Polyolefin Compounds

Abstract

The crosslinkable polyolefin formulation comprises (A) a polyethylene polymer and (B) an aryl ketone of formula (I) as defined herein. Products made therefrom, methods for making and using them, and articles containing them.

Description

[Technical Field]

[0001] Patents and published patent applications in this technical field include European Patent No. 0111043(A1), European Patent No. 2886595, British Patent No. 1461331(A), U.S. Patent No. 3482033, U.S. Patent No. 3941759, U.S. Patent No. 3981856, U.S. Patent No. 4495311, U.S. Patent No. 6696154(B2), U.S. Patent No. 7351744(B2), U.S. Patent No. 8680399(B2), U.S. Patent No. 9133320(B2), U.S. Patent No. 9343198(B2), U.S. Patent Application Publication No. 2015 / 0267036(A1), U.S. Patent Application Publication No. Examples of such a method include U.S. Patent Application Publication No. 20160096950(A1), U.S. Patent Application Publication No. 20160276061(A1), U.S. Patent Application Publication No. 20160304699(A1), U.S. Patent Application Publication No. 20160312007(A1), U.S. Patent Application Publication No. 20190233627(A1), U.S. Patent Application Publication No. 2020 / 0115477(A1), International Publication No. 2001008166, International Publication No. 2010028721(A1), International Publication No. 2012044521, International Publication No. 2014172107(A1), and International Publication No. 2014209661(A1).

[0002] Introduction U.S. Patent Application Publication No. 2016 / 0304699(A1) to Markus Jarvid et al. and U.S. Patent No. 9,133,320(B2) to Villgot Englund et al. refer to polyolefin compositions for medium / high / extra-high voltage cables containing benzyl-type voltage stabilizers.

[0003] Insulated conductors typically comprise a conductive core coated with an insulating layer. The conductive core may be solid or stranded (e.g., a bundle of wires). Some insulated conductors may also contain one or more additional elements, such as semiconductive layer(s) and / or protective jackets (e.g., windings, tapes, or sheaths). Examples are coated metallic wire and power cables, including low-voltage ("LV," >0 to <5 kilovolts (kV)), medium-voltage ("MV," 5 to <69 kV), high-voltage ("HV," 69 to 230 kV), and extra-high-voltage ("EHV," >230 kV) power cables and their use in transmission / distribution applications. AEIC / ICEA specifications and / or IEC test methods can be used to evaluate power cables. Summary of the Invention

[0004] The present inventors have recognized that the majority of high-voltage power cables contain an insulation layer comprised of an insulating material that includes a host polymer and one or more additives, such as one or more antioxidants, colorants, and hindered amine stabilizers. The dielectric breakdown strength (also known as dielectric strength) of an insulating material determines how thick the insulation layer needs to be to meet industry standards for power cable performance at a particular voltage. All other things being equal, an insulating material with a higher dielectric breakdown strength allows for a thinner insulation layer at the same dielectric breakdown strength, and therefore a thinner cable. A thinner cable advantageously allows for less cable mass per unit cable length to be used to achieve a given dielectric breakdown strength. This, in turn, usefully increases the length of cable that can be wound onto a standard-sized cable roll. A longer cable then reduces the number of joints or splices required to connect two or more thinner cables together. Alternatively, an insulating material with a higher dielectric breakdown strength allows for a higher dielectric breakdown strength for an insulation layer with the same thickness, and therefore for a cable of the same diameter. A higher breakdown strength for the same cable diameter advantageously allows the cable geometry to transmit higher voltages. Transmitting power at higher voltages reduces energy losses.

[0005] The present inventors have discovered aryl ketones that have beneficial voltage stabilizing properties. When a host polyolefin polymer is blended with one or more of these aryl ketones, the resulting crosslinkable polyolefin blend has increased dielectric breakdown strength compared to a host polyolefin that does not contain (B) an aryl ketone. In some embodiments, the dielectric breakdown strength of the blends of the present invention is advantageously greater than that of comparable blends containing benzyl and / or benzyl derivatives. The present inventors contemplate the following embodiments:

[0006] A crosslinkable polyolefin formulation comprising (A) a polyethylene polymer and (B) an aryl ketone of formula (I):

[0007] [ka] (In the formula, R 1 ~R 6 are each a hydrogen atom (H) or R 1 and R 2 , or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6 are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 1 ~R 6 The remaining four of 2 , R 3 , and R 4 are bonded together to form two fused 6-membered aryl rings with the carbon atoms in formula (I) to which they are attached and the nearest bridgehead carbon atoms in formula (I), and R 1 , R 5 , and R 6 are H and R A. and R B one of which is of the formula -C(=O)-R 7 is a group of R A and R B the other is H or R A is the formula -C(=O)-R 7 is a group of R B and R 1 are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 2 ~R 6 is as defined above, and R 7 is unsubstituted (C1 to C 40 ) alkyl group).

[0008] 1. A method for making a crosslinkable polyolefin blend comprising contacting (A) a polyethylene polymer with (B) an aryl ketone of formula (I) to make the blend.

[0009] A method for producing a crosslinked polyolefin product, the method comprising: (A) subjecting a formulation to curing conditions to crosslink a polyethylene polymer, thereby producing a crosslinked polyolefin product.

[0010] A crosslinked polyolefin product made by the above method.

[0011] Articles comprising crosslinkable polyolefin formulations and / or crosslinked polymer products.

[0012] The method for testing the dielectric breakdown strength will be described later. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram of the shape of a test sample for measuring dielectric breakdown strength. DETAILED DESCRIPTION OF THE INVENTION

[0014] The Summary and Abstract are incorporated herein by reference. Embodiments are described below, some of which are described as numbered aspects for ease of reference.

[0015] Aspect 1. A crosslinkable polyolefin blend comprising: (A) a polyethylene polymer; and (B) an aryl ketone of formula (I):

[0016] [ka] (In the formula, R 1 ~R 6 are each a hydrogen atom (H) or R 1 and R 2 , or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 1 ~R 6 The remaining four of 2 , R 3 , and R 4 are bonded together to form two fused 6-membered aryl rings with the carbon atoms in formula (I) to which they are attached and the nearest bridgehead carbon atoms in formula (I), and R 1 , R 5 , and R 6 are H and R A. and R B one of which is of the formula -C(=O)-R 7 is a group of R A and R B the other is H or R A is the formula -C(=O)-R 7 is a group of R B and R 1 are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 2 ~R 6 is as defined above, and R 7 is unsubstituted (C1 to C 40) hydrocarbyl group), the (A) polyethylene polymer comprises 51 to 100 weight percent (wt%) of ethylene-derived structural units and 49 to 0 wt% of alpha-olefin-derived structural units, respectively, based on the weight of the (A) polyethylene polymer, and the crosslinkable polyolefin blend comprises 30.0 to 99.9 wt% of the (A) polyethylene polymer, based on the total weight of the crosslinkable polyolefin blend, and 0.1 to 3.0 wt% of the (B) aryl ketone, based on the total weight of the crosslinkable polyolefin blend. The crosslinkable polyolefin blend may further comprise 0, 1, 2, 3, or more optional additives, including or consisting of additives (C) to (M) described below. The total weight of the crosslinkable polyolefin blend, including components (A), (B), and any optional additives, is 100.0 wt%. The crosslinkable polyolefin blend has increased dielectric breakdown strength compared to crosslinked (A) polyethylene polymer not containing the (B) aryl ketone. The (A) polyethylene polymer can be any one of the embodiments thereof described in Aspect 6 below or below in the section “(A) Polyethylene Polymer.”

[0017] Aspect 2. The (B) aryl ketone has Formula (Ia) or (Ib):

[0018] [ka] (In the formula, R 1 ~R 7 and R B and are independently as defined for Formula (I). In some embodiments, the (B) aryl ketone is of Formula (Ia). Alternatively, the (B) aryl ketone is of Formula (Ib). In some embodiments of Formula (Ia), R 1 ~R 6 and R 8 are each H. In some embodiments of Formula (Ia), R 1 and R 2, or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6 are joined together with the carbon atoms in formula (Ia) to which they are attached to form a fused 6-membered aryl ring, and R 1 ~R 6 The remaining four of each are H, and R B is H. In some embodiments of Formula (Ia), R 2 , R 3 , and R 4 are bonded together with the carbon atoms in formula (Ia) to which they are attached and the nearest bridgehead carbon atoms in formula (Ia) to form two fused 6-membered aryl rings, and R 1 , R 5 , and R 6 are H and R B is H. In some embodiments of Formula (Ia), R B and R 1 are joined together with the carbon atoms in formula (Ia) to which they are attached to form a fused 6-membered aryl ring, and R 2 ~R 6 is H. In some embodiments of Formula (Ib), R 1 ~R 6 are each H. In some embodiments of Formula (Ib), R 1 and R 2 , or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6 are joined together with the carbon atoms in formula (Ib) to which they are attached to form a fused 6-membered aryl ring, and R 1 ~R 6 The remaining four of are each H. In some embodiments of Formula (Ib), R 2 , R 3 , and R 4 are bonded together with the carbon atoms in formula (Ib) to which they are attached and the nearest bridgehead carbon atoms in formula (Ib) to form two fused 6-membered aryl rings, and R1 , R 5 , and R 6 are each H. In the above embodiments of formulas (Ia) and (Ib), each R 7 are independently unsubstituted (C1 to C 40 ) alkyl group.

