Flame retardant polymer composition

Abstract

The present invention relates to a polymer composition comprising a silane-functionalized polyolefin, a brominated flame retardant having a temperature of 5% mass loss from 350°C to 500°C and a retained mass at 650°C from 2 wt% to 50 wt%. The 5% mass loss and the retained mass at 650°C are measured according to thermogravimetric analysis. The polymer composition further comprises a zinc (Zn) flame retardant synergist. The polymer composition is free of antimony trioxide and has a zinc to bromine (Br) molar ratio (Zn:Br molar ratio) greater than 0.0 to 0.160.

Description

Background Technology Technical Field

[0002] This disclosure relates to a composition suitable for wire and cable applications, and more particularly to a halogenated flame retardant composition. Background Technology

[0004] Polymer compositions containing halogenated flame retardants are known. Examples of halogenated flame retardants include brominated flame retardants. Polymer compositions that rely solely on halogenated flame retardants to provide flame retardancy typically require high loadings of the flame retardant and often fail to meet the most stringent flammability requirements. High loadings of the flame retardant adversely affect the processability and mechanical properties of the polymer composition, such as tensile elongation and impact strength.

[0005] During exposure to heat or flame, halogenated flame retardant fillers are believed to form a halogenated vapor phase. This halogenated vapor phase is believed to delay flame development via a free radical flame poisoning mechanism. In this mechanism, readily available free radicals that would otherwise promote further exothermic reactions combine with and are neutralized by halogens in the halogenated vapor.

[0006] One approach to overcoming the processability and mechanical property problems associated with high halogenated filler concentrations is to incorporate flame retardant synergists or combinations thereof. A common combination of flame retardant synergists includes zinc compounds and antimony trioxide. Zinc synergists are believed to act partly by catalyzing the release of halogens from the halogenated filler, followed by the formation of zinc halides and zinc oxide halides in the halogenated vapor. Additionally, zinc synergists are known to promote char formation and prevent dripping of burning material. Antimony trioxide is believed to act by releasing volatile but dense antimony halide vapors through the continuous transformation of antimony halide-antimony oxide complexes produced by the reaction between the halogenated flame retardant and antimony oxide at elevated temperatures. This combination of antimony and halogens produces a variety of vapor phase compounds with greater stability than antimony-free halogenated vapor phases. Greater stability and higher antimony halide density prolong the residence time of the halogenated vapor phase near the combustion zone, where free radical chain reactions occur, resulting in a greater number of free radicals being poisoned and inhibiting flame development.

[0007] The use of antimony trioxide as a flame retardant synergist faces various constraints. For example, antimony trioxide faces regulatory pressures in some jurisdictions leading to reduced or abandoned use. Furthermore, the availability of antimony trioxide may be limited due to the location of natural deposits and geopolitical tensions. Therefore, there is a desire to reduce the use of antimony trioxide; however, U.S. Patent Application Publication No. 2019 / 0185654 indicates that insufficient antimony trioxide can cause compositions to exhibit unacceptable flammability test characteristics. Additionally, simply increasing the halogenated filler component may adversely affect the mechanical properties of the composition. While zinc synergists function in halogenated flame retardant technology in a manner somewhat similar to that of antimony trioxide, they are known to be ineffective flame retardant synergists in the absence of antimony trioxide. Given the beneficial effects of zinc synergists being less toxic and relatively more cost-effective than antimony trioxide, it would be crucial to replace some or all of antimony trioxide with corresponding zinc synergists while achieving equivalent or better flame retardant performance.

[0008] In light of the foregoing, it is surprising that the discovery of antimony trioxide-free polymer compositions enables coated conductors made from these compositions to pass the VW-1 combustion test and have a zinc to bromine (“Zn:Br”) molar ratio greater than 0 to 0.160. Summary of the Invention

[0009] The present invention provides a polymer composition that is free of antimony trioxide and enables coated conductors made from the polymer composition to pass the VW-1 combustion test and have a Zn:Br molar ratio greater than 0 to 0.160.

[0010] The inventors of this application have discovered that polymer compositions containing silanol-functionalized polyolefins, brominated flame retardants, and zinc flame retardant synergists, having a Zn:Br molar ratio greater than 0.0 to 0.160, can be antimony trioxide-free and enable coated conductors made from said polymer compositions to pass the VW-1 flammability test. This polymer composition is surprising because, despite a full understanding of the importance of antimony trioxide to flame retardant properties, coated conductors made from said polymer compositions still pass the VW-1 flammability test. It is also surprising that, despite the multiple beneficial effects of adding zinc-based synergists, the coated conductors containing the composition that pass the VW-1 flammability test have a lower Zn:Br molar ratio than conventional synergist-to-bromine molar ratios. The removal of antimony trioxide is particularly advantageous due to increasing regulatory pressure on the use of antimony trioxide worldwide. Furthermore, it has been found that a sufficiently large Zn:Br molar ratio allows the use of inexpensive zinc synergists to replace relatively expensive brominated flame retardants, thereby reducing the production cost of the polymer compositions.

[0011] The polymer compositions of the present invention are particularly suitable for manufacturing wires and cables.

[0012] According to a first feature of this disclosure, the polymer composition comprises a silane-functionalized polyolefin, a brominated flame retardant having a 5% mass loss at a temperature ranging from 350°C to 500°C, and a retention mass at 650°C ranging from 2% to 50% by weight. The 5% mass loss and the retention mass at 650°C are measured by thermogravimetric analysis. The polymer composition also comprises a zinc (Zn) flame retardant synergist. The polymer composition is free of antimony trioxide and has a zinc to bromine (Br) molar ratio (Zn:Br molar ratio) greater than 0.0 to 0.160.

[0013] According to a second feature of this disclosure, the polymer composition comprises 0.001% to 5.0% by weight of a silanol condensation catalyst based on the total weight of the polymer composition.

[0014] According to a third feature of this disclosure, the polymer composition further comprises 5% to 30% by weight of a second polyolefin based on the total weight of the polymer composition, wherein the crystallinity of the second polyolefin at 23°C is 0% to 80% by weight, as measured by a crystallinity test.

[0015] According to the fourth feature of this disclosure, the brominated flame retardant includes ethylene bis(tetrabromophthalimide).

[0016] According to the fifth feature of this disclosure, the polymer composition comprises 5% to 45% by weight of ethylene bis(tetrabromophthalimide) based on the total weight of the polymer composition.

[0017] According to a sixth feature of this disclosure, the polymer composition comprises 20% to 80% by weight of a silane-functionalized polyolefin based on the total weight of the polymer composition.

