Polymeric compositions comprising cure boosters

Abstract

A polymeric composition includes an ethylene-based polymer, 0.75 wt% to 1.5 wt% of a free radical generator based on the total weight of the polymeric composition, 0.8 wt% to 5 wt% of one or more cure boosters based on the total weight of the polymeric composition. The cure boosters comprise 2 or more vinyl moieties. The polymeric composition also includes 0.1 wt% to 2 wt% a polyalkylene glycol based on the total weight of the polymeric composition and 0.1 wt% to 2 wt% of one or more antioxidants based on the total weight of the polymeric composition.

Description

[0001] POLYMERIC COMPOSITIONS COMPRISING CURE BOOSTERS

[0002] BACKGROUND

[0003] Field of the disclosure

[0004] The disclosure generally relates to polymeric compositions and more specifically to polymeric compositions comprising cure boosters.

[0005] Introduction

[0006] Polymeric compositions must meet a variety of different properties based on the use environment of the composition. For example, polymeric compositions utilized in wires and cables often must meet mechanical and thermal properties to ensure reliable transmission of electricity and telecommunications. The mechanical and thermal properties of polymeric compositions are often increased by crosslinking, or curing, of the polymers of the polymeric composition. Crosslinking is achieved by introducing one or more free radical generators to the polymeric composition such that hydrogen is abstracted from backbones of polymeric chains forming free radical sites. Typically, about 1.7 weight percent (“wt%”) dicumyl peroxide is used. The free radical sites on the backbones then form covalent bonds between the backbones. The free radicals are often generated using a free radical generator such as a peroxide, and the crosslinking may be enhanced with one or more cure boosters. Cure boosters are typically a multifunctional (e.g., vinyl) monomer capable of reacting with two or more free radical sites across two or more polymer backbones. United States patent number 4,440,671 (“the ‘671 patent”) discloses the use of dicumyl peroxide as a free radical generator as well as a siloxane cure booster. World Intellectual Property Organization publication W02014040237 discloses triallylisocyanurate (“TAIC”) as another cure booster. Typically, a polymeric composition is considered sufficiently cured if it exhibits a maximum torque in moving die rheometer testing (“MDR:MH”) of 2.6 in-lb or greater as measured according to MDR:MH Testing.

[0007] Crosslinking polymeric compositions does not come without drawbacks. The use of peroxides, such as dicumyl peroxide, often means that the resulting crosslinked products need the be degassed. Degassing refers to a manufacturing process where trapped gases, primarily byproducts of the crosslinking reaction, are removed from the polymeric insulation material (like XLPE) used in power cables, significantly improving the cable's electrical properties and reliability by reducing potential micro-voids and enhancing dielectric performance. Degassing, however, is costly from a money and time perspective.Mechanical and thermal properties are not the only properties of interest in polymeric compositions. For example, water is present to some degree in most environments, and it can negatively impact the electrical properties of polymeric compositions. One property of particular interest with respect to water is water tree resistance. Water trees are networks of micro-voids and channels filled with water that form in the insulation of power cables. Water trees are caused by water and alternating electric fields emanating from contaminants or voids positioned within the insulation.

[0008] Polymeric compositions can be made water tree resistant through the incorporation of water tree retardant additives such as alkylene glycols and antioxidants. Unfortunately, the additives designed to combat water trees directly act against the crosslinking reaction. For example, antioxidants quench free radical sites thereby decreasing the crosslinking efficacy of the peroxides used. Further, the alkylene glycol preferentially develops free radical sites relative to the polyethylene. The alkylene glycol preferentially develops the radical sites because oxygen molecules of the alkylene glycol are more electronegative than carbon and therefore the hydrogens on the adjacent carbons are more likely to be abstracted by free radical generators. Such a result is not advantageous because this results in lower rates of polymeric backbones crosslinking and cure booster crosslinking. The ‘671 patent demonstrates this effect in control sample C where antioxidants and polyethylene glycol are added, but the cure level is the lowest of the samples despite the same amount of peroxide curing agent.

[0009] In view of the foregoing, it would be surprising to discover a polymeric composition comprising less than 1.7 wt% of a free radical generator, polyethylene glycol and antioxidants that still exhibits a cure of 2.6 in-lb or greater as measured according to MDR:MH Testing.

[0010] SUMMARY OF THE DISCLOSURE

[0011] The inventors of the present application have discovered a polymeric composition comprising less than 1.7 wt% of a free radical generator, polyethylene glycol and antioxidants, that still exhibits a cure of 2.6 in-lb or greater as measured according to MDR:MH Testing.

