Ultra-high temperature and low scorch method for producing a crosslinkable compound composition

Abstract

A method of ultra-high temperature and low scorch for rapidly producing a crosslinkable compound composition comprising a thermoplastic polyolefin, an antioxidant, and a homogeneous mixture of a curable additive containing one or more organic peroxides and one or more multi-alkenyl crosslinking aids. By this method, immersion towers and long immersion times are avoided, and a completely crosslinkable and homogeneous compound composition is produced that minimizes or completely eliminates premature crosslinking of the thermoplastic polyolefin(s).

Description

Technical Field

[0001] This technical field includes a method for producing a crosslinkable polyolefin formulation.

[0002] Patents in this field include U.S. Patent No. 5,245,084, U.S. Patent No. 9,957,405 (B2), and U.S. Patent No. 10,941,278 (B2). Patent application publications in this field include Chinese Patent Application Publication No. 101747553 (A), Chinese Patent Application Publication No. 109370003 (A), European Patent Application Publication No. 3 192 633 (A1), British Patent Application Publication No. 1535038 (A), U.S. Patent Application Publication No. 2020 / 0181374 (A1), U.S. Patent Application Publication No. 2020 / 0189166 (A1), U.S. Patent Application Publication No. 2021 / 0139671 (A1), International Publication No. 2013 / 112781 (A1), International Publication No. 2019 / 000311 (A1), and International Publication No. 2019 / 000654 (A1).

[0003] Introduction Methods decades old for preventing premature crosslinking or "scorch" of organoperoxide-containing crosslinkable polyolefin compositions involve impregnating granules of a peroxide-free composition just prior to completion, which includes a polyolefin and non-curing additives (such as antioxidants), with an organoperoxide. This is done on a large scale using one or more immersion towers. First, after melt compounding the non-curing additives into the melt of the polyolefin, the resulting compounded mixture is granulated (e.g., pelletized) to obtain solid granules of the peroxide-free composition just prior to completion, thereby producing peroxide-free granules. The melt compounding / granulation process can be carried out rapidly in less than a total of 1 hour. Next, the pellets are added to the immersion tower(s), and the organoperoxide is impregnated into the solid granules at a temperature that is sufficiently lower than the -O-O- bond cleavage temperature of the organoperoxide (e.g., 50 °C to 80 °C for dicumyl peroxide) and the melt temperature of the solid granules, but high enough to accelerate the movement of the organoperoxide into the solid granules. Impregnation typically takes 6 to 12 hours, and for this reason, undesirably, the overall manufacturing time becomes many times the melt compounding / granulation time. Also, what can be produced by impregnation is, undesirably, non-uniformly impregnated granules having an organoperoxide concentration gradient that is higher on the surface of the solid granules and lower in the center. Also, the immersion tower undesirably adds an additional cost of 35% to 50% to the construction cost of a new production line. Summary of the Invention

[0004] The inventors have discovered an ultra-high temperature low scorch method for rapidly producing a crosslinkable compound composition comprising a homogeneous mixture of a thermoplastic polyolefin, an antioxidant, and a curable additive comprising one or more organoperoxides and one or more multi-alkenyl crosslinking aids. By this method, immersion towers and long impregnation times are avoided, and furthermore, a completely crosslinkable homogeneous compound composition is produced that minimizes or completely suppresses premature crosslinking of the thermoplastic polyolefin(s). Brief Description of the Drawings

[0005]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0006] A method of ultra-high temperature and low scorch for rapidly producing a crosslinkable compound composition comprising a homogeneous mixture of a thermoplastic polyolefin, an antioxidant, and a curable additive comprising one or more organic peroxides and one or more multi-alkenyl crosslinking aids is described. By this method, immersion towers and long immersion times are avoided, and furthermore, a completely crosslinkable and homogeneous compound composition is produced that minimizes or eliminates premature crosslinking of the thermoplastic polyolefin(s).

[0007] This method can be adapted to produce extruded articles. Examples of extruded articles are coatings, films, and laminates. The extruded article also includes pellets of the crosslinkable compound composition, which can be stored and later melt extruded into the aforementioned articles. Since the degree of premature crosslinking or scorch occurring during this method is very low, the crosslinkable compound composition in the extruded article has sufficient curability to produce a cured article. Examples of these cured articles include fully cured insulating layers for power cables and communication cables.

[0008] Advantageously, the method of the present invention is more efficient, faster, and less expensive than the method of the comparative example based on the immersion of organic peroxides as described hereinafter. The improved efficiency of the method of the present invention includes the use of fewer unit operations (e.g., not using an immersion tower), and can reduce the energy usage compared to the method of the comparative example. The method is flexible in that it can be adapted to various embodiments.

[0009] One embodiment includes a method for producing a crosslinkable compound composition that is a homogeneous mixture of one or more thermoplastic polyolefins, one or more antioxidants, and a combination of curable additives including one or more organic peroxides (C-O-O-C-containing compounds) and one or more multi-alkenyl crosslinking aids (non-polymer compounds containing two or more alkenyl groups that can be selected from the group consisting of vinyl, allyl, acryloyl, and methacryloyl) (including no scorch), the method comprising: a solid conveying section (apparatus, e.g., including a hopper for polymer solid conveying), a melting / mixing zone, and an ultra-high temperature mixing zone, wherein the temperature of the ultra-high temperature mixing zone is 150.1 °C to 180.0 °C, or 155 °C to 174 °C, or 159 °C to 172 °C, or 162 °C to 171 °C, preparing a melt compounding apparatus (e.g., an extruder) having an ultra-high temperature mixing zone in sequence; in the melting / mixing zone of the melt compounding apparatus (e.g., an extruder), materials (a) to (c): (a) a pellet / aid (plural possible) premix prepared by contacting solid pellets of an intermediate compound that initially contains one or more thermoplastic polyolