Filled water crosslinkable polymer composition

Abstract

A polymer composition comprising an ethylene-silane copolymer containing units derived from ethylene monomers and silane monomers, wherein the ethylene-silane copolymer has a copolymer silane content of 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 metal hydrates, silica, and combinations thereof.

Description

[Technical Field]

[0001] This disclosure relates to polymer compositions, and more specifically to filled moisture-crosslinkable polymer compositions. [Background technology]

[0002] Introduction Ethylene-silane copolymers are used to form moisture-crosslinkable polymer compositions. Such polymer compositions are used to manufacture wires and cables (i.e., coated conductors) including low-voltage cable structures and can be used as either jackets or electrical insulators in cable structures. The silane comonomer copolymerized with ethylene to produce the ethylene-silane copolymer promotes crosslinking of the polymer composition. Crosslinking of the polymer composition is achieved by "curing" the coated conductor under wet conditions. The copolymer silane content of the copolymer can be adjusted according to the desired curing level of the polymer composition. For example, U.S. Patent No. 8,460,770 ("'770 Patent") discloses that ethylene-silane copolymers may contain 0.5% to 5% by weight of silane comonomers.

[0003] The silane content of a copolymer (having a given silane) affects the curing rate, in addition to the final level of crosslinking the polymer composition undergoes. Higher levels of copolymerized silane advantageously accelerate the curing rate of the polymer composition, increase the degree of final curing (crosslinking), and improve mechanical properties such as peak tensile stress, but other mechanical properties such as tensile strain at fracture are impaired with increasing copolymerized silane content. The use of ethylene-silane copolymers with a silane content of 0.4 mol% or more results in lower tensile strain at fracture values ​​than those obtained with comparable ethylene-silane copolymers with a silane content of less than 0.4 mol%. For coated conductors, tensile strain at fracture of 20% or more is measured at a displacement rate of 20 inches per minute according to Underwriter's Laboratory ("UL") 2556, Section 3.5. Tensile properties can also be measured for extruded tapes and compression-molded specimens according to ASTM D638-14 at a displacement rate of 20 inches per minute (using type IV dogbone-shaped test specimens obtained from tapes and compression-molded specimens).

[0004] The inclusion of fillers in polymers is known to have detrimental effects on the tensile strain (also known as tensile elongation) at the break of the polymer composition. Figure 4 in the Journal of Saudi Chemical Society, Volume 19, Issue 1, January 2015, Pages 88-91 clearly illustrates this phenomenon with polyethylene and various fillers (including calcium carbonate). In the case of wires and cables, typical fillers used to prepare polymer compositions include calcium carbonate, carbon black, halogenated flame retardants, and flame retardant synergists (e.g., antimony trioxide), all of which typically reduce the tensile strain at the break of the polymer composition. The inhibitory effect of fillers on the tensile strain at the break of cable insulators and jackets can be controlled by using ethylene-silane copolymers with a low copolymer silane content (typically less than 0.4 mol% silane) to prepare water-crosslinkable polymer compositions, although the benefits of faster curing rates and increased curing levels are lost due to the reduced silane content.

[0005] As described above, using a given silane, the silane content of the ethylene-silane copolymer affects the rate and level of curing the polymer composition undergoes. A commonly used measure of the final level of crosslinking of silane-functionalized polymers is to measure the percentage of thermal creep achieved by the polymer composition after curing in a 90°C water bath for at least 4 hours and up to 72 hours ("final curing"). Prior to or following this, curing can be adjusted for several hours, days, or weeks at 23°C and 50% relative humidity, from 0 hours to 12 weeks. Thermal creep is measured at a specific temperature (either 200°C or 150°C) under a fixed stress (e.g., 0.2 MPa) by the aforementioned test method, based on Underwriter's Laboratory ("UL") 2556 Section 7.9 and the Insulated Cable Engineers Association (ICEA) standard for power cable insulation materials, ICEA-T-28-562-2003. Ideally, the polymer composition should achieve a thermal creep of 175% or less after final curing, as measured according to UL2556 Section 7.9 or ICEA-T-28-562-2003.

[0006] Considering the foregoing, it would be remarkable to discover a filled moisture-crosslinkable polymer composition that, compared to polymer compositions using ethylene-silane copolymers with a silane copolymer content of less than 0.4 mol%, does not suffer tensile strain loss at fracture (and even shows an increase in tensile strain at fracture), and achieves a thermal creep of 175% or less after final curing, as measured according to UL2556 section 7.9 or ICEA-T-28-562-2003. [Overview of the project]

[0007] The inventors of this disclosure have, surprisingly, discovered a filled moisture-crosslinkable polymer composition that, compared to polymer compositions using ethylene-silane copolymers with a silane copolymer content of less than 0.4 mol%, suffers no loss of tensile strain at fracture (and even shows an increase in tensile strain at fracture), and achieves a thermal creep of 175% or less after final curing, as measured according to UL2556 Section 7.9 and ICEA-T-28-562-2003.

[0008] This invention is the result of the discovery that, unlike other filler materials, incorporating a halogen-free flame retardant filler containing a metal hydrate into an ethylene-silane copolymer with a silane copolymer content of 0.40 to 1.00 mol% surprisingly improves the tensile strain at fracture of the polymer composition. This result is surprising, as other types of fillers have an inhibitory effect on the observed mechanical properties. Although not bound by theory, it is thought that the hydroxyl groups of the metal hydrate filler help to compatibilize the ethylene-silane copolymer with the flame retardant filler, thereby increasing the mechanical properties of the polymer composition. Fillers such as silica with hydroxyl groups on its surface, along with fillers having hydroxyl groups, are also within the scope of this invention. Such features are advantageous in providing flame retardancy to the polymer composition while achieving the desired tensile strain at fracture. Furthermore, the remarkable effect of metal hydrate fillers on the mechanical properties of polymer compositions means that ethylene-silane copolymers with a silane copolymer content of 0.40–1.00 mol% can be used, which means that the cables can achieve the target thermal creep value more quickly and to a greater final degree. In addition, a relatively large amount of non-silane functionalized polymer (e.g., linear polyethylene) can be incorporated into the formulation to improve properties (if desired) while maintaining the desired degree of crosslinking.

[0009] The present invention is particularly useful in the manufacture of wires and cables.

[0010] According to the first feature of this disclosure, the polymer composition comprises an ethylene-silane copolymer comprising units derived from ethylene monomers and silane monomers, wherein the ethylene-silane copolymer has a copolymer silane content of 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 metal hydrates, silica, and combinations thereof.

[0011] According to the second feature of this disclosure, the Lewis acid catalyst is selected from the group consisting of dibutyltin dilaurate, dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethylhydroxytin oleate, dioctyltin maleate, di-n-butyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octanoate, lead naphthenate, zinc caprylate, and cobalt naphthenate, as well as combinations thereof.

[0012] According to the third feature of this 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.

[0013] According to the fourth feature of this disclosure, the polymer composition contains 10% to 80% by weight of a halogen-free flame retardant based on the total weight of the polymer composition.

[0014] According to the fifth feature of this disclosure, the polymer composition comprises 10% to 90% by weight of ethylene-silane copolymer based on the total weight of the polymer composition.

[0015] According to the sixth feature of this disclosure, the polymer composition exhibits a filler-to-catalyst weight ratio of 75 to 1000.

[0016] According to the seventh feature of this disclosure, the ethylene-silane copolymer exhibits a crystallinity of 40% to 46% by weight at 23°C, as measured according to a crystallinity test.

[0017] According to an eighth feature of the present disclosure, the ethylene-silane copolymer has a copolymerized silane content of 0.45 mol% to 0.85 mol%.

[0018] According to a ninth feature of the present disclosure, the polymer composition exhibits at least one of a heat creep of 175% or less after final curing when measured according to ICEA-T-28-562-2003 and a tensile strain at break of 20% or more when measured according to ASTM D638-14.

[0019] According to a tenth feature of the present disclosure, the coated conductor includes a conductor and a polymer composition.

[0020] According to an eleventh feature of the present disclosure, the polymer composition of the coated conductor exhibits at least one of a heat creep of 175% or less after final curing when measured according to ICEA-T-28-562-2003 and a tensile strain at break of 20% or more when measured according to UL2556, Section 3.5.