[0012] The invention is a result of discovering that cure boosters are the most preferential target for the free radical generators. Without being bound by theory, inclusion of the cure boosters in the polymeric composition concentrates free radicals on the cure booster as opposed to polyalkylene glycols and antioxidants. Such an effect is advantageous as radicals on the cure boosters are effective at promoting crosslinking, whereas free radical interaction with the polyalkylene glycol and antioxidants does not promote crosslinking. In essence, the inclusion of cure boosters maximizes the curing potential of the free radical generator to promotecrosslinking while not negatively impacting the water tree performance of the polymeric composition.

[0013] According to a first feature of the disclosure, a polymeric composition comprises, an ethylene-based polymer; 0.75 wt% to 1.5 wt% of a free radical generator based on the total weight of the polymeric composition; 0.8 wt% to 5 wt% of one or more cure boosters based on the total weight of the polymeric composition, wherein the cure boosters comprise 2 or more vinyl moieties: 0.1 wt% to 2 wt% a polyalkylene glycol based on the total weight of the polymeric composition; and 0.1 wt% to 2 wt% of one or more antioxidants based on the total weight of the polymeric composition.

[0014] According to another feature of the disclosure, the ethylene-based polymer exhibits one or more of features (i) to (iii): (i) the ethylene-based polymer has a density of 0.910 g / cc to 0.940 g / cc as measured according to ASTM D1238; (ii) the polymeric composition comprises 87.00 wt% or greater of the ethylene-based polymer based on the total weight of the polymeric composition; and (iii) the ethylene-based polymer is an ethylene homopolymer.

[0015] According to another feature of the disclosure, the free radical generator exhibits one or more of features (i) to (iv): (i) the free radical generator is a peroxide; (ii) the free radical generator comprises dicumyl peroxide; (iii) the free radical generator is present in the polymeric composition in an amount of 0.8 wt% to 1.5 wt% based on the total weight of the polymeric composition; and (iv) the free radical generator is present in the polymeric composition in an amount of 0.98 wt% to 1.2 wt% based on the total weight of the polymeric composition.

[0016] According to another feature of the disclosure, the polymeric composition comprises from 0.2 wt% to 1.0 wt% of the one or more antioxidant based on the total weight of the polymeric composition.

[0017] According to another feature of the disclosure, the wherein the polyalkylene glycol exhibits one or more of features (i) to (iii): (i) wherein the polyalkylene glycol comprises polyethylene glycol; (ii) the polyalkylene glycol has a weight average molecular weight of from 5,000 g / mol to 30,000 g / mol as measured according to gel permeation chromatography; and (iii) the polyalkylene glycol is present in the polymeric composition in an amount from 0.1 wt% to 1.0 wt% based on the total weight of the polymeric composition

[0018] According to another feature of the disclosure, the polymeric composition comprises from 1.0 wt% to 2.0 wt% of cure boosters based on the total weight of the polymeric composition.According to another feature of the disclosure, the polymeric composition comprises from 1.1 wt% to 1.5 wt% of cure boosters based on the total weight of the polymeric composition.

[0019] According to another feature of the disclosure, the cure booster exhibits one or more of features (i) to (vii): (i) wherein the cure booster comprises 3 or more vinyl moieties; (ii) wherein the cure booster comprises 4 or more vinyl moieties; (iii) wherein the cure booster comprises nitrogen; (iv) wherein the cure booster comprises oxygen; (v) wherein the cure booster comprises silicon; (vi) wherein cure booster comprises triallylisocyanurate; and (vii) wherein cure booster comprises 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.

[0020] According to another feature of the disclosure, a method comprises the steps of: crosslinking the polymeric composition of claim 1 to a cure of 2.6 in-lb or greater to form a crosslinked polymeric coating; and degassing the polymeric composition for a time period of 2 weeks or less.

[0021] According to another feature of the disclosure, a coated conductor, comprises a conductor; and the crosslinked polymeric coating of claim 9 positioned around the conductor.

[0022] DETAILED DESCRIPTION

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

[0024] All ranges include endpoints unless otherwise stated.

[0025] Test methods refer to the most recent test method as of the priority date of this document unless a date is indicated with the test method number as a hyphenated two-digit number. References to test methods contain both a reference to the testing society and the test method number. Test method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly known as American Society for Testing and Materials); EN refers to European Norm; DIN refers to Deutsches Institut fur Normung; and ISO refers to International Organization for Standards.

[0026] As used herein, the term weight percent (“wt%”) designates the percentage by weight a component is of a total weight of the polymeric composition unless otherwise specified.Melt index (I2) values herein refer to values determined according to ASTM method DI 238 at 190 degrees Celsius (°C) with a 2.16 Kilogram (kg) mass and are provided in units of grams eluted per ten minutes (“g / 10 min”).

[0027] Density values herein refer to values determined according to ASTM D792 at 23 °C and are provided in units of grams per cubic centimeter (“g / cc”).

[0028] As used herein, Chemical Abstract Services registration numbers (“CAS#”) refer to the unique numeric identifier as most recently assigned as of the priority date of this document to a chemical compound by the Chemical Abstracts Service.