[0018] According to the seventh feature of this disclosure, the zinc flame retardant synergist is selected from: zinc borate, zinc carbonate, zinc carbonate hydroxide, hydrated zinc borate, zinc phosphate, zinc stannate, zinc hydrostannate, zinc sulfide, zinc oxide, and combinations thereof.

[0019] According to the eighth feature of this disclosure, the Zn:Br molar ratio is greater than 0.0 to 0.135.

[0020] According to a ninth feature of this disclosure, the coated conductor comprises a conductor and a polymer composition disposed at least partially around the conductor.

[0021] According to the tenth feature of this disclosure, the coated conductor passes the horizontal burning test.

[0022] According to the eleventh feature of this disclosure, the coated conductor passes the VW-1 combustion test. Detailed Implementation

[0023] 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 may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone; contain B alone; contain C alone; contain A and B in combination; contain A and C in combination; contain B and C in combination; or contain A, B, and C in combination.

[0024] Unless otherwise stated, all ranges include the endpoints.

[0025] A test method refers to the most recent test method as of the priority date of this document, unless the date is indicated by a two-digit test method number with a hyphen. References to a test method include references to both the testing association and the test method number. Testing method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly known as the American Society for Testing and Materials); EN refers to European Standards; DIN refers to the German Institute for Standardization; and ISO refers to the International Organization for Standardization.

[0026] As used herein, unless otherwise specified, the term weight percentage (“wt%”) means the weight percentage of a component relative to the total weight of the polymer composition.

[0027] As used in this article, “CAS number” is a chemical abstract registration number assigned by the Chemical Abstracts Service.

[0028] polymer composition

[0029] This disclosure relates to polymer compositions. The polymer compositions comprise a silane-functionalized polyolefin, a brominated flame retardant, and a zinc flame retardant synergist. The polymer compositions have a zinc (Zn) to bromine (Br) molar ratio (Zn:Br molar ratio) greater than 0.0 to 0.160. The polymer compositions may optionally comprise a second polyolefin.

[0030] Silane-functionalized polyolefins

[0031] The polymer composition comprises a silane-functionalized polyolefin. "Silane-functionalized polyolefin" is a polymer containing silane and an α-olefin polymerized in amounts equal to or greater than 50% by weight or the majority of the total weight of the silane-functionalized polyolefin. "Polymer" means a macromolecular compound prepared by reacting the same or different types of monomers (i.e., polymerization). As described above, the polymer composition comprises a silane-functionalized polyolefin. The silane-functionalized polyolefin is crosslinked, and this crosslinking increases the resistance to flow of the polymer composition at elevated temperatures.

[0032] Silane-functionalized polyolefins may include α-olefin and silane copolymers, silane-grafted polyolefins, and / or combinations thereof. “α-olefin and silane copolymers” (α-olefin / silane copolymers) are formed by copolymerizing α-olefins (such as ethylene) and hydrolyzable silane monomers (such as vinylsilane monomers), such that the hydrolyzable silane monomers are incorporated into the backbone of the polymer chain, and then the polymer is incorporated into a polymer composition. “Silane-grafted polyolefins” or “Si-g-PO” can be formed via the Sioplas process, in which the hydrolyzable silane monomers are grafted onto the backbone of the base polyolefin via processes such as extrusion before the polymer is incorporated into the polymer composition.

[0033] In examples where the silane-functionalized polyolefin is an α-olefin and a silane copolymer, the silane-functionalized polyolefin is prepared by copolymerization of at least one α-olefin and a hydrolyzable silane monomer. In examples where the silane-functionalized polyolefin is a silane-grafted polyolefin, the silane-functionalized polyolefin is prepared by grafting one or more hydrolyzable silane monomers onto the polymeric α-olefin backbone of the polymer.

[0034] As measured using nuclear magnetic resonance (NMR) or Fourier transform infrared (FTIR) spectroscopy, silane-functionalized polyolefins may contain 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, or 91% or more, or 92% or more, or 93% or more, or 94% or more, or 95% or more, or 96% or more, or 97% or more, or 97.5% or more. α-olefins comprising 98% or more, or 99% or more, and simultaneously 99.5% or less, or 99% or less, or 98% or less, or 97% or less, or 96% or less, or 95% or less, or 94% or less, or 93% or less, or 92% or less, or 91% or less, or 90% or less, or 85% or less, or 80% or less, or 70% or less, or 60% or less. α-olefins may include C2 or C3 to C4, or C6, or C8, or C... 10 or C 12 or C 16 or C 18 or C 20α-Olefins, such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Other units of the silane-functionalized polyolefin may be derived from one or more polymerizable monomers, including (but not limited to) unsaturated esters. Unsaturated esters may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylate esters. The alkyl group may have 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The carboxylate ester 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, tert-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of vinyl carboxylate esters include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butyrate.

[0035] The density of silane-functionalized polyolefins, as measured by ASTM D792, is 0.860 g / cm³ or greater, or 0.870 g / cc or greater, or 0.880 g / cc or greater, or 0.890 g / cc or greater, or 0.900 g / cc or greater, or 0.910 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. Large, or 0.925g / cc to 0.930g / cc or greater, or 0.935g / cc or greater, while simultaneously 0.970g / cc or less, or 0.960g / cc or less, or 0.950g / cc or less, or 0.940g / cc or less, or 0.935g / cc or less, or 0.930g / cc or less, or 0.925g / cc or less, or 0.920g / cc or less, or 0.915g / cc or less.

[0036] A “hydrolyzable silane monomer” is a silane-containing monomer that can be effectively copolymerized with α-olefins (e.g., ethylene) to form α-olefin / silane copolymers (such as ethylene / silane copolymers), or grafted onto α-olefin polymers (i.e., polyolefins) to form Si-g-polyolefins, thus enabling subsequent crosslinking of silane-functionalized polyolefins. A representative, but non-limiting, example of a hydrolyzable silane monomer has a structure (I):

[0037]

[0038] Where R 1 It 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 2Independently a hydrolyzable organic group, such as an alkoxy group (e.g., methoxy, ethoxy, butoxy), an aryloxy group (e.g., phenoxy), an arylalkoxy group (e.g., benzoxy), an aliphatic acyloxy group (e.g., formoxy, acetoxy, propionyloxy), an amino or substituted amino group (e.g., alkylamino, arylamino), or a low-carbon alkyl group (e.g., 1 to 6 carbon atoms), provided that the three Rs are present. 2 No more than one group in the group is alkyl. Hydrolyzable silane monomers can be copolymerized in a reactor with α-olefins (such as ethylene) (such as through a high-pressure process) to form α-olefin / silane copolymers. In the example where the α-olefin is ethylene, such copolymers are referred to herein as ethylene / silane copolymers. Hydrolyzable silane monomers can also be grafted onto polyolefins (such as polyethylene) using an organic peroxide such as 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane to form Si-g-PO or in-situ Si-g-PO. In-situ Si-g-PO is formed by a process such as the MONOSIL process, in which the hydrolyzable silane monomer is grafted onto the main chain of the polyolefin during the extrusion of the compositions of the present invention to form a coated conductor, as described, for example, in USP 4,574,133.