Mode for Carrying Out the Invention

[0021] As used herein, the term "and / or" means that in a listing of two or more items, any one of the listed items can be used by itself or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0022] Unless otherwise specified, all ranges include their endpoints.

[0023] Unless otherwise indicated with a hyphenated two-digit test method number, the test method refers to the most recent test method as of the priority date of this document. References to test methods include both references to the testing association and the test method number. Test method organizations are referred to by one of the following abbreviations: ASTM refers to ASTM International (formerly the American Society for Testing and Materials), EN refers to European Norm, DIN refers to the German Institute for Standardization (Deutsches Institut fuer Normung), and ISO refers to the International Organization for Standardization.

[0024] The term "polymer" refers to polymeric materials prepared by polymerizing monomers, whether of the same or different types. The general term "polymer" encompasses homopolymers, interpolymers, and copolymers.

[0025] "Ethylene polymer" refers to a polymer that contains units derived from ethylene. Typically, an ethylene polymer contains at least 50% by weight of units derived from ethylene.

[0026] As used herein, the term weight percentage ("weight %) refers to the weight percentage of an ingredient relative to the total weight of a polymer composition, unless otherwise specified. As used herein, “CAS number” is a chemical service registration number assigned by the Chemical Abstracts Service.

[0027] As used herein, the term "ambient conditions" refers to an air atmosphere having a temperature of 5°C to 50°C and a relative humidity of 5% to 100%.

[0028] Polymer composition This disclosure relates to polymer compositions. The polymer compositions include ethylene-silane copolymers containing units derived from ethylene monomers and silane monomers, Lewis acid catalysts, and halogen-free flame retardants containing metal hydrates.

[0029] Ethylene-silane copolymer The polymer composition contains an ethylene-silane copolymer (a form of silane-functionalized ethylene polymer). The ethylene-silane copolymer contains units derived from ethylene monomers and silane monomers. The term "copolymer" refers to a high-molecular-weight compound prepared by reacting (i.e., polymerizing) two or more monomers of different types. The ethylene-silane copolymer is prepared by copolymerization of ethylene and silane monomers.

[0030] The polymer composition may contain 10% or more by weight, or 15% or more by weight, or 20% or more by weight, or 25% or more by weight, or 30% or more by weight, or 35% or more by weight, or 40% or more by weight, or 45% or more by weight, or 50% or more by weight, or 55% or more by weight, or 60% or more by weight, or 65% or more by weight, or 70% or more by weight, or 75% or more by weight, or 80% or more by weight, or 85% or more by weight, but at the same time may contain 90% or less by weight, or 85% or less by weight, or 80% or less by weight, or 75% or less by weight, or 70% or less by weight, or 65% or less by weight, or 60% or less by weight, or 55% or less by weight, or 50% or less by weight, or 45% or less by weight, or 40% or less by weight, or 35% or less by weight, or 30% or less by weight, or 25% or less by weight, or 20% or less by weight, or 15% or less by weight of ethylene-silane copolymer.

[0031] Ethylene-silane copolymers, when measured according to ASTM D792, have a density of 0.910 grams / cubic centimeter ("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 to 0.930 g / cc or more, or 0.935 g / cc or more, while simultaneously having a density of 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.

[0032] Ethylene-silane copolymers, when measured according to ASTM D1238 under conditions of 190°C / 2.16 kg weight, have a melt index, which is reported as grams of elution per 10 minutes (g / 10 min). The melt index of ethylene-silane copolymers is 0.5 g / 10 min or higher, or 1.0 g / 10 min or higher, or 1.5 g / 10 min or higher, or 2.0 g / 10 min or higher, or 2.5 g / 10 min or higher, or 3.0 g / 10 min or higher, or 3.5 g / 10 min or higher, or 4.0 g / 10 min or higher, or 4.5 g / 10 min or higher, simultaneously, or 30.0 g / 10 min or lower, or 25.0 g / 10 min. It may be less than or equal to 20.0g / 10 min or less, or 15.0g / 10 min or less, or 10.0g / 10 min or less, or 5.0g / 10 min or less, or 4.5g / 10 min or less, or 4.0g / 10 min or less, or 3.5g / 10 min or less, or 3.0g / 10 min or less, or 2.5g / 10 min or less, or 2.0g / 10 min or less, or 1.5g / 10 min or less, or 1.0g / 10 min or less.

[0033] Ethylene-silane copolymers, when measured using Fourier transform infrared (FTIR) spectroscopy, contain 90% or more by weight, or 91% or more by weight, or 92% or more by weight, or 93% or more by weight, or 94% or more by weight, or 95% or more by weight, or 96% or more by weight, or 96.5% or more by weight, or 97% or more by weight, or 97.5% or more by weight, or 98% or more by weight, or 99% or more by weight, and simultaneously contain 99.5% or less by weight, or 99% or less by weight, or 98% or less by weight, or 97% or less by weight, or 96% or less by weight, or 95% or less by weight, or 94% or less by weight, or 93% or less by weight, or 92% or less by weight, or 91% or less by weight of alpha-olefins (α-olefins). α-olefins are C2, or C3-C4, or C6, or C8, or C 10 , or C 12 , or C 16 , or C 18 , or C 20 α-olefins may include, for example, ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-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 (i.e., the term “ethylene-silane copolymer” as used herein also includes ethylene-silane-unsaturated ester terpolymers). The unsaturated ester may be alkyl acrylate, alkyl methacrylate, or vinyl carboxylate. The alkyl group may have 1 to 8 carbon atoms or 1 to 4 carbon atoms. The carboxylate group may have 2 to 8 carbon atoms or 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate.

[0034] Ethylene-silane copolymers may contain 0.40 mol% to 1.00 mol% copolymerized silane. For example, based on the total moles of the ethylene-silane copolymer, the ethylene-silane copolymer may contain 0.40 mol% or more, or 0.42 mol% or more, or 0.44 mol% or more, or 0.45 mol% or more, or 0.46 mol% or more, or 0.48 mol% or more, or 0.50 mol% or more, or 0.55 mol% or more, or 0.60 mol% or more, or 0.65 mol% or more, or 0.70 mol% or more, or 0.75 mol% or more, or 0.80 mol% or more, or 0.85 mol% or more, or 0.90 mol% or more. , or 0.95 mol% or more, and simultaneously, it may contain copolymerized silane in amounts of 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. The copolymerized silane content present in the ethylene-silane copolymer is determined by a silane test, as will be explained in more detail below.

[0035] The silane comonomer used to produce ethylene-silane copolymers may be a hydrolyzable silane monomer. A "hydrolyzable silane monomer" is a silane-containing monomer that effectively copolymerizes with α-olefins (e.g., ethylene) to form α-olefin / silane copolymers (such as ethylene-silane copolymers). A hydrolyzable silane monomer has the following structure (I):

[0036] [ka] In the formula, R 1 x 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 2is independently a hydrolyzable organic group, such as an alkoxy group having 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 1 to 12 carbon atoms (e.g., formyloxy, acetyloxy, propanoyloxy), an amino group or a substituted amino group (e.g., alkylamino, arylamino), or a lower alkyl group having 1 to 6 carbon atoms, provided that no more than one of the three R 2 groups is alkyl. The hydrolyzable silane monomer may copolymerize with an α-olefin (such as ethylene) in a reactor such as a high-pressure process to form an α-olefin-silane reactor copolymer. In an example where the α-olefin is ethylene, such a copolymer is referred to herein as an ethylene-silane copolymer.