[0029] Polymeric Composition

[0030] The present disclosure is directed to a polymeric composition. The polymeric composition comprises an ethylene-based polymer, a free radical generator, one or more cure boosters, a polyalkylene glycol, and one or more antioxidants. The polymeric composition may exhibit an MDR:MH value of 2.6 in-lb or greater as measured according to MDR:MH Testing. For example, the polymeric composition may exhibit an MDR:MH value of 2.6 in-lb or greater, or 2.7 in-lb or greater, or 2.8 in-lb or greater, or 3.0 in-lb or greater, or 3.2 in-lb or greater, or 3.4 in-lb or greater, or 3.6 in-lb or greater, or 3.8 in-lb or greater, or 4.0 in-lb or greater as measured according to MDR:MH Testing.

[0031] Ethylene-Based Polymer

[0032] As noted above, the composition may comprise the ethylene-based polymer. The ethylene -based polymer may have one or more of features (i) to (iii): (i) the ethylene-based polymer has a density of 0.910 g / cc to 0.940 g / cc as measured according to ASTM D1238; (ii) the polymeric composition comprises 87.00 wt% or greater of the ethylene-based polymer based on the total weight of the polymeric composition; and (iii) the ethylene-based polymer is an ethylene homopolymer.

[0033] As used herein, “ethylene -based” polymers are polymers in which greater than 50 wt% of the monomers are ethylene though other co-monomers may also be employed. Ethylenebased polymers include ethylene and one or more C3-C20 a-olefin comonomers such as propylene, 1 -butene, 1 -pentene, 4-methyl-l -pentene, 1 -hexene, and 1 -octene. In a specific example, the ethylene-based polymer is a copolymer of ethylene and hexene. In another example, the ethylene-based polymer may be a copolymer of ethylene and butene. In another example, the ethylene-based polymer is a homopolymer of ethylene.The ethylene -based polymer may comprise 50 wt% or greater, 60 wt% or greater, 70 wt% or greater, 80 wt% or greater, 85 wt% or greater, 90 wt% or greater, or 91 wt% or greater, or 92 wt% or greater, or 93 wt% or greater, or 94 wt% or greater, or 95 wt% or greater, or 96 wt% or greater, or 97 wt% or greater, or 97.5 wt% or greater, or 98 wt% or greater, or 99 wt% or greater, while at the same rime, 99.5 wt% or less, or 99 wt% or less, or 98 wt% or less, or 97 wt% or less, or 96 wt% or less, or 95 wt% or less, or 94 wt% or less, or 93 wt% or less, or 92 wt% or less, or 91 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or 70 wt% or less, or 60 wt% or less of ethylene monomers as measured using Nuclear Magnetic Resonance (NMR) or Fourier-Transform Infrared (FTIR) Spectroscopy.

[0034] Other units of ethylene-based polymers may be derived from one or more polymerizable monomers including, but not limited to, polar monomers such as unsaturated esters. The unsaturated esters (i.e. polar monomers) may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have from 1 to 8 carbon atoms, or from 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8 carbon atoms, or from 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2 ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate. The ethylene-based polymer may have a polar comonomer content of 40 wt% or less, or 35 wt% or less, or 30 wt% or less, or 25 wt% or less, or 20 wt% or less, 15 wt%, or 10 wt%, or 5 wt% or less, or 3 wt% or less, or 1 wt% or less, or 0 wt% based on the total weight of the ethylene-based polymer as measured using Nuclear Magnetic Resonance (NMR) or Fourier-Transform Infrared (FTIR) Spectroscopy.

[0035] The ethylene-based polymer can have a unimodal or a multimodal molecular weight distribution and can be used alone or in combination with one or more other types of ethylenebased polymers (e.g., a blend of two or more ethylene-based polymers that differ from one another by monomer composition and content, catalytic method of preparation, molecular weight, molecular weight distributions, densities, etc.). If a blend of ethylene-based polymers is employed, the polymers can be blended by any in-reactor or post-reactor process. The term “multimodal polymer” refers to polymers that are characterized by having at least two distinct peaks in a gel permeation chromatography (GPC) chromatogram depicting the molecular weight distribution of the composition. Accordingly, the generic term multimodal polymer includes bimodal polymers, which have two primary fractions: a first fraction, which may be alow molecular weight fraction and / or component, and a second fraction, which may be a high molecular weight fraction and / or component.

[0036] The polymeric composition may comprise from 60 wt% to 99 wt% of the ethylenebased polymer based on a total weight of the polymeric composition. For example, the polymeric composition may comprise from 60 wt% or greater, or 65 wt% or greater, or 70 wt% or greater, or 75 wt% or greater, or 80 wt% or greater, or 85 wt% or greater, or 90 wt% or greater, or 92 wt% or greater, or 94 wt% or greater, or 96 wt% or greater, or 97 wt% or greater, while at the same time, 99 wt% or less, or 98 wt% or less, or 96 wt% or less, or 94 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or 75 wt% or less, or 70 wt% or less, or 65 wt% or less of the ethylene-based polymer based on a total weight of the polymeric composition.

[0037] The ethylene -based polymer has a density of 0.885 g / cc to 0.940 g / cc as measured according to ASTM D792. For example, the ethylene-based polymer has a density of 0.885 g / cc or greater, or 0.89 g / cc or greater, or 0.90 g / cc or greater, or 0.91 g / cc or greater, or 0.92 g / cc or greater, or 0.94 g / cc or greater, or 0.96 g / cc or greater while at the same time, 0.940 g / cc or less, or 0.930 g / cc or less, or 0.920 g / cc or less, or 0.910 g / cc or less, or 0.900 g / cc or less, or 0.890 g / cc or less as measured according to ASTM D792.

[0038] The ethylene -based polymer has a melting peak temperature of 100°C to 130°C as measured according to Differential Scanning Calorimetry. For example, the ethylene-based polymer has a melting peak temperature of 100°C or greater, or 102°C or greater, or 104°C or greater, or 106°C or greater, or 108°C or greater, or 110°C or greater, or 112°C or greater, or 114°C or greater, 116°C or greater, or 118°C or greater, 120°C or greater, or 122°C or greater, 124°C or greater, or 126°C or greater, 128°C or greater, while at the same time, 130°C or less, or 128°Corless, or 126°C or less, or 124°Cor less, or 122°C or less, or 120°Corless, or 118°C or less, or 116°C or less, or 114°C or less, or 112°C or less, orll0°C or less, or 108°C or less, or 106°C or less, or 104°C or less, or 102°C or less as measured according to Differential Scanning Calorimetry.

[0039] The ethylene-based polymer may have a melt index (I2) of 0.1 g / 10 min to 10 g / 10 min. as measured according to ASTM D1238. For example, the ethylene-based polymer may have a melt index (I2) of 0.3 g / 10 min or greater, or 0.4 g / 10 min or greater, or 0.5 g / 10 min or greater, or 0.6 g / 10 min or greater, or 0.7 g / 10 min or greater, or 0.8 g / 10 min or greater, or 0.9 g / 10 min or greater, or 1.0 g / 10 min or greater, or 1.9 g / 10 min or greater, or 2.0 g / 10 min or greater, or 4.0 g / 10 min or greater, or 6.0 g / 10 min or greater, or 8.0 g / 10 min or greater, while at the same time, 10 g / 10 min or less, or 8.0 g / 10 min or less, or 6.0 g / 10 min or less, or 4.0g / 10 minor less, or 2.0 g / 10 min or less, or 1.9 g / 10 min or less, or 1.0 g / 10 min or less, or 0.9 g / 10 min or less, or 0.8 g / 10 min or less, or 0.7 g / 10 min or less, or 0.6 g / 10 min or less, or 0.5 g / 10 min or less, or 0.4 g / 10 min or less, or 0.3 g / 10 min or less, or 0.2 g / 10 min or less as measured according to ASTM D1238.

[0040] Free Radical Generator

[0041] The polymeric composition comprises a free radical generator. As used herein, the term “free radical generator” means a molecule that can create one or more free radicals. As used herein, the term “free radical” means an atom, molecule, moiety or ion that has at least one unpaired valence electron. The free radical generator may comprise a peroxide, an organic peroxide, tert-Butyl hydroperoxide, dicumyl peroxide, tert-butylperoxybenzoate, dibenzoyl peroxide, peroxyacetic acid, azonitriles, azobisisobutyronitrile, azirines and combinations thereof.

[0042] The polymeric composition may comprise 0.75 wt% to 1.5 wt% of a free radical generator based on the total weight of the polymeric composition. For example, the polymeric composition may comprise 0.75 wt% or greater, or 0.8 wt% or greater, or 0.9 wt% or greater, or 0.98 wt% or greater, or 1.0 wt% or greater, or 1.1 wt% or greater, or 1.2 wt% or greater, or 1.3 wt% or greater, or 1.4 wt% or greater, while at the same time, 1.5 wt% or less, or 1.4 wt% or less, or 1.3 wt% or less, or 1.2 wt% or less, or 1.1 wt% or less, or 1.0 wt% or less, or 0.98 wt% or less, or 0.9 wt% or less, or 0.8 wt% or less of a free radical generator based on the total weight of the polymeric composition

[0043] Cure Booster

[0044] The polymeric composition comprises one or more cure boosters. A "cure booster" is a chemical additive that is added to a polymer system to increase efficiency of the curing, or crosslinking, process relative to systems without cure boosters. As used herein, a “cure booster” is an organic molecule comprising two or more vinyl moieties. Cure boosters may comprise three or more vinyl moieties, four or more vinyl moieties. The cure boosters may also comprise nitrogen, oxygen, silicon and other elements. Exemplary cure boosters include triallylisocyanurate, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, triallyl cyanurate, 2,4,6-trimethylstyrene, trimethylolpropanetriacrylate, triallyltrimelitate, and polybutadiene, N,N,N',N',N",N''-hexaallyl-l,3,5- triazine-2,4,6-triamine; triallyl orthoformate; pentaerythritol triallyl ether: triallyl citrate; or triallyl aconitate, other cure boosters and combinations thereof.The polymeric composition may comprise 0.8 wt% to 5 wt% of one or more cure boosters based on the total weight of the polymeric composition. For example, the polymeric composition may comprise 0.8 wt% or greater, or 1.0 wt% or greater, or 1.1 wt% or greater, or 1.2 wt% or greater, or 1.4 wt% or greater, or 1.6 wt% or greater, or 1.8 wt% or greater, or 2.0 wt% or greater, or 2.2 wt% or greater, or 2.4 wt% or greater, or 2.6 wt% or greater, or 2.8 wt% or greater, or 3.0 wt% or greater, or 3.2 wt% or greater, or 3.4 wt% or greater, or 3.6 wt% or greater, or 3.8 wt% or greater, or 4.0 wt% or greater, or 4.2 wt% or greater, or 4.4 wt% or greater, or 4.6 wt% or greater, or 4.8 wt% or greater, while at the same time, 5.0 wt% or less, or 4.8 wt% or less, or 4.6 wt% or less, or 4.4 wt% or less, or 4.2 wt% or less, or 4.0 wt% or less, or 3.8 wt% or less, or 3.6 wt% or less, or 3.4 wt% or less, or 3.2 wt% or less, or 3.0 wt% or less, or 2.8 wt% or less, or 2.6 wt% or less, or 2.4 wt% or less, or 2.2 wt% or less, or 2.0 wt% or less, or 1.8 wt% or less, or 1.6 wt% or less, or 1.4 wt% or less, or 1.2 wt% or less, or 1.0 wt% or less of one or more cure boosters based on the total weight of the polymeric composition.

[0045] Polyalkylene Glycol

[0046] The polymeric composition comprises the polyalkylene glycol. The polyalkylene glycol comprises a plurality of alkylene glycol monomeric units along its backbone. For example, the polyalkylene glycol may comprise ethylene oxide, propylene oxide, butylene oxide, or combinations thereof. In a specific example, the polyalkylene glycol may be 50 wt% or greater, or 60 wt% or greater, or 70 wt% or greater, or 80 wt% or greater, or 90 wt% or greater, or 99 wt% or greater of ethylene oxide based on the total weight of the polyalkylene glycol. Alternatively, the polyalkylene glycol may be a homopolymer of any of the aforementioned alkylene glycols.

[0047] The polyalkylene glycol may have a weight average molecular weight of 500 g / mol to 50,000 g / mol as measured according to Gel Permeation Chromatography. For example, the polyalkylene glycol may have a weight average molecular weight of 200 g / mol or greater, or 500 g / mol or greater, or 1000 g / mol or greater, or 2000 g / mol or greater, or 3000 g / mol or greater, or 4000 g / mol or greater, or 5000 g / mol or greater, or 6000 g / mol or greater, or 7000 g / mol or greater, or 8000 g / mol or greater, or 9000 g / mol or greater, or 10000 g / mol or greater, or 11000 g / mol or greater, or 12000 g / mol or greater, or 13000 g / mol or greater, or 14000 g / mol or greater, or 15000 g / mol or greater, or 16000 g / mol or greater, or 17000 g / mol or greater, or 18000 g / mol or greater, or 19000 g / mol or greater, or 20000 g / mol or greater, or 30000 g / mol or greater, or 40000 g / mol or greater, while at the same time, 50,000 g / mol or less, or 40000g / mol or less, or 30000 g / mol or less, or 20000 g / mol or less, or 19000 g / mol or less, or 18000 g / mol or less, or 17000 g / mol or less, or 16000 g / mol or less, or 15000 g / mol or less, or 14000 g / mol or less, or 13000 g / mol or less, or 12000 g / mol or less, or 11000 g / mol or less, or 10000 g / mol or less, or 9000 g / mol or less, or 8000 g / mol or less, or 7000 g / mol or less, or 6000 g / mol or less, or 5000 g / mol or less, or 4000 g / mol or less, or 3000 g / mol or less, or 2000 g / mol or less, or 1000 g / mol or less, or 500 g / mol or less as measured according to Gel Permeation Chromatography.