[0019] Aspect 3. The (B) aryl ketone is represented by formula (Ia-1), (Ia-2), or (Ia-3):

[0020] [ka] (In the formula, each R 7 and are independently as defined for Formula (I). In some embodiments, the (B) aryl ketone is of Formula (Ia-1) or (Ia-2), alternatively the (B) aryl ketone is of Formula (Ia-1) or (Ia-3), alternatively the (B) aryl ketone is of Formula (Ia-2) or (Ia-3), alternatively the (B) aryl ketone is of Formula (Ia-1), alternatively the (B) aryl ketone is of Formula (Ia-2), alternatively the (B) aryl ketone is of Formula (Ia-3).

[0021] Aspect 4. The (B) aryl ketone has the formula (Ib-1):

[0022] [ka] (In the formula, R 7 and (I) are independently as defined for formula (I).

[0023] Aspect 5.R 7 is an unsubstituted (C1-C5) alkyl group or an unsubstituted (C6-C 405. The crosslinkable polyolefin formulation of any one of aspects 1-4, wherein R is an alkyl group. 7 is an unsubstituted (C1-C5) alkyl group. In some embodiments, R 7 is methyl or ethyl. In some embodiments, R 7 is methyl (i.e., -CH3).

[0024] Aspect 6. The crosslinkable polyolefin blend of any one of Aspects 1-5, wherein the (A) polyethylene polymer comprises 100 wt. % ethylene-derived units and is (A1) a low-density polyethylene homopolymer (LDPE); or the (A) polyethylene polymer comprises 51 to 99.9 wt. % ethylene-derived units and 49 to 0.1 wt. % alpha-olefin-derived units and is (A2) an ethylene / alpha-olefin copolymer. The (A2) ethylene / alpha-olefin copolymer may be an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, or a blend of any two thereof. In some embodiments, the (A) polyethylene polymer is an (A2) ethylene / alpha-olefin copolymer that is an ethylene / 1-butene copolymer, or (A2) is an ethylene / 1-hexene copolymer. In some embodiments, the (A) polyethylene polymer comprises a low-density polyethylene (LDPE) polymer. LDPE polymers are made by polymerizing ethylene in a high-pressure reactor in the absence of a metal-based polymerization catalyst and in the presence of small amounts of a free-radical initiator (e.g., peroxide or O2) and a chain transfer agent (CTA). The CTA may be propylene, which may be used at 1 wt. % based on the total weight of ethylene and propylene in the high-pressure reactor. LDPE polymers have a viscosity of 0.910-0.930 g / cm. 3 and a melt index (I2) of 1.0 to 5 g / 10 min. The LDPE polymer may be LDPE-1 as described in the examples.

[0025] Aspect 7. The crosslinkable polyolefin formulation of any one of Aspects 1-6, further comprising at least one additive, each additive independently selected from the group consisting of (C) organic peroxides, (D) scorch inhibitors, (E) antioxidants, (F) fillers, (G) flame retardants, (H) hindered amine stabilizers, (I) tree inhibitors, (J) methyl radical scavengers, (K) crosslinking coagents, (L) nucleating agents, (M) colorants (e.g., carbon black or titanium dioxide), and combinations of any two or more of additives (C)-(M). The total weight of the crosslinkable polyolefin formulation comprising components (A), (B), and at least one additive (C)-(M) is 100.0 wt.%. In some embodiments, the crosslinkable polyolefin formulation further comprises (C) an organic peroxide and (E) an antioxidant; alternatively, the crosslinkable polyolefin formulation further comprises (C) an organic peroxide, (E) an antioxidant, and (K) a crosslinking coagent; alternatively, the crosslinkable polyolefin formulation further comprises (C) an organic peroxide, (E) an antioxidant, and (M) a colorant; alternatively, the crosslinkable polyolefin formulation further comprises (C) an organic peroxide, (E) an antioxidant, (K) a crosslinking coagent, and (M) a colorant. In some embodiments, the crosslinkable polyolefin formulation comprises one or more additives selected from components (A), (B), and components (C) through (M). In some embodiments, at least one additive is selected from the group consisting of all but one of components (C) through (M) (i.e., one of components (C) through (M) is excluded from the group). The total amount of each of the one or more additives (C) to (M) may be 0.1 to 69 weight percent, alternatively 0.1 to 20 weight percent, alternatively 0.1 to 10 weight percent, or alternatively 0.1 to 5.0 weight percent of the crosslinkable polyolefin formulation, and the total amount of components (A) and (B) may be 99.9 to 31 weight percent, alternatively 99.9 to 80 weight percent, alternatively 99.9 to 90 weight percent, or alternatively 99.9 to 95.0 weight percent of the crosslinkable polyolefin formulation. In some embodiments, the crosslinkable polyolefin formulation is any one of the examples of the present invention described below. The crosslinkable polyolefin formulation has increased dielectric breakdown strength compared to a crosslinked (A) polyethylene polymer not containing the (B) aryl ketone.In some embodiments, the crosslinkable polyolefin formulation comprises (C) an organic peroxide.

[0026] Aspect 8. A method of making a crosslinkable polyolefin blend according to any one of Aspects 1-7, comprising contacting the (A) polyethylene polymer with the (B) aryl ketone of Formula (I) to produce the blend. The blend may be a heterogeneous or homogeneous blend of components (A) and (B). The contacting step comprises contacting components (A) and (B) with one another (from a previously uncontacted state). The contacting step may further comprise mixing the contacted (A) and (B) together to form a homogeneous mixture thereof. In some embodiments, the method further comprises mixing at least one of optional additives (C)-(M) with (A) and (B). The mixing may comprise melt-blending component (B) and, optionally, one or more additives (C)-(M) into a melt of component (A). The melt-blending may be performed in an extruder configured to melt-mix the polyolefin and additives. The resulting molten blend can be extruded through a die to form strands and then pelletized to provide the crosslinkable polyolefin blend in pellet form, or the molten blend can be extruded through a die designed to form an article of manufacture comprising the crosslinkable polyolefin blend.

[0027] Aspect 9. A method for producing a crosslinked polyolefin product, comprising subjecting a crosslinkable polyolefin formulation according to any one of Aspects 1-7 or made by the method of Aspect 8 to curing conditions to crosslink the (A) polyethylene polymer, thereby producing a crosslinked polyolefin product. The curing conditions can include exposing the formulation to ultraviolet light or heating the formulation with (C) an organic peroxide and, optionally, a (K) crosslinking coagent. An embodiment of the method can include heating an embodiment of the crosslinkable polyolefin formulation according to any one of Aspects 1-7, comprising a (C) organic peroxide and, optionally, a (K) crosslinking coagent, to crosslink the (A) polyethylene polymer, thereby producing a crosslinked polyolefin product. When a (K) crosslinking coagent is not used, crosslinking comprises forming covalent carbon-carbon bonds between molecules of the (A) polyolefin polymer. When a (K) crosslinking coagent is included, crosslinking includes forming covalent carbon-carbon bonds between molecules of the (A) polyolefin polymer and forming covalent carbon-carbon bonds between molecules of the (K) crosslinking coagent and molecules of the (A) polyolefin polymer.

[0028] Aspect 10. A crosslinked polyolefin product produced by the method of Aspect 9. The crosslinked polyolefin product has increased dielectric breakdown strength compared to a crosslinked (A) polyethylene polymer that does not contain the (B) aryl ketone. The crosslinked polyolefin product can include an (A) polyethylene polymer or an (A') crosslinked (networked) polyethylene polymer produced by crosslinking a combination of the (A) polyethylene polymer with a (K) crosslinking coagent and an (B) aryl ketone of Formula (I). The crosslinked polyolefin product may further include at least one additive selected from the following: (E) antioxidant, (F) filler, (G) flame retardant, (H) hindered amine stabilizer, (I) tree inhibitor, (J) methyl radical scavenger, (L) nucleating agent, and (M) colorant (e.g., carbon black or titanium dioxide). The crosslinked polyolefin product has increased dielectric breakdown strength compared to a crosslinked (A) polyethylene polymer that does not contain the (B) aryl ketone.

[0029] Embodiment 11. An article of manufacture comprising a shaped article of the crosslinkable polyolefin formulation of any one of embodiments 1-7 or the crosslinked polyolefin product of embodiment 10. In some embodiments, the article of manufacture is selected from coatings, films, sheets, extruded articles (not pellets), and injection-molded articles. For example, coated conductors, insulation layers for wires and cables for power transmission or communication, agricultural films, automotive parts, containers, food packaging, garment bags, grocery bags, heavy-duty bags, industrial sheeting, pallets and shrink wrap, bags, buckets, freezer containers, lids, toys. The article of manufacture has increased dielectric breakdown strength compared to the crosslinked host polyolefin not comprising (B) the aryl ketone.