[0037] The hydrolyzable silane monomer may include a silane monomer containing an ethylenically unsaturated hydrocarbyl group such as vinyl, allyl, isopropenyl, butenyl, cyclohexenyl, or gamma (meth)acryloxyallyl group, and a hydrolyzable group such as, for example, a hydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group. The hydrolyzable group may include methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, and an alkyl or arylamino group. In a specific example, the hydrolyzable silane monomer is an unsaturated alkoxysilane, which can be grafted onto a polyolefin or copolymerized with an α-olefin (such as ethylene) in a reactor. Examples of the hydrolyzable silane monomer include vinyltrimethoxysilane ("VTMS"), vinyltriethoxysilane ("VTES"), vinyltriacetoxysilane, and gamma-(meth)acryloxypropyltrimethoxysilane. With respect to structure (I), for VTMS, x = 0, R 1 = hydrogen, and R 2 = methoxy, for VTES, x = 0, R 1 = hydrogen, and R 2= For ethoxy and vinyltriacetoxysilane, x=0, R 1 =H and R 2 = Acetoxy

[0038] Ethylene-silane copolymers may have a crystallinity of 40% to 46% by weight at 23°C, as measured according to the crystallinity test provided below. For example, the crystallinity of ethylene-silane copolymer at 23°C, when measured according to a crystallinity test, may be 40.0% by weight or more, or 40.5% by weight or more, or 41.0% by weight or more, or 41.5% by weight or more, or 42.0% by weight or more, or 42.5% by weight or more, or 43.0% by weight or more, or 43.5% by weight or more, or 44.0% by weight or more, or 44.5% by weight or more, or 45.0% by weight or more, or 45.5% by weight or more, and at the same time may be 46.0% by weight or less, or 45.5% by weight or less, or 45.0% by weight or less, or 44.5% by weight or less, or 44.0% by weight or less, or 43.5% by weight or less, or 43.0% by weight or less, or 42.5% by weight or less, or 42.0% by weight or less, or 41.5% by weight or less, or 41.0% by weight or less, or 40.5% by weight or less.

[0039] Non-silane-functionalized ethylene polymers The polymer composition may contain one or more ethylene polymers that are not silane-functionalized. The ethylene polymers that are not silane-functionalized may contain ethylene and one or more C3-C3 polymers such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. 20It may contain α-olefin comonomers. In one embodiment, the ethylene polymer that is not silane-functionalized is a homopolymer. In one embodiment, the ethylene polymer that is not silane-functionalized is an ethylene / α-olefin copolymer. In one embodiment, the ethylene polymer that is not silane-functionalized is an ethylene / unsaturated ester copolymer. The unsaturated ester may be an alkyl acrylate, an alkyl methacrylate, or a vinyl carboxylate. The alkyl group may have 1 to 8 carbon atoms or 1 to 4 carbon atoms. The carboxylate group may have 2 to 8 carbon atoms or 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate. Non-silane-functionalized ethylene polymers can have unimodal and multimodal molecular weight distributions and can be used alone or in combination with one or more other types of ethylene polymers (e.g., blends of two or more ethylene polymers that differ from one another in monomer composition and content, catalytic method of preparation, molecular weight, molecular weight distribution, density, etc.). When blends of ethylene polymers are used, the polymers can be blended by any in-reactor or post-reactor process.

[0040] When measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy, ethylene polymers that are not silane-functionalized are found to have a content of 50% or more by weight, 60% or more by weight, 70% or more by weight, 80% or more by weight, 85% or more by weight, 90% or more by weight, or 91% or more by weight, or 92% or more by weight, or 93% or more by weight, or 94% or more by weight, or 95% or more by weight, or 96% or more by weight, or 97% or more by weight, or 97.5% or more by weight, or It may contain ethylene in amounts of 98% or more by weight, or 99% or more by weight, and at the same time, 100% or less by weight, or 99.5% or less by weight, or 99% or less by weight, or 98% or less by weight, or 97% or less by weight, or 96% or less by weight, or 95% or less by weight, or 94% or less by weight, or 93% or less by weight, or 92% or less by weight, or 91% or less by weight, or 90% or less by weight, or 85% or less by weight, or 80% or less by weight, or 70% or less by weight, or 60% or less by weight. Other units of ethylene polymers include C3, C4, C6, C8, or C3, such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. 10 , or C 12 , or C 16 , or C 18 , or C 20 α-olefins can be cited as examples.

[0041] The polymer composition may contain 0% to 60% by weight of ethylene polymer, which is not silane-functionalized. For example, the polymer composition may contain 0% or more by weight, or 5% or more by weight, or 10% or more by weight, or 15% or more by weight, or 20% or more by weight, or 25% or more by weight, or 30% or more by weight, or 35% or more by weight, or 40% or more by weight, or 45% or more by weight, or 50% or more by weight, or 55% or more by weight, and at the same time contain 60% or less by weight, or 55% or less by weight, or 50% or less by weight, or 45% or less by weight, or 40% or less by weight, or 35% or less by weight, or 30% or less by weight, or 25% or less by weight, or 20% or less by weight, or 15% or less by weight, or 10% or less by weight, or 5% or less by weight of silane-functionalized ethylene polymer.

[0042] Non-silane-functionalized ethylene polymers include, but are not limited to, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ethylene vinyl acetate (EVA) copolymer, ethylene ethyl acrylate (EEA) copolymer, and various elastomers (such as ENGAGE® and INFUSE® resins available from Dow Chemical Company).

[0043] Halogen-free flame retardant The polymer composition contains a halogen-free flame retardant. The halogen-free flame retardant in the polymer composition may inhibit, suppress, or delay the generation of flames. As used herein, "halogen-free" and similar terms mean that the flame retardant filler has no halogen content, or substantially no halogen content, i.e., contains less than 10,000 mg of halogen per kg of flame retardant filler as measured by ion chromatography (IC) and similar analytical methods. Halogen content below this amount is considered insignificant to the effectiveness of the flame retardant filler, for example, in coated conductors. Examples of halogen-free flame retardants suitable for use in polymer compositions include, but are not limited to, metal hydrates (e.g., aluminum hydroxide, magnesium hydroxide), metal carbonates, red phosphorus, silica, alumina, brucite (a mineral form of magnesium hydroxide), titanium dioxide, carbon nanotubes, talc, clay, organically modified clay, calcium carbonate, zinc borate, antimony trioxide, wollastonite, mica, ammonium octamolybdate, frit, hollow glass microspheres, expandable compounds, expandable graphite, and combinations thereof. In one embodiment, the halogen-free flame retardant is selected from fillers having hydroxide groups (such as metal hydrates) and / or hydroxyl groups (such as silica). In one 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 one embodiment, the halogen-free flame retardant is selected from the group consisting of metal hydrates, silica, and combinations thereof. Halogen-free flame retardants may be surface-treated (coated) with a metal salt of a saturated or unsaturated carboxylic acid or acid containing 8 to 24 carbon atoms or 12 to 18 carbon atoms. Exemplary surface treatments are described in U.S. Patents 4,255,303, 5,034,442, 7,514,489, U.S. Patent Application Publication 2008 / 0251273, and International Publication 2013 / 116283. Alternatively, the acid or salt may be added to the composition in similar amounts simply, rather than using a surface treatment procedure.Other surface treatments known in the art, including silanes, titanates, phosphates, and zirconates, may also be used.

[0044] Examples of commercially available halogen-free flame retardants suitable for use in polymer compositions include, but are not limited to, APYRAL® 40CD aluminum hydroxide from Nabaltec AG, MAGNIFIN® H5 magnesium hydroxide from Magnifin Magnesiaprodukte GmbH & Co KG, Microcarb 95T ultrafine and treated calcium carbonate from Reverte, and combinations thereof.

[0045] The polymer composition contains 10% or more by weight, or 12% or more by weight, or 14% or more by weight, or 16% or more by weight, or 18% or more by weight, or 20% or more by weight, or 22% or more by weight, or 24% or more by weight, or 26% or more by weight, or 28% or more by weight, or 30% or more by weight, or 32% or more by weight, or 34% or more by weight, or 36% or more by weight, or 38% or more by weight, or 40% or more by weight, or 42% or more by weight, based on the total weight of the polymer composition. It is % by weight or more, or 44% by weight or more, or 46% by weight or more, or 48% by weight or more, or 50% by weight or more, or 52% by weight or more, or 54% by weight or more, or 56% by weight or more, or 58% by weight or more, or 60% by weight or more, or 62% by weight or more, or 64% by weight or more, or 66% by weight or more, or 68% by weight or more, or 70% by weight or more, or 72% by weight or more, or 74% by weight or more, or 76% by weight or more, or 78% by weight or more. However, at the same time, 80% by weight or less, or 78% by weight or less, or 76% by weight or less, or 74% by weight or less, or 72% by weight or less, or 70% by weight or less, or 68% by weight or less, or 66% by weight or less, or 64% by weight or less, or 62% by weight or less, or 60% by weight or less, or 58% by weight or less, or 56% by weight or less, or 54% by weight or less, or 52% by weight or less, or 50% by weight or less, or 48% by weight or less, or 46% by weight or less, or It may contain halogen-free flame retardants in concentrations of 44% by weight or less, or 42% by weight or less, or 40% by weight or less, or 38% by weight or less, or 36% by weight or less, or 34% by weight or less, or 32% by weight or less, or 30% by weight or less, or 28% by weight or less, or 26% by weight or less, or 24% by weight or less, or 22% by weight or less, or 20% by weight or less, or 18% by weight or less, or 16% by weight or less, or 14% by weight or less, or 12% by weight or less.