[0048] The polymeric composition may comprise 0.1 wt% to 2.0 wt% of the polyalkylene glycol based on the total weight of the polymeric composition. For example, the polymeric composition may comprise 0.1 wt% or greater, or 0.2 wt% or greater, or 0.3 wt% or greater, or 0.4 wt% or greater, or 0.5 wt% or greater, or 0.6 wt% or greater, or 0.7 wt% or greater, or 0.8 wt% or greater, or 0.9 wt% or greater, or 1.0 wt% or greater, or 1.1 wt% or greater, or 1.2 wt% or greater, or 1.3 wt% or greater, or 1.4 wt% or greater, or 1.5 wt% or greater, or 1.6 wt% or greater, or 1.7 wt% or greater, or 1.8 wt% or greater, or 1.9 wt% or greater, while at the same time, 2.0 wt% or less, or 1.9 wt% or less, or 1.8 wt% or less, or 1.7 wt% or less, or 1.6 wt% or less, or 1.5 wt% or less, or 1.4 wt% or less, or 1.3 wt% or less, or 1.2 wt% or less, or 1.1 wt% or less, or 1.0 wt% or less, or 0.9 wt% or less, or 0.8 wt% or less, or 0.7 wt% or less, or 0.6 wt% or less, or 0.5 wt% or less, or 0.4 wt% or less, or 0.3 wt% or less, or 0.2 wt% or less of the polyalkylene glycol based on the total weight of the polymeric composition.

[0049] Additives

[0050] The polymeric composition may comprise additional additives in the form of antioxidants, carbon black, cross-linking co-agents, cure boosters and scorch retardants, processing aids, coupling agents, ultraviolet stabilizers (including UV absorbers), antistatic agents, additional nucleating agents, slip agents (i.e., silicone gums), lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, extender oils, acid scavengers, antidrip agents (e.g., ethylene vinyl acetate) and metal deactivators. The polymeric composition may comprise from 0.01 wt% to 20 wt% of one or more of the additional additives.

[0051] The UV light stabilizers and antioxidants may comprise hindered amine light stabilizers (“HALS”) and UV light absorber (“UVA”) additives. Representative UVA additives include benzotriazole types such as TINUVIN 326™ light stabilizer and TINUVIN 328™ light stabilizer commercially available from BASF, Inc. Blends of HAL’s and UVA additives are also effective.The antioxidants may comprise hindered phenols such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydro-cinnamate)]methane; bis[(beta-(3,5-ditert-butyl-4-hydroxybenzyl) methylcarboxy ethyl)] -sulphide, 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiobis(2-tert-butyl-5-methylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), and thiodiethylene bis(3,5-di-tert-butyl-4-hydroxy)-hydrocinnamate; phosphites and phosphonites such as tris(2,4-di-tert-butylphenyl)phosphite and di-tert-butylphenyl-phosphonite; thio compounds such as dilaurylthiodipropionate, dimyristylthiodipropionate. and distearylthiodipropionate; various siloxanes; polymerized 2,2,4-trimethyl-l,2-dihydroquinoline, n,n’-bis(l ,4-dimethylpentyl-p-phenylenediamine), alkylated diphenylamines, 4,4’-bis(alpha, alpha-dimethylbenzyl)diphenylamine, diphenyl-p-phenylenediamine, mixed di-aryl-p-phenylenediamines, and other hindered amine anti-degradants or stabilizers.

[0052] The processing aids may comprise metal salts of carboxylic acids such as zinc stearate or calcium stearate; fatty acids such as stearic acid, oleic acid, or erucic acid; fatty amides such as stearamide, oleamide, erucamide, or N,N'-ethylene bis-stearamide; polyethylene wax; oxidized polyethylene wax; polymers of ethylene oxide; copolymers of ethylene oxide and propylene oxide; vegetable waxes; petroleum waxes; non-ionic surfactants; silicone fluids, polysiloxanes. fluoropolymers, and / or fluoroelastomers.

[0053] The polymeric composition may comprise from 0.1 wt% to 2 wt% of one or more antioxidants based on the total weight of the polymeric composition. For example, the polymeric composition may comprise 0.1 wt% or greater, or 0.2 wt% or greater, or 0.3 wt% or greater, or 0.4 wt% or greater, or 0.5 wt% or greater, or 0.6 wt% or greater, or 0.7 wt% or greater, or 0.8 wt% or greater, or 0.9 wt% or greater, or 1.0 wt% or greater, or 1.1 wt% or greater, or 1.2 wt% or greater, or 1.3 wt% or greater, or 1.4 wt% or greater, or 1.5 wt% or greater, or 1.6 wt% or greater, or 1.7 wt% or greater, or 1.8 wt% or greater, or 1.9 wt% or greater, while at the same time, 2.0 wt% or less, or 1.9 wt% or less, or 1.8 wt% or less, or 1.7 wt% or less, or 1.6 wt% or less, or 1.5 wt% or less, or 1.4 wt% or less, or 1.3 wt% or less, or 1.2 wt% or less, or 1.1 wt% or less, or 1.0 wt% or less, or 0.9 wt% or less, or 0.8 wt% or less, or 0.7 wt% or less, or 0.6 wt% or less, or 0.5 wt% or less, or 0.4 wt% or less, or 0.3 wt% or less, or 0.2 wt% or less of the antioxidant based on the total weight of the polymeric composition.

