Polyolefin formulation and method of making the same, method of making a crosslinked polyolefin product and a crosslinked polyolefin product made thereby, an article comprising the same, a coated conductor, and method of transmitting electricity

Abstract

A polyolefin formulation is provided, comprising (A) a polyolefin polymer; x wt% (wt%) of an alkoxyphenol compound of formula (I) (B); and y wt% of a diphenyl ketone compound of formula (II) (C), wherein R1 and Ar1 are as described herein; wherein y is 1 to 8 wt%; wherein x is 0.1 to 3.0 wt%, limited to x being less than 0.5y; and wherein wt% is based on the total weight of the polyolefin formulation. Crosslinked products manufactured therefrom are also provided; methods of their manufacture and use; and articles containing therefrom.

Description

[Technical Field]

[0001] The technical field includes polyolefin formulations for use in wires and cables. [Previous Technology]

[0002] Patents in this field include US3413263, US6696154B2, US8680399B2, US9133320B2 and US9343198B2. Patent applications published in this field include EP0111043A1, EP2886595, GB1461331A, US20160304699A1, US20160312007A1, WO2010028721A1, WO2012044521, WO2014209661A1 and WO2014172107A1. Publications include: About the Significance of Peroxide Decomposition Products in XLPE Cable Insulations, H. Wagner and J. Wartusch, IEEE Trans. Electr. Insul, Vol. EI-12, No. 6, December 1977.

[0003] Insulated electrical conductors typically consist of a conductive core covered by an insulating layer. The conductive core can be solid or stranded (e.g., wire harness). Some insulated electrical conductors may also contain one or more additional elements, such as one or more semiconductor layers and / or protective sheaths (e.g., coils, tapes, or sheaths). Examples include coated metal wires and power cables, including metal wires and power cables used in low voltage ("LV", 0 to < 5 kV), medium voltage ("MV", 5 to < 69 kV), high voltage ("HV", 69 to 230 kV), and ultra-high voltage ("EHV", > 230 kV) power cables and their electrical transmission / distribution applications. The evaluation of power cables may be performed using AEIC / ICEA specifications and standards and / or IEC test methods.

[0004] Most high-voltage and ultra-high-voltage power cables contain an insulation layer composed of an insulating material comprising a main polymer and one or more additives. These additives may include antioxidants, colorants, and / or hindered amine stabilizers. The electrical breakdown strength (also known as dielectric strength) of the insulating material determines the required thickness of the insulation layer to meet industry specifications for power cable performance at a specific voltage.

[0005] All else being equal, insulation with higher electrical breakdown strength allows a thinner insulation layer to have the same electrical breakdown strength as a comparable thicker layer. All else being equal, a thinner insulation layer means a thinner cable. A thinner cable advantageously allows for a smaller amount of cable mass per unit length to achieve a given electrical breakdown strength. This, in turn, helps to increase the length of cable that can be wound onto a standard-sized cable reel. A longer cable, in turn, reduces the number of joints or connections required to connect two or more thinner cables together. Alternatively, insulation with higher electrical breakdown strength allows for insulation layers of the same thickness, and therefore allows for cables of the same thickness but with higher electrical breakdown strength. Cables of the same thickness with higher electrical breakdown strength advantageously allow for carrying higher voltage in that cable geometry. Transmitting power at higher voltage reduces energy loss. [Summary of the Invention]

[0006] We have discovered a voltage stabilizer additive combination with beneficial voltage stabilizing effects, comprising an alkoxyphenol compound and a diphenyl ketone compound. This effect is considered synergistic, as described later. When a host polyolefin polymer is formulated with these compounds, the resulting polyolefin formulation exhibits increased electrical breakdown strength compared to a host polyolefin without (B) the alkoxyphenol compound and (C) the diphenyl ketone compound. In some embodiments, the electrical breakdown strength of the formulations of the present invention is advantageously greater than that of comparative formulations containing benzoethylene glycol and / or benzoethylene glycol derivatives. We consider the following examples.

[0007] A polyolefin formulation comprising (A) a polyolefin polymer; (B) an alkoxyphenol compound of formula (I): (I), wherein R1 is (C1-C20) alkyl; and (C) a diphenyl ketone compound of formula (II): (II), wherein Ar1 is phenyl or alkylphenyl.

[0008] A method for manufacturing a polyolefin formulation, the method comprising contacting (A) a polyolefin polymer with (B) an alkoxyphenol compound and (C) a diphenyl ketone compound to manufacture the formulation.

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

[0010] A cross-linked polyolefin product, which is manufactured by the above method.

[0011] An article comprising a polyolefin formulation and / or a crosslinked polymer product.

Implementation Method

[0013] The summary and abstract of the invention are incorporated herein by reference. Some of the embodiments described herein are numbered for ease of reference.

[0014] Formula 1. A polyolefin formulation comprising (A) a polyolefin polymer; x wt% of an alkoxyphenol compound of formula (I) of formula (B): (I), wherein R1 is a (C1-C20) alkyl group; and y wt% of a diphenyl ketone compound of formula (II) of formula (C): (II), wherein Ar1 is a phenyl or alkylphenyl group; wherein y is 1 to 8 wt%; wherein x is 0.1 to 3.0 wt%, with the limitation that x is less than 0.5y; and wherein wt% is based on the total weight of the polyolefin formulation. The formulation may contain one and only one (B) alkoxyphenol compound and one and only one (C) diphenyl ketone compound. The polyolefin formulation has increased electrical breakdown strength relative to the (A) polyolefin polymer which does not contain one or both of components (B) and (C).

[0015] Form 2. The polyolefin formulation of Form 1, wherein Ar1 is phenyl; and R1 is selected from the group consisting of: (i) (C1-C5)alkyl; (ii) (C6-C10)alkyl; (iii) methyl; and (iv) heptyl; or wherein Ar1 is alkylphenyl; and R1 is selected from the group consisting of: (i) (C1-C5)alkyl; (ii) (C6-C10)alkyl; (iii) methyl; and (iv) heptyl. In other embodiments, R1 is selected from the group consisting of: (v) (C2-C8)alkyl; (C4-C8)alkyl; and (viii) (C6-C8)alkyl.

[0016] Form 3. A polyolefin formulation of any one of Forms 1 to 2, wherein the R1 is methyl or heptyl and the Ar1 is phenyl.

[0017] Form 4. A polyolefin formulation of any one of Forms 1 to 3, wherein the (A) polyolefin polymer is selected from the group consisting of: low-density polyethylene polymer, ethylene / (C4-C20) α-olefin copolymer, ethylene / (unsaturated carboxylic acid ester) copolymer, ethylene / (monocyclic organosiloxane) copolymer, ethylene / propylene copolymer, ethylene / propylene / (diene monomer) trimer, and propylene homopolymer.

[0018] Form 5. A polyolefin formulation of any one of Forms 1 to 4, comprising 50.0 to 99.7 wt% of the (A) polyolefin polymer; x = 0.3 wt% to x = 0.9 wt% of the (B) alkoxyphenol compound; 1.9 to 7.4 wt% of the (C) diphenyl ketone compound; and a total of 0.1 to 43 wt% of at least one additive, wherein each of the at least one additive is different from components (A), (B), and (C) and is independently selected from the group consisting of: (D) organic peroxides; (E) scorch inhibitors; (F) antioxidants; (G) fillers; (H) flame retardants; (I) hindered amine stabilizers; (J) tree retardants; (K) methyl radical scavengers; (L) crosslinking aids; (M) processing aids; (N) colorants; and combinations of any two or more of additives (D) to (N).

[0019] Form 6. The polyolefin formulation of Form 5, comprising 85 to 99.5 wt% of the (A) polyolefin polymer, which is a low-density polyethylene polymer; 0.30 to 0.50 wt% of the (B) alkoxyphenol compound, which is a compound of formula (I), wherein R1 is methyl or heptyl; 1.5 to 2.4 wt% of the (C) diphenyl ketone compound of formula (II), wherein Ar1 is phenyl; and 0.1 to 1.5 wt% of at least one (F) antioxidant.

[0020] Sample 7. A method for manufacturing a polyolefin formulation as described in any one of Samples 1 to 6, the method comprising mixing the (A) polyolefin polymer with the (B) alkoxyphenol compound and the (C) diphenyl ketone compound, and, if applicable, at least one additive to manufacture the formulation. The manufactured formulation may be a heterogeneous or homogeneous blend of components (A), (B), and (C). The contacting step comprises contacting components (A), (B), and (C) with each other (which have not been previously contacted). The contacting step may further comprise mixing the contacted (A), (B), and (C) together to form a homogeneous mixture thereof. In some embodiments, the method further comprises mixing at least one of additives (D) to (N), if applicable, with (A) and (B). The mixing may comprise melt-blending components (B), (C), and, if applicable, additives (D) to (N) into the melt of component (A). The melt blending may be performed in an extruder configured for melt-blending polyolefins and additives. The molten blend obtained by die extrusion can be used to form strands, which can then be granulated to obtain a polyolefin formulation in pellet form. Alternatively, the molten blend can be extruded using a die designed to form an article containing the polyolefin formulation.

[0021] Sample 8. A method for manufacturing a crosslinked polyolefin product, the method comprising subjecting a polyolefin formulation as described in any one of Samples 1 to 6 to curing conditions to crosslink the (A) polyolefin polymer, thereby producing the crosslinked polyolefin product. The curing conditions may include exposing the formulation to ultraviolet light or heating the formulation together with the (D) organic peroxide and, if applicable, the (L) crosslinking aid. An embodiment of the method may include heating an embodiment of a polyolefin formulation as described in any one of Samples 1 to 7, thereby crosslinking the (A) polyolefin polymer to produce a crosslinked polyolefin product, the polyolefin formulation comprising the (D) organic peroxide and, if applicable, the (L) crosslinking aid. When the (L) crosslinking aid is not used, crosslinking involves the formation of carbon-carbon covalent bonds between molecules of the (A) polyolefin polymer. When the (L) crosslinking aid is included, crosslinking involves the formation of carbon-carbon covalent bonds between molecules of the (A) polyolefin polymer and between molecules of the (L) crosslinking aid and molecules of the (A) polyolefin polymer.