[0039] Hydrolyzable silane monomers may include silane monomers comprising an olefinically unsaturated hydrocarbon group (such as vinyl, allyl, isopropenyl, butenyl, cyclohexenyl, or γ-(meth)acryloyloxyallyl group) and a hydrolyzable group (such as, for example, an alkyloxy, alkylacryloyl, or alkylamino group). The hydrolyzable group may include methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, and alkyl or arylamino groups. In a specific example, the hydrolyzable silane monomer is an unsaturated alkoxysilane that may be grafted onto a polyolefin or copolymerized with an α-olefin (e.g., ethylene) in a reactor. Examples of hydrolyzable silane monomers include vinyltrimethoxysilane (VTMS), vinyltriethoxysilane (VTES), vinyltriacetoxysilane, and γ-(meth)acryloyloxypropyltrimethoxysilane. In the context of structure (I), for VTMS, x = 0; R 1 = Hydrogen; and R 2 =Methoxy; For VTES: x = 0; R 1 = Hydrogen; and R 2 =ethoxy; and for vinyltriacetoxysilane: x = 0; R 1 =H; and R 2 = Acetoxyloxy

[0040] Examples of suitable ethylene / silane copolymers can be seen as SI-LINK TM DFDA-5451NT and SI-LINK TMACDFDB-5451 NT is commercially available and can be purchased from The Dow Chemical Company (Midland, MI). A suitable example of Si-g-PO can be found in PEXIDAN. TM A-3001 was purchased from SACO AEI Polymers (Shebyogan, WI) and used as a SYNCURE. TM S1054A was purchased from PolyOne (Avon Lake, OH).

[0041] The polymer composition may contain 20% to 80% by weight of silane-functionalized polyolefin. The polymer composition may contain 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, or 44% or more by weight, or 46% or more by weight, or 48% or more by weight, or 50% or more by weight, or 52% or more by weight, or 54% or more by weight, or 56% or more by weight, or 58% or more by weight, or 60% or more by weight, or 65% or more by weight, or 70% or more by weight, or 75% by weight, based on the total weight of the polymer composition. Or greater, while simultaneously 80% or less, or 75% or less, or 70% or less, or 65% or less, or 60% or less, or 58% or less, or 56% or less, or 54% or less, or 52% or less, or 40% or less, or 48% or less, or 46% or less, or 44% or less, or 42% or less, or 40% or less, or 38% or less, or 36% or less, or 34% or less, or 32% or less, or 30% or less, or 28% or less, or 26% or less, or 24% or less, or 22% or less silane-functionalized polyolefins.

[0042] The melt index of silane-functionalized polyolefins is measured according to ASTM D1238 at 190°C / 2.16 kg / min and reported in grams eluted per 10 minutes (g / 10min). The melt index of silane-functionalized polyolefins can be 0.5 g / 10min or greater, or 1.0 g / 10min or greater, or 1.5 g / 10min or greater, or 2.0 g / 10min or greater, or 2.5 g / 10min or greater, or 3.0 g / 10min or greater, or 3.5 g / 10min or greater, or 4.0 g / 10min or greater, or 4.5 g / 10min or greater, while simultaneously being 30.0 g / 10min or less, or 25.0 g / 10min or less. Or 20.0g / 10min or less, or 15.0g / 10min or less, or 10.0g / 10min or less, or 5.0g / 10min or less, or 4.5g / 10min or less, or 4.0g / 10min or less, or 3.5g / 10min or less, or 3.0g / 10min or less, or 2.5g / 10min or less, or 2.0g / 10min or less, or 1.5g / 10min or less, or 1.0g / 10min or less.

[0043] Brominated flame retardants

[0044] The polymer composition contains a brominated flame retardant. As explained below, the brominated flame retardant can have a 5% mass loss temperature ranging from 350°C to 500°C, as measured by thermogravimetric analysis. The 5% mass loss temperature, as measured by thermogravimetric analysis, can be 350°C or higher, or 360°C or higher, or 370°C or higher, or 380°C or higher, or 390°C or higher, or 400°C or higher, or 410°C or higher, or 420°C or higher, or 430°C or higher, or 440°C or higher, or 450°C or higher, or 460°C or higher, or 470°C or higher, or 480°C or higher. The temperature ranges from 350°C to 500°C, with values ​​of 490°C or higher, and simultaneously 500°C or lower, or 490°C or lower, or 480°C or lower, or 470°C or lower, or 460°C or lower, or 450°C or lower, or 440°C or lower, or 430°C or lower, or 420°C or lower, or 410°C or lower, or 400°C or lower, or 390°C or lower, or 380°C or lower, or 370°C or lower, or 360°C or lower. A 5% mass loss temperature is associated with the dehydrobromination of the brominated flame retardant. Premature dehydrobromination negatively impacts flame retardancy as much as late dehydrobromination, and therefore a 5% mass loss temperature from 350°C to 500°C is advantageous in increasing flame retardancy.

[0045] As explained below, brominated flame retardants, as measured by thermogravimetric analysis, have a retention mass at 650°C ranging from 2 wt% to 50 wt%. Brominated flame retardants may have a retention mass at 650°C of 2 wt% or more, or 5 wt% or more, or 10 wt% or more, or 13 wt% or more, or 15 wt% or more, or 18 wt% or more, or 20 wt% or more, or 25 wt% or more, or 30 wt% or more, or 35 wt% or more, or 40 wt% or more, or 45 wt% or more, while simultaneously having a retention mass at 650°C of 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 18 wt% or less, or 15 wt% or less, or 13 wt% or less, or 10 wt% or less, or 5 wt% or less. The retention mass at 650°C is the sole indicator of the ability of brominated flame retardants to form char, which is typically a carbonaceous material that insulates the protected material, slows pyrolysis, and creates a barrier that impedes oxygen / air diffusion and the release of additional gases into fuel combustion. Therefore, according to the well-known fire triangle, char formation is advantageous because it reduces heat transfer in addition to reducing contact between oxygen and the polymer composition.