[0054] Method

[0055] The present disclosure is also directed to degassing a polymeric composition. The method includes steps of crosslinking the polymeric composition to a cure of 2.6 in-lb orgreater to form a crosslinked polymeric coating. Curing, or crosslinking, of the polymeric composition may be accomplished by heating the polymeric composition to a temperature range of from about 160°C to 200°C or a temperature sufficiently high to activate the free radical generator. Once the polymeric composition has been cured into a crosslinked polymeric coating, a step of degassing the polymeric composition for a time period of two weeks or less, or 1 week or less, or 72 hours or less or 50 hours or less, or 20 hours or less, or 10 hours or less, or 1 hour or less. In various examples, the degassing may not need to be performed and as such the degassing is performed for 0 hours. Degassing of the polymeric composition or coating is performed by heating the polymeric composition to a temperature of 40°C to 90°C.

[0056] Coated Conductor

[0057] The polymeric composition may be utilized in a coated conductor. In some examples, the coated conductor may be a cable. In other examples, the coated conductor may be a fiber optic cable. The coated conductor may include a conductor and a crosslinked coating on the conductor, the coating including the polymeric composition. The polymeric composition or coating is at least partially positioned around the conductor to produce the coated conductor. The conductor may comprise a conductive metal or an optically transparent structure.

[0058] In optical fiber cable examples, the coated conductor comprises a conductor and the polymeric composition is positioned around the conductor. The polymeric composition may be in the form of a buffer tube, one or more jacketing layers on the conductor, and / or as other components in the coated conductor. The conductor may include optical fibers or other transmissive components.

[0059] Examples

[0060] Materials

[0061] The following materials were used in the formation of the inventive examples (“IE”) and the comparative examples (“CE”).

[0062] PE is a low density polyethylene homopolymer having a density of 0.92 g / cc as measured according to ASTM D792 and is available from The Dow Chemical Company, Midland, Michigan.

[0063] DCPis dicumyl peroxide and is commercially available from Sigma-Aldrich, St. Louis, Missouri.

[0064] CB 1 is triallylisocyanurate and is commercially available as TRILINK™ from Lianda, Twinsburg, Ohio.CB2 is tetravinyltetramethylcyclotetrasiloxane V4 and is commercially available from Hubei Silanon Co, Hubei, China.

[0065] PEG is polyethylene glycol having a weight average molecular weight of 20,000 g / mol as measured according to gel permeation chromatography. The PEG is commercially available from The Dow Chemical Company, Midland Michigan.

[0066] AO1 is 4,4’-Thiobis(2-t-butyl-5-methylphenol) commercially available under the tradename LO WINOX™ TBM-6 and is available from Addivant, Danbury, CT.

[0067] HALS is a hindered amine light stabilizer having the CAS# of 106990-43-6 and is commercially available as SABOSTAB™ UV 119 from Song won Industrial Co LTD, Korea.

[0068] AMSD is alpha-methylstryene dimer and is commercially available as NOFMER™ MSD from Nof Corp., Tokyo, Japan,

[0069] Sample Preparation

[0070] The samples were prepared by first creating a masterbatch of the PE, PEG, AO1, and HALS via hot compounding in a twin-screw extruder. Afterwards, the masterbatch, DCP, CB 1, CB2, and AMSD were added to jars and rolled in an oven at 70°C for 2 hours to form the samples. Plaques were then prepared using a Wabash ASTM press using ASTM Method D 4703. Samples were weighed out and put into a 6.35 mm mold. The samples were then pressed at 120°C on low pressure at 3.45 MPa for 3 minutes and then high pressure at 17.24 MPa for 3 minutes.

[0071] Test Methods

[0072] MDR testing: For MDR testing, 25 mm diameter samples were cut from the prepared sample plaques. Using mylar sheets on the bottom and top of the sample, the samples were tested at 182°C, a nominal 0.385 mm gap, and a 0.5° arc for 12 minutes in a MDR rheometer that was calibrated by adjusting the gap to achieve the correct torque measurements. The MDR:MH was recorded as the maximum torque. Additional 25 mm diameter samples were then cut from the plaques and then tested at 140°C for 4 hours. The tsl was recorded as the time for the torque to increase by 1 in-lb, and if the torque never increased by 1 in-lb, then a null result was recorded.