[0022] Sample 9. A crosslinked polyolefin product manufactured by the method of Sample 8. The crosslinked polyolefin product has increased electrical breakdown strength relative to a crosslinked (A) polyolefin polymer that does not contain one or both of components (B) and (C). The crosslinked polyolefin product may comprise (Aʹ) a crosslinked (network) polyethylene polymer manufactured by crosslinking the following: the (A) polyolefin polymer or a combination of the (A) polyolefin polymer and the (L) crosslinking aid; and components (B) and (C). The crosslinked polyolefin product may further comprise at least one additive selected from: (F) an antioxidant; (G) a filler; (H) a flame retardant; (I) a hindered amine stabilizer; (J) an anti-repair agent; (K) a methyl radical scavenger; (M) a nucleating agent; and (N) a colorant (e.g., carbon black or titanium dioxide). The crosslinked polyolefin product has increased electrical breakdown strength relative to a crosslinked (A) polyolefin polymer that does not contain components (B) and (C).

[0023] Sample 10. An article comprising a polyolefin formulation as described in any one of Samples 1 to 6 or a crosslinked polyolefin product as described in Sample 9. The article has increased electrical breakdown strength relative to an article containing the (A) polyolefin polymer and excluding one or both of components (B) and (C). In some samples, the finished article is selected from: coatings, films, sheets, extruded articles (not pellets), and injection-molded articles. For example, coated conductors, insulation layers for wires and cables used for transmitting electricity or telecommunications, agricultural films, automotive parts, containers, food packaging, clothing bags, grocery bags, bulk bags, industrial sheets, pallets and shrink wraps, bags, barrels, refrigerator containers, lids, and toys. The finished article has increased electrical breakdown strength relative to a crosslinked main polyolefin excluding the (B) alkoxyphenol compound and the (C) diphenyl ketone compound.

[0024] Sample 11. 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 cross-linked polyolefin product as described in Sample 9. The coated conductor and its insulating layer have increased electrical breakdown strength relative to a coated conductor or insulating layer containing the polyolefin polymer (A) and excluding one or both of components (B) and (C). The conductive core may be a wire having a proximal end and a distal end, at least one end of which may be free of the insulating layer.

[0025] State 12. A method for transmitting electricity, the method comprising applying a voltage across a conductive core of a coated conductor as shown in State 10 to generate a current through the conductive core. The method of transmitting data via a coated conductor of the present invention, including an insulated electrical conductor, is also contemplated.

[0026] Specimen 13. The invention as described in any one of Specimens 1 to 12, wherein the polyolefin formulation has an electrical breakdown strength value improved (increased) by at least +10.0 percentage points (%) relative to the electrical breakdown strength value of a comparative formulation which does not contain either the (B) alkoxyphenol compound or the (C) diphenyl ketone compound; wherein the electrical breakdown strength value is determined using the Weibull statistics method for a failure probability value of 63.2% according to the electrical breakdown strength test method and the Weibull statistics method described in this description. In some embodiments, the improvement (increase) of the electrical breakdown strength value of the Specimen 1 (for a failure probability value of 63.2%) relative to the electrical breakdown strength value of the (A) polyolefin polymer without the voltage stabilizer (e.g., relative to the electrical breakdown strength value of Comparative Example 0 (CE0) described later in the examples) is at least +25%, alternatively at least +45%, alternatively at least +49%. In some embodiments, the improvement of the electrical breakdown strength value Itaη (for a failure probability of 63.2%) relative to the electrical breakdown strength value of the (A) polyolefin polymer without voltage stabilizer (e.g., relative to the electrical breakdown strength value of CEO) is further characterized as at most 75%, alternatively at most +65%, alternatively at most +59%, and alternatively at most 55%. In some embodiments, the improvement of the electrical breakdown strength value Itaη (for a failure probability of 63.2%) relative to the electrical breakdown strength value of the (A) polyolefin polymer without voltage stabilizer (e.g., relative to the electrical breakdown strength value of CEO) is +45% to +54%. In some embodiments, the improvement of the electrical breakdown strength value Itaη (for a failure probability of 63.2%) relative to the electrical breakdown strength value of the (A) polyolefin polymer without voltage stabilizer (e.g., relative to the electrical breakdown strength value of CEO) is +50% ± 5%. In some embodiments, the crosslinked polyolefin product made from the polyolefin formulation has any of the aforementioned improvements of the invention with an electrical breakdown strength value of Itaη (for a failure probability of 63.2%). All of the aforementioned percentage improvements in electrical breakdown strength, Itaη, are determined according to the electrical breakdown strength test method (for a failure probability of 63.2%) described later. In some embodiments, the value of Itaη (for a failure probability of 63.2%) is further characterized as a 90% confidence level beta β determined according to the electrical breakdown strength test method and Weber statistical method described later.

[0027] Form 14. The present invention as described in any one of Forms 1 to 13, wherein the polyolefin formulation has an improved (increased) electrical breakdown strength value, itaη, which is greater than the sum of the itaη values ​​of a first comparative formulation containing only (A) polyolefin polymer and diphenyl ketone and a second comparative formulation containing (A) polyolefin polymer, 2-naphthyl ethyl ketone and 9-acetyl anthracene, wherein the weight percentage (wt%) of the diphenyl ketone in the first comparative formulation is the same as the wt% of the (C) diphenyl ketone compound in the polyolefin formulation; wherein the wt% of the 2-naphthyl ethyl ketone in the second comparative formulation is the same as the wt% of the (B) alkoxyphenol compound in the polyolefin formulation; and wherein the wt% of the 9-acetyl anthracene in the second comparative formulation is the same as the wt% of the (B) alkoxyphenol compound in the polyolefin formulation.

[0028] The coated conductor can be a power cable with a near end and a far end, and electricity can flow from the near end through the conductive core to the far end, or vice versa. The conductive core can be an electrical wire. The power cable can be a medium voltage (MV), high voltage (HV), or ultra-high voltage (EHV) power cable. The power cable is suitable for electrical transmission applications.

[0029] (A) Polyolefin polymer. Composed of polyethylene macromolecules, which independently comprise at least 5, or alternatively 10 to 200,000, constituent units derived from polymerized ethylene and zero, one or more other olefin functional monomers. The density of (A) polyolefin polymer may be 0.870 to 0.975 g / cm³, or alternatively 0.890 to 0.930 g / cm³ (e.g., LDPE or LLDPE), or alternatively 0.910 to 0.930 g / cm³ (e.g., LDPE or LLDPE), or alternatively 0.931 to 0.945 g / cm³ (e.g., MDPE), or alternatively 0.945 to 0.970 g / cm³ (e.g., HDPE), all values ​​measured according to ASTM D792-13 Method B.

[0030] Polyethylene can be a homopolymer or a copolymer. Homopolymers are manufactured by polymerizing only ethylene. Copolymers are manufactured by polymerizing at least two different olefin monomers, one of which is ethylene. Copolymers can be dimers made by polymerizing ethylene and one different olefin monomer, trimers made by polymerizing ethylene and two different olefin monomers, or tetramers made by polymerizing ethylene and three different olefin monomers. The polyolefin in the copolymer can be a block copolymer or a random copolymer.

[0031] Examples of olefin-functional monomers used in the manufacture of (A) polyolefin polymers include ethylene, propylene, (C4-C20) α-olefins, cyclic olefins (e.g., norbornene), dienes (e.g., 1,3-butadiene), unsaturated carboxylic acid esters, and olefin-functional hydrolyzable silanes. Examples of (C4-C20) α-olefins are (C4-C8) α-olefins, such as 1-butene, 1-hexene, or 1-octene; and (C10-C20) α-olefins. Examples of dienes are 1,3-butadiene. Examples of unsaturated carboxylic acid esters are alkyl acrylates, alkyl methacrylates, and vinyl carboxylic acid esters (e.g., vinyl acetate). Examples of olefin-functional hydrolyzable silanes are vinyltrialkoxysilanes, vinyltrialkylaminosilanes, and vinyltrioximesilanes.

[0032] In some embodiments, (A) the polyolefin polymer is a vinyl polymer. The vinyl polymer comprises 51 wt% to 100 wt% of olefinic units derived from polymerized ethylene and 49 wt% to 0 wt% of comonomer units derived from polymerized one or more alternative olefin functional monomers (comonomers). The comonomer may be selected from propylene, (C4-C20) α-olefins, and 1,3-butadiene. The (C4-C20) α-olefin may be (C4-C8) α-olefins, such as 1-butene, 1-hexene, or 1-octene.

[0033] Examples of suitable vinyl polymers are polyethylene homopolymers, ethylene / (C4-C20) α-olefin copolymers, ethylene / propylene copolymers, ethylene / propylene / diene monomer (EPDM) copolymers such as ethylene / propylene / 1,3-butadiene trimers, and ethylene / 1-butene / styrene copolymers. Examples of suitable ethylene / (C4-C20) α-olefin copolymers are ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, and ethylene / 1-octene copolymers. Vinyl polymers may 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 vinyl polymers are sold by The Dow Chemical Company under trade names such as AFFINITY, ATTANE, DOWLEX, ENGAGE, FLEXOMER, or INFUSE. Other vinyl polymers are sold by other suppliers under trade names such as TAFMER, EXCEED, and EXACT. LDPE and LLDPE differ in composition due to their different polymerization conditions: LDPE is produced 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 produced in a standard pressure polymerization reactor in the presence of an olefin polymerization catalyst and without a free radical initiator.

[0034] In some samples, (A) is a polyolefin polymer-based polyethylene homopolymer, such as low-density polyethylene (LDPE). All its component units are ethylene repeating units. LDPE can be produced 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 to 0.4 wt%) of a free radical initiator (e.g., peroxide or a mixture of peroxide or O2) and 1 wt% of a chain transfer agent, propylene.

[0035] In some embodiments, (A) the polyolefin polymer consists of only one type of vinyl polymer (e.g., only LLDPE, or only LDPE, or only MDPE, or only HDPE). In some embodiments, (A) the polyolefin polymer consists of LDPE. When (A) the polyolefin polymer consists of LDPE, in some such embodiments, the polyolefin formulation may not contain any organic polymers other than LDPE.

[0036] (A) The polyolefin polymer may be an ethylene / α-olefin copolymer. The ethylene / α-olefin copolymer may be an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, or any combination thereof. The component unit of the ethylene / (C4-C20)α-olefin copolymer consists of 51 to 99.9 wt% ethylene-derived component units and 49 to 0.1 wt% α-olefin-derived component units.

[0037] (A) The polyolefin polymer may be an ethylene / propylene copolymer. The component units of the ethylene / propylene copolymer consist of ethylene monomer units, propylene comonomer units, and diene comonomer units, depending on the situation.

[0038] (A) The polyolefin polymer may be an ethylene / (unsaturated carboxylic acid ester) copolymer. The unsaturated carboxylic acid ester is vinyl acetate, alkyl acrylate, or alkyl methacrylate.

[0039] (A) The polyolefin polymer may be an ethylene / (monocyclic organosiloxane) copolymer. The monocyclic organosiloxane has the formula (III): [R1,R2SiO2 / 2]n(III), wherein the subscript n is an integer greater than or equal to 3; each R1 is independently (C2-C4)alkenyl or H2C=C(R1a)-C(=O)-O-(CH2)m-, wherein R1a is H or methyl, and the subscript m is an integer from 1 to 4; and each R2 is independently H, (C1-C4)alkyl, phenyl, or R1.

[0040] (A) The polyolefin polymer may comprise a blend of two or more different vinyl polymers. In some embodiments, the two or more different vinyl polymers of the blend comprise at least one LDPE.

[0041] In some samples, (A) the polyolefin polymer is composed of a low-density polyethylene (LDPE) polymer. The LDPE polymer is manufactured 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 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% relative to the total weight of ethylene and propylene in the high-pressure reactor. The LDPE polymer may have a density of 0.910 to 0.930 g / cm3 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.

[0042] The polyolefin formulation may contain 60.0 to 99.9 wt% of (A) polyolefin polymer; alternatively, 70.0 to 99.9 wt% of (A) polyolefin polymer; alternatively, 85.0 to 99.9 wt% of (A) polyolefin polymer; alternatively, 90.0 to 99.9 wt% of (A) polyolefin polymer; all based on the total weight of the polyolefin formulation.

[0043] (B) Alkoxyphenol compounds of formula (I): (I), wherein R1 is a (C1-C20) alkyl group. In some embodiments, R1 is a (C11-C20) alkyl group; alternatively (C1-C10) alkyl group; alternatively (C1-C8) alkyl group; alternatively (C1-C3) alkyl group; alternatively (C6-C8) alkyl group; alternatively methyl group; alternatively ethyl group; alternatively propyl group; alternatively butyl group; alternatively 1-methylpropyl group; alternatively pentyl group; alternatively hexyl group; alternatively heptyl group; alternatively octyl group; alternatively decyl group. R1 may be methyl or heptyl and the alkoxyphenol compound of formula (I) may be 4-methoxyphenol (CAS 150-76-5) or 4-heptoxyphenol (CAS 13037-86-0). Alternatively, R1 may be decyl (CH3(CH2)9-) and the alkoxyphenol compound of formula (B) (I) may be 4-decoxyphenol.

[0044] (C) Diphenyl ketone compounds of formula (II): (II), wherein Ar1 is a phenyl or alkyl phenyl group.

[0045] The Ar1 group in formula (II) may be an alkylphenyl group. Alkylphenyl groups are phenyl groups that are independently substituted with 1 to 5 (C1-C20) alkyl groups. Without being bound by theory, it is believed that (one or more) alkyl substituents on the phenyl group contribute to the solubility of (C) diphenyl ketone compounds having such (one or more) alkyl substituents in (A) polyolefin polymers.

[0046] The alkylphenyl group may be (C1)alkylphenyl (i.e., methylphenyl), (C2-C20)alkylphenyl, or a combination thereof. Examples of (C1)alkylphenyl (i.e., methylphenyl) include 4-methylphenyl; 2,4-dimethylphenyl; 2,5-dimethylphenyl; 2,4,5-trimethylphenyl; and 2,3,4,t-tetramethylphenyl. Examples of (C2-C20)alkylphenyl include 4-ethylphenyl; 4-hexylphenyl; 4-decylphenyl; and 4-nonadenylatedphenyl. Examples of combinations include 2-methyl-4-hexylphenyl.

[0047] In some embodiments, Ar1 is a phenyl or methyl-substituted phenyl; alternatively, it is phenyl. Ar1 may be phenyl and the diphenyl ketone compound of formula (II) may be diphenyl ketone itself (CAS 119-61-9). Alternatively, Ar2 may be 4-methylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl, or 4-(1,1-dimethylethyl)phenyl and the diphenyl ketone compound of formula (II) may be 4-methyldiphenyl ketone (CAS 134-84-9), 2,4'-dimethyldiphenyl ketone (CAS 1140-14-3), 3,4'-dimethyldiphenyl ketone (CAS 2571-39-3), or 4-tributyldiphenyl ketone (CAS 22679-54-5).

[0048] Except for (B) alkoxyphenol compound and (C) diphenyl ketone compound, the polyolefin formulation and the cross-linked polyolefin products manufactured therefrom may be free of any voltage stabilizer compound. Alternatively, the polyolefin formulation and the cross-linked polyolefin products manufactured therefrom may contain a third voltage stabilizer compound, which is different from (B) alkoxyphenol compound and (C) diphenyl ketone compound.

[0049] The restriction condition "x is less than 0.5y" means that the wt% of the loading x of the (B) alkoxyphenol compound in the formulation is less than half the wt% of the loading y of the (C) diphenyl ketone compound in the formulation. Surprisingly, if the wt% of the loading x of the (B) alkoxyphenol compound in the formulation is too high relative to the wt% of the loading y of the (C) diphenyl ketone compound in the formulation, the voltage stabilizing effect of the combination of (B) and (C) is reduced or even reversed, that is, the relative effect becomes voltage destabilization. Depending on the wt% of the loading y of the (C) diphenyl ketone compound in the formulation, the wt% of the loading x of the (B) alkoxyphenol compound in the formulation can be from 0.03y to 0.30y, or alternatively from 0.05y to 0.24y.

[0050] Within the limitation of "x is less than 0.5y", in some embodiments, the amount of (B) alkoxyphenol compound is 0.15 to 0.94 wt%, alternatively 0.20 to 0.44 wt%, alternatively 0.35 to 0.44 wt%. In some embodiments, the amount of (C) diphenyl ketone compound is 1.0 to 7.4 wt%, alternatively 1.5 to 7.5 wt%, alternatively 1.5 to 2.9 wt%, alternatively 1.8 to 2.4 wt%. All wt% are based on the total weight of the polyolefin formulation or the total weight of the crosslinked polyolefin product.

[0051] Component (D) Organic peroxide: A molecule containing a carbon atom, a hydrogen atom, and two or more oxygen atoms and having at least one -OO- group, wherein when more than one -OO- group is present, each -OO- group is indirectly bonded to another -OO- group via one or more carbon atoms; or a collection of such molecules. (D) Organic peroxide may be added to a polyolefin formulation for curing, the curing comprising heating the polyolefin formulation containing components (A), (B), and (D) to a temperature equal to or higher than the decomposition temperature of (D) organic peroxide. (D) Organic peroxide may be a monoperoxide of the formula RO-OO-RO, wherein each RO is independently (C1-C20)alkyl or (C6-C20)aryl. Each (C1-C20)alkyl group is independently unsubstituted or substituted with one or two (C6-C12)aryl groups. Each (C6-C20)aryl group is unsubstituted or substituted with one to four (C1-C10)alkyl groups. Alternatively, (D) may be a diperoxide of the formula RO-OOROO-RO, wherein R is a divalent hydrocarbon group, such as (C2-C10) alkyl, (C3-C10) cycloalkyl, or phenyl, and each RO is as defined above. (D) The organic peroxide may be 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)valerate; butyl ester; 1,1-bis(1,1-dimethylethylperoxy)-3,3,5-trimethylcyclohexane; benzoyl peroxide; tributyl peroxybenzoate; di- and tri-pentyl peroxide ("DTAP"); bis(α-) - Tri-butylperoxyisopropylbenzene ("BIPB"); isopropylisopropylphenyl tri-butylperoxide; tri-butylisopropylphenylperoxide; di-tri-butylperoxide; 2,5-bis(tri-butylperoxy)-2,5-dimethylhexane; 2,5-bis(tri-butylperoxy)-2,5-dimethylhexyn-3,1,1-bis(tri-butylperoxy)-3,3,5-trimethylcyclohexane; isopropylisopropylphenyl isopropylphenylperoxide; 4,4-bis(tri-butylperoxy)valerate; or di(isopropylisopropylphenyl)peroxide; or dicumyl peroxide. (D) The organic peroxide may be dicumyl peroxide. In some formulations, blends of two or more (D) organic peroxides are used, such as a 20:80 (wt / wt) blend of tributylisopropylphenyl peroxide and bis(tributylperoxyisopropyl)benzene (e.g., LUPEROX D446B, commercially available from Arkem). In some formulations, at least one, or alternatively each (D) organic peroxide, contains an -OO- group.(D) The organic peroxide may be 0.29 to 0.44 wt% of the carrier mixture, or 0.30 to 39 wt% of the polyolefin formulation, or 0.30 to 0.37 wt% of the polyolefin formulation.