[0046] Brominated flame retardants may include ethylene bis(tetrabromophthalimide). Ethylene bis(tetrabromophthalimide) has the CAS number 32588-76-4 and can be traded under the name SAYTEX. TMBT-93W is commercially available from Albemarle (Charlotte, North Carolina, USA). The polymer composition may contain 5% or more, 10% or more, 11% or more, or 13% or more, or 15% or more, or 20% or more, or 25% or more, or 30% or more, or 31% or more, or 32% or more, or 33% or more, or 34% or more, or 35% or more, or 36% or more, or 37% or more, or 38% or more, or 39% or more, or 40% or more, or 41% or more, or 42% or more, or 43% or more, or 44% or more, based on the total weight of the polymer composition. Meanwhile, 45% or less, or 44% or less, or 43% or less, or 42% or less, or 41% or less, or 40% or less, or 39% or less, or 38% or less, or 37% or less, or 36% or less, or 35% or less, or 34% or less, or 33% or less, or 32% or less, or 31% or less, or 30% or less, or 25% or less, or 20% or less, or 15% or less, or 13% or less, or 11% or less, or 10% or less ethylene bis(tetrabromophthalimide). The bromine content of ethylene bis(tetrabromophthalimide) is 67.2% by weight.

[0047] Zinc flame retardant synergist

[0048] The polymer composition contains a zinc flame retardant synergist. As used herein, a "zinc flame retardant synergist" is a compound that enhances the flame retardant properties of a flame retardant and contains elemental zinc. Zinc flame retardant synergists can be selected from: zinc borate, zinc carbonate, zinc carbonate hydroxide, hydrated zinc borate, zinc phosphate, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc oxide, and combinations thereof. An example of a zinc flame retardant synergist is FIREBRAKE. TM ZB-fine was purchased from Rio Tinto (London, England).

[0049] The polymer composition may contain 0.5% or more, or 1% or more, or 2% or more, or 3% or more, or 4% or more, or 5% or more, or 6% or more, or 7% or more, or 8% or more, or 9% or more, or 10% or more, or 11% or more, or 12% or more, or 13% or more, or 14% or more, while simultaneously 15% or less, or 14% or less, or 13% or less, or 12% or less, or 11% or less, or 10% or less, or 9% or less, or 8% or less, or 7% or less, or 6% or less, or 5% or less, or 4% or less, or 3% or less, or 2% or less, or 1% or less of zinc flame retardant synergist.

[0050] As stated above, the polymer composition is free of antimony trioxide. Additionally, the polymer composition may be antimony-free. As used herein, the term "free" is defined as meaning a polymer composition contains a compound of an element that is present in less than 0.1% by weight of the total weight of the polymer composition, or is free of the element. The absence of antimony trioxide in the polymer composition is surprising, as coated conductors containing conventional polymer compositions require both antimony trioxide and zinc flame retardant synergists, or antimony trioxide, to pass the VW-1 flammability test; however, the coated conductors utilizing the polymer compositions of this disclosure are antimony-free and pass the VW-1 flammability test.

[0051] Second polyolefin

[0052] The polymer composition may optionally contain a second polyolefin. Similar to silane-functionalized polyolefins, the second olefin comprises a polymerized α-olefin and optionally an unsaturated ester. The α-olefin may include C2 or C3 to C4, or C6, or C8, or C6. 10 or C 12 or C 16 or C 18 or C 20α-Olefins, such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Unsaturated esters may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylic acids. The second polyolefin may not be silane-functionalized. The crystallinity of the second polyolefin at 23°C may be from 0% to 80% by weight, as measured according to the crystallinity test provided below. For example, the crystallinity of the second polyolefin at 23°C may be 0% or greater, or 5% or greater, or 10% or greater, or 15% or greater, or 20% or greater, or 25% or greater, or 30% or greater, or 35% or greater, or 40% or greater, or 45% or greater, or 50% or greater, or 55% or greater, or 60% or greater, or 65% or greater, or 70% or greater. Large, or 75% by weight or greater, while at the same time 80% by weight or less, or 75% by weight or less, or 70% by weight or less, or 65% by weight or less, or 60% by weight or less, or 55% by weight or less, or 50% by weight or less, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less, or 30% by weight or less, or 25% by weight or less, or 20% by weight or less, or 15% by weight or less, or 10% by weight or less.

[0053] The second polyolefin can be ultra-low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene-ethyl acrylate copolymer, or ethylene-vinyl acetate copolymer. As measured by ASTM D792, the density of the second polyolefin can be 0.860 g / cc or greater, 0.870 g / cc or greater, or 0.880 g / cc or greater, or 0.890 g / cc or greater, or 0.900 g / cc or greater, or 0.904 g / cc or greater, or 0.910 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. cc or greater, or 0.935g / cc or greater, while simultaneously 0.970g / cc or less, or 0.960g / cc or less, or 0.950g / cc or less, or 0.940g / cc or less, or 0.935g / cc or less, or 0.930g / cc or less, or 0.925g / cc or less, or 0.920g / cc or less, or 0.915g / cc or less, or 0.910g / cc or less, or 0.905g / cc or less, or 0.900g / cc or less.

[0054] The melt index of the second polyolefin is measured according to ASTM D1238 at 190°C / 2.16 kg / min and reported as grams eluted per 10 minutes (g / 10min). The melt index of the silane-functionalized polyolefin may be 0.5 g / 10min or greater, or 1.0 g / 10min or greater, or 1.5 g / 10min or greater, or 2.0 g / 10min or greater, or 2.5 g / 10min or greater, or 3.0 g / 10min or greater, or 3.5 g / 10min or greater, or 4.0 g / 10min or greater, or 4.5 g / 10min or greater, while simultaneously being 30.0 g / 10min or less, or 25.0 g / 10min or less. Or 20.0g / 10min or less, or 15.0g / 10min or less, or 10.0g / 10min or less, or 5.0g / 10min or less, or 4.5g / 10min or less, or 4.0g / 10min or less, or 3.5g / 10min or less, or 3.0g / 10min or less, or 2.5g / 10min or less, or 2.0g / 10min or less, or 1.5g / 10min or less, or 1.0g / 10min or less.

[0055] The polymer composition may contain 0% to 30% by weight of a second polyolefin based on the total weight of the polymer composition. The polymer composition may contain 0% or more, or 5% or more, or 10% or more, or 15% or more, or 20% or more, or 25% or more, while simultaneously containing 30% or less, or 25% or less, or 20% or less, or 15% or less, or 10% or less of a second polyolefin.