[0073] Gel permeation chromatography: The weight average molecular weight for polyalkylene glycols is determined using room temperature gel permeation chromatography (GPC). The weight average molecular weight may be determined using a 120 ± 20 mg sampleweighed into a 20 mL vial along with 10 mL tetrahydrofuran (THF). The sample is tested in a calibrated high performance liquid chromatography system.

[0074] Results

[0075] Table 1 provides the compositional properties of CE1-CE8 and IE1-IE10 and Table 2 provides the performance data of the examples.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080] Referring now to Tables 1 and 2, it can be seen that the inventive examples demonstrate a polymeric composition comprising less than 1.7 wt% of a free radical generator, polyethylene glycol and antioxidants, but still exhibits a cure of 2.6 in-lb or greater as measured according to MDR:MH Testing. CE1 and CE2 demonstrate that low levels of dicumyl peroxide are not able to achieve the targeted MDR: MH value. CE3 and CE6 demonstrates that even with more than 0.75 wt% of free radical generator, there is not enough cure boosters to achieve the targeted MDR: MH value. CE4 demonstrates conventional technical understandings but would require excessive degassing. CE5 demonstrates that without free radical generators cure boosters are unable to achieve the targeted MDR: MH value. IE1-IE12 surprisingly demonstrate that despite the incorporation of water tree retardants, less free radical generator can be used while still achieving the targeted MDR: MH value if cure boosters are also used.

Claims

CLAIMSWhat is claimed is1. A polymeric composition, comprising :an ethylene-based polymer;0.75 wt% to 1.5 wt% of a free radical generator based on the total weight of the polymeric composition;0.8 wt% to 5 wt% of one or more cure boosters based on the total weight of the polymeric composition, wherein the cure boosters comprise 2 or more vinyl moieties;0.1 wt% to 2 wt% a polyalkylene glycol based on the total weight of the polymeric composition; and0.1 wt% to 2 wt% of one or more antioxidants based on the total weight of the polymeric composition.

2. The polymeric composition of claim 1, wherein the ethylene-based polymer exhibits one or more of features (i) to (iii):(i) the ethylene-based polymer has a density of 0.910 g / cc to 0.940 g / cc as measured according to ASTM D1238;(ii) the polymeric composition comprises 87.00 wt% or greater of the ethylene-based polymer based on the total weight of the polymeric composition; and(iii) the ethylene -based polymer is an ethylene homopolymer.

3. The polymeric composition of any one of claims 1 and 2, wherein the free radical generator exhibits one or more of features (i) to (iv):(i) the free radical generator is a peroxide;(ii) the free radical generator comprises dicumyl peroxide;(iii) the free radical generator is present in the polymeric composition in an amount of 0.8 wt% to 1.5 wt% based on the total weight of the polymeric composition; and(iv) the free radical generator is present in the polymeric composition in an amount of 0.98 wt% to 1.2 wt% based on the total weight of the polymeric composition.

4. The polymeric composition of any one of claims 1-3, wherein the polymeric composition comprises from 0.2 wt% to 1.0 wt% of the one or more antioxidant based on the total weight of the polymeric composition.

5. The polymeric composition of any one of claims 1-4, wherein the wherein the polyalkylene glycol exhibits one or more of features (i) to (iii):(i) wherein the polyalkylene glycol comprises polyethylene glycol;(ii) the polyalkylene glycol has a weight average molecular weight of from 5,000 g / mol to 30,000 g / mol as measured according to gel permeation chromatography; and(iii) the polyalkylene glycol is present in the polymeric composition in an amount from 0.1 wt% to 1.0 wt% based on the total weight of the polymeric composition6. The polymeric composition of any one of claims 1-5, wherein the polymeric composition comprises from 1.0 wt% to 2.0 wt% of cure boosters based on the total weight of the polymeric composition.

7. The polymeric composition of any one of claims 1-6, wherein the polymeric composition comprises from 1.1 wt% to 1.5 wt% of cure boosters based on the total weight of the polymeric composition.

8. The polymeric composition of any one of claims 1-4, wherein the cure booster exhibits one or more of features (i) to (vii):(i) wherein the cure booster comprises 3 or more vinyl moieties;(ii) wherein the cure booster comprises 4 or more vinyl moieties;(iii) wherein the cure booster comprises nitrogen;(iv) wherein the cure booster comprises oxygen;(v) wherein the cure booster comprises silicon;(vi) wherein cure booster comprises triallylisocyanurate; and(vii) wherein cure booster comprises 2,4,6,8-tetramethyl-2,4,6,8- tetravinylcyclotetrasiloxane.

9. A method of degassing a polymeric composition, the method comprising the steps of:crosslinking the polymeric composition of claim 1 to a cure of 2.6 in-lb or greater to form a crosslinked polymeric coating; anddegassing the polymeric composition for a time period of 2 weeks or less.

10. A coated conductor, comprising:a conductor; andthe crosslinked polymeric coating of claim 9 positioned around the conductor.

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