 19.05 mm extruder with variable speed drive, a 25:1 L/D mixing screw, a BRABENDER™ cross-head wire die, lab water cooling trough with air wipe, a laser micrometer, and a variable speed wire puller. The wire samples were extruded at 40 RPM screw speed with a temperature profile of 140°C/155^oC/165^oC/165°C (across zone 1, zone 2, zone 3 and head/die) and a 40/40 US mesh screen pack. The wires (coated conductors) were cured in a 90°C water bath for two or three days, to achieve ultimate cure. After further conditioning at 23°C and 50% relative humidity for several hours, the properties of cured coatings or the coated conductors were tested.

Referring now to Table 5, compared with CE2 and CE3, IE3 to IE6 exhibited desirably lower hot creep values (indicative of increased crosslinking), similar flame retardant properties (char length and FWCL values) and surprisingly improved or similar tensile properties. The tensile property results are suggestive of enhanced compatibilization of the magnesium hydroxide filler with increased content of copolymerized VTMS in the ethylene-silane copolymer.

CE4 did exhibit low hot creep values as well as good flame retardant and tensile properties. However, the Si-g-POE used in CE4 was not an ethylene-silane copolymer. Additionally, the Si-g-POE was made from an ethylene polymer having a crystallinity at 23 °C of 36 wt%. The lower crystallinity of the ethylene polymer used to make Si-g-POE, relative to the crystallinities of the various ethylene-silane copolymers, is not desirable for abrasion and pinch resistance properties as flexibility or softness increases with decreasing crystallinity.

CE5 also yielded a good balance of properties, however, the Si-g-LDPE used in CE5 was not an ethylene-silane copolymer and also had a crystallinity at 23 °C of 47 wt%. The higher crystallinity of the ethylene polymer used to make Si-g-LDPE, relative to the crystallinities of the various ethylene-silane copolymers used in the inventive examples, is not desirable as it increases rigidity excessively.

Table 5: Compositions and properties of IE3 to IE6 and CE2 to CE5.

Sample Preparation and Results: CE6 and CE7

A carbon black containing intermediate compound based on an ESC (either ESC 1 or ESC3) was prepared as follows: The ESC was melt-blended with carbon black as the filler (at 70/30 wt% proportion of ESC/carbon black). A Brabender mixer equipped with Banbury blades and a bowl volume of 375 mL was used with a rotor speed of 30 RPM and set temperature of 150°C to make a batch weighing approximately 283 grams (by fluxing the ESC for 5 minutes, and then adding the carbon black, and mixing for another 5 minutes). The melt-blended composition was removed from the mixing bowl and compression molded into a plaque of 75 mil (1.9 mm) thickness at 120°C by applying 500 psi pressure for 5 minutes. Two batches of each formulation were made to yield approximately 500 grams quantity in total, which was cut using a guillotine into strips that were fed to a pelletizer (granulator) to make "chips". Next, the “chips” were introduced into a Brahender 19.05 mm extruder (25:1 L/D) operated at 40 RPM with a mixing screw (of 3:1 compression ratio) and set temperatures of 150°C across all zones as well as the head/die (using a 40/60/40 US mesh screen pack) and fabricated into a strand that in turn was converted to pellets using a pelletizer. The pellets were packaged in sealed foil bags.

The carbon black containing intermediate compound based on the ESC was melt blended with a silanol condensation catalyst masterbatch (CAT2 MB) in the proportions indicated in Table 6. The catalyst masterbatch was dried beforehand for 16 to 24 hours at 70°C in a vacuum oven and thereafter packaged in a vacuum-sealed foil bag until the time of use. Physical blends (in a plastic bag) were made of the pellets of intermediate compounds and the catalyst masterbatch, which were subsequently fed to a Brabender 19.05 mm extruder equipped with 25:1 Maddock screw, to make tapes of approximately 60 mil (1.5 mm) thickness. The set temperature profile across the zones was 160°C, 170°C, 180°C, and 185°C at the head/die. A 40/60/40 US mesh screen pack was employed and the screw speed was 40 RPM. The tapes were cured in a 90°C water bath for 20 hours to achieve ultimate cure. After further conditioning at 23°C and 50% relative humidity for several hours, the properties of the cured tapes were tested.

Compared with CE7, CE6 exhibited substantially inferior tensile elongation value. That is, with carbon black as the sole filler in the composition, increased copolymerized VTMS content in the ethylene-silane copolymer led to worse tensile elongation (consistent with no apparent compatibilization of this filler).

Table 6: Compositions and properties of CE6 and CE7.

Sample Preparation and Results: CE8-CE13

CE8-CE13 were prepared by mixing pellets of the components of Table 7 in a fiber drum. Next, the samples were melt-mixed during extrusion to make coated conductors having a 0.762 mm thick coating of the polymeric composition on a 14 AWG solid copper conductor to form a wire. The wires were fabricated using a 63.5 mm Davis Standard extruder with a double-flighted Maddock screw and 20/40/60/20 mesh screens, at the following set temperatures (°C) across zone 1/zone 2/zone 3/zone 4/zone 5/head/die: 129.4/135.0/143.3/148.9/151.7/165.6/165.6. The length-to-diameter (L/D) ratio of the screw was 26 (measured from the beginning of the screw flight to the screw tip) or 24 (measured from the screw location corresponding to the end of the feed casing to the screw tip). The wire constructions were fabricated at a line speed of 91.44 meters per minute, using the following screw speeds: 38 RPM for CE8 and CE9; 37 RPM for CE10 and CE11 ; and 39 RPM for CE12 and CE13.The wires (coated conductors) were cured at 23°C and 50% relative humidity (RH) for 3 to 7 weeks, followed by 20 hours in 90°C water bath, to achieve ultimate cure.

Comparing CE8 with CE9 and CE10 with CE11, increased copolymerized VTMS content in the ethylene- silane copolymer led to worse tensile elongation. That is, since FR MB contained halogenated flame retardant and antimony trioxide as fillers, and CB MB and CC MB both contained carbon black as filler, there was no apparent compatibilization of these fillers with increased copolymerized VTMS content in the ethylene-silane copolymer.

Comparing CE12 versus CE I 3, both of which did not contain any fillers, increased copolymerized VTMS content in the ethylene-silane copolymer resulted in inferior tensile elongation.

Table 7: Compositions and properties of CE8 to CE13.

As demonstrated above, the polymeric composition of the present disclosure does not suffer a loss in tensile strain at break (or even exhibits increased tensile strain at break) in comparison to polymeric compositions using an ethylene-silane copolymer of less than 0.4 mol% copolymerized silane and achieves a hot creep of 175% or less after Ultimate Cure as measured according to UL 2556 Section 7.9 or ICEA-T-28-562-2003.

Comparing IE1 and IE2 with CE1, when magnesium hydroxide was used as the filler, increased copolymerized VTMS content in the ethylene-silane copolymer unexpectedly resulted in enhanced tensile strength and elongation (upon crosslinking - using a Lewis acid, dibutyltin dilaurate, as silanol condensation catalyst). In contrast, when carbon black was utilized as filler, the opposite effect on tensile elongation was observed (see CE6 and CE7).

Comparing CE2 and CE3 with IE3 to IE6, also employing magnesium hydroxide as filler and dibutyltin dilaurate as silanol condensation catalyst, improved or similar tensile properties were obtained irrespective of copolymerized VTMS content in the ethylene-silane copolymer used. These results are consistent with those on IE1 and IE2 versus CE1, and are suggestive of enhanced compatibilization of magnesium hydroxide filler with increased content of copolymerized VTMS in the ethylene-silane copolymer.

Although combinations of metal hydrate fillers with silane-grafted ethylene polymers (such as POE and LDPE as used for CE4 and CE5) have been disclosed in the prior art, the effects of grafted VTMS contents on tensile elongation values are different depending on the type of ethylene polymer used, meaning that it is not obvious what trends would be observed when ethylene-silane copolymers (an entirely different class of silane functionalized polyethylenes) are used as the moisture curable resin.

Use of halogenated flame retardant and antimony trioxide along with carbon black as fillers with ethylene-silane copolymers also resulted in worsening of tensile elongation as the copolymerized VTMS content in the copolymer increased (CE8 to CE13). These findings are consistent with those on use of carbon black as the sole filler (CE6 and CE7), i.e., there was no apparent compatibilization of these fillers by ethylene-silane copolymers.

Claims

CLAIMS What is claimed is

1. A polymeric composition, comprising: an ethylene-silane copolymer comprising units derived from an ethylene monomer and a silane monomer, wherein the ethylene-silane copolymer has a copolymerized silane content from 0.40 mol% to 1 .00 mol% based on the total moles of the ethylene-silane copolymer; a Lewis acid catalyst; and a halogen-free flame retardant selected from the group consisting of a metal hydrate, silica and combinations thereof.

2. The polymeric composition of claim 1, wherein the Lewis acid catalyst is selected from the group consisting of dibutyl tin dilaurate, dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethyl hydroxy tin oleate, dioctyl tin maleate, di-n-butyl tin maleate, dibutyl tin diacetate, dibutyl tin dioctoate, stannous acetate, stannous octoate, lead naphthenate, zinc caprylate and cobalt naphthenate, and combinations thereof.

3. The polymeric composition of one of claims 1 and 2, wherein the metal hydrate is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, Brucite, calcium hydroxide, zinc hydroxide, iron hydroxide, copper hydroxide, and combinations thereof.

4. The polymeric composition of one of claims 1-3, wherein the polymeric composition comprises from 10 wt% to 80 wt% of the halogen-free flame retardant based on the total weight of the polymeric composition.

5. The polymeric composition of one of claims 1-4, wherein the polymeric composition comprises from 10 wt% to 90 wt% of the ethylene-silane copolymer based on the total weight of the polymeric composition.

6. The polymeric composition of one of claims 1-5, wherein the polymeric composition exhibits a Filler to Catalyst Weight Ratio from 75 to 1000.

7. The polymeric composition of one of claims 1-6, wherein the ethylene-silane copolymer exhibits a crystallinity at 23 °C of 40 wt% to 46 wt% as measured according to Crystallinity Testing.

8. The polymeric composition of one of claims 1-7, wherein the ethylene-silane copolymer has a copolymerized silane content from 0.45 mol% to 0.85 mol%.

9. The polymeric composition of one of claims 1-8, wherein the polymeric composition exhibits one or more of a hot creep of 175% or less after Ultimate Cure as measured according to ICEA-T-28-562-2003 and a tensile strain at break of 20% or greater as measured according to ASTM D638-14.

10. A coated conductor, comprising: a conductor; and the polymeric composition of any one of claims 1-9.

11. The coated conductor of claim 10 in which the polymeric composition exhibits one or more of a hot creep of 175% or less after Ultimate Cure as measured according to ICEA-T-28- 562-2003 and a tensile strain at break of 20% or greater as measured according to UL 2556, Section 3.5.