[0056] additive

[0057] The polymer composition may contain one or more additives. Non-limiting examples of suitable additives include antioxidants, colorants, corrosion inhibitors, lubricants, silanol condensation catalysts, ultraviolet (UV) absorbers or stabilizers, anti-blocking agents, flame retardants, coupling agents, compatibilizers, plasticizers, fillers, processing aids, and combinations thereof.

[0058] The polymer composition may contain antioxidants. Non-limiting examples of suitable antioxidants include phenolic antioxidants, sulfur-based antioxidants, phosphate antioxidants, and hydrazine metal passivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenols, phenols having primary or secondary carbonyl substituents, 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; pentaerythritol tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4′-methylenebis(2,6-tert-butylphenol); 4,4′-thiobis(6-tert-butyl-o-cresol)2,6-di-tert-butylphenol; 6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5-triazine; ethyl 3,5-di-tert-butyl-4-hydroxybenzoic acid (di-n-octylthio); and hexa[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]sorbitol ester. In one embodiment, the composition comprises pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid), which is available from BASF via Irganox. TM Commercially available from 1010. A suitable methyl-substituted phenol, non-limiting example, isobutylenebis(4,6-dimethylphenol). A suitable hydrazine-based metal passivator, non-limiting example, is oxaloylbis(benzylhydrazine). In one embodiment, the composition contains 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 composition.

[0059] Polymer compositions may contain silanol condensation catalysts, such as Lewis acids and bases, as well as Brønsted acids and bases. The “silanol condensation catalyst” promotes the crosslinking of silane-functionalized polyolefins through hydrolysis and condensation reactions. A Lewis acid is a chemical species that accepts electron pairs from a Lewis base. A Lewis base is a chemical substance that accepts electron pairs from a Lewis base. Non-limiting examples of suitable Lewis acids include tin carboxylate such as dibutyltin dilaurate (DBTDL), dimethyl hydroxytin oleate, dioctyltin maleate, di-n-butyltin maleate, dibutyltin diacetate, dibutyltin dioctanoate, stannous acetate, stannous octanoate, and various other organometallic compounds such as lead naphthenate, zinc octanoate, and cobalt naphthenate. Non-limiting examples of suitable Lewis bases include primary amines, secondary amines, and tertiary amines. Non-limiting examples of suitable Brønsted acids are methanesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, or alkylnaphthalenesulfonic acid. Silanol condensation catalysts may contain end-capped sulfonic acids. End-capped sulfonic acids can be as defined in US 2016 / 0251535 A1, and can be compounds that, upon heating, optionally generate sulfonic acids in situ in the presence of moisture or alcohol. Examples of end-capped sulfonic acids include amine sulfonates and alkyl sulfonates. End-capped sulfonic acids can consist of a carbon atom, a hydrogen atom, one sulfur atom, and three oxygen atoms, and optionally a nitrogen atom. These catalysts are commonly used in moisture-curing applications. The polymer composition contains 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% of a silanol condensation catalyst based on the total weight of the composition. Silanol condensation catalysts are typically added to article-making extruders (such as during cable manufacturing) so that they are present during the final melt extrusion process. Therefore, silane-functionalized polyolefins can undergo some degree of crosslinking before leaving the extruder, and after leaving the extruder, crosslinking is usually completed when exposed to moisture (e.g., sauna, hot bath, or cooling bath) and / or humidity present in the environment of storage, transportation, or use.

[0060] Silanol condensation catalysts may be included in catalyst masterbatch blends, and the catalyst masterbatch may be included in the composition. Non-limiting examples of suitable catalyst masterbatches include those produced by The Dow Chemical Company under the trade name SI-LINK. TM Those for sale, including SI-LINK TM DFDA-5481 Natural and SI-LINK TMAC DFDA-5488 NT. 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 catalyst masterbatch based on the total weight of the composition.

[0061] The polymer composition may contain an ultraviolet (UV) absorber or a stabilizer. A non-limiting example of a suitable UV stabilizer is a hindered amine light stabilizer (HALS). A non-limiting example of a suitable HALS is 1,3,5-triazine-2,4,6-triamine, N,N-1,2-ethylenedimethylbisN-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-tetra[4,6-bis(n-butyl-n-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2-yl]-1,5,8,12-tetraazadodecane, which, as SABO TM STAB UV-119 is commercially available from SABO SpA (Levate, Italy). In one embodiment, the composition contains 0 wt%, or 0.001 wt%, or 0.002 wt%, or 0.005 wt%, or 0.006 wt%, or 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%, or 1.0 wt%, or 2.0 wt%, or 2.5 wt%, or 3.0 wt% of UV absorber or stabilizer based on the total weight of the composition.

[0062] The polymer composition may contain fillers. Non-limiting examples of suitable fillers include carbon black, organoclay, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesia, calcium magnesium carbonate, hydrotalcite, boehmite, magnesium carbonate, magnesium phosphate, calcium hydroxide, calcium sulfate, silica, silicone rubber, talc, and combinations thereof. The filler may or may not have flame-retardant properties. In one embodiment, the filler is coated with a material that prevents or inhibits any tendency of the filler to interfere with the silane curing reaction. Stearic acid illustrates such a filler coating. 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 8.0% by weight, or 10.0% by weight, or 20% by weight of filler, based on the total weight of the polymer composition.

[0063] In one embodiment, the composition comprises a processing aid. Non-limiting examples of suitable processing aids include oils, polydimethylsiloxanes, organic acids (such as stearic acid), and metal salts of organic acids (such as 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 of processing aids.

[0064] In one embodiment, the composition contains 0% by weight, or greater than 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, 1.0% by weight, or 2.0% by weight, or 2.5% by weight, or 3.0% by weight, or 4.0% by weight, or 5.0% to 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, or 30% by weight, or 40% by weight, or 50% by weight of additives based on the total weight of the composition.

[0065] One or more of brominated flame retardants, zinc flame retardant synergists, and additives can be combined to form premixed masterbatches. Such masterbatches are typically formed by dispersing the brominated flame retardant, zinc flame retardant synergist, and / or additives into an inert plastic resin such as low-density polyethylene. Masterbatches are best formed by melt blending.

[0066] One or more of the components or masterbatches may be dried prior to compounding or extrusion, or the mixture of components or masterbatches may be dried after compounding or extrusion, to reduce or eliminate potential scorching that may be caused by moisture present in or associated with components, such as fillers. Compositions can be prepared in the absence of silanol condensation catalysts to extend shelf life, and silanol condensation catalysts may be added as a final step in the preparation of cable structures via extrusion processes.