[0030] Aspect 12. A coated conductor comprising a conductive core and an insulating layer at least partially coating the conductive core, wherein at least a portion of the insulating layer comprises the crosslinkable polyolefin formulation of any one of Aspects 1-7 or the crosslinked polyolefin product of Aspect 11. The coated conductor and its insulating layer have increased dielectric breakdown strength. The conductive core may be a wire having a proximal end and a distal end, at least one of which may be free of an insulating layer.

[0031] Embodiment 13. A method of transmitting electricity, comprising applying a voltage across the conductive core of the coated conductor of embodiment 12 so as to cause a flow of electricity through the conductive core.

[0032] Aspect 14. The invention of any one of Aspects 1-13, wherein the crosslinkable polyolefin formulation exhibits at least a +5 percent (%) improvement (increase) in dielectric breakdown strength value eta, η, compared to an (A) polyethylene polymer that does not contain a voltage stabilizer, the dielectric breakdown strength value eta, η at a 63.2% probability of failure determined using Weibull statistics according to the dielectric breakdown strength test method described herein. In some embodiments, the improvement (increase) in dielectric breakdown strength value eta, η (at a 63.2% probability of failure) of the invention compared to an (A) polyethylene polymer that does not contain a voltage stabilizer (e.g., compared to Comparative Example 0 (CE0) described in the Examples below) is at least +5%, alternatively at least +25%, alternatively at least +31%, alternatively at least +34%, alternatively at least +38%, alternatively at least +48%, alternatively at least +53%. In some embodiments, the improvement in the dielectric breakdown strength value eta, η (at a 63.2% probability of failure) of the present invention relative to the (A) polyethylene polymer without a voltage stabilizer (e.g., compared to CE0) is further characterized as being up to 75%, alternatively up to +65%, alternatively up to +59%, alternatively up to 54%. In some embodiments, the improvement in the dielectric breakdown strength value η (at a 63.2% probability of failure) of the present invention relative to the (A) polyethylene polymer without a voltage stabilizer (e.g., compared to CE0) is +5% to +54%, alternatively +31% to +54%, alternatively +34% to +54%, alternatively +48% to +54%. In some embodiments, the improvement in the dielectric breakdown strength value eta, η (at a 63.2% probability of failure) of the present invention relative to the (A) polyethylene polymer without a voltage stabilizer (e.g., compared to CE0) is +38%±5%, alternatively +50%±9%. Alternatively, the inventive improvement in dielectric breakdown strength may be any one of the aforementioned percentage values ​​relative to an eta, η, of 18.49 (18.5) kV / mm (for a probability of failure value of 63.2%). In some embodiments, the crosslinked polyolefin product made from the crosslinkable polyolefin formulation has any one of the aforementioned inventive improvements in dielectric breakdown strength value eta, η (for a probability of failure value of 63.2%).The aforementioned dielectric breakdown strength improvement values ​​eta, η (for a failure probability of 63.2%) are all determined according to the dielectric breakdown strength test method described below. In some embodiments, the values ​​eta, η (for a failure probability of 63.2%) are further characterized by a 90% confidence level beta, β, determined according to the dielectric breakdown strength test method and Weibull statistics described below.

[0033] The coated conductor may be a power cable having a proximal end and a distal end, and electricity may flow from the proximal end to the distal end through the conductive core, or vice versa. The conductive core may be a wire. The power cable may be a medium-voltage (MV), high-voltage (HV), or extra-high-voltage (EHV) power cable. The power cable is useful in electricity transmission applications.

[0034] (A) Polyethylene polymers. Comprised of polyethylene macromolecules containing independently at least 5, or alternatively 10 to 200,000 constitutional units derived from the polymerization of ethylene and zero, one, or more other olefin-functional monomers. (A) Polyethylene polymers have a viscosity of 0.870 to 0.975 grams per cubic centimeter (g / cm). 3 ), or 0.890 to 0.930 g / cm 3 (e.g., LDPE or LLDPE), or 0.910 to 0.930 g / cm 3 (e.g., LDPE or LLDPE), or 0.931 to 0.945 g / cm 3 (e.g., MDPE), or 0.945 to 0.970 g / cm 3 (e.g., HDPE), all measured according to ASTM D792-13, Method B.

[0035] Polyethylene may be a homopolymer or a copolymer. Homopolymers are made by polymerizing only ethylene. Copolymers are made by polymerizing at least two different olefin monomers, one of which is ethylene. Copolymers can be bipolymers, made by polymerizing ethylene and one olefin monomer, terpolymers, made by polymerizing ethylene and two different olefin monomers, or tetrapolymers, made by polymerizing ethylene and three different olefin monomers. Polyolefins that are copolymers can be block copolymers or random copolymers.

[0036] (A) Examples of olefin functional monomers used to make polyethylene polymers are ethylene, propene, (C4-C 20 ) alpha-olefins, cyclic alkenes (e.g., norbornene), dienes (e.g., 1,3-butadiene), unsaturated carboxylic acid esters, and olefin-functional hydrolyzable silanes. (C4-C 20 Examples of alpha-olefins include (C4-C8) alpha-olefins such as 1-butene, 1-hexene, or 1-octene, and (C 10 ~C 20 ) alpha-olefins. An example of a diene is 1,3-butadiene. Examples of unsaturated carboxylic acid esters are alkyl acrylates, alkyl methacrylates, and vinyl carboxylates (e.g., vinyl acetate). Examples of olefin-functional hydrolyzable silanes are vinyltrialkoxysilanes, vinyltris(dialkylamino)silanes, and vinyl(trioximo)silanes.

[0037] In some embodiments, (A) the polyethylene polymer is an ethylene-based polymer. The ethylene-based polymer comprises 51 to 100 weight percent ethylene units derived from the polymerization of ethylene and 49 to 0 weight percent comonomer units derived from the polymerization of one or two olefin-functional monomers (comonomers). The comonomers include propylene, (C4 to C6 20) alpha-olefins, and 1,3-butadiene. (C4-C 20 The alpha-olefin may be a (C4-C8) alpha-olefin such as 1-butene, 1-hexene, or 1-octene.

[0038] Examples of suitable ethylene-based polymers include polyethylene homopolymers, ethylene / (C4-C 20 ) alpha-olefin copolymers, ethylene / propylene copolymers, ethylene / propylene / diene monomer (EPDM) copolymers, such as ethylene / propylene / 1,3-butadiene terpolymers, and ethylene / 1-butene / styrene copolymers. Preferred ethylene / (C4-C 20Examples of alpha-olefin copolymers are ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, and ethylene / 1-octene copolymer. The ethylene-based polymer can be ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), or ultra-high-density polyethylene (UHDPE). Many ethylene-based polymers are sold by The Dow Chemical Company under trade names such as AFFINITY, ATTANE, DOWLEX, ENGAGE, FLEXOMER, or INFUSE. Other ethylene-based polymers are sold by other suppliers under trade names such as TAFMER, EXCEED, and EXACT. LDPE and LLDPE differ compositionally due to how they are made under different polymerization conditions: LDPE is made in a high-pressure polymerization reactor in the presence of a free-radical initiator (peroxide or O2) and without an olefin polymerization catalyst, while LLDPE is made in a standard-pressure polymerization reactor in the presence of an olefin polymerization catalyst but in the absence of a free-radical initiator.

[0039] In some embodiments, the (A) polyethylene polymer consists of only one ethylene-based polymer (e.g., only LLDPE, or only LDPE, or only MDPE, or only HDPE). In some embodiments, the (A) polyethylene polymer consists of LDPE. When the (A) polyethylene polymer consists of LDPE, in some such embodiments, the crosslinkable polyolefin blend may not include any organic polymers other than LDPE.

[0040] In other embodiments, the (A) polyethylene polymer comprises a blend of two or more different ethylene-based polymers. In some embodiments, the two or more different ethylene-based polymers of the blend comprise at least one LDPE.

[0041] The crosslinkable polyolefin blend may comprise 60.0 to 99.9 wt. % of the (A) polyethylene polymer, alternatively 70.0 to 99.9 wt. % of the (A) polyethylene polymer, alternatively 80.0 to 99.9 wt. % of the (A) polyethylene polymer, alternatively 90.0 to 99.9 wt. % of the (A) polyethylene polymer, all based on the total weight of the crosslinkable polyolefin blend.

[0042] In some embodiments of Formula (I), (Ia), or (Ib), R 1 ~R 7 are each H, and when the (B) aryl ketone is of formula (Ia), it is the (B) aryl ketone of formula (Ia-1) below, and when the (B) aryl ketone is of formula (Ib), it is the (B) aryl ketone of formula (Ib-1) above. In some embodiments, R 1 and R 2 are bonded together with the carbon atoms in formula (I), (Ia), or (Ib) to which they are attached to form a fused 6-membered aryl ring, and the remaining R 3 ~R 6 are each H. In some embodiments, R 3 and R 4 are bonded together with the carbon atoms in formula (I), (Ia), or (Ib) to which they are attached to form a fused 6-membered aryl ring, and the remaining R 1 , R 2 , R 5 , and R 6 are each H. In some embodiments, R 4 and R 5 are bonded together with the carbon atoms in formula (I), (Ia), or (Ib) to which they are attached to form a fused 6-membered aryl ring, and the remaining R 1 ~R 3 and R6 are each H, which is (B) an aryl ketone of formula (Ia-2) above. In some embodiments, R 5 and R 6 are bonded together with the carbon atoms in formula (I), (Ia), or (Ib) to which they are attached to form a fused 6-membered aryl ring, and the remaining R 1 ~R 4 are each H. In some embodiments, R 2 , R 3 , and R 4 are joined together with the carbon atoms in formula (I), (Ia), or (Ib) to which they are attached to form two fused 6-membered aryl rings, and R 1 , R 5 , and R 6 are each H, which is (B) an aryl ketone of the above formula (Ia-3).