[0052] Component (E) scorch inhibitor, selected as appropriate: 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 α-methylstyrene dimer or AMSD); and allyl-containing compounds described in column 2, line 62 to column 3, line 46 of US 6277925B1. In some cases, polyolefin formulations and crosslinked polyolefin products do not contain (E). If present, the (E) scorch inhibitor may be 0.01 to 1.5 wt% of the polyolefin formulation, alternatively 0.05 to 1.2 wt%, alternatively 0.1 to 1.0 wt%.

[0053] Component (F) Antioxidant, selected as appropriate: Organic molecules that inhibit oxidation, or a collection of such molecules. (F) Antioxidants are used to provide antioxidant properties to polyolefin formulations and / or cross-linked polyolefin products. Suitable examples of (F) are bis(4-(1-methyl-1-phenylethyl)phenyl)amine (e.g., NAUGARD 445); 2,2'-methylene-bis(4-methyl-6-tert-butylphenol) (e.g., VANOX MBPC); 2,2'-thiobis(2-tert-butyl-5-methylphenol) (CAS No. 90-66-4; 4,4'-thiobis(2-tert-butyl-5-methylphenol) (also known as 4,4'-thiobis(6-tert-butyl-m-cresol), CAS No. 96-69-5, purchased from LOWINOX TBM-6); 2,2'-thiobis(6-tert-butyl-4-methylphenol) (CAS No. 90-66-4, purchased from LOWINOX). TBP-6); [(4-tri-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-trimethyl-2,4,6-trione (e.g., CYANOX 1790). Neopentyl tetrakis(3-(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)propionate (e.g., IRGANOX 1010, CAS No. 6683-19-8); 2,2'-thiodiethylene glycol 3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropionate (e.g., IRGANOX 1035, CAS No. 41484-35-9); distearate thiodipropionate ("DSTDP"); dilauryl thiodipropionate (e.g., IRGANOX PS 800); stearate 3-(3,5-bis-tri-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]propionhydrazine (IRGANOX) 1024). In some formulations, (F) is 4,4'-thiobis(2-tributyl-5-methylphenol) (also known as 4,4'-thiobis(6-tributyl-m-cresol); 2,2'-thiobis(6-tributyl-4-methylphenol); seroton[(4-tributyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triquid-2,4,6-trione; distearate of thiodipropionate; or dilauryl thiodipropionate; or any combination of two or more thereof. The combination may be seroton[(4-tributyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triquid-2,4,6-trione and distearate of thiodipropionate. In some formulations, polyolefin formulations and crosslinked polyolefin products do not contain (F).If present, the antioxidant (F) may be 0.01 to 1.5 wt% of the polyolefin formulation, or alternatively 0.05 to 1.2 wt% or alternatively 0.1 to 1.0 wt%.

[0054] Component (G) filler, selected as appropriate: a finely segmented granular solid or gel that occupies space in the host material and, where appropriate, affects the function of the host material. The (G) filler may be calcined clay, organoclay, or hydrophobic fumed silica, such as that available from Cabot Corporation under the trade name CAB-O-SIL. The (G) filler may have flame-retardant properties. In some formulations, the polyolefin formulation and cross-linked polyolefin product do not contain (G). If present, the (G) filler may be 1 to 40 wt% of the polyolefin formulation, alternatively 2 to 30 wt%, or alternatively 5 to 20 wt%.

[0055] Component (H) flame retardant selected as appropriate: a molecule or substance that inhibits combustion, or a collection of such molecules. (H) can be a halogenated or halogen-free compound. Examples of halogenated (H) flame retardants are organochlorides and organobromines. Examples of organochlorides are chlorobridged acid derivatives and chlorinated paraffins. Examples of organobromines are decabromodiphenyl ether, decabromodiphenyl ethane, polybrominated compounds such as brominated polystyrene, brominated carbonate oligomers, brominated epoxy resin oligomers, tetrabromophthalic anhydride, tetrabromobisphenol A, and hexabromocyclododecane. Halogenated (H) flame retardants are typically used in combination with synergists to enhance their efficiency. Synergists can be antimony trioxide. Examples of halogen-free (H) flame retardants are inorganic minerals, organic nitrogen-inflating compounds, and phosphorus-based inflating compounds. Examples of inorganic minerals are aluminum hydroxide and magnesium hydroxide. Examples of phosphorus-based swelling compounds include organophosphonic acids, phosphonates, phosphonites, phosphonate diesters, hypophosphonates, phosphine oxides, phosphine, phosphites, phosphate esters, phosphazenes, phosphatidylinosyl chlorides, phosphatidylinosyl phosphates, phosphonate phosphatidylinosyl phosphates, melamine and its melamine derivatives, including melamine polyphosphate, melamine pyrophosphate and melamine cyanuric acid, and mixtures of two or more of these materials. Examples include phenyl bis(dodecanyl) phosphate, phenyl bis(neopentyl) phosphate, phenyl vinyl hydrogen phosphate, phenyl bis(3,5,5'-trimethylhexyl) phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di(p-tolyl) phosphate, diphenyl phosphate, p-tolyl bis(2-ethylhexyl) phosphate, tricresyl phosphate, bis(2-ethylhexyl)-phenyl phosphate, tri(nonylphenyl) phosphate, phenyl methyl phosphate, di(dodecyl)-p-tolyl phosphate, tricresyl phosphate, triphenyl phosphate, dibutylphenyl phosphate, 2-chloroethyldiphenyl phosphate, p-tolyl bis(2,5,5'-trimethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, and diphenyl hydrogen phosphate. Phosphate esters of the type 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); solid phosphates such as ammonium polyphosphate (APP); pyrophosphate and polyphosphate. Ammonium polyphosphate is often used with flame retardant auxiliary additives such as melamine derivatives. Melafine (DSM) (2,4,6-triamino-1,3,5-trimethylamine; finely ground melamine) may also be used. In some cases, the polyolefin formulations and crosslinked polyolefin products are free of (H). If present, the concentration of (H) may be 0.01 to 70 wt% of the polyolefin formulation, alternatively 0.05 to 40 wt%, or alternatively 1 to 20 wt%.

[0056] Component (I) Hindered amine stabilizer, selected as appropriate: a molecule, or a collection of such molecules, containing a basic nitrogen atom bonded to at least one sterically large organic group and acting as an inhibitor of degradation or decomposition. (I) is a compound having a sterically hindered amine functional group and inhibiting oxidative degradation, and may also increase the shelf life of embodiments of polyolefin formulations containing (D) organic peroxides. Examples suitable for (I) are dimethyl succinate, a polymer having 4-hydroxy-2,2,6,6-tetramethyl-1-piperidin-ethanol (CAS No. 65447-77-0, commercially available at LOWILITE 62); and N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (CAS No. 124172-53-8, commercially available at Uvinul 4050 H). In some cases, polyolefin formulations and crosslinked polyolefin products do not contain (I). If present, then (I) the hindered amine stabilizer may be 0.001 to 1.5 wt%, or alternatively 0.002 to 1.2 wt%, or alternatively 0.002 to 1.0 wt%, or alternatively 0.005 to 0.5 wt%, or alternatively 0.01 to 0.2 wt%, or alternatively 0.05 to 0.1 wt% of the polyolefin formulation.

[0057] Component (J) Anti-treeing agent selected as appropriate: Molecules or aggregates of such molecules that inhibit water treeing and / or electrical treeing. The anti-treeing agent may be an anti-water treeing agent or an anti-electric treeing agent. An anti-water treeing agent is a compound that inhibits water treeing, which is the degradation process of polyolefins when exposed to a combination of an electric field and moisture or water. An anti-electric treeing agent, also known as a voltage stabilizer, is a compound that inhibits electrical treeing, which is the electrical pre-breakdown process in solid electrical insulation caused by partial discharge. Electrical treeing can occur in the absence of water. Water treeing and electrical treeing are problems in cables containing coated conductors (wherein the coating contains polyolefins). (J) may be poly(ethylene glycol) (PEG). In some cases, the polyolefin formulation and cross-linked polyolefin product do not contain (J). If present, the anti-treeing agent (J) may be 0.01% to 1.5 wt% of the polyolefin formulation, alternatively 0.05% to 1.2 wt%, alternatively 0.1% to 1.0 wt%.

[0058] Component (K) selected as appropriate: Methyl radical scavenger: a molecule or a collection of such molecules that reacts with methyl radicals. (K) reacts with methyl radicals in polyolefin formulations or cross-linked polyolefin products. (K) may be a "TEMPO" derivative of 2,2,6,6-tetramethyl-1-piperidinyl-N-oxy or 1,1-diarylethylene. Examples of TEMPO derivatives are 4-acryloxy-2,2,6,6-tetramethyl-1-piperidinyl-N-oxy (CAS No. 21270-85-9, "acrylate TEMPO"), 4-allyloxy-2,2,6,6-tetramethyl-1-piperidinyl-N-oxy (CAS No. 217496-13-4, "allyl TEMPO"), bis(2,2,6,6-tetramethyl-1-piperidinyl-N-oxy) sebacate ( CAS No. 2516-92-9, "BisTEMPO"; N,N-bis(acrylyl-4-amino)-2,2,6,6-tetramethyl-1-piperidinyl-N-oxy (CAS No. 1692896-32-4, "Diacrylamide TEMPO"); and N-acrylyl-4-amino-2,2,6,6-tetramethyl-1-piperidinyl-N-oxy (CAS No. 21270-88-2, "Monoacrylamide TEMPO"). Examples of 1,1-diarylethylene are 1,1-stilbene and α-methylstyrene. In some cases, the polyolefin formulations and crosslinked polyolefin products do not contain (K). If present, the (K) methyl radical scavenger may be 0.01 to 1.5 wt% of the polyolefin formulation, alternatively 0.05 to 1.2 wt%, alternatively 0.1 to 1.0 wt%.