[0067] Zn:Br molar ratio

[0068] The polymer composition contains a zinc flame retardant synergist and a brominated filler, wherein the relative amounts of the zinc flame retardant synergist and the brominated filler result in a zinc (Zn) to bromine (Br) molar ratio (Zn:Br molar ratio) greater than 0.0 to 0.160. For example, the Zn:Br molar ratio may be 0.010 or greater, or 0.020 or greater, or 0.030 or greater, or 0.040 or greater, or 0.050 or greater, or 0.060 or greater, or 0.070 or greater, or 0.080 or greater, or 0.090 or greater, or 0.100 or greater, or 0.110 or greater, or 0.120 or greater, or 0.130 or greater, or 0.140 or greater, or 0.150 or greater. Meanwhile, the Zn:Br molar ratio is calculated according to the following equation (1): 0.160 or less, or 0.150 or less, or 0.140 or less, or 0.130 or less, or 0.120 or less, or 0.110 or less, or 0.100 or less, or 0.090 or less, or 0.080 or less, or 0.070 or less, or 0.060 or less, or 0.050 or less, or 0.040 or less, or 0.030 or less, or 0.020 or less, or 0.010 or less.

[0069]

[0070] The number of moles of bromine from the brominated flame retardant in the polymer composition is calculated according to the following equation (1A):

[0071]

[0072] The atomic weight of bromine is 79.904 g / mol.

[0073] The number of moles of zinc from the zinc flame retardant synergist in the polymer composition is calculated according to the following equation (1B):

[0074]

[0075] The atomic weight of zinc is 65.38 g / mol.

[0076] The grams of bromine in the polymer composition can be easily determined by the amount of brominated flame retardant in the polymer composition and the amount of bromine in the brominated flame retardant. The grams of zinc in the polymer composition can be easily determined by the amount of zinc flame retardant synergist in the polymer composition and the amount of zinc in the zinc flame retardant synergist.

[0077] Coated conductor

[0078] This disclosure also provides a coated conductor. The coated conductor includes a conductor and a coating on the conductor, the coating comprising a polymer composition. The polymer composition is disposed at least partially around the conductor to produce a coated conductor.

[0079] A method for producing a coated conductor includes mixing a polymer composition and heating it to at least the melt temperature of a silane-functionalized polyolefin in an extruder, and then coating the polymeric melt blend onto a conductor. The term "on" includes direct or indirect contact between the polymeric melt blend and the conductor. The polymeric melt blend is in an extrudable state.

[0080] A polymer composition is disposed on and / or around a conductor to form a coating. The coating may be one or more inner layers, such as an insulating layer. The coating may completely or partially cover or otherwise surround or encapsulate the conductor. The coating may be the only component surrounding the conductor. Alternatively, the coating may be one layer in a multi-layered sheath or outer layer covering a metallic 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.

[0081] The resulting coated conductor (cable) is cured under humid conditions for a sufficient time to allow the coating to achieve the desired degree of crosslinking. The temperature during curing is typically above 0°C. In one embodiment, the cable is cured (aged) in a 90°C water bath for at least 4 hours. In another embodiment, the cable is cured (aged) under ambient conditions for up to 30 days, including air atmosphere, ambient temperature (e.g., 20°C to 40°C), and ambient relative humidity (e.g., 10% to 96% relative humidity (%RH)).

[0082] The coated conductor can pass the horizontal burning test. To pass the horizontal burning test, the total charring of the coated conductor must be less than 100 mm, and the cotton placed underneath must not ignite. A self-extinguishing time of less than 80 seconds is required. The coated conductor may have a total charring of 0 mm, or 5 mm, or 10 mm to 50 mm, or 55 mm, or 60 mm, or 70 mm, or 75 mm, or 80 mm, or 90 mm, or less than 100 mm during the horizontal burning test. The coated conductor may have a self-extinguishing time of 0 seconds, or 5 seconds, or 10 seconds to 30 seconds, or 35 seconds, or 40 seconds, or 50 seconds, or 60 seconds, or 70 seconds, or less than 80 seconds during the horizontal burning test.

[0083] The coated conductor can pass the VW-1 flammability test. To pass the VW-1 flammability test and thus achieve a VW-1 rating, the coated conductor must self-extinguish within 60 seconds (≤60 seconds) after the burner is removed, exhibiting ≤25% mark flammability and not exhibiting cotton-like burning, for each of five 15-second flame-spray cycles. In one embodiment, the self-extinguishing time of the coated conductor during the VW-1 flammability test is 0 to 20 seconds, or 30 seconds, or 40 seconds, or 50 seconds, or 60 seconds, or less than 60 seconds during each of the five individual cycles. In one embodiment, during the VW-1 combustion test, the length of the non-charring mark on the coated conductor is 20 mm, or 40 mm, or 50 mm, or 75 mm to 100 mm, or 110 mm, or 120 mm, or 130 mm, or 140 mm, or 150 mm, or 160 mm, or 180 mm, or 200 mm, or 250 mm, or 300 mm, or 350 mm, or 400 mm, or 500 mm, or 508 mm.

[0084] The coated conductor possesses one, some, or all of the following characteristics: (i) total charring from 0 mm to less than 100 mm during a horizontal burning test; (ii) self-extinguishing time from 0 seconds to less than 80 seconds during a horizontal burning test; and (iii) self-extinguishing time from 0 seconds to less than 60 seconds during a VW-1 test, during each of five individual cycles. The coated conductor passes both the horizontal burning test and / or the VW-1 burning test.

[0085] Example

[0086] Test methods

[0087] Density: Measured according to ASTM D792 Method B. Results are recorded in grams per cubic centimeter (g / cc).

[0088] Melt index: The melt index (MI) is measured according to ASTM D1238 at 190°C / 2.16 kg weight and reported in grams eluted per 10 minutes (g / 10 min).

[0089] Thermogravimetric analysis: using data from TA INSTRUMENTS TM Thermogravimetric analysis was performed using a Q5000 thermogravimetric analyzer. The thermogravimetric analysis was conducted in the following manner: at a flow rate of 100 cm⁻¹. 3 Under nitrogen atmosphere at a rate of 20°C / min, the material sample was placed on a platinum disk in a thermogravimetric analyzer. After equilibration at 40°C, the temperature was increased from 40°C to 650°C at a rate of 20°C / min, while simultaneously measuring the sample mass. From the generated data, a curve correlating temperature with the remaining mass % was plotted to determine the temperature at which a 5% mass loss of the sample was achieved. Similarly, from the generated data, a curve correlating temperature with the remaining mass % was plotted to determine the remaining mass % of the sample at 650°C, thus obtaining the retained mass at 650°C.

[0090] Crystallinity Test: The melting peak and percentage (%) or weight percentage (wt%) crystallinity of the ethylene-based polymer at 23°C were determined using a differential scanning calorimeter (DSC) instrument DSC Q1000 (TA Instruments). (A) Baseline Calibration of the DSC Instrument. The software calibration wizard was used. A baseline was obtained by heating the cells in an aluminum DSC disk from -80°C to 280°C without any sample. The sapphire standard was then used as indicated by the calibration wizard. Fresh indium samples from 1 mg to 2 mg were analyzed by heating the standard sample to 180°C, cooling it to 120°C at a cooling rate of 10°C / min, holding the standard sample isothermally at 120°C for 1 min, and then heating the standard sample from 120°C to 180°C at a heating rate of 10°C / min. The heat of fusion of the indium standard sample was determined to be 28.71 ± 0.50 J / g and the melting initiation was determined to be 156.6°C ± 0.5°C. (B) Perform DSC measurements on the test sample using a baseline-calibrated DSC instrument. Press the semi-crystalline ethylene polymer test sample into a film at 160°C. Weigh 5 mg to 8 mg of the test sample film into an aluminum DSC pan. Press the lid onto the pan to seal it and ensure a closed atmosphere. Place the lid-sealed pan in the DSC cell and allow the cell to equilibrate at 30°C. Then heat to 190°C at a rate of approximately 100°C / min, hold the sample at 190°C for 3 minutes, cool the sample to -60°C at a rate of 10°C / min to obtain the heat of fusion (Hf) of the cold curve, and hold isothermally at -60°C for 3 minutes. Then reheat the sample to 190°C at a rate of 10°C / min to obtain the heat of fusion (ΔHf) of the second heating curve.f Using a second heating curve, the temperature was measured from -20°C (for ethylene homopolymers, copolymers of ethylene and hydrolyzable silane monomers, with a density greater than or equal to 0.90 g / cm³). 3 In the case of ethylene-α-olefin copolymers) or -40°C (in the case of copolymers of ethylene and unsaturated esters, and with a density less than 0.90 g / cm³) 3 In the case of ethylene-α-olefin copolymers, the "total" heat of fusion (J / g) is calculated by integrating to the melting endpoint. Using a second heating curve, the "room temperature" heat of fusion (J / g) from 23°C (room temperature) to the melting endpoint is calculated by vertical drop at 23°C. The "total crystallinity" (calculated from the "total" heat of fusion) and the "crystallization at room temperature" (calculated from the heat of fusion at 23°C) are measured and reported. The heat of fusion (ΔH) from the second heating curve of the test sample is also calculated. f Crystallinity is measured by the heat of fusion of 100% crystalline polyethylene and normalized to its heat of fusion, and reported as a percentage (%) or weight percentage (wt%) of the polymer crystallinity, where % crystallinity or weight % crystallinity = (ΔH) / (wt%). f *100%) / 292J / g, where ΔH f As defined above, * represents mathematical multiplication, / represents mathematical division, and 292 J / g is the heat of fusion (ΔH) of 100% crystalline polyethylene. f The literature value of ).

[0091] VW-1 Burning Test: The VW-1 burning test is conducted by subjecting three samples of a specific coated conductor to the protocol outlined in Section 9.4 of UL 2556. This involves applying a 125 mm flame and striking a vertically oriented specimen (610 mm (24 in) at a 20° angle for five 15-second periods. A 12.5 ± 1 mm (0.5 ± 0.1 in) strip of kraft paper is attached to the specimen at a distance of 254 ± 2 mm (10 ± 0.1 in) above the point of impact with the flame. A continuous horizontal layer of cotton is placed on the floor of the test chamber, centered on the vertical axis of the test specimen, with the upper surface of the cotton 235 ± 6 mm (9.25 ± 0.25 in) below the point where the blue inner cone tip of the flame strikes the specimen. Failure is based on the criteria of burning 25% of the kraft paper strip mark, igniting the cotton, or the specimen burning for more than 60 seconds in any of the five flame applications. As an additional measurement of burning performance, the length of the uncharred insulation (uncharred mark length) is measured at the end of the test. Take the average self-extinguishing time of 3-5 samples and 5 cycles to determine the “VW-1 Average Self-Extinguishing Time” provided in Table 2. The VW-1 cotton ignition indicator shows whether the falling material ignites the cotton bed.

[0092] Horizontal Burning Test: The horizontal burning test is performed according to UL-2556. The test is performed by placing the coated conductor in a horizontal position. Cotton is placed below the coated conductor. The burner is set at a 20° angle relative to the horizontal sample (14AWG copper wire with a coating wall thickness of 30 mils). A one-time flame is applied to the center of the sample for 30 seconds. The sample fails the test when (i) the cotton ignites and / or (ii) the sample chars beyond 100 mm. The char length is measured according to UL-1581, 1100.4.

[0093] Molar number of zinc: from the following FIREBRAKE in the polymer composition TM The number of moles of zinc in ZB-Fine zinc borate is calculated according to the following equation (2):

[0094]

[0095] Among them, FIREBRAKE TM The molecular weight of ZB-Fine (zinc borate = 2ZnO·3B2O3·3.5H2O) is 434.66 g / mol. Based on the safety data sheet, FIREBRAKE... TM ZB-FINE has a purity greater than 98.8% and a relative molar ratio of zinc to zinc borate of 2.

[0096] Material

[0097] Materials used in the embodiments are provided below.

[0098] The silane-functionalized polyolefin is an ethylene / silane copolymer with a density of 0.922 g / cc, a crystallinity of 46.9% by weight at 23°C, and a melt index of 1.5 g / 10 min (190°C / 2.16 kg). It can also be used as a SI-LINK... TM DFDA-5451NT was commercially available from The Dow Chemical Company (Midland, Michigan). As measured by thermogravimetric analysis (except for a rate of 10 °C / min, which is not 20 °C / min used for brominated FR), silane-functionalized polyolefins have a 5% mass loss at 425 °C. As measured by thermogravimetric analysis (except for a rate of 10 °C / min, which is not 20 °C / min used for brominated FR), silane-functionalized polyolefins have a 0% (wt%) mass retention at 650 °C.

[0099] ULDPE is a polyethylene resin with a density of 0.904 g / cc, a crystallinity of 37% by weight at 23°C, and a melt index of 4 g / 10 min (190°C / 2.16 kg). It can also be used as an ATTANE...TM 4404G was purchased from The Dow Chemical Company (Midland, Michigan).

[0100] FR bromide is ethylene bis(tetrabromophthalimide) and can be used as SAYTEX. TM BT-93W was commercially available from Albemarle (Charlotte, North Carolina). As measured by thermogravimetric analysis, FR bromide has a 5% mass loss at 442°C. As measured by thermogravimetric analysis, FR bromide has a retention mass of 10% to 20% by weight at 650°C.

[0101] Zn FR is 2ZnO·3B2O3·3.5H2O with a median particle size of 2.1 μm, as measured by laser diffraction, and can be used as a firebrake. TM ZB-fine was purchased from Rio Tinto (London, England).

[0102] AO can be used as IRGANOX TM 1010 is a sterically hindered phenolic antioxidant with the chemical name pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid), which was commercially available from BASF (Ludwigshafen, Germany).

[0103] The catalyst masterbatch is a blend of polyolefins, phenolic compounds and 1.7% by weight of dibutyltin dilaurate as a silanol condensation catalyst.

[0104] Sample preparation

[0105] By using the materials in Table 1, excluding the catalyst masterbatch, in BRABENDER TM Samples were prepared by melt blending at 70 rpm for 3 minutes at a temperature between 140°C and 195°C in a mixer. The melt-blended samples were pressed into blocks and then cut into granules. The granules were dried in a vacuum oven at 70°C for 16 hours. The granules were then blended with granules of the specified catalyst masterbatch in solid form. A 3 / 4-inch branender was used. TM An extruder and a standard polyethylene screw melt-mix the combined granules at a temperature distribution of 150°C / 180°C / 180°C / 180°C. The material is extruded onto 14AWG solid copper wire to form a cable with a polymer sheath of 0.762mm thickness. The cable is cured in a 90°C water bath for 16 hours.

[0106] Table 1 provides the materials used to form Comparative Examples (“CE”) 1 and 2 and Embodiment 1 of the present invention (“IE”). The amount of each material used is given as a weight percentage based on the total weight of the respective embodiment.

[0107] Table 1

[0108] Silane-functionalized polyolefins 38.80 38.80 38.80 ULDPE 14.36 14.36 14.36 FR bromide 43.65 34.92 32.79 Zn FR 0 8.73 10.86 AO 0.19 0.19 0.19 Catalyst masterbatch 3.00 3.00 3.00 gross weight% 100.00 100.00 100.00 Zn:Br molar ratio 0.0 0.135 0.179

[0109] result

[0110] Table 2 provides the test results for Comparative Examples 1 and 2, as well as Example 1 of the present invention.

[0111] Table 2

[0112]

[0113] As can be seen from Table 2, CE1 and IE1 passed the VW-1 flammability test, while CE2 did not. The average self-extinguishing time of CE1 is reported as 9 / 13 because two sets of tests were conducted, one with an average time of 9 seconds and the other with an average time of 13 seconds. This result is surprising, as it is expected that increasing the weight percentage of the flame retardant synergist would enhance the flame retardant properties of the polymer composition. However, it has been found that zinc flame retardant synergists can be added to the polymer composition to help compensate for the concentration of the relatively more expensive brominated flame retardant, but only up to a certain point, after which the polymer composition begins to fail the VW-1 flammability test. Therefore, polymer compositions that do not contain antimony trioxide and have a Zn:Br molar ratio greater than 0.0 to 0.160 not only pass the VW-1 flammability test but also offer polymer compositions with lower manufacturing costs and reduced environmental impact compared to conventional polymer compositions. The VW-1 flammability test is more stringent than the horizontal flammability test. Therefore, coated conductors that pass the VW-1 flammability test are likely to pass the horizontal flammability test as well.

Claims

1. A polymer composition comprising: Based on the total weight of the polymer composition, 20% to 80% by weight of silane-functionalized polyolefin; A brominated flame retardant having a 5% mass loss at temperatures ranging from 350°C to 500°C and a retention mass at 650°C ranging from 2% to 50% by weight, wherein the 5% mass loss and the retention mass at 650°C are measured by thermogravimetric analysis; and 0.5% by weight or more and 10% by weight or less of a zinc (Zn) flame retardant synergist, wherein the zinc flame retardant synergist is selected from: zinc borate, zinc carbonate, zinc carbonate hydroxide, hydrated zinc borate, zinc phosphate, zinc stannate, zinc hydroxystannate, zinc sulfide, zinc oxide, and combinations thereof. The polymer composition thereof is free of antimony trioxide and has a zinc to bromine (Br) molar ratio (Zn:Br molar ratio) greater than 0.0 to 0.

160.

2. The polymer composition according to claim 1, wherein the polymer composition further comprises: From 0.001% to 5.0% by weight of the silanol condensation catalyst based on the total weight of the polymer composition.

3. The polymer composition according to claim 1 or 2, wherein the polymer composition further comprises: The second polyolefin comprises 5% to 30% by weight of the total weight of the polymer composition, wherein the crystallinity of the second polyolefin at 23°C is 0% to 80% by weight, as measured by a crystallinity test.

4. The polymer composition according to claim 1 or 2, wherein the brominated flame retardant comprises ethylene bis(tetrabromophthalimide).

5. The polymer composition according to claim 4, wherein the polymer composition comprises 5% to 45% by weight of ethylene bis(tetrabromophthalimide) based on the total weight of the polymer composition.

6. The polymer composition according to claim 1 or 2, wherein the polymer composition comprises 30% to 52% by weight of the silane-functionalized polyolefin based on the total weight of the polymer composition.

7. The polymer composition according to claim 1 or 2, wherein the zinc flame retardant synergist is selected from zinc borate, zinc borate hydrate, and combinations thereof.

8. The polymer composition according to claim 1 or 2, wherein the Zn:Br molar ratio is greater than 0.0 to 0.

135.

9. The polymer composition according to claim 1 or 2, wherein the Zn:Br molar ratio is from 0.010 to 0.

160.

10. The polymer composition according to claim 1 or 2, wherein the Zn:Br molar ratio is from 0.050 to 0.

150.

11. The polymer composition according to claim 1 or 2, wherein the Zn:Br molar ratio is from 0.100 to 0.

140.

12. A coated conductor, the coated conductor comprising: conductor; as well as A polymer composition according to any one of claims 1 to 11, disposed at least partially around the conductor.

13. The coated conductor of claim 12, wherein the coated conductor passes a horizontal burning test.

14. The coated conductor according to claim 12 or 13, wherein the coated conductor passes the VW-1 combustion test.

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