[0043] The crosslinkable polyolefin formulations and crosslinked polyolefin products made therefrom may be free of any voltage stabilizer compounds other than the (B) aryl ketone of formula (I).

[0044] The crosslinkable polyolefin formulation and the crosslinked polyolefin product made therefrom may contain 0.1 to 3.0 wt. % of the (B) aryl ketone of formula (I), alternatively 0.2 to 2.0 wt. % of the (B) aryl ketone of formula (I), alternatively 0.3 to 1.4 wt. % of the (B) aryl ketone of formula (I), alternatively 0.4 to 1.2 wt. % of the (B) aryl ketone of formula (I), alternatively 0.45 to 1.04 wt. % of the (B) aryl ketone of formula (I), alternatively 0.5±0.1 wt. % of the (B) aryl ketone of formula (I), alternatively 1.0±0.2 wt. % of the (B) aryl ketone of formula (I), all based on the total weight of the crosslinkable polyolefin formulation or the total weight of the crosslinked polyolefin product, respectively.

[0045] Component (C) Organic Peroxide: A molecule or collection of such molecules containing carbon, hydrogen, and two or more oxygen atoms and having at least one -OO- group, with the proviso that when there is more than one -OO- group, each -OO- group is indirectly bonded to another -OO- group through one or more carbon atoms. The (C) organic peroxide may be added to a crosslinkable polyolefin formulation containing components (A), (B), and (C) for curing, which comprises heating the crosslinkable polyolefin formulation to a temperature above the decomposition temperature of the (C) organic peroxide. The (C) organic peroxide is represented by the formula R O -OOR O [In the formula, each R O are independently (C1~C 20 ) alkyl group, or (C6-C 20 ) aryl group]. 20 ) alkyl groups are independently unsubstituted or contain one or two (C-C 12 ) substituted with an aryl group. 20 The aryl group is unsubstituted or contains 1 to 4 (C1-C 10 ) alkyl group. Alternatively, (C) is a group of formula R O -OOROOR O [Wherein R is (C2 to C 10 ) alkylene, (C3-C 10 ) a divalent hydrocarbon group such as cycloalkylene or phenylene, and each R O(C) The organic peroxide may be a diperoxide of bis(1,1-dimethylethyl)peroxide, bis(1,1-dimethylpropyl)peroxide, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexane, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexyne, 4,4-bis(1,1-dimethylethylperoxy)valeric acid, butyl ester, 1,1-bis(1,1-dimethylethylperoxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, tert-butyl peroxybenzoate, di-tert-amyl peroxide ("DTAP"), bis(alcohol), ...butyl peroxybenzoate, di-tert-butyl peroxide ("DTAP"), bis(alcohol), tert-butyl peroxybenzoate, di-tert-butyl peroxide ("DTAP"), bis(alcohol), (C) The organic peroxide may be di-tert-butyl-peroxyisopropyl)benzene ("BIPB"), isopropylcumyl t-butyl peroxide, t-butylcumyl peroxide, di-tert-butyl peroxide, 2,5-bis(t-butylperoxy)-2,5-dimethylhexane, 2,5-bis(t-butylperoxy)-2,5-dimethylhexyne-3,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, isopropylcumyl cumyl peroxide, butyl 4,4-di(tert-butylperoxy)valerate, or di(isopropylcumyl)peroxide, or dicumyl peroxide. In some embodiments, only a blend of two or more (C) organic peroxides is used, such as a 20:80 (w / w) blend of t-butylcumyl peroxide and bis(t-butylperoxyisopropyl)benzene (e.g., LUPEROX D446B, available from Arkema). In some embodiments, at least one, or each, (C) organic peroxide contains one -OO- group. The (C) organic peroxide may be 0.29 to 0.44 wt. %, alternatively 0.30 to 39 wt. %, alternatively 0.30 to 0.37 wt. % of the carrier mixture or of the crosslinkable polyolefin formulation.

[0046] Optional component (D) scorch inhibitor: a molecule or aggregate of such molecules that inhibits premature curing. Examples of scorch inhibitors are hindered phenols, semi-hindered phenols, TEMPO, TEMPO derivatives, 1,1-diphenylethylene, 2,4-diphenyl-4-methyl-1-pentene (also known as alpha-methylstyrene dimer or AMSD), and allyl-containing compounds described in U.S. Pat. No. 6,277,925 B1, column 2, line 62 to column 3, line 46. In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product do not contain (D). When present, the (D) scorch inhibitor may be present in an amount of 0.01 to 1.5 wt %, alternatively 0.05 to 1.2 wt %, alternatively 0.1 to 1.0 wt % of the crosslinkable polyolefin formulation.

[0047] Optional Component (E) Antioxidant: An organic molecule, or collection of such molecules, that inhibits oxidation. The (E) Antioxidant functions to impart antioxidant properties to the crosslinkable polyolefin formulation and / or crosslinked polyolefin product. Examples of suitable (E) compounds include bis(4-(1-methyl-1-phenylethyl)phenyl)amine (e.g., NAUGARD 445), 2,2'-methylene-bis(4-methyl-6-t-butylphenol) (e.g., VANOX MBPC), 2,2'-thiobis(2-t-butyl-5-methylphenol) (CAS No. 90-66-4, 4,4'-thiobis(2-t-butyl-5-methylphenol) (also known as 4,4'-thiobis(6-tert-butyl-m-cresol)), CAS No. 96-69-5, commercially available LOWINOX TBM-6), 2,2'-thiobis(6-t-butyl-4-methylphenol) (CAS No. 90-66-4, commercially available LOWINOX TBM-6), and 2,2'-thiobis(6-tert-butyl-4-methylphenol) (CAS No. 90-66-4, commercially available LOWINOX TBM-6). TBP-6), tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione) (e.g., CYANOX 1790), pentaerythritol tetrakis(3-(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)propionate (e.g., IRGANOX 1010, CAS No. 6683-19-8), 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid 2,2'-thiodiethanediyl ester (e.g., IRGANOX 1035, CAS No. 41484-35-9), distearyl thiodipropionate ("DSTDP"), dilauryl thiodipropionate (e.g., IRGANOX PS800), stearyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (e.g., IRGANOX 1076), 2,4-bis(dodecylthiomethyl)-6-methylphenol (IRGANOX 1726), 4,6-bis(octylthiomethyl)-o-cresol (e.g., IRGANOX 1520), and 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide (IRGANOX 1024).In some embodiments, (E) is 4,4'-thiobis(2-t-butyl-5-methylphenol) (also known as 4,4'-thiobis(6-tert-butyl-m-cresol)), 2,2'-thiobis(6-t-butyl-4-methylphenol), tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, distearyl thiodipropionate, or dilauryl thiodipropionate, or any two or more thereof. A combination of (E) antioxidants may be used. The combination may be tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione and distearyl thiodipropionate. In some embodiments, the crosslinkable polyolefin formulation and the crosslinked polyolefin product do not contain (E). When present, the (E) antioxidant may be present in an amount of 0.01 to 1.5 wt %, alternatively 0.05 to 1.2 wt %, alternatively 0.1 to 1.0 wt % of the crosslinkable polyolefin formulation.

[0048] Optional Component (F) Filler: A finely divided, particulate solid or gel that occupies space in the host material and optionally influences its functionality. The (F) filler may be calcined clay, organoclay, or hydrophobized fumed silica, such as that commercially available from Cabot Corporation under the trade name CAB-O-SIL. The (F) filler may have a flame retardant effect. In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product do not contain (F). When present, the (F) filler may be 1 to 40 wt. % of the crosslinkable polyolefin formulation, alternatively 2 to 30 wt. %, alternatively 5 to 20 wt. %.

[0049] Regarding (F) fillers, in some embodiments, the crosslinkable polyolefin formulation does not contain 20% by weight or more, or 15% by weight or more, or 10% by weight or more, or no inorganic fillers selected from the group consisting of aluminum oxide, aluminum silicate, calcium silicate, magnesium silicate, silica, titanium dioxide, and mixtures thereof. In some embodiments, the crosslinkable polyolefin formulation does not contain 20% by weight or more, or 15% by weight or more, or 10% by weight or more, or no inorganic fillers selected from the group consisting of Al-containing solids, Ca-containing solids, Mg-containing solids, Si-containing solids, Ti-containing solids, and mixtures thereof. In some embodiments, the crosslinkable polyolefin formulation does not contain silsesquioxanes or any siloxanes other than component (B). In some embodiments, the crosslinkable polyolefin formulation does not contain silsesquioxanes or any one of the aforementioned inorganic fillers. For the avoidance of doubt, the term "inorganic filler" does not include carbon black.

[0050] Optional component (G) flame retardant: a molecule or substance that inhibits combustion, or an aggregate of such molecules. (G) can be a halogenated or halogen-free compound. Examples of halogenated (G) flame retardants are organic chlorides and organic bromides. Examples of organic chlorides are chlorendic acid derivatives and chlorinated paraffins. Examples of organic bromides are polymeric brominated compounds such as decabromodiphenyl ether, decabromodiphenyl ethane, brominated polystyrene, brominated carbonate oligomers, brominated epoxy oligomers, tetrabromophthalic anhydride, tetrabromobisphenol A, and hexabromocyclododecane. Typically, halogenated (G) flame retardants are used in combination with a synergist to improve their efficiency. The synergist can be antimony trioxide. Examples of halogen-free (G) flame retardants are inorganic minerals, organic nitrogen intumescent compounds, and phosphorus-based intumescent compounds. Examples of inorganic minerals are aluminum hydroxide and magnesium hydroxide. Examples of phosphorus-based intumescent compounds are organic phosphonic acids, phosphonates, phosphinates, phosphonites, phosphinites, phosphine oxides, phosphines, phosphites, phosphates, phosphorus nitrite chlorides, phosphoramidates, phosphoric acid amides, phosphonic acid amides, phosphinic acid amides, melamine and melamine derivatives thereof, including melamine polyphosphate, melamine pyrophosphate and melamine cyanurate, and mixtures of two or more of these materials.Examples include phenyl bis dodecyl phosphate, phenyl bis neopentyl phosphate, phenyl ethylene hydrogen phosphate, phenyl bis-3,5,5' trimethylhexyl phosphate, ethyl diphenyl phosphate, 2 ethylhexyl di(p-tolyl) phosphate, diphenyl hydrogen phosphate, bis(2-ethyl-hexyl) para-tolyl phosphate, tritolyl phosphate, bis(2-ethylhexyl)-phenyl phosphate, tri(nonylphenyl) phosphate, phenylmethyl hydrogen phosphate, di(dodecyl) p-tolyl phosphate, tricresyl phosphate, triphenyl phosphate, triphenyl phosphate, dibutylphenyl phosphate, 2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5'-trimethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, and diphenyl hydrogen phosphate. The types of phosphate esters described in U.S. Patent No. 6,404,971 are examples of phosphorus-based flame retardants. Additional examples include liquid phosphates such as bisphenol A diphosphate (BAPP) (Adeka Palmarole) and / or resorcinol bis(diphenyl phosphate) (Fyroflex RDP) (Supresta, ICI), and solid phosphorus such as ammonium polyphosphate (APP), piperazine pyrophosphate, and piperazine polyphosphate. Ammonium polyphosphate is often used with flame retardant co-additives such as melamine derivatives. Melafine (DSM) (2,4,6-triamino-1,3,5-triazine, finely divided melamine) is also useful. In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product do not contain (G). When present, (G) can be present in a concentration of 0.01 to 70 wt. % of the crosslinkable polyolefin formulation, alternatively 0.05 to 40 wt. %, alternatively 1 to 20 wt. %.

[0051] Optional component (H) hindered amine stabilizer: a molecule or aggregate of molecules containing a basic nitrogen atom bonded to at least one sterically bulky organic group and functioning as an inhibitor of degradation or decomposition. (H) is a compound with a sterically hindered amino functional group that inhibits oxidative degradation and can also extend the shelf life of crosslinkable polyolefin formulations containing (C) organic peroxides. Examples of suitable (H) include butanedioic acid dimethyl ester, a polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine-ethanol (CAS No. 65447-77-0, commercially available as LOWILITE 62), and N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (CAS No. 124172-53-8, commercially available as Uvinul 4050H). In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product are free of (H). When present, the (H) hindered amine stabilizer can be 0.001 to 1.5 wt. %, alternatively 0.002 to 1.2 wt. %, alternatively 0.002 to 1.0 wt. %, alternatively 0.005 to 0.5 wt. %, alternatively 0.01 to 0.2 wt. %, alternatively 0.05 to 0.1 wt. % of the crosslinkable polyolefin formulation.

[0052] Optional Component (I) Tree Suppressant: A molecule or aggregate of such molecules that inhibits water and / or electrical treeing. The tree suppressant can be a water tree suppressant or an electrical tree suppressant. Water tree suppressants are compounds that inhibit water treeing, a process that degrades polyolefins when exposed to the combined effects of an electric field and humidity or moisture. Electrical tree suppressants, also known as voltage stabilizers, are compounds that inhibit electrical treeing, a pre-breakdown electrical process in solid electrical insulation caused by partial discharge. Electrical treeing can occur in the absence of water. Water treeing and electrical treeing are a concern for electrical cables containing coated conductors, where the coating contains a polyolefin. (I) can be poly(ethylene glycol) (PEG). In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product do not contain (I). When present, (I) tree suppressant can be 0.01 to 1.5 wt. %, alternatively 0.05 to 1.2 wt. %, alternatively 0.1 to 1.0 wt. % of the crosslinkable polyolefin formulation.

[0053] Optional component (J) methyl radical scavenger: a molecule or aggregate of such molecules that reacts with methyl radicals. (J) reacts with methyl radicals in the crosslinkable polyolefin formulation or crosslinked polyolefin product. (J) can be 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl or a "TEMPO" derivative of 1,1-diarylethylene. Examples of TEMPO derivatives include 4-acryloxy-2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (CAS No. 21270-85-9, "acrylate TEMPO"), 4-allyloxy-2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (CAS No. 217496-13-4, "allyl TEMPO"), bis(2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl) sebacate (CAS Examples of 1,1-diarylethylenes are 1,1-diphenylethylene and alpha-methylstyrene. In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product are free of (J). When present, the (J) methyl radical scavenger can be 0.01 to 1.5 wt %, alternatively 0.05 to 1.2 wt %, alternatively 0.1 to 1.0 wt % of the crosslinkable polyolefin formulation.

[0054] Optional Component (K) Coagent: A molecule or aggregate of such molecules containing a backbone or ring substructure and one or more propenyl, acrylate, and / or vinyl groups attached thereto, the substructure consisting of carbon atoms and optionally nitrogen atoms. The (K) coagent does not contain silicon atoms. The (K) coagent may be a propenyl-functional conventional coagent as described by any one of the following constraints (i) through (v): (i) (K) is 2-allylphenyl allyl ether, 4-isopropenyl-2,6-dimethylphenyl allyl ether, 2,6-dimethyl-4-allylphenyl allyl ether, 2-methoxy-4-allylphenyl allyl ether, 2,2'-diallyl bisphenol A, O,O'-diallyl bisphenol A, or tetraallyl bisphenol A. (ii) (K) is 2,4-diphenyl-4-methyl-1-pentene or 1,3-diisopropenylbenzene; (iii) (K) is triallyl isocyanurate ("TAIC"), triallyl cyanurate ("TAC"), triallyl trimellitate ("TATM"), N,N,N',N',N",N"-hexaallyl-1,3,5-triazine-2,4,6-triamine ("HATATA"), N 2 ,N 2 ,N 4 ,N 4 ,N 6 ,N 6(iv) (K) is a mixture of any two of the propenyl-functional coagents in (i). Alternatively, (K) may be an acrylate-functional coagent selected from trimethylolpropane triacrylate ("TMPTA"), trimethylolpropane trimethyl acrylate ("TMPTMA"), ethoxylated bisphenol A dimethacrylate, 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, and propoxylated glyceryl triacrylate. Alternatively, (K) may be a vinyl-functional coagent selected from polybutadiene having a 1,2-vinyl content of at least 50% by weight and trivinylcyclohexane ("TVCH"). Alternatively, (K) may be a coagent described in U.S. Pat. No. 5,346,961 or U.S. Pat. No. 4,018,852. Alternatively, (K) may be a combination of the foregoing coagents or any two or more thereof. In some embodiments, the crosslinkable polyolefin formulation and crosslinked polyolefin product do not contain (K). When present, the (K) coagent may be present in an amount of 0.01 to 4.5 wt. %, alternatively 0.05 to 2 wt. %, alternatively 0.1 to 1 wt. %, alternatively 0.2 to 0.5 wt. % of the crosslinkable polyolefin formulation.

[0055] Optional component (L) nucleating agent: an organic or inorganic additive that improves the crystallization rate of polyolefin polymers. Examples of (L) include calcium carbonate, titanium dioxide, barium sulfate, ultra-high molecular weight polyethylene, potassium hydrogen phthalate, benzoic acid compounds, sodium benzoate compounds, disodium bicyclo[2.2.1]heptane-2,3-dicarboxylate, zinc monoglycerate, and 1,2-cyclohexanedicarboxylic acid, calcium salts, and zinc stearate. In some embodiments, the crosslinkable polyolefin formulation and the crosslinked polyolefin product do not contain (L). When present, (L) may be present in a concentration of 0.01 to 1.5 wt %, alternatively 0.05 to 1.2 wt %, or alternatively 0.1 to 1.0 wt % of the crosslinkable polyolefin formulation.