[0046] The polymer composition may exhibit a filler-to-catalyst weight ratio of 75 to 1000. For example, the filler-to-catalyst weight ratio is 75 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more, or 100 or more, or 125 or more, or 150 or more, or 175 or more. In addition, it may be 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 weight percentage of all combined fillers present in the polymer composition by the total weight percentage of the Lewis acid catalyst in the polymer composition.

[0047] additives The polymer composition may contain one or more additives. Non-limiting examples of suitable additives include antioxidants, dehydrators, 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 (including polypropylene homopolymers, random copolymer polypropylene, and impact copolymer polypropylene homopolymers and copolymers), and combinations thereof. Non-limiting examples of suitable dehydrators include alkylalkoxysilanes and combinations thereof. Non-limiting examples of alkylalkoxysilanes include octyltriethoxysilane, octyltrimethoxysilane, and hexadecyltrimethoxysilane. In one embodiment, the dehydrator is octyltriethoxysilane. The moisture-removing agent is present in an amount of 0% by weight, or 0.01% by weight or more, or 0.03% by weight or more, or 0.05% by weight or more, or 0.1% by weight or more, or 0.3% by weight or more, or 0.5% to 1.0% by weight, 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, based on the total weight of the polymer composition. In further embodiments, the moisture-removing agent is present in an amount of 0% by weight, or 0.01% to 5.0% by weight, or 0.05% to 3.0% by weight, or 0.1% to 2.0% by weight, or 0.3% to 1.0% by weight, based on the total weight of the polymer composition.

[0048] The polymer composition may contain antioxidants. Non-limiting examples of suitable antioxidants include phenolic antioxidants, thio-based antioxidants, phosphoric acid-based antioxidants, and hydrazine-based metal deactivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenols, phenols having substituents with primary or secondary carbonyl groups, and polyfunctional 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, pentaerythrityltetrakis-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-tert-butylphenol, Examples include 6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine, di-n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, and sorbitol hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]. The polymer composition may include pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), which is commercially available from BASF as Irganox® 1010. A non-limiting example of a suitable methyl-substituted phenol is isobutylidenebis(4,6-dimethylphenol). A non-limiting example of a suitable hydrazine-based metal deactivator is oxalylbis(benzylidenehydrazide). The polymer composition may contain 0% by weight, or 0.001% by weight, or 0.01% by weight, or 0.02% by weight, or 0.05% by weight, or 0.1% by weight, or 0.2% by weight, or 0.3% by weight, or 0.4% to 0.5% by weight, or 0.6% by weight, or 0.7% by weight, or 0.8% by weight, or 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight of an antioxidant, based on the total weight of the polymer composition.

[0049] The polymer composition may contain a silanol condensation catalyst such as a Lewis acid. The "silanol condensation catalyst" promotes the crosslinking of silane-functionalized polyolefins through hydrolysis and condensation reactions. A Lewis acid is a chemical species that can accept an electron pair from a Lewis base. A Lewis base is a chemical species that can donate an electron pair to a Lewis acid. Non-limiting examples of suitable Lewis acids include tin carboxylates, e.g., dibutyltin dilaurate (DBTDL), dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethylhydroxytin oleate, dioctyltin maleate, di-n-butyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octanoate, and various other organometallic compounds, e.g., lead naphthenate, zinc caprylate, and cobalt naphthenate, as well as combinations thereof. The polymer composition contains 0% by weight, or 0.001% by weight, or 0.005% by weight, or 0.01% by weight, or 0.02% by weight, or 0.03% to 0.05% by weight, or 0.1% by weight, or 0.2% by weight, or 0.5% by weight, or 1.0% by weight, or 3.0% by weight, or 5.0% by weight, or 10% by weight of the silanol condensation catalyst. The silanol condensation catalyst is typically added to the article manufacturing extruder (e.g., during cable manufacturing) so that the silanol condensation catalyst is present during the final melt extrusion process. Thus, the silane-functionalized polyolefin may undergo some crosslinking before it leaves the extruder, and crosslinking is completed after it leaves the extruder, typically when it is exposed to moisture (e.g., a sauna, hot bath, or cooling bath) and / or moisture present in the environment in which the silane-functionalized polyolefin is stored, transported, or used.

[0050] The Lewis acid silanol condensation catalyst may be included in the catalyst masterbatch blend, or the catalyst masterbatch may be included in the composition. Non-limiting examples of suitable silanol condensation catalyst masterbatches include those sold by The Dow Chemical Company under the trade name SI-LINK®, such as SI-LINK® DFDB-5480NT and SI-LINK® DFDA-5481NT. In one embodiment, the composition contains 0% by weight, or 0.001% by weight, or 0.01% by weight, or 0.5% by weight, or 1.0% by weight, or 2.0% by weight, or 3.0% by weight, or 4.0% to 5.0% by weight, or 6.0% by weight, or 7.0% by weight, or 8.0% by weight, or 9.0% by weight, or 10.0% by weight, or 15.0% by weight, or 20.0% by weight of the silanol condensation catalyst masterbatch, based on the total weight of the composition.

[0051] This polymer composition may contain ultraviolet (UV) absorbers or stabilizers. 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-triazine-2,4,6-triamine, N,N-1,2-ethanediylbis-N-3-4,6-bisbutyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino-1,3,5-triazine-2-ylaminopropyl-N,N-dibutyl-N,N-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-1,5,8,12-tetrakis[4,6-bis(n-butyl-n-1,2,2,6,6-pentamethyl-4-piperidylamino)-1,3,5-triazine-2-yl]-1,5,8,12-tetraazadodecane (which is commercially available from SABO SpA (Levate, Italy) as SABO® STAB UV-119). In one embodiment, the composition contains 0% by weight, or 0.001% by weight, or 0.002% by weight, or 0.005% by weight, or 0.006% to 0.007% by weight, or 0.008% by weight, or 0.009% by weight, or 0.01% by weight, or 0.2% by weight, or 0.3% by weight, or 0.4% by weight, or 0.5% by weight, or 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight of a UV absorber or stabilizer, based on the total weight of the composition.

[0052] The composition may contain processing aids. Non-limiting examples of suitable processing aids include oils, organic acids (e.g., stearic acid), and metal salts of organic acids (e.g., zinc stearate). In one embodiment, the composition contains 0% by weight, or 0.01% by weight, or 0.02% by weight, or 0.05% by weight, or 0.07% by weight, or 0.1% by weight, or 0.2% by weight, or 0.3% by weight, or 0.4% to 0.5% by weight, or 0.6% by weight, or 0.7% by weight, or 0.8% by weight, or 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight, or 5.0% by weight, or 10.0% by weight, or 20.0% by weight, or 20.0% by weight of processing aids, based on the total weight of the composition.

[0053] The composition may contain additives in amounts of 0% or more by weight, or 0.001% or more by weight, or 0.002% or more by weight, or 0.005% or more by weight, or 0.006% or more by weight, or 0.008% or more by weight, or 0.009% or more by weight, or 0.01% or more by weight, or 0.2% or more by weight, or 0.3% or more by weight, or 0.4% or more by weight, or 0.5% or more by weight, or 1.0% or more by weight, or 2.0% or more by weight, or 3.0% or more by weight, or 4.0% or more by weight, or 5.0% or more by weight, or 10.0% or more by weight, or 15.0% or more by weight, or 20.0% or more by weight, or 30% or more by weight, or 40% or more by weight, or 50% or more by weight, based on the total weight of the polymer composition.

[0054] Masterbatch One or more of ethylene-silane copolymers, halogen-free flame retardants, and additives may be combined as a premixed masterbatch. Such masterbatches are typically formed by dispersing the flame retardant and additives in an inert plastic resin. Masterbatches are conveniently formed by melt compounding.

[0055] One or more of the components or masterbatches may be dried before compounding or extrusion, or a mixture of components or masterbatches may be dried after compounding or extrusion to reduce or eliminate potential scorching (i.e., premature crosslinking during compounding or extrusion) that may be caused by moisture present in or associated with the components, such as fillers. For a long shelf life, the composition may be prepared in the absence of a silanol condensation catalyst, which may be added as a final step in the production of cable structures (coated conductors) by an extrusion process. Alternatively, the catalyst may be combined with one or more other components in the form of a masterbatch.

[0056] Insulated conductor This disclosure also provides a coated conductor. The coated conductor comprises a conductor and a coating on the conductor, the coating comprising the polymer composition. The polymer composition is disposed at least partially around the conductor to produce the coated conductor. The conductor may include a conductive metal and / or an optical waveguide.

[0057] The process for manufacturing a coated conductor involves mixing a polymer composition, heating it in an extruder to at least the melting temperature of the ethylene-silane polymer to form a polymer molten blend, and then coating a conductor with the polymer molten blend. The term "on" includes direct or indirect contact between the polymer molten blend and the conductor. The polymer molten blend is in an extrudeable state.

[0058] The polymer 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 cover the conductor entirely or partially, or otherwise surround or enclose it. The coating may be the sole component surrounding the conductor as an insulator or jacket. Alternatively, the coating may be one layer of a multilayer jacket or sheath enclosing the conductor. The coating may be in direct contact with the conductor. The coating may be in direct contact with the insulating layer surrounding the conductor.

[0059] The resulting coated conductor is cured under humid conditions for a sufficient amount of time to allow the coating to reach the desired degree of crosslinking. The temperature during curing is generally above 0°C. In one embodiment, curing is carried out in a 90°C water bath for at least 4 hours. In one embodiment, curing is carried out for up to 200 days under ambient conditions including an air atmosphere, ambient temperature (e.g., 5°C to 50°C), and ambient relative humidity (e.g., 5 to 100% relative humidity (%RH)).

[0060] In one embodiment, the polymer composition is coated onto a 10 U.S. wire gauge ("AWG") conductor (diameter: 2.59 mm) to a thickness of 1.524 mm.

[0061] The polymer composition of a coated conductor may exhibit a tensile strain at break of 20% or more when measured according to UL2556, Section 3.5. For example, the polymer composition of a coated conductor may exhibit a tensile strain at break of 20% or more, or 25% or more, or 30% or more, or 40% or more, or 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more, or 100% or more, or 150% or more, or 200% or more, or 250% or more, or 300% or more, or 400% or more, or 500% or more, while simultaneously exhibiting a tensile strain at break of 600% or less, or 500% 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. The polymer composition of the coated conductor may exhibit a thermal creep of 175% or less after final curing, as measured according to UL2556 Section 7.9 and ICEA-T-28-562-2003. For example, the polymer composition of the coated conductor may exhibit a thermal 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 final curing, as measured according to UL2556 Section 7.9 and ICEA-T-28-562-2003.

[0062] The tensile strain at fracture of polymer compositions prepared in the form of extruded tapes and compression-molded samples may be 20% or more, as measured according to ASTM D638-14. For example, an extruded tape or compression-molded sample made from a polymer composition may exhibit a tensile strain at break of 20% or more, or 25% or more, or 30% or more, or 40% or more, or 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more, or 100% or more, or 150% or more, or 200% or more, or 250% or more, or 300% or more, or 400% or more, or 500% or more, while simultaneously exhibiting a tensile strain at break of 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.

[0063] The thermal creep of polymer compositions prepared in the form of extruded tapes and compression-molded specimens may be 175% or less after final curing, as measured according to UL2556 Section 7.9 and ICEA-T-28-562-2003. For example, extruded tapes and compression-molded specimens prepared from polymer compositions may exhibit thermal 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 final curing, as measured according to UL2556 Section 7.9 and ICEA-T-28-562-2003. [Examples]

[0064] Test method Density: Density is measured according to ASTM D792, Method B. The results are recorded in grams per cubic centimeter (g) (g / cc).

[0065] Melt Index: The melt index (MI) is measured according to ASTM D1238, under conditions of 190°C / 2.16 kg weight, and reported as grams of elution per 10 minutes (g / 10 min).

[0066] Silane Test: X-ray fluorescence spectroscopy ("XRF") is used to determine the weight percentage (Wt%) of silicon atoms (Si) in the ethylene-silane copolymer test sample, and then the unit weight percentage of the silane comonomer is calculated. Using a Buehler Simpli Met300 automatic mounting press preheated to 115.6°C (240°F) for 3 minutes, the powdered test sample is pressed for 1 minute at 8.3 megapascals (MPa, 1,200 lbs / square inch (psi)) to form a plaque approximately 6 mm thick, and the plaque is cooled to 25°C. The Si atom content of the plaque is analyzed by wavelength-dispersive XRF using a wavelength-dispersive X-ray fluorescence spectrometer from PANalytical Axios. The Si atom content is determined by comparing the line intensity of the XRF spectrum with a calibration curve of Si atom content established using polymer standards of known Si atom concentrations, which are individually measured using activation analysis (NAA) or inductively coupled plasma (ICP) methods. The weight percentage of hydrolyzable silyl group comonomers (i.e., the weight percentage of hydrolyzable silyl groups) in ethylene-silane copolymers is calculated using the weight percentage of Si atoms measured by XRF and the molecular weight of at least one silane comonomer derived from the hydrolyzable silyl group. For hydrolyzable silyl groups derived from vinyltrimethoxysilane (VTMS), the molecular weight of VTMS (148.23 g / mol) is used. To calculate the hydrolyzable silyl group content of ethylene-silane copolymers (weight percentage of hydrolyzable silyl group comonomer units), the weight percentage of Si atoms ("C") obtained by XRF and the following formula: p=C * Using (m / 28.086)(1 / 10000ppmw), in the formula, *∫ represents multiplication, ∫ / represents division, p is the weight % of hydrolyzable silyl groups in the ethylene-silane copolymer, C is the weight of Si atoms in parts per million (ppmw) (XFR), m is the molecular weight in g / mol of the silane comonomer derived by the hydrolyzable silyl groups, 28.086 is the atomic weight of the silicon atom, and 10000 ppmw is 1 part per million in 1.00 wt%. For example, if XRF indicates 379 ppmw of Si atoms in the ethylene-silane copolymer and the comonomer used to produce the ethylene-silane copolymer is VTMS with a molecular weight of 148.23 g / mol, then the weight % comonomer content is 0.20 wt%. To calculate the molar % of hydrolyzable silyl group comonomer units in the ethylene-silane copolymer of the silane comonomer used, use the calculated weight % of hydrolyzable silyl group comonomer units in the ethylene-silane copolymer and the following formula: G=100 * (p / m) / [(p / m)+(100.00wt%-p) / 28.05g / mol], in the formula, *The symbol (x) represents multiplication, where 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, and m is the molecular weight in g / mol of the silane comonomer from which the hydrolyzable silyl groups are derived, with 28.05 g / mol being the molecular weight of the monomer ethylene (H2C=CH2). For example, if the comonomer content is 2.0 wt% and the comonomer is VTMS, then p=2.0 wt%, m=148.23 g / mol, and G=0.38 mol%. If the comonomer content is 5.0 wt% and the comonomer is VTMS, then p=5.0 wt%, m=148.23 g / mol, and G=0.99 mol%. When preparing ethylene-silane copolymers using two or more silane comonomers with different molecular weights, the molecular weight used to calculate the total molar percentage of all hydrolyzable silyl groups in the ethylene-silane copolymer is the weighted average molecular weight of the comonomers. The weighting can be determined by the proportion of comonomers supplied to the reactor. Alternatively, it can be determined by NMR spectroscopy of the ethylene-silane copolymer to determine the relative amounts of different comonomer units in the 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.

[0067] Crystallinity Test: The melting peak and percentage (%) and weight percentage (W%) crystallinity of the ethylene polymer at 23°C are determined using a differential scanning calorimeter (DSC) instrument, DSCQ1000 (TA Instruments). (A) Baseline Calibration of DSC Instrument. Use the software calibration wizard. Obtain the baseline by heating the cell from -80°C to 280°C with no sample in the aluminum DSC pan. Then, use a sapphire standard according to the instructions of the calibration wizard. Analyze 1-2 milligrams (mg) of fresh indium sample by heating the standard sample to 180°C, cooling to 120°C at a cooling rate of 10°C / min, then holding the standard sample isothermally at 120°C for 1 minute, and then heating the standard sample from 120°C to 180°C at a heating rate of 10°C / min. (B) The indium standard sample is determined to have a heat of fusion of 28.71 ± 0.50 joules (J / g) per gram and a melting onset of 156.6° ± 0.5°C. DSC measurements are then performed on the test sample using a baseline-calibrated DSC instrument. The semicrystalline ethylene polymer test sample is pressed into a thin film at a temperature of 160°C. 5-8 mg of the test sample film is weighed into an aluminum DSC pan. The pan is sealed by pressing the lid onto it to ensure a sealed atmosphere. The covered pan is placed in a DSC cell, the cell is equilibrated at 30°C, then heated to 190°C at a rate of approximately 100°C / min, the sample is held at 190°C for 3 minutes, the sample is cooled to -60°C at a rate of 10°C / min to obtain the cooling curve heat of fusion (Hf), and the sample is held isothermally at -60°C for 3 minutes. Next, the sample is heated again to 190°C at a rate of 10°C / min to obtain a second heating curve for the heat of fusion (ΔHf). Using the second heating curve, -20°C (ethylene homopolymer, copolymer of ethylene and hydrolyzable silane monomer, and 0.90 g / cm³) 3 (For ethylene alpha-olefin copolymers of the above density), or -40°C (Ethylene and unsaturated ester copolymer, and 0.90 g / cm³) 3The "total" heat of fusion (J / g) is calculated by integrating from the end of melting (for ethylene alpha-olefin copolymers with densities less than 1 / 2) to the end of melting. The "room temperature" heat of fusion (J / g) from 23°C (room temperature) to the end of melting is calculated by using a second heating curve and descending vertically at 23°C. The "total crystallinity" (calculated from the "total" heat of fusion) and the "crystallinity at room temperature" (calculated from the heat of fusion at 23°C) are measured and reported. Crystallinity is measured and reported as the percentage (%) or weight percentage (W%) crystallinity of the polymer from the second heating curve heat of fusion (ΔHf) of the test sample and its normalization relative to the heat of fusion of 100% crystalline polyethylene, where % crystallinity or W% crystallinity = (ΔHf * 100%) / 292J / g, where ΔHf is defined above. * The symbol ∫ represents mathematical multiplication, the symbol ∫ represents mathematical division, and 292 J / g is the literature value for the heat of fusion (ΔHf) of 100% crystalline polyethylene.

[0068] Thermal creep (also known as thermal creep elongation of polymer compositions) is measured after final curing and is measured at a specific temperature (200°C or 150°C) under a fixed stress (0.2 MPa) in accordance with UL2556 Section 7.9 and ICEA-T-28-562-2003.

[0069] Tensile peak stress and tensile strain at fracture: For coated conductors, the tensile peak stress (also known as tensile strength) and tensile strain at fracture (also known as tensile elongation) of the polymer composition are measured according to Underwriter's Laboratory ("UL") 2556, Section 3.5, at a displacement rate of 20 inches / min, 23°C, and 50% relative humidity. The average of four or five measurements is taken. Each specimen is prepared by removing the polymer composition coating (insulator) from a fully cured coated conductor without damaging it. Tensile properties can also be measured according to ASTM D638-14, at a displacement rate of 20 inches / min (using Type IV dogbone-shaped specimens obtained from tape and compression-molded samples), for extruded tapes and compression-molded samples made from the polymer composition.

[0070] Char Length and Filler-Weighted Char Length (FWCL) Value: The FWCL value of a coated conductor is first determined by performing International Electrotechnical Commission Test 60332-1-2:2004, which specifies a procedure for testing the resistance of a single vertical coated conductor to vertical flame propagation. Test 60332-1-2:2004 measures the length of the char formed on the coated conductor during the test ("char length"). The FWCL value is calculated by multiplying the char length in centimeters by the weight percentage of the flame-retardant filler present in the polymer composition used to form the coated conductor and dividing by 100.

[0071] material The materials used in the examples ("IE") and comparative examples ("CE") of the present invention are provided below.

[0072] ESC1 is an ethylene-silane copolymer ("ESC") characterized by a melt index (I2) of 2.0 g / 10 min, a density of 0.922 g / cc, a copolymer VTMS content of 0.65 mol%, and a crystallinity of 44.58 wt% at 23°C. ESC1 is available from The Dow Chemical Company (Midland, Michigan).

[0073] ESC2 is ESC1 with a water-removing agent added. It has the same melt index (I2), density, copolymer VTMS content, and crystallinity at 23°C as ESC1 (because the water-removing agent does not affect these properties). ESC2 is available from The Dow Chemical Company (Midland, Michigan).

[0074] ESC3 is characterized by a melt index (I2) of 1.5 g / 10 min, a density of 0.921 g / cc, a copolymer VTMS content of 0.31 mol%, and a crystallinity of 46.83 wt% at 23°C. ESC3 is available from The Dow Chemical Company (Midland, Michigan).

[0075] ESC4, ESC5, ESC6, and ESC7 are prepared as follows: A mixture of ethylene, VTMS, and propylene used as a chain transfer agent is placed in a stirred autoclave reactor with a capacity of 545 ml (mL). An organic peroxide (75 wt% aliphatic hydrocarbon solution of tert-butyl peroxyacetate) is added at a load of 0.2 wt% based on the total weight of ethylene, VTMS, propylene, and organic peroxide. The reactor is pressurized to 193 MPa and heated to 250°C. Ethylene, VTMS, and propylene are continuously supplied to the reactor, and the prepared ESCs are removed from the reactor. The ESCs are converted into pellet form by melt extrusion. ESC4, ESC5, ESC6, and ESC7 are prepared under the effective process conditions shown in Table 1 and characterized by the properties shown in Table 2.

[0076] [Table 1]

[0077] [Table 2]

[0078] ESC8 is ESC3 with a water-removing agent added. It has the same melt index (I2), density, copolymer VTMS content, and crystallinity at 23°C as ESC3 (because the water-removing agent does not affect these properties). ESC8 is available from The Dow Chemical Company (Midland, Michigan).

[0079] Si-g-POE is a silane-grafted polyolefin elastomer characterized by a melt index (I2) of 21.9 g / 10 min and a grafted VTMS content of 0.75 mol%. It is prepared from an ethylene polymer (a copolymer of ethylene and 1-octene, with an octene comonomer content of 5.6 mol%) and has a melt index (I2) of 30 g / 10 min, a density of 0.902 g / cc, and a crystallinity of 35.7 wt% at 23°C. The preparation of Si-g-POE is described as the "Si-g-POE2" sample in World Intellectual Property Organization International Publication No. 2021 / 252312.

[0080] Si-g-LDPE is a silane-grafted low-density polyethylene characterized by a melt index (I2) of 1.9 g / 10 min and a grafted VTMS content of 0.57 mol%. It is prepared from low-density polyethylene (LDPE) having a melt index (I2) of 8 g / 10 min, a density of 0.918 g / cc, and a crystallinity of 47.1 wt% at 23°C. The preparation of Si-g-LDPE is described as the "Si-g-LDPE" sample in World Intellectual Property Organization publication number 2021 / 252312.

[0081] CAT1 MB is a silanol condensation catalyst masterbatch (a blend of thermoplastic ethylene polymer, antioxidants, and approximately 2% by weight of dibutyltin dilaurate) developed for use in conjunction with water-curable ethylene-silane copolymers, and is commercially available from The Dow Chemical Company in Midland, Michigan, as SI-LINK® DFDB-5480NT.

[0082] CAT2MB is a silanol condensation catalyst masterbatch (a blend of thermoplastic ethylene polymer, antioxidants, and approximately 3% by weight of dibutyltin dilaurate) developed for use in conjunction with water-curable ethylene-silane copolymers, and is marketed as SI-LINK® DFDA-5481NT by The Dow Chemical Company in Midland, Michigan.

[0083] OBC is an olefin block copolymer with a density of 0.877 g / cc and a melt index (I2) of 15 g / 10 min. OBC is commercially available as INFUSE® 9817 from The Dow Chemical Company in Midland, Michigan.