[0059] Component (L) crosslinking aid selected as appropriate: a molecule containing a main structure or cyclic structure and one, or alternatively two or more, propylene, acrylate and / or vinyl groups bonded thereto, wherein the substructure is composed of carbon atoms and, where appropriate, nitrogen atoms; or a collection of such molecules. (L) The crosslinking aid does not contain silicon atoms. (L) The crosslinking aid may be an propylene-functional crosslinking aid, as described in any of (i) to (v): (i) (L) is 2-allylphenylallyl ether; 4-isopropenyl-2,6-dimethylphenylallyl ether; 2,6-dimethyl-4-allylphenylallyl ether; 2-methoxy-4-allylphenylallyl ether; 2,2'-diallyl bisphenol A; O,O'-diallyl bisphenol A; or tetramethyldiallyl bisphenol A; (ii) (L) is 2,4-diphenyl-4-methyl-1-pentene or 1,3-diisopropenylbenzene; (iii) (L) refers to triallyl isocyanate (“TAIC”); triallyl cyanate (“TAC”); triallyl benzotriglyceride (“TATM”); N,N,N',N',N",N"-hexamethylene-1,3,5-triquid-2,4,6-triamine (“HATATA”; also known as N2,N2,N4,N4,N6,N6-hexamethylene-1,3,5-triquid-2,4,6-triamine); triallyl orthoformate; neopentyl tetral triallyl ether; triallyl citrate; or triallyl aconitate; (iv) (L) refers to a mixture of any two of the propylene functionalized additives in (i). Alternatively, (L) may be an acrylate-functional crosslinking agent selected from the following: trimethylolpropane triacrylate (“TMPTA”), trimethylolpropane trimethacrylate (“TMPTMA”), ethoxylated bisphenol A dimethacrylate, 1,6-hexanediol diacrylate, neopentyl tert-acrylate, dinepentyl tert-acrylate, triisocyanate (2-hydroxyethyl) ester, and propoxylated glyceryl triacrylate. Alternatively, (L) may be a vinyl-functional crosslinking agent selected from polybutadiene and trivinylcyclohexane (“TVCH”) having a 1,2-vinyl content of at least 50 wt%. Alternatively, (L) may be a crosslinking agent described in US 5,346,961 or US 4,018,852. Alternatively, (L) may be a combination of the foregoing crosslinking agents or any two or more thereof. In some formulations, the polyolefin formulation and the crosslinked polyolefin product do not contain (L). If present, the (L) crosslinking aid may be 0.01 to 4.5 wt% of the polyolefin formulation, or alternatively 0.05 to 2 wt%, or alternatively 0.1 to 1 wt%, or alternatively 0.2 to 0.5 wt%.

[0060] Component (M) processing aid, selected as appropriate: an organic or organosiloxane additive that enhances the melt flowability of the (A) polyolefin polymer during extrusion. Examples of (M) are poly(vinyl fluoride) polymers and polydimethylsiloxane. In some cases, the polyolefin formulation and crosslinked polyolefin product do not contain (M). If present, the concentration of (M) may be 0.01 to 1.5 wt% of the polyolefin formulation, alternatively 0.05 to 1.2 wt%, or alternatively 0.1 to 1.0 wt%.

[0061] Component (N) colorant (e.g., carbon black or TiO2) selected as appropriate. Carbon black: a fine powder form of crystalline carbon with a high surface area-to-volume ratio, but less than that of activated carbon. Examples of carbon black are furnace black, acetylene black, and conductive carbon (e.g., carbon fibers, carbon nanotubes, graphene, graphite, and expanded graphite sheets). In some cases, the polyolefin formulation and cross-linked polyolefin product do not contain (N). If present, the concentration of (N) may be 0.01 to 40 wt% of the polyolefin formulation, alternatively 0.05 to 35 wt%, alternatively 0.1 to 20 wt%, alternatively 0.5 to 10 wt%, or alternatively 1 to 5 wt%.

[0062] To avoid any doubt, (G) filler is different from (N) colorant.

[0063] In addition, the polyolefin formulation may independently further include one or more other additives selected from the following, as appropriate: carrier resin, lubricant, slip agent, plasticizer, surfactant, extender oil, deacidifier, and metal deactivator.

[0064] Crosslinked polyolefin products may also contain curing byproducts, such as alcohol and ketone byproducts of the reaction of (D) organic peroxides. When the polyolefin formulation further contains any additives or components selected as appropriate, such as one or more of (F) antioxidants, the crosslinked polyolefin product may also contain any additives or components selected as appropriate, such as (F), or one or more reaction products formed during the curing of the polyolefin formulation.

[0065] Crosslinked polyolefin products may be in separate solid or continuous form. Separate solid forms may include granules, pellets, powders, or any combination of both or more thereof. Continuous forms may be finished articles, such as molded parts (e.g., injection-molded parts) or extruded parts (e.g., coated conductors or cables).

[0066] Coated conductor. The coated conductor may be an insulated electrical conductor. The insulated electrical conductor may be a coated metal wire or cable, including power cables for low voltage ("LV", > 0 to < 5 kV), medium voltage ("MV", 5 to < 69 kV), high voltage ("HV", 69 to 230 kV) or ultra-high voltage ("EHV", > 230 kV) data transmission and electrical transmission / distribution applications. "Wire" means a single strand or monofilament conductive material, such as a conductive metal, such as copper or aluminum. "Cable" and "power cable" are synonymous and mean an insulated electrical conductor comprising at least one wire housed within a sheath, protective outer sheath, or coating. Insulated electrical conductors can be designed and constructed for medium voltage, high voltage, or ultra-high voltage applications. Examples of suitable cable designs are shown in US 5,246,783; US 6,496,629; and US 6,714,707.

[0067] The insulated electrical conductor may contain a conductor / transmitter core and an external single-layer or multi-layer covering surrounding it to protect the conductor / transmitter core and isolate it from the external environment. The conductor / transmitter core may consist of one or more metal wires. When the conductor / transmitter core contains two or more metal wires, the metal wires may be further divided into separate wire bundles. Each wire in the conductor / transmitter core, whether or not it is bundled, may be individually coated with an insulating layer and / or the separate bundles may be coated with an insulating layer. The single-layer or multi-layer covering (e.g., a single-layer or multi-layer coating or sheath) primarily serves to protect the conductor / transmitter core or isolate it from the external environment (such as sunlight, water, heat, oxygen, other conductive materials (e.g., to prevent short circuits) and / or other corrosive materials (e.g., chemical fumes)).

[0068] A single-layer or multi-layer cover for an insulating electrical conductor can be configured differently depending on its intended use. For example, viewed in cross-section, a multi-layer cover for an insulating electrical conductor, from its innermost layer to its outermost layer, can be sequentially configured with the following components: an inner semiconductor layer, a cross-linked polyolefin insulating layer comprising a cross-linked polyolefin product (the cross-linked product of this invention), an outer semiconductor layer, a metal shield, and a protective sheath. The layers and sheath are circumferentially and coaxially (longitudinally) continuous. The metal shield (grounded) is coaxially continuous and circumferentially continuous (one layer) or discontinuous (a strip or a line). Depending on the intended application, a multi-layer cover for an insulated optical fiber may omit the semiconductive layer and / or the metal shield. The outer semiconductive layer (if present) may be composed of a peroxide-crosslinked semiconductive product, which may be bonded to the cross-linked polyolefin layer or peeled off from the cross-linked polyolefin layer.

[0069] In some embodiments, a method for manufacturing a coated conductor is provided, comprising extruding a coating comprising a layer of polyolefin formulation onto a conductor / transmitter core to obtain a coated core, and passing the coated core through a CV apparatus configured with suitable continuous vulcanization (CV) conditions for curing the polyolefin formulation to obtain a coated conductor. CV conditions include temperature, atmosphere (e.g., nitrogen), and linear velocity or time period through the CV apparatus. Suitable CV conditions provide a coated conductor exiting the CV apparatus, wherein the coated conductor contains a cross-linked polyolefin layer formed by layer curing a cross-linked polyolefin layer.

[0070] Dielectric breakdown strength (dielectric strength): The maximum electric field (applied voltage divided by the electrode spacing) that an electrically insulating material can withstand without experiencing an electrical breakdown event, i.e., without conducting electricity. It is expressed in volts using standard electrode spacing.

[0071] Any compound, composition, formulation, material, mixture, or reaction product described herein may be free from any 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; the limitation is that the chemical elements inherently required by the compound, composition, formulation, material, mixture, or reaction product are not omitted (e.g., C and H required for polyethylene, or C, H, and O required for alcohols).

[0072] Alternatives precede unique embodiments. ANSI is the American National Standards Institute organization, headquartered in Washington, DC, USA. ASME is the American Society of Mechanical Engineers, headquartered in New York City, New York, USA. ASTM is the international standards organization, ASTM International, West Conshohocken, Pennsylvania, USA. Any comparative examples are for illustrative purposes only and should not be considered prior art. "Free of" or "lack" means completely absent; alternatives are undetectable. IEC is the International Electrotechnical Commission, 3 rue de Varemb, Case postale 131, CH-1211, Geneva 20, Switzerland, http: / / www.iec.ch. IUPAC stands for International Union of Pure and Applied Chemistry (IUPAC Secretariat, Research Triangle Park, North Carolina, USA). The periodic table is the IUPAC version as of May 1, 2018. Permitted options may be assigned, but are not mandatory. "Operable" means functionally feasible or effective. "Selectable" (as appropriate) means not present (or excluded), or alternatively present (or included). Properties can be measured using standard test methods and conditions. Ranges include endpoints, subranges, and all values ​​and / or fractions, except for integer ranges which do not include fractional values. Room temperature: 23℃ ± 1℃.