[0056] Optional Component (M) Colorant (e.g., carbon black or TiO2). Carbon black: A microcrystalline form of quasicrystalline carbon having a high surface area to volume ratio, but lower than that of activated carbon. Examples of carbon black are furnace carbon black, acetylene carbon black, and conductive carbon (e.g., carbon fiber, carbon nanotubes, graphene, graphite, and expanded graphite platelets). In some embodiments, the crosslinkable polyolefin formulation and the crosslinked polyolefin product do not contain (M). When present, (M) can be 0.01 to 40% by weight of the crosslinkable polyolefin formulation, alternatively 0.05 to 35% by weight, alternatively 0.1 to 20% by weight, alternatively 0.5 to 10% by weight, or alternatively 1 to 5% by weight.

[0057] Additionally, the crosslinkable polyolefin formulation may further comprise one or more other optional additives independently selected from carrier resins, lubricants, processing aids, slip agents, plasticizers, surfactants, extender oils, acid scavengers, and metal deactivators.

[0058] The crosslinked polyolefin product may also contain a curing by-product, such as (C) a by-product of the reaction of an organic peroxide with an alcohol and a ketone. If the crosslinkable polyolefin formulation further contains one or more optional additives or components, such as (E) an antioxidant, the crosslinked polyolefin product may also contain any one or more of the optional additives or components, such as (E), or one or more reaction products formed therefrom during the curing of the crosslinkable polyolefin formulation. The crosslinked polyolefin product may be in a divided solid form or a continuous form. The divided solid form may include granules, pellets, powder, or a combination of any two or more thereof. The continuous form may be a molded part (e.g., an injection-molded part) or an extrusion-molded part (e.g., a coated conductor or cable).

[0059] Coated conductor. A coated conductor may be an insulated electrical conductor. An insulated conductor may be a coated metal wire or electrical cable, including power cables for use in low voltage ("LV", >0 to <5 kilovolts (kV)), medium voltage ("MV", 5 to <69 kV), high voltage ("HV", 69 to 230 kV), or extra high voltage ("EHV", >230 kV) data transmission and power transmission / distribution applications. "Wire" means a single strand or filament of conductive material, e.g., a conductive metal such as copper or aluminum. "Cable" and "power cable" are synonymous and refer to an insulated electrical conductor including at least one wire disposed within a covering, which may be referred to as a sheath, jacket (protective outer jacket), or coating. Insulated conductors may be designed and configured for use in medium voltage, high voltage, or extra high voltage applications. Examples of suitable cable designs are shown in US Pat. Nos. 5,246,783, 6,496,629, and 6,714,707.

[0060] An insulated conductor may include a conductor / transmission core and an outer single-layer or multi-layer coating disposed therearound to protect and insulate the conductor / transmission core from the external environment. The conductor / transmission core may be composed of one or more metal wires. When the conductor / transmission core contains two or more metal wires, the metal wires may be subdivided into individual wire bundles. Each wire within the conductor / transmission core, whether bundled or unbundled, may be individually coated with an insulating layer, and / or the individual bundles may be coated with an insulating layer. The single-layer or multi-layer coating (e.g., single-layer or multi-layer coating, or sheath) primarily functions to protect or insulate the conductor / transmission core from the external environment, such as sunlight, water, heat, oxygen, other conductive materials (e.g., to prevent short circuits), and / or other corrosive substances (e.g., chemical gases).

[0061] The single-layer or multi-layer coatings from one insulated conductor to the next may be configured differently depending on their intended use. For example, when viewed in cross-section, a multi-layer coating of an insulated conductor may be configured sequentially from its innermost layer to its outermost layer to have the following components: an inner semiconducting layer, a cross-linked polyolefin insulating layer containing a cross-linked polyolefin product (the cross-linked product of the present invention), an outer semiconducting layer, a metallic shield, and a protective sheath. The layers and sheath are circumferentially and coaxially (longitudinally) continuous. The metallic shield (ground) is coaxially continuous and either circumferentially continuous (layer) or discontinuous (tape or wire). Depending on the intended application, multi-layer coatings for insulated optical fibers may omit the semiconducting layer and / or the metallic shield. The outer semiconducting layer, if present, may be composed of a peroxide-cross-linked semiconducting product bonded to or peelable from the cross-linked polyolefin layer.

[0062] In some embodiments, a method of making a coated conductor includes extruding a coating comprising a layer of a crosslinkable polyolefin formulation onto a conductor / transmission core to obtain a coated core, and passing the coated core through a continuous vulcanization (CV) apparatus configured with suitable CV conditions to cure the crosslinkable polyolefin formulation to obtain a coated conductor. CV conditions include temperature, atmosphere (e.g., nitrogen gas), and line speed or duration through the CV apparatus. Suitable CV conditions can provide a coated conductor exiting the CV apparatus, the coated conductor containing a crosslinked polyolefin layer formed by curing the crosslinked polyolefin layer.

[0063] Methods of Conducting Electrical Conduction. Methods of conducting electrical conduction of the present invention can use the coated conductors of the present invention, including insulated conductor embodiments. Methods of transmitting data using the coated conductors of the present invention with insulated conductors are also contemplated.

[0064] Dielectric Breakdown Strength (Dielectric Strength): The maximum electric field (applied voltage divided by electrode separation) that an electrically insulating material can withstand without experiencing a breakdown event, i.e., becoming conductive. Expressed in volts using standard electrode separation distances.

[0065] Any compound, composition, formulation, material, mixture, or reaction product herein may be free of any one of the chemical elements selected from the group consisting of H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, lanthanides, and actinides, provided that chemical elements essentially required by the compound, composition, formulation, material, mixture, or reaction product (e.g., C and H required for polyethylene, or C, H, and O required for alcohol) are not excluded.

[0066] or precedes a different embodiment. ANSI is the American National Standards Institute (headquartered in Washington, DC, USA). ASME is the American Society of Mechanical Engineers (headquartered in New York City, New York, USA). ASTM is the standardization organization ASTM International (West Conshohocken, Pennsylvania, USA). Any comparative examples are used for illustrative purposes only and are not prior art. "Not containing" or "lacking" means complete absence or undetectable. IEC is the International Electrotechnical Commission (3 rue de Varemb, Case postale 131, CH-1211, Geneva 20, Switzerland, http: / / www.iec.ch.). IUPAC (International Union of Pure and Applied Chemistry) is the International Union of Pure and Applied Chemistry (IUPAC Secretariat, Research Triangle Park, North Carolina, USA). The Periodic Table of Elements is the IUPAC version of May 1, 2018. "May" gives a permitted option, not a required one. "Operative" means functionally possible or effective. "Optional" means absent (or excluded) or present (or included). Properties can be measured using standard test methods and conditions. Ranges include endpoints, subranges, and whole and / or fractional values ​​contained therein, except that integer ranges do not include decimals. Room temperature: 23°C ± 1°C.

[0067] Unless otherwise stated, definitions of terms used herein are taken from the IUPAC Compendium of Chemical Technology ("Gold Book"), 2.3.3 edition, dated February 24, 2014.

[0068] Density is measured according to ASTM D792-13, Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement, Method B (for testing solid plastics in liquids other than water, e.g., liquid 2-propanol). Results are reported in grams per cubic centimeter (g / cm). 3 or g / cc).

[0069] Melt index (I2) is measured in accordance with ASTM D1238-04 (190°C, 2.16 kg), Standard Test Method for Melt Flow Rate of Thermoplastics by Extrusion Platometer, using the 190°C / 2.16 kilogram (kg) condition, formerly known as "Condition E," also known as I2. Results are reported in grams dissolved per 10 minutes (g / 10 min) or the equivalent in decigrams per 1.0 minute (dg / 1 min). 10.0 dg = 1.00 g.

[0070] Embodiments of the present invention also include the following dielectric breakdown strength test method. For clarity, the description of the method is divided into Sections 1-3. Section 1 addresses materials used to prepare the test assembly. Section 2 addresses procedures for preparing a test plaque representing an insulating layer and preparing the test assembly. The test assembly includes a sandwich of a test plate representing the insulating layer and two conductor disks, with the test plate (insulating layer) positioned between the conductor disks. Section 3 addresses procedures for applying an increasing test voltage to the test assembly and detecting a dielectric breakdown event in the insulating layer.

[0071] Section 1: Dielectric Breakdown Strength Test Method (Materials): The conductors are multiple 40 millimeter (mm) diameter aluminum disks and multiple 29 mm diameter aluminum disks, each 75 micrometers thick. A test insulation layer is sandwiched between the conductors so that the total sandwich thickness is 350 to 500 micrometers. After failure, the Al disks are removed and the thickness of the insulation layer is measured at the location of failure.

[0072] Section 2: Dielectric Breakdown Strength Test Method (Procedure for Assembling Electrodes and Test Plaques into a Test Assembly). A two-stage thermoforming process is used to prepare test insulation layer samples. Step 1: Weigh the polymer pellets. Place the weighed pellets in a compression mold (an 8-inch x 8-inch square compression molding frame, approximately 150 to 900 micrometers thick). Preheat the polymer pellets to 140°C under approximately 7 pounds per square inch (psi) for 3 minutes. At the same temperature, switch to a high pressure of approximately 382 psi and hold for 3 minutes. Cool the resulting polymer plaque to room temperature under the same pressure within approximately 15 minutes. Step 2: Cut multiple conductive aluminum (Al) disks with diameters of 29 mm and 40 mm from a 75-micrometer-thick aluminum sheet. Place the conductive Al disks on top and bottom of the plaque (prepared in Step 1), with the 29 mm diameter disk on one side and the 40 mm diameter disk on the other side. The two conductive Al disks face each other and are approximately concentric with each other. A 3x3 array of nine pairs of such conductive Al disks is spaced on each side of an 8"x8" polymer plaque. The resulting assembly is hot-compressed in the same compression mold and under the same protocol as in step 1. The assembly is then placed between two brass electrodes to obtain a test assembly. Each test assembly has nine pairs of upper and lower brass electrodes, nine pairs of upper and lower conductive Al disks, and a single plaque sandwiched between the nine pairs of upper and lower conductive Al disks.

[0073] The test assembly portions 1 are shown in FIG. 1. Each test assembly has nine portions 1. Each test assembly portion 1 includes one of nine pairs of upper and lower brass electrodes 11 and 15, one of nine pairs of upper and lower conductive Al discs 21 and 25, and a portion of a single plaque 30 (FIG. 1). Each pair of brass electrodes 11 and 15 is in electrical communication with a device (not shown) configured to apply current, detect dielectric breakdown, and measure voltage therethrough. Such devices are well known; see, for example, ASTM D149-20, Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies; and IEC 243-1, Methods of Test for Electrical Strength of Solid Insulating Materials Part 1: Tests at Power Frequencies. The brass electrodes 11 and 15 are used to apply current to their respective pairs of conductive Al discs 21 and 25. The upper conductive Al disk 21 has an independent lower surface 22 and an independent upper surface 23, and its disk thickness is the distance between them (i.e., from 22 to 23). The lower conductive Al disk 25 has an independent lower surface 27 and an independent upper surface 26, and its disk thickness is the distance between them (i.e., from 26 to 27). Different portions of the plaque 30 are sandwiched between different pairs of spaced apart conductive Al disks 21 and 25. The thickness of the plaque 30 between the conductive Al disks 21 and 25 is the distance between the lower surface 22 of the upper conductive Al disk 21 and the upper surface 26 of the lower conductive Al disk 25. Each portion of the plaque 30 has an independent upper surface 31. The thickness T of the portion of the plaque 30 used to determine the breakdown strength in Section 3 below is the distance between the upper surface 26 of the lower conductive Al disk 25 and the upper surface 31 of the plaque 30.This thickness T is measured at the location of the channel formed by the breakdown event, indicated by "}T" in FIG.

[0074] Section 3: Dielectric Breakdown Strength Test Method: A procedure for applying an alternating current (AC) to a test assembly while increasing the test voltage to detect a breakdown event. The assembly prepared above is immersed in insulating oil and contacted with brass electrodes at the top and bottom. A voltage is applied. The voltage is gradually increased at a rate of 500 V / S (volts per second, 50 Hz) until a breakdown event occurs, forming a channel through the polymer. The breakdown event is detected as a sudden increase in current. The kilovolts (V) applied when this jump in current event occurs is recorded. Such a breakdown event is due to the formation of a channel by the voltage applied to the insulating layer. The thickness of the insulating layer at the location of the channel is measured and used as the insulation thickness in the following calculation of the actual breakdown strength: E act = V / T (where V is the breakdown voltage in kilovolts (kV), T is the insulation thickness in millimeters (mm) measured at the channel), and E act is the actual breakdown strength in kilovolts per millimeter (kV / mm). For reporting purposes, in the tables below, the actual breakdown strength E act is normalized to a thickness of 1.016 millimeters (mm, equal to 40 mils) and reported in kV / mm as the normalized breakdown strength, E. The normalized breakdown strength, E, is calculated according to Equation 1 (Equation 1): E=(V / T) * (T / T0)^(1 / 2) (Equation 1) (where ^(1 / 2) denotes the square root, V is the kilovolts applied when the breakdown event occurred, each T is a measurement of the thickness of the insulating layer (plaque, location of breakdown), and T0 is 1.016 mm thick (equivalent to 40 mils) so that T / T0 normalizes the breakdown strength values ​​to 1.016 mm thickness). The voltage at which the breakdown event occurs is recorded. The effectiveness of the voltage stabilizer is evaluated by comparing the breakdown field strength of the same polymer both with and without the additive.

[0075] In the dielectric breakdown strength test method of the present invention, the voltage at which a dielectric breakdown event occurs varies depending on the thickness of the insulating layer. The normalized dielectric breakdown strength E, which has units of kV / mm, is analyzed using well-known two-parameter Weibull statistics according to the following Weibull statistical method:

[0076] Weibull statistical method. Equation 2

[0077]

number

[0078] The breakdown strength value used to determine the improvement or reduction compared to the baseline value of CE is the value eta, η, predicted for a 63.2% probability of failure value, determined from the normalized field strength E value using the Weibull statistics described above. Also reported are the 90% confidence level (upper and lower bounds) beta, β, values, b, obtained using the Weibull statistics described above. All other things being equal, the higher the β value, the narrower the range of field strengths over which test sample N will fail, and therefore the narrower the range of E at the 90% confidence level.

[0079] All other conditions, including the thickness of the insulating layer, are equal, the higher the voltage at which breakdown occurs, the greater the breakdown strength of the insulating material. Determine the percentage increase (improvement) or decrease (deterioration) in the voltage of the test plaques (N=8 or 9) at which the breakdown event occurs compared to the voltage of 17 control plaques (N=153 or 155) at which the breakdown event occurs. The greater the percentage increase, the greater the improvement in breakdown strength. The greater the percentage decrease, the greater the deterioration in breakdown strength. [Example]

[0080] Polyethylene polymer (A)-1: Low-density polyethylene homopolymer-1 (LDPE-1). LDPE-1 was prepared in advance by polymerizing ethylene in a high-pressure reactor in the absence of a metal-based polymerization catalyst and in the presence of a small amount (e.g., 0.3-0.4 wt%) of a free-radical initiator (e.g., peroxide or a mixture of peroxides or O2) and 1 wt% of a chain transfer agent, which was propylene. LDPE-1 had a density of 0.920 g / cm. 3 and a melt index of 2.0 g / 10 min.

[0081] Aryl ketone (B)-1 of the present invention: R 7 is methyl, which is 1-acetonaphthone (i.e., 1-acetylnaphthalene).

[0082] Aryl ketone (B)-2 of the present invention: R 7 9-acetylanthracene, a compound of formula (Ia-2), wherein is methyl.

[0083] Aryl ketone (B)-3 of the present invention: R 7 1-acetylpyrene, a compound of formula (Ia-3), wherein is methyl.

[0084] Aryl ketone (B)-4 of the present invention: R 7 is methyl, which is 2-acetonaphthone (i.e., 2-acetylnaphthalene).

[0085] Comparative Aryl Ketone 1: Structure:

[0086] [ka] 2-acetylfluorene having

[0087] Comparative Aryl Ketone 2: Structure:

[0088] [ka] Benzyl is a compound having the formula:

[0089] Comparative Aryl Ketone 3: Structure:

[0090] [ka] The compound having the formula: 4,4'-bis(dimethylamino)-benzyl.

[0091] Comparative aryl aldehyde 1: structure below:

[0092] [ka] 1-pyrenecarboxaldehyde is a compound having the formula:

[0093] The effect of crosslinkable polyolefin formulations on dielectric breakdown strength is evaluated using test compounds containing (B) an aryl ketone of formula (I) and a comparative (non-inventive) ketone. The crosslinkable polyolefin formulation of the present invention includes a test compound that is an aryl ketone of formula (I) (B) and a polyethylene polymer (A)-1. The comparative crosslinkable polyolefin formulation includes a test compound that is a comparative (non-inventive) aryl ketone, an aryl aldehyde (or other voltage stabilizer not of formula (I)), and a polyethylene polymer (A)-1. Test formulations are prepared by melt blending a known amount of test compound into polyethylene polymer (A)-1 so that the concentration of the test compound in the test formulation is 0.1 to 3.0 wt.% based on the total weight of the formulation. The formulations are separately fabricated into test plaques according to the procedure previously described for the dielectric breakdown strength test method, and the voltage at which a dielectric breakdown event occurs is determined. Results are reported as eta values ​​for a 63.2% probability of failure, as determined according to the Weibull statistics.

[0094] Comparative Example 0 ("CE0"): A single batch of stabilizer-free comparative formulation consisting of 100.00% by weight polyethylene polymer (A)-1 is prepared. The stabilizer-free comparative formulation batch does not contain a voltage stabilizer or any additives. In separate experiments, different samples of the stabilizer-free comparative formulation are melt-blended into 17 test plaques. The dielectric breakdown strength of each test plaque is measured using a 3 x 3 array of nine pairs of electrodes to obtain 153 actual dielectric breakdown strength values. The dielectric breakdown strength values ​​are normalized to a 40 mm plaque thickness according to Equation 1 below. The normalized dielectric breakdown strength value for CE0 is an eta, η, value of 18.49 kV / mm (for a failure probability value of 63.2%) with a 90% confidence level, beta being 18.18 to 18.81 kV / mm (lower to upper limit). All comparisons of percent improvement and eta, η, values ​​of the present invention at a failure probability of 63.2% are compared to the baseline (unimproved or unreduced) normalized breakdown strength value of 18.5 kV / mm at a failure probability of 63.2%.