[0084] The compatibilizer is maleic anhydride grafted ethylene vinyl acetate copolymer, which is commercially available as FUSABOND® C250 from The Dow Chemical Company in Midland, Michigan.

[0085] The filler is magnesium hydroxide (HFFR), which is commercially available as FR-20-100 from Israel Chemicals Ltd. of Tel Aviv-Yafo, Israel.

[0086] AO1 is a sterically hindered phenolic antioxidant with the chemical name pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid), and is marketed as IRGANOX® 1010 by BASF in Ludwigshafen, Germany.

[0087] AO2 is distearyl thiodipropionate and is marketed as NAUGARD® DSTDP by Addivant in Danbury, Connecticut.

[0088] OBH is oxalylbis(benzylidene)hydrazide, which is commercially available from Sigma-Aldrich, St. Louis, MO.

[0089] The silicone is DOWSIL® Si powder resin modifier 4-7081, which is commercially available from The Dow Chemical Company, Midland, MI.

[0090] OTS is octyltriethoxysilane, which is marketed as PROSIL(trademark) 9202 by Milliken & Co.'s SiVance LLC.

[0091] The carbon black is VulcanXC72, which is commercially available from Cabot Corporation (Alpharetta, GA).

[0092] The carbon black containing an intermediate compound based on ESC1 consists of 70% by weight of ESC1 and 30% by weight of carbon black. Its preparation is described previously (see CE6).

[0093] The carbon black containing an ESC3-based intermediate compound consists of 70% by weight of ESC3 and 30% by weight of carbon black. Its preparation is described previously (see CE7).

[0094] FR MB is a flame retardant masterbatch that is a blend of thermoplastic ethylene polymers, antioxidants, hindered amine stabilizers, and 60% by weight of fillers (brominated flame retardants and antimony trioxide). FR MB is available from The Dow Chemical Company in Midland, Michigan.

[0095] CB MB is a carbon black masterbatch containing a blend of thermoplastic ethylene polymers, antioxidants, and approximately 40% by weight of carbon black (filler). CB MB is available from The Dow Chemical Company in Midland, Michigan.

[0096] CA MB is a catalytic masterbatch containing a blend of thermoplastic ethylene polymers, antioxidants, and approximately 3% by weight of aryl sulfonic acid (Brønsted acid). CA MB is available from The Dow Chemical Company in Midland, Michigan.

[0097] CC MB is a catalyst and carbon black combination masterbatch containing a blend of thermoplastic ethylene polymers, water removers, antioxidants, stabilizers, approximately 31% by weight of carbon black (filler), and approximately 1.5% by weight of aryl sulfonic acid (Brønsted acid). CC MB is available from The Dow Chemical Company in Midland, Michigan.

[0098] The HFFR masterbatch is a halogen-free flame-retardant masterbatch formed by combining the materials listed in Table 3. HFFR MB was prepared by combining magnesium hydroxide and other components with OBC in a BRABENDER® mixer equipped with cam blades at a rotor speed of 40 revolutions per minute ("RPM") and a jacket (mixing bowl set) temperature of 160°C. After fluxing the OBC for 5 minutes, solid additives were added and mixed for a further 10 minutes. Then, the liquid additives of HFFR MB were added and mixed for a further 5 minutes. The HFFR MB mixture was removed and compressed in a press to produce 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 into a Brabender 19.05 mm single-screw extruder (25:1 L / D) operated at 40 RPM using a two-stage mixing screw (compression ratio 3:1), with temperature profiles set to 150°C / 160°C / 170°C / 180°C across all zones and head / die (using 40 / 60 / 40 US mesh screen packs), processed into strands, and converted into pellets using a pelletizer. The pellets were then packaged in sealed foil bags.

[0099] [Table 3]

[0100] Sample preparation and results: IE1, IE2, and CE1 Wire preparations were made using HFFR MB, silanol condensation catalyst masterbatch (CAT1 MB), and ethylene-silane copolymer (ESC). Prior to wire preparation, the HFFR MB and CAT1 MB pellets were dried separately in a vacuum oven at 60°C for 48 hours and in a 70°C oven for 16–24 hours to remove moisture. Wire preparation was performed by physically blending the ESC pellets with the HFFR MB and CAT1 MB pellets in the specific proportions shown in Table 4. The physical blends were then melt-mixed during extrusion to produce wire structures on solid copper of 10 American wire gauge ("AWG") with a nominal wall thickness of 1.524 mm. The wire preparation unit included a BRABENDER® 19.05 mm extruder with a variable speed drive, a 25:1 L / D mixing screw, a BRABENDER® crosshead wire die, a laboratory water-cooled trough with an air wipe, a laser micrometer, and a variable speed wire puller. The wire samples were extruded at a screw speed of 40 RPM with temperature profiles of 140°C / 155°C / 165°C / 165°C (across zones 1, 2, 3, and head / die) and screen packing with a 40 / 40 US mesh.

[0101] The wire (coated conductor) was cured in a 90°C water bath for 72 hours to achieve final curing. After further adjustment for several hours at 23°C and 50% relative humidity, the properties of the cured coating or coated conductor were tested.

[0102] Compared to CE1, IE1 and IE2 exhibited preferably lower thermal creep values ​​(indicating increased crosslinking), improved flame retardancy (char length and FWCL value), and remarkably improved tensile properties. The tensile property results suggest improved compatibility of magnesium hydroxide fillers with increasing copolymer VTMS content in the ethylene-silane copolymer.

[0103] [Table 4]

[0104] Sample preparation and results: IE3-IE6 and CE2-5 Wires were prepared using HFFR MB, silanol condensation catalyst masterbatch (CAT1 MB), and either ethylene-silane copolymer (ESC), silane-grafted polyolefin elastomer (Si-g-POE), or silane-grafted low-density polyethylene (Si-g-LDPE) as shown in Table 3. Before wire preparation, the HFFR MB and CAT1 MB pellets were dried separately in a vacuum oven at 60°C for 48 hours or in a 70°C oven for 16–24 hours to remove moisture. The ESC, Si-g-POE, or Si-g-LDPE pellets were physically blended with the HFFR MB and CAT1 MB pellets in the specific proportions shown in Table 5. The blends were then melt-mixed during extrusion to fabricate wire structures on 10AWG solid copper with a nominal wall thickness of 1.524 mm. The wire preparation unit included a BRABENDER® 19.05 mm extruder with a variable speed drive, a 25:1 L / D mixing screw, a BRABENDER® crosshead wire die, a laboratory water-cooled trough with an air wipe, a laser micrometer, and a variable speed wire puller. Wire samples were extruded at a screw speed of 40 RPM with temperature profiles of 140°C / 155°C / 165°C / 165°C (across zones 1, 2, 3, and head / die) and a 40 / 40 US mesh screen pack. The wire (coated conductor) was cured in a 90°C water bath for 2 or 3 days to achieve final curing. After further adjustment for several hours at 23°C and 50% relative humidity, the properties of the cured coating or coated conductor were tested.

[0105] Referring to Table 5, compared to CE2 and CE3, IE3–IE6 showed preferably lower thermal creep values ​​(indicating increased crosslinking), similar flame retardancy (char length and FWCL value), and remarkably improved and similar tensile properties. The tensile property results suggest improved compatibility of magnesium hydroxide fillers with increasing copolymer VTMS content in ethylene-silane copolymers.

[0106] CE4 exhibited a low thermal creep value as well as good flame retardancy and tensile properties. However, the Si-g-POE used in CE4 was not an ethylene-silane copolymer. Furthermore, the Si-g-POE was made from an ethylene polymer with a crystallinity of 36 wt% at 23°C. The low crystallinity of the ethylene polymer used to produce Si-g-POE compared to the crystallinity of various ethylene-silane copolymers is undesirable for abrasion and pinch resistance properties, as flexibility and pliability increase as crystallinity decreases.

[0107] While CE5 also yielded a good balance of properties, the Si-g-LDPE used in CE5 was not an ethylene-silane copolymer and had a crystallinity of 47% by weight at 23°C. Compared to the crystallinity of various ethylene-silane copolymers used in the examples of the present invention, the higher crystallinity of the ethylene polymer used to produce the Si-g-LDPE is undesirable because it excessively increases the stiffness.

[0108] [Table 5]

[0109] Sample preparation and results: CE6 and CE7 Carbon black containing an intermediate compound based on ESC (either ESC1 or ESC3) was prepared as follows: ESC was melt-blended with carbon black as a filler (in a ratio of 70 / 30 wt% ESC / carbon black). A Bravender mixer with a Banbury blade and a 375 mL bowl capacity was used at a rotor speed of 30 RPM and a set temperature of 150°C to produce batches weighing approximately 283 grams (by fluxing the ESC for 5 minutes, then adding the carbon black and mixing for a further 5 minutes). The melt-blended composition was removed from the mixing bowl and compressed into plaques 75 mil (1.9 mm) thick at 120°C by applying a pressure of 500 psi for 5 minutes. Two batches of each formulation were prepared to obtain a total of approximately 500 grams, which were cut into strips using a guillotine and fed into a pelletizer (granulator) to produce "chips". Next, the "chips" were introduced into a Brabender 19.05mm extruder (25:1 L / D) operated at 40 RPM with a mixing screw (3:1 compression ratio) and set to a temperature of 150°C across all zones and head / die (using 40 / 60 / 40 US mesh screen packs) to process into strands, which were then converted into pellets using a pelletizer. The pellets were then packaged in sealed foil bags.

[0110] Carbon black containing an ESC-based intermediate compound was melt-blended with a silanol condensation catalyst masterbatch (CAT2MB) in the proportions shown in Table 6. The catalyst masterbatch was pre-dried in a vacuum oven at 70°C for 16–24 hours and then packaged in a vacuum-sealed foil bag until use. A physical blend of the intermediate compound pellets and the catalyst masterbatch (in a plastic bag) was prepared and subsequently fed into a Brabender 19.05 mm extruder with a 25:1 Maddock screw to produce a tape approximately 60 mil (1.5 mm) thick. The set temperature profiles across zones were 160°C, 170°C, 180°C, and 185°C at the head / die. A 40 / 60 / 40 US mesh screen pack was used, and the screw speed was 40 RPM. The tape was cured in a 90°C water bath for 20 hours to achieve final curing. After further adjustment for several hours at 23°C and 50% relative humidity, the properties of the cured tape were tested.

[0111] Compared to CE7, CE6 exhibited substantially inferior tensile elongation. Specifically, when carbon black was used as the sole filler in the composition, an increase in the copolymerized VTMS content in the ethylene-silane copolymer resulted in worse tensile elongation (consistent with the lack of apparent compatibility of this filler).

[0112] [Table 6]

[0113] Sample preparation and results: CE8~CE13 CE8-CE13 were prepared by mixing pellets of the components listed in Table 7 in a fiber drum. The samples were then melt-mixed during extrusion to produce coated conductors with a 0.762 mm thick coating of the polymer composition on a 14 AWG solid copper conductor, thereby forming wires. Wires were manufactured using a 63.5 mm Davis Standard extruder equipped with a double-fly Maddock screw and 20 / 40 / 60 / 20 mesh screens at the following set temperatures (°C) across zones 1 / 2 / 3 / 4 / 5 / head / die: 129.4 / 135.0 / 143.3 / 148.9 / 151.7 / 165.6 / 165.6. The screw length-to-diameter (L / D) ratio was 26 (measured from the start of screw flight to the screw tip) or 24 (measured from the screw position corresponding to the end of the feed casing to the screw tip). The wire structures were manufactured 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 curing in a 90°C water bath for 20 hours to achieve final curing.

[0114] Comparing CE8 and CE9, and CE10 and CE11, an increase in the copolymerized VTMS content in the ethylene-silane copolymer resulted in worse tensile elongation. Specifically, since FR MB contained halogenated flame retardants and antimony trioxide as fillers, and both CB MB and CC MB contained carbon black as a filler, there was no apparent compatibility of these fillers with the increased copolymerized VTMS content in the ethylene-silane copolymer.

[0115] Comparing CE12 and CE13 (both without fillers), tensile elongation decreased as the copolymer VTMS content in the ethylene-silane copolymer increased.

[0116] [Table 7]

[0117] As demonstrated above, the polymer compositions of this disclosure do not suffer tensile strain loss at fracture (and even show increased tensile strain at fracture) compared to polymer compositions using ethylene-silane copolymers with a silane copolymer content of less than 0.4 mol%, and achieve a thermal creep of 175% or less after final curing, as measured according to UL2556 section 7.9 or ICEA-T-28-562-2003.

[0118] Comparing IE1 and IE2 with CE1, the use of magnesium hydroxide as a filler unexpectedly resulted in improved tensile strength and elongation as the copolymer VTMS content in the ethylene-silane copolymer (when crosslinked using Lewis acid and dibutyltin dilaurate as silanol condensation catalysts). In contrast, the use of carbon black as a filler had the opposite effect on tensile elongation (see CE6 and CE7).

[0119] When comparing CE2 and CE3, which used magnesium hydroxide as a filler and dibutyltin dilaurate as a silanol condensation catalyst, with IE3-IE6, improved and similar tensile properties were obtained regardless of the copolymerized VTMS content in the ethylene-silane copolymer used. These results are consistent with the results for IE1 and IE2 compared to CE1, suggesting improved compatibility of magnesium hydroxide filler with increasing copolymerized VTMS content in the ethylene-silane copolymer.

[0120] While combinations of metal hydrate fillers with silane-grafted ethylene polymers (such as POE and LDPE used in CE4 and CE5) are disclosed in the prior art, the effect of grafted VTMS content on tensile elongation values ​​varies depending on the type of ethylene polymer used, meaning that it is unclear what trends will be observed when ethylene-silane copolymers (completely different classes of silane-functionalized polyethylene) are used as water-curable resins.

[0121] The use of halogenated flame retardants and antimony trioxide along with carbon black as fillers, in addition to ethylene-silane copolymers, also resulted in a deterioration of tensile elongation as the copolymer VTMS content in the copolymer increased (CE8-CE13). These findings are consistent with those obtained when carbon black was used as the sole filler (CE6 and CE7), i.e., there was no apparent compatibility of these fillers with ethylene-silane copolymers.

Claims

1. A polymer composition, An ethylene-silane copolymer comprising units derived from ethylene monomers and silane monomers, wherein the ethylene-silane copolymer has a copolymerized silane content of 0.40 mol% to 1.00 mol% based on the total moles of the ethylene-silane copolymer, Lewis acid catalyst and A polymer composition comprising a halogen-free flame retardant selected from the group consisting of metal hydrates, silica, and combinations thereof.

2. The polymer composition according to claim 1, wherein the Lewis acid catalyst is selected from the group consisting of dibutyltin dilaurate, dioctyltin dilaurate, aluminum chloride, titanium chloride, zinc chloride, dimethylhydroxytin oleate, dioctyltin maleate, di-n-butyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octanoate, lead naphthenate, zinc caprylate, and cobalt naphthenate, and combinations thereof.

3. The polymer composition according to any one of claims 1 or 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 polymer composition according to any one of claims 1 to 3, wherein the polymer composition comprises 10% to 80% by weight of the halogen-free flame retardant based on the total weight of the polymer composition.

5. The polymer composition according to any one of claims 1 to 4, wherein the polymer composition comprises 10% to 90% by weight of the ethylene-silane copolymer based on the total weight of the polymer composition.

6. The polymer composition according to any one of claims 1 to 5, wherein the polymer composition exhibits a filler-to-catalyst weight ratio of 75 to 1000.

7. The polymer composition according to any one of claims 1 to 6, wherein the ethylene-silane copolymer exhibits a crystallinity of 40% to 46% by weight at 23°C when measured according to a crystallinity test.

8. The ethylene-silane copolymer is A polymer composition according to any one of claims 1 to 7, having a copolymer silane content of 0.45 mol% to 0.85 mol%.

9. The polymer composition according to any one of claims 1 to 8, wherein the polymer composition exhibits one or more of the following: a thermal creep of 175% or less after final curing, as measured according to ICEA-T-28-562-2003, and a tensile strain at fracture of 20% or more, as measured according to ASTM D638-14.

10. Insulated conductor, A conductor and A coated conductor comprising a polymer composition according to any one of claims 1 to 9.

11. The coated conductor according to claim 10, wherein the polymer composition exhibits one or more of the following characteristics when measured according to ICEA-T-28-562-2003: a thermal creep of 175% or less after final curing, and a tensile strain at break of 20% or more when measured according to UL2556, Section 3.5.

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