[0073] Unless otherwise stated, the definitions of terms used herein are derived from version 2.3.3 of the IUPAC Compendium of Chemical Technology ("Gold Book"), dated February 24, 2014.

[0074] In some embodiments, either the term "comprising" or "comprises" may be replaced by the phrases "consisting essentially of" or "consists essentially of". The phrase "consisting essentially of" is partially closed and means that the polyolefin formulation and the crosslinked polyolefin products made therefrom do not contain excluded materials. For example, excluded materials may include any voltage stabilizer that is not the only compound (B) alkoxyphenol and (C) diphenyl ketone. The use of the term "comprises / comprising" when referring to the following materials or features does not negate the partially closed nature of "consisting essentially of / consists essentially of", but only allows any additional materials or features not expressly excluded by "consisting essentially of / consists essentially of". In some embodiments, either the term "comprising" or "comprises" may be replaced by "consisting of" or "consists of". The phrase "consisting of" is closed and excludes any elements or features not expressly listed.

[0075] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, a range from any lower limit may be combined with any upper limit to describe a range not explicitly described. Furthermore, a range from any lower limit may be combined with any other lower limit to describe a range not explicitly described; and in the same manner, a range from any upper limit may be combined with any other upper limit to describe a range not explicitly described.

[0076] Density Test Method: The measurement is performed according to ASTM D792-13, "Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement," Method B (for testing solid plastics in liquids other than water, such as liquid 2-propanol). Results are reported in grams per cubic centimeter (g / cm³).

[0077] The melt flow index (I2) is measured according to ASTM D1238-04 (190°C, 2.16 kg), "Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Platometer", using conditions 190°C / 2.16 kg (formerly known as "Condition E"), and is also referred to as I2. It is reported in grams eluted per 10 minutes (g / 10 min.) or equivalently in decigrams per 1.0 minute (dg / 1 min.). 10.0 dg = 1.00 g.

[0078] Embodiments of the present invention can be tested according to the following electrical breakdown strength test method. For clarity, the description of the method is separated into parts 1 to 3. Part 1 relates to materials used to prepare the test assembly. Part 2 relates to steps for preparing a test plate representing an insulating layer and preparing the test assembly. The test assembly includes a sandwich between a test plate representing an insulating layer and two conductor disks, wherein the test plate (insulating layer) is disposed between the conductor disks. Part 3 relates to steps for applying an increased test voltage to the test assembly and detecting an electrical breakdown event in the insulating layer.

[0079] Part 1: Electrical Breakdown Strength Test Method (Materials): The conductors are a plurality of aluminum discs with a diameter of 40 mm and a plurality of aluminum discs with a diameter of 29 mm; each disc is 75 micrometers thick. An insulating layer is sandwiched between the conductors, such that the total thickness of the sandwich is 350 to 500 micrometers. After breakdown, the aluminum discs are removed and the thickness of the insulating layer at the breakdown location is measured.

[0080] Part 2: Electrical Breakdown Strength Test Method (Procedure for assembling electrodes and test plates into a test assembly). Samples of the test insulation layer are prepared in a two-step hot molding process: Step 1: Weighing polymer pellets. The weighed pellets are placed in a compression mold (an 8-inch × 8-inch square compression molded frame with a thickness of approximately 150 to 900 micrometers). The polymer pellets are preheated to 140°C at approximately 7 pounds per square inch (psi) for 3 minutes. At the same temperature, the pressure is switched to approximately 382 psi and maintained for 3 minutes. The resulting polymer plate is cooled to room temperature over approximately 15 minutes at the same pressure. Step 2: Multiple conductive aluminum (Al) disks with diameters of 29 mm and 40 mm are cut from a 75-micrometer-thick aluminum sheet. The conductive Al disks are placed on the top and bottom of the plate (prepared in Step 1), with a 29 mm diameter disk on one side and a 40 mm diameter disk on the opposite side. Two conductive Al disks are arranged opposite each other and approximately concentrically. Nine such conductive Al disks are placed in a 3 × 3 array on each side of an 8 inch × 8 inch polymer plate. The resulting assembly is heat-compressed in the same mold as in step 1 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 plate sandwiched between the nine pairs of upper and lower conductive Al disks.

[0081] Part 1 of the test assembly is shown in Figure 1. Each test assembly has nine parts 1. Part 1 of the test assembly includes nine pairs of upper and lower brass electrodes 11 and 15 respectively; nine pairs of upper and lower conductive Al disks 21 and 25 respectively; and a portion of a single plate 30 (Figure 1). Each pair of brass electrodes 11 and 15 is electrically connected to a device (not shown) configured to supply current, detect electrical breakdown, and measure its voltage. Such devices are well known, for example, see 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". Brass electrodes 11 and 15 are used to apply current to their pair of conductive Al disks 21 and 25, respectively. The upper conductive Al disk 21 has a lower surface 22 and an upper surface 23, and its disk thickness is the distance between them (i.e., the distance from 22 to 23). The lower conductive Al disk 25 has a lower surface 27 and an upper surface 26, and its disk thickness is the distance between them (i.e., the distance from 26 to 27). Different portions of plate 30 are respectively sandwiched between spaced-apart and different pairs of conductive Al disks 21 and 25. The thickness of plate 30 between 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 plate 30 independently has an upper surface 31. The thickness T of the portion of plate 30 used to measure the electrical breakdown strength in Part 3 below is the distance between the upper surface 26 of the lower conductive Al disk 25 and the upper surface 31 of plate 30. This thickness T is indicated by "T" in Figure 1 and is measured at the location of the channel generated by the electrical breakdown event mentioned in Part 3.

[0082] Part 3: Electrical Breakdown Strength Test Method: The procedure involves applying an alternating current (AC) with an increasing test voltage to the test assembly and detecting an electrical breakdown event. The prepared assembly is immersed in insulating oil and contacted at the top and bottom with brass electrodes. A voltage is applied. The voltage is gradually increased at a rate of 500 volts / second (V / s, 50 Hz) until a breakdown event occurs, thereby creating a channel through the polymer. A breakdown event is detected as a sudden increase in current. The applied kilovolts (V) at the point of this current jump is recorded. This breakdown event is caused by a channel created by applying voltage in the insulation layer. The thickness of the insulation layer at the channel location is measured and used as the insulation thickness in the following calculation of actual breakdown strength: (Eact) = V / T, where V is the breakdown voltage in kilovolts (kV) and T is the insulation thickness in millimeters (mm) measured at the channel location, and Eact is the breakdown strength in kilovolts per millimeter (kV / mm). For reporting purposes, in the table below, the actual breakdown strength Eact is normalized for a thickness of 1.016 mm (equal to 40 mils) and reported as the normalized breakdown strength E in kV / mm. The normalized breakdown strength E is calculated according to Equation 1 (Eq. 1): E = (V / T)*(T / T0)^(1 / 2) (Eq. 1), where ^(1 / 2) indicates the square root, V is the kilovolt applied at the time of the breakdown event, T is the thickness of the insulation layer (plate, at the breakdown location) measured in each case, and T0 is 1.016 mm (equivalent to 40 mils) thickness, thus T / T0 normalizes the breakdown strength value for a thickness of 1.016 mm. The voltage at the time of the electrical breakdown event is recorded. The effectiveness of the voltage stabilizer is evaluated by comparing the breakdown electric field strength of the same polymer with and without the additive.

[0083] In the electrical breakdown strength test method of the present invention, the voltage at which an electrical breakdown event occurs will vary depending on the thickness of the insulation layer. The standardized breakdown strength E, in kV / mm, is analyzed using the well-known two-parameter Weber statistical method described below.

[0084] Weiber statistical method. The electrical breakdown strength values ​​(etaη and betaβ) of a test sample set of size N are determined using the two-parameter Weiber statistical method according to Equation 2 (Eq. 2): Eq. 2. E is the standardized field strength measured in kV / mm as described above. F(E) is the cumulative fraction of samples that failed under the standardized field strength E. To obtain a proper curve fit, the F(E) of the sample set N is determined by calculating the median rank of each sample in the sample set N according to steps (1) and (2): (1) The normalized electric field strengths E are sorted in ascending order from 1 to N at failure (for a sample set of size N); (2) The median rank (MR) of each sample i is determined according to Equation 3 using the Bernard approximation: MR = F(E) = (i - 0.3) / (N + 0.4) (Eq. 3), where i is in the range of 1 to N (e.g., if N = 9, then the first sample is i = 1, the second sample is i = 2, and so on). In the graph, the cumulative fraction F(E) values ​​are plotted on the y-axis on a scale of 1 to 99, and the normalized field strength E values ​​(or any range of E values ​​that is convenient for plotting) are plotted on the x-axis on a scale of 5 to 100 kV / mm. Knowing the cumulative scores F(E) and E of the sample set N, curve fitting is performed based on Eq. 2 to obtain the ita η and beta β values. Ita η is equivalent to the field strength at which 63.2% of the samples have failed. Beta β is related to the range of normalized field strength E within which all (100%) samples N have failed. All other things being equal, a higher β value corresponds to a narrower range of field strengths at which the test samples N have failed. For example, if all samples in the first sample set fail within the range of E 16 kV / mm to E 29 kV / mm (distributed within a 13 kV / mm range between the lowest E 16 kV / mm and the highest E 29 kV / mm), then the first beta β of the first sample set (N=9) will be higher than the second beta β of the second sample set (N=9), where all samples in the second sample set fail within the range of E 16 kV / mm to E 30 kV / mm (distributed within a 14 kV / mm range between the lowest E 16 kV / mm and the highest E 30 kV / mm).