[0095] Comparative Examples 1-4 (CE1-CE4): In separate experiments, polyethylene polymer (A)-1 is melt-blended with known amounts of any one of comparative aryl ketones 1-3 or comparative aryl aldehyde 4 shown in Table 1 below to obtain comparative crosslinkable polyolefin blends CE1-CE4, respectively. The blends are tested according to the dielectric breakdown strength test method. The test results are shown in Table 2.

[0096] [Table 1]

[0097] [Table 2]

[0098] N / r not reported. As shown by the data in Table 2, compared to CE0, which does not contain the voltage stabilizer additive, benzyl (CE2) and 1-pyrenecarboxaldehyde (CE4) each improved or slightly improved the breakdown strength (increased the voltage), whereas 2-acetylfluorene (CE1) did not change the breakdown strength, and 4,4'-bis(dimethylamino)-benzyl (CE3) decreased the breakdown strength (decreased the voltage).

[0099] Inventive Example 1 (IE1, prophetic): Polyethylene polymer (A)-1 is melt blended with 0.1-3.0 wt % of aryl ketone (B)-1 (1-acetonaphthone) to obtain inventive crosslinkable polyolefin blend IE1, where wt % is based on the total weight of blend IE1.

[0100] Inventive Examples 2-7 (IE2-IE7): In separate experiments, polyethylene polymer (A)-1 is melt-blended with known amounts of any one of aryl ketones (B)-2, (B)-3, or (B)-4 according to Table 3 below to obtain inventive crosslinkable polyolefin blends IE2-IE7. The blends are tested according to the dielectric breakdown strength test method. The test results are shown in Table 4.

[0101] [Table 3]

[0102] The data in Table 3 show that crosslinkable polyolefin blends IE2 to IE7 are examples of crosslinkable polyolefin blends of the present invention.

[0103] [Table 4]

[0104] As shown by the data in Table 4, all of the inventive aryl ketones of formula (I) improved breakdown strength (increased voltage) compared to CE0, which did not contain a voltage stabilizer additive. Furthermore, when comparing IE2 with IE3, IE4 with IE5, and IE6 with IE7, the improvement in breakdown strength positively correlated with the concentration of aryl ketone in the formulation.

[0105] Inventive Example 8 (IE8, prognostic): A polyethylene polymer (A)-1 is melt-blended with 2.5 wt% of an aryl ketone (B)-1 (1-acetonaphthone) to obtain a first inventive crosslinkable polyolefin blend. 1.0 wt% of dicumyl peroxide is immersed therein to obtain a second inventive crosslinkable polyolefin blend, IE8. The weight percentages are based on the total weight of the blend, IE8. The resulting inventive blend is heated at 120°C for 1 hour, thereby producing an inventive crosslinked polyolefin product, IE8.

[0106] Inventive Examples 9-13 (IE9-IE13, prophetic): In separate experiments, the procedure of IE8 is repeated except that the aryl ketone (B)-1 is replaced with an equal amount of any one of aryl ketones (B)-2, (B)-3, or (B)-4 to obtain inventive crosslinked polyolefin products IE9-IE13. The present application also relates to the following aspects: (1) A coated conductor comprising a conductive core and an insulating layer at least partially covering the conductive core, wherein at least a portion of the insulating layer comprises a crosslinkable polyolefin formulation comprising (A) a polyethylene polymer and (B) an aryl ketone of formula (I): [ka] (In the formula, R 1 ~R 6 are each a hydrogen atom (H) or or R 1 and R 2 , or R 3 and R 4 , or R 4 and R 5 , or R 5 and R 6 are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 1 ~R 6 The remaining four of 2 、R 3 , and R 4 are bonded together to form two fused 6-membered aryl rings with the carbon atoms in formula (I) to which they are attached and the nearest bridgehead carbon atoms in formula (I), and R 1 、R 5 , and R 6 are each H, and one of R A and R B is a group of the formula -C(=O)-R 7 and the other of R A and R B is H, or R A is a group of the formula —C(═O)—R 7 and R and R 1 are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R 2 and R 6 is as defined above; R7 is unsubstituted (C 1 ~C 40 ) a hydrocarbyl group), the (A) polyethylene polymer comprises 51 to 100 weight percent (wt%) of ethylene-derived structural units and 49 to 0 wt% of alpha-olefin-derived structural units, respectively, based on the weight of the (A) polyethylene polymer, and the crosslinkable polyolefin blend comprises 30.0 to 99.9 wt% of the (A) polyethylene polymer, based on the total weight of the crosslinkable polyolefin blend, and 0.1 to 3.0 wt% of the (B) aryl ketone, based on the total weight of the crosslinkable polyolefin blend. (2) The (B) aryl ketone is (Ia) or (Ib):

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Claims

1. 1. A coated conductor comprising a conductive core and an insulating layer at least partially covering the conductive core, wherein at least a portion of the insulating layer comprises a crosslinkable polyolefin formulation comprising: (A) a polyethylene polymer; and (B) an aryl ketone of formula (I): 【Chemistry 1】 (In the formula, R １ ~R ６ are each a hydrogen atom (H), or or R １ and R ２ , or R ３ and R ４ , or R ４ and R ５ , or R ５ and R ６ are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R １ ~R ６ The remaining four of ２ , R ３ , and R ４ are bonded together to form two fused 6-membered aryl rings with the carbon atoms in formula (I) to which they are attached and the nearest bridgehead carbon atoms in formula (I), and R １ , R ５ , and R ６ are each H, and R Ａ． and R Ｂ one of which is of the formula -C(=O)-R ７ is a group of R Ａ and R Ｂ the other is H or R Ａ is represented by the formula -C(=O)-R ７ is a group of R Ｂ and R １ are joined together with the carbon atoms in formula (I) to which they are attached to form a fused 6-membered aryl ring, and R ２ and R ６ is as defined above; R ７ is unsubstituted (C １ ~C ４０ ) a hydrocarbyl group), the (A) polyethylene polymer comprises 51 to 100 weight percent (wt %) of ethylene-derived constitutional units and 49 to 0 wt % of alpha-olefin-derived constitutional units, each based on the weight of the (A) polyethylene polymer, and the crosslinkable polyolefin blend comprises 30.0 to 99.9 wt % of the (A) polyethylene polymer, based on the total weight of the crosslinkable polyolefin blend, and 0.1 to 3.0 wt % of the (B) aryl ketone, based on the total weight of the crosslinkable polyolefin blend.

2. The (B) aryl ketone is (Ia) or (Ib): 【Chemistry 2】 (In the formula, R １ ~R ７ and R Ｂ and are independently as defined for formula (I).

3. The (B) aryl ketone is represented by formula (Ia-1), (Ia-2), or (1a-3): 【Transformation 3】 (In the formula, each R ７ and are independently as defined for formula (I).

4. The (B) aryl ketone is represented by formula (Ib-1): 【Chemistry 4】 (In the formula, R ７ and are independently as defined for formula (I).

5. R ７ is unsubstituted (C １ ~C ５ ) alkyl group or unsubstituted (C ６ ~C ４０ 5. The coated conductor according to claim 1, wherein the alkyl group is a methyl group.

6. The coated conductor according to any one of claims 1 to 5, wherein the (A) polyethylene polymer comprises 100% by weight of ethylene-derived structural units and is (A1) a low-density polyethylene homopolymer, or the (A) polyethylene polymer comprises 51 to 99.9% by weight of ethylene-derived structural units and 49 to 0.1% by weight of alpha-olefin-derived structural units and is (A2) an ethylene / alpha-olefin copolymer.

7. 7. The coated conductor according to claim 1, further comprising at least one additive, each additive independently selected from the group consisting of (C) organic peroxides, (D) scorch inhibitors, (E) antioxidants, (F) fillers, (G) flame retardants, (H) hindered amine stabilizers, (I) tree inhibitors, (J) methyl radical scavengers, (K) crosslinking coagents, (L) nucleating agents, (M) colorants, and combinations of any two or more of the additives (C) to (M).

8. 8. A cured coated conductor comprising a conductive core and an insulating layer at least partially coating the conductive core, wherein at least a portion of the insulating layer comprises a cross-linked polyolefin product, the cured coated conductor being made by a method comprising subjecting the coated conductor of any one of claims 1 to 7 to curing conditions such as to cross-link the (A) polyethylene polymer, thereby producing the cross-linked polyolefin product.

9. 10. A method of transmitting electricity comprising applying a voltage across the conductive core of the coated conductor of claim 8 so as to cause a flow of electricity through the conductive core.

10. 9. The coated conductor of any one of claims 1-8, wherein the crosslinkable polyolefin formulation exhibits at least a +5 percent (%) improvement (increase) in dielectric breakdown strength value eta, η compared to the (A) polyethylene polymer without a voltage stabilizer, wherein the dielectric breakdown strength value eta, η at a probability of failure value of 63.2% is determined using Weibull statistics in accordance with the dielectric breakdown strength test method and Weibull statistics method described herein.

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