[0085] The electrical breakdown strength value used to determine the improvement or reduction relative to the CEO baseline is η, which is predicted for a failure probability of 63.2% and determined using the Weber statistics described above based on the normalized field strength E value. A 90% confidence level (upper and lower limits) beta β value b is also reported, obtained using the Weber statistics described above. All other things being equal, the higher the β value, the narrower the range of field strengths for failure in test sample N, and therefore the narrower the range of E at a 90% confidence level.

[0086] All other things being equal, including the thickness of the insulation layer, the higher the voltage at which electrical breakdown occurs, the greater the electrical breakdown strength of the insulation material. The percentage increase (improvement) or decrease (reduction) in voltage of the test board (N=8 or 9) at which an electrical breakdown event occurred was measured relative to the voltages of the 17 control boards (N=153 or 155) at which the electrical breakdown event occurred. A greater percentage increase indicates a greater improvement in electrical breakdown strength. A greater percentage decrease indicates a greater reduction in electrical breakdown strength. Example

[0087] Polyethylene polymer (A)-1: Low-density polyethylene (LDPE-1). LDPE-1 has a density of 0.920 g / cm3 and a melt index of 2.0 g / 10 min. Purchased from Dow Chemical Company as DFDK-7423NT.

[0088] The alkoxyphenol compound (B)-1:4-methoxyphenol of the present invention is a compound of formula (I), wherein R1 is a methyl group.

[0089] The alkoxyphenol compound (B)-2:4-heptoxyphenol of the present invention is a compound of formula (I), wherein R1 is a heptyl group.

[0090] The present invention relates to diphenyl ketone compound (C)-1: diphenyl ketone, which is a compound of formula (II), wherein Ar1 is a phenyl group.

[0091] The test compounds, including (B) alkoxyphenol itself (comparative), (C) diphenyl ketone itself (comparative), and their blends (in this invention), are used to evaluate the effect of test compounds on the electrical breakdown strength of polyolefin formulations. Test examples of polyolefin formulations of this invention include test compound (B) alkoxyphenol, test compound (C) diphenyl ketone of formula (II), and polyethylene polymer (A)-1. A first comparative polyolefin formulation includes test compound (B) alkoxyphenol and polyethylene polymer (A)-1, but does not contain diphenyl ketone of formula (C). A second comparative polyolefin formulation includes diphenyl ketone of formula (C) and polyethylene polymer (A)-1, but does not contain (B) alkoxyphenol. A third comparative formulation includes polyethylene polymer (A)-1, but does not contain either compound (B) or (C). A formulation for testing is prepared by melt-mixing a known quantity of the test compound into polyethylene polymer (A)-1, such that the concentration of the test compound in the formulation is 0.1 to 10.0 wt% based on the total weight of the formulation. Concentrations of 0.5 wt% and 1.0 wt% of the test compound are suitable amounts for testing purposes, but higher concentrations may be used if necessary. The formulation is individually fabricated into test plates according to the steps previously described for the electrical breakdown strength test method, and the voltage at which an electrical breakdown event occurs is measured. The results are reported as ital values ​​for a failure probability of 63.2%, as determined according to the Weber statistics described above.

[0092] Comparative Example 0 (CE0). A single-batch, stabilizer-free comparative formulation was prepared, consisting of 100.00 wt% of polyethylene polymer (A)-1. This stabilizer-free comparative formulation contained no voltage stabilizers or any additives. In separate experiments, different samples of the stabilizer-free comparative formulation were melt-mixed into 17 test plates. The electrical breakdown strength of each test plate was measured using a 3 × 3 array of nine electrode pairs to obtain 153 actual electrical breakdown strength values. The electrical breakdown strength values ​​were normalized for a plate thickness of 40 mm according to Eq. 1 previously described. The normalized electrical breakdown strength values ​​for CE0 were 18.49 kV / mm for the ita η value (for a failure probability of 63.2%) and 18.18 kV / mm to 18.81 kV / mm (lower to upper limits) with a 90% confidence level beta. All comparisons and inventions of the Ita η value with a failure probability of 63.2% are compared with the standardized electrical breakdown strength value of 18.5 kV / mm as the baseline (unmodified or unreduced) for the failure probability of 63.2%.

[0093] The procedure described below for performing the experiments of the comparative examples and the examples of the invention comprises the following steps: (1) With the mixing bowl empty, turn on the Brabender mixer to heat it until the recorded temperature is about 140°C. (2) Add about 260 g of (A) polyethylene polymer resin to the Brabender mixing bowl and mix it at 40 rpm for up to 10 minutes until it melts. (3) Reduce the mixing speed (rpm), reverse the rotation of the twin screw, and allow some samples to be taken out for further testing. (4) Add additional amounts of (A) polyethylene polymer and compounds (B) and (C), thereby refilling the mixing bowl to 260 g at the target additive load, and increase the rpm back to 40 rpm. (5) Mix the resulting samples for up to 5 minutes. (6) Reduce the mixing speed (rpm), reverse the rotation of the twin screw, and allow some samples to be taken out for further testing. (7) Repeat steps 4 to 6 to produce a series of additive concentrations of up to 2 wt% in polyethylene. Typically, mixing is carried out at 0.5 wt%, 1 wt%, and 2 wt%. (8) Reduce the mixing speed (rpm), reverse the rotation of the twin screw, and allow some samples to be removed for further testing. (9) Step 9 marks the end of the experiment. (10) Press the sample into a plate approximately 15 mils thick. (11) Embed the aluminum disc into the sample at the top and bottom for electrical testing (see the measurement section below for an overview of the method). Note on the preparation of additives for the blend: The blend is prepared by adding two additives in equal weight proportions to a weighing bowl and then mixing them with a spatula.

[0094] Comparative Examples 1 to 6 (CE1 to CE6): In an independent operation, the polyethylene polymer (A)-1 was melted, wherein (CE1) is a first known amount of (B)-1, i.e., 4-methoxyphenol; (CE2) is a second known amount of (B)-1; (CE3) is a known amount of (B)-2, i.e., 4-heptoxyphenol; (CE4) is a first known amount of (C)-1, i.e., diphenyl ketone; (CE5) is a second known amount of (C)-1, i.e., diphenyl ketone; or (CE6) is a third known amount of (C)-1, i.e., diphenyl ketone, all as shown in Table 1 below, to obtain comparative polyolefin formulations CE1 to CE6. The formulations were tested according to the electrical breakdown strength test method. The test results are shown in Table 2.

[0095] Comparative Example 7 (CE7): A comparative polyolefin formulation CE7 was obtained by melting a compound polyethylene polymer (A)-1 with a known amount of 4-methoxyphenol (B)-1 and a known amount of diphenyl ketone (C)-1, wherein the amount (wt%) of (B)-1 in the formulation is greater than half the amount (wt%) of (C)-1 in the formulation, that is, the relative amounts of (B)-1 and (C)-1 violate the "limit condition x < 0.5y". The formulation was tested according to the electrical breakdown strength test method. The test results are shown in Table 2. Table 1: Composition of formulations CE0 to CE7 (0 = 0.00) Components (wt%) CE0 CE1 CE2 CE3 CE4 CE5 CE6 CE7 Polyethylene polymer (A)-1 (LDPE-1) 100 99.5 98.0 99.5 99.5 98.0 93.0 97.6 4-Methoxyphenol (B)-1 0 0.5 2.0 0 0 0 0 2.0 4-Heptyloxyphenol(B)-2 0 0 0 0.5 0 0 0 0 Diphenyl ketone (C)-1 0 0 0 0 0.5 2.0 7.0 0.4 total 100 100 100 100 100 100 100 100 Table 2: Electrical breakdown strength test results for formulations CE0 to CE6 Electrical breakdown strength CE0 CE1 CE2 CE3 CE4 CE5 CE6 CE7 Voltage stabilizer / destabilizer none (B)-1 (B)-1 (B)-2 (C)-1 (C)-1 (C)-1 (B)-1 + (C)-1 Total concentration (wt%) of comparative voltage stabilizer / destabilizer 0 0.5 2.0 0.5 0.5 2.0 7.0 2.4 Compared to the voltage at CE0, the percentage increase in voltage (improvement, +%) or the percentage decrease in voltage (reduction, -%). 0% 2.6 0.26 N / m 17, 19 29 25 13 N / m = Not measured.

[0096] N / r is not reported. As indicated in Table 2, 2.0 wt% of diphenyl ketone increases the voltage breakdown strength by 29% (CE5) compared to CE0 without voltage stabilizer additives. The combination of 2.4 wt% of 2.0 / 0.4 (wt / wt) 4-methoxyphenol with diphenyl ketone, i.e., the combination of 2.0 wt% (B) and 0.4 wt% (C), does not satisfy the constraint x < 0.5y, resulting in a decrease in voltage breakdown strength (CE7) relative to the sum of the improvements of CE2 + CE4 (= 17.26% to 19.26%).

[0097] Examples 1 to 3 (IE1 to IE3): In independent operations, according to Table 3 below, compound polyethylene polymer (A)-1 is melted with known amounts of 4-methoxyphenol (B)-1 and diphenyl ketone (C)-1, or compound polyethylene polymer (A)-1 is melted with known amounts of 4-heptoxyphenol (B)-2 and diphenyl ketone (C)-1 to obtain the polyolefin formulations of the present invention, IE1 to IE3. The formulations are tested according to the electrical breakdown strength test method. The test results are shown in Table 4.

[0098] Example 4 (IE4): Predictive. In a separate operation, according to Table 3 below, compound polyethylene polymer (A)-1 was melted with known amounts of 4-methoxyphenol (B)-1, 4-heptoxyphenol (B)-2, and diphenyl ketone (C)-1 to obtain the polyolefin formulation of the present invention, IE4. The formulation was tested according to the electrical breakdown strength test method. Table 3: Composition of formulations CE0, IE1 to IE3 (O=0.00) Components (parts by weight) CE0 IE1 IE2 IE3 IE4 (Predictive) Polyethylene polymer (A)-1 (LDPE-1) 100 92.6 97.6 97.6 98.6 4-Methoxyphenol (B)-1 0 0.4 0.4 0 0.2 4-Heptyloxyphenol(B)-2 0 0 0 0.4 0.2 Diphenyl ketone (C)-1 0 7.0 2.0 2.0 2.0 total 100 100 100 100 100

[0099] The data in Table 3 indicates that the polyolefin formulations IE1 to IE4 are examples of the polyolefin formulations of this invention. Table 4: Electrical breakdown strength test results of formulations CE0, IE1 to IE3 Electrical breakdown strength CE0 IE1 IE2 IE3 IE4 (Predictive) Voltage stabilizer / destabilizer none (B)-1 + (C)-1 (B)-1 + (C)-1 (B)-2 + (C)-1 (B)-1 + (B)-2 + (C)-1 Total concentration (wt%) of comparative voltage stabilizer / destabilizer 0 7.4 2.4 2.4 2.4 Compared to the voltage at CE0, the percentage increase in voltage (improvement, +%) or the percentage decrease in voltage (reduction, -%). 0% +39% +38% +46% The expected value is approximately 42%.

[0100] As indicated in Table 4, compared to CE0 without voltage stabilizer additives, the combination of 0.4 wt% 4-methoxyphenol (B)-1 and 2.0 wt% diphenyl ketone (C)-1 resulted in a 38% improvement in voltage breakdown strength. As shown in Table 2, 0.5 wt% 4-methoxyphenol (B)-1 alone resulted in only a 2.6% improvement (CE1) and 2.0 wt% diphenyl ketone (C)-1 alone resulted in only a 29% improvement (CE5), for a total improvement of CE1 + CE5 = 31.6%. The combination of 0.4 wt% 4-methoxyphenol (B)-1 and 7.0 wt% diphenyl ketone (C)-1 resulted in a 39% improvement in voltage breakdown strength. As shown in Table 2, 0.5 wt% of 4-methoxyphenol (B)-1 alone causes only a 2.6% improvement (CE1), and 7.0 wt% of diphenyl ketone (C)-1 alone causes only a 25% improvement (CE6), for a total improvement of CE1 + CE6 = 27.6%. Therefore, the voltage stabilization improvement of the polyolefin formulation of the present invention can be considered synergistic, the polyolefin formulation comprising (A) a polyolefin polymer; (B) a 4-alkoxyphenol compound of formula (I), wherein R1 is a (C1-C20) alkyl group; and (C) a diphenyl ketone compound of formula (II).

[0101] As indicated in Table 4, the combination of 0.4 wt% of 4-heptoxyphenol (B)-2 and 2.0 wt% of (C)-1 diphenyl ketone in IE3 outperformed the combination of 0.4 wt% of 4-methoxyphenol (B)-1 and the same 2.0 wt% of (C)-1 diphenyl ketone in IE1.

[0102] Inventive Examples 5a to 5c, 6a to 6c, 7a to 7c, and 8a to 8c (IE5a to IE5c, IE6a to IE6c, IE7a to IE7c, and IE8a to IE8c, all of which are illustrative): In a separate operation, Inventive Example IE1 is repeated, but the polyethylene polymer (A)-1 is replaced with high-density polyethylene polymer (HDPE, IE5a to IE5c), ethylene / vinyl acetate copolymer (EVA, IE6a to IE6c), ethylene / methyl methacrylate copolymer (EMA, IE7a to IE7c), or ethylene / (monocyclic tetravinyl-tetramethyl-tetrasiloxane) copolymer) (IE8a to IE8c), to obtain the first polyolefin formulation of the present invention IE5a, IE6a, IE7a, or IE8a, respectively. In a separate operation, 1.0 wt% of dicumyl peroxide is immersed in it to obtain second polyolefin formulations of the present invention, namely IE3b, IE4b, IE5b, or IE6b. wt% is based on the total weight of each individual second formulation. In a separate operation, the obtained formulations of the present invention, IE5b, IE6b, IE7b, or IE8b, are heated at 120°C for 1 hour to produce crosslinked polyolefin products of the present invention, namely IE5c, IE6c, IE7c, or IE8c.

[0103] Example 9 of the Invention (Introductory): Manufacturing a Coated Conductor. The polyolefin formulation of the present invention from any of the foregoing examples is introduced into a wire coating extrusion line to manufacture a coated wire having a coating substantially composed of a formulation forming a wire structure on 14 AWG solid copper wire. The wire coating extrusion line consists of a Brabant 1.9 cm extruder with a variable speed drive, a 25:1 standard PE screw, a Brabant crosshead wire die, a laboratory water cooling tank with an air wiper, a laser micrometer, and a variable speed wire tensioner. Samples with a wall thickness of 0.76 mm (30 mils) are extruded at a screw speed of 40 rpm. Wires are manufactured using a set temperature distribution of 160°C / 170°C / 180°C / 190°C at regions 1 / 2 / 3 / and the head / die, respectively, at a winding speed of 3.1 m / min (10 ft / min). The coating on the wire is substantially composed of one of the polyolefin formulations of the present invention. The wire can be passed through a vulcanization tube set at a curing temperature of 220°C to allow the homogeneous mixture to be fully cured, resulting in a wire with a coating, wherein the coating is substantially composed of the crosslinking product of the present invention.

[0104] Example 10 of the Invention (Indicative): Conductivity. The coating is stripped from each end of the coated wire manufactured above to expose the wire. A voltage is applied across the coated wire (coated conductor) to the wire (e.g., the conductive core), thereby generating a current through the wire. The applied voltage may originate from a battery, a power grid, or a solar panel containing a converter. [Simplified Explanation of the Diagram]

[0012] Figure 1 is a diagram of the geometric structure of a test sample used to measure electrical breakdown strength.

Claims

1. A polyolefin formulation comprising (A) a polyolefin polymer; x wt% (wt%) of an alkoxyphenol compound of formula (I) of formula (B): (I), wherein R1 is (C1-C20) alkyl; and y wt% of a diphenyl ketone compound of formula (II) of formula (C): (II), wherein Ar1 is phenyl or alkylphenyl; wherein y is from 1 to 8 wt%; wherein x is from 0.1 to 3.0 wt%, wherein x is less than 0.5y; and wherein wt% is based on the total weight of the polyolefin formulation.

2. The polyolefin formulation of claim 1, wherein the Ar1 is phenyl; and the R1 is selected from the group consisting of (i) (C1-C5) alkyl; and (ii) (C6-C10) alkyl; or wherein the Ar1 is alkylphenyl; and the R1 is selected from the group consisting of (i) (C1-C5) alkyl; and (ii) (C6-C10) alkyl.

3. The polyolefin formulation of any one of claims 1 to 2, wherein the R1 group is methyl or heptyl and the Ar1 group is phenyl.

4. The polyolefin formulation of any one of claims 1 to 2, wherein the (A) polyolefin polymer is selected from the group consisting of: low-density polyethylene polymer, ethylene / (C4-C20) α-olefin copolymer, ethylene / (unsaturated carboxylic acid ester) copolymer, ethylene / (monocyclic organosiloxane) copolymer, ethylene / propylene copolymer, ethylene / propylene / (diene monomer) trimer, and propylene homopolymer.

5. A polyolefin formulation as claimed in any one of claims 1 to 2, comprising from 50.0 to 99.7 wt% of the (A) polyolefin polymer; from x = 0.2 wt% to x = 0.9 wt% of the (B) alkoxyphenol compound; from 1.6 to 7.4 wt% of the (C) diphenyl ketone compound; and from 0.1 to 43 wt% of at least one additive, wherein each of the at least one additive is different from components (A), (B), and (C) and is independently selected from the group consisting of: (D) organic peroxides; (E) scorch inhibitors; (F) antioxidants; (G) fillers; (H) flame retardants; (I) hindered amine stabilizers; (J) resin inhibitors; (K) methyl radical scavengers; (L) crosslinking aids; (M) processing aids; (N) colorants; and combinations of any two or more of additives (D) to (N).

6. The polyolefin formulation of claim 5, comprising from 85 to 99.5 wt% of the (A) polyolefin polymer, which is a low-density polyethylene polymer; from 0.30 to 0.50 wt% of the (B) alkoxyphenol compound, which is a compound of formula (I), wherein R1 is methyl or heptyl; from 1.5 to 2.4 wt% of the (C) diphenyl ketone compound of formula (II), wherein Ar1 is phenyl; and from 0.1 to 1.5 wt% of at least one (F) antioxidant.

7. A method for manufacturing a polyolefin formulation as claimed in any one of claims 1 to 6, the method comprising mixing the (A) polyolefin polymer with the (B) alkoxyphenol compound and the (C) diphenyl ketone compound, and, if applicable, at least one additive, in such a manner as to manufacture the formulation.

8. A method for manufacturing a crosslinked polyolefin product, the method comprising subjecting a polyolefin formulation as claimed in any one of claims 1 to 6 to curing conditions in a manner that causes the (A) polyolefin polymer to crosslink, thereby manufacturing the crosslinked polyolefin product.

9. A cross-linked polyolefin product manufactured by the method of claim 8.

10. An article comprising a polyolefin formulation, a cross-linked polyolefin product, or a combination thereof, comprising a polyolefin formulation as claimed in any one of claims 1 to 6, a cross-linked polyolefin product as claimed in claim 9, or a combination thereof.

11. A coated conductor comprising a conductive core and an insulating layer at least partially covering the conductive core, wherein the insulating layer comprises a cross-linked polyolefin product as claimed in claim 9.

12. A method for transmitting electricity, the method comprising applying a voltage across a conductive core of a coated conductor as claimed in claim 11 to generate a current through the conductive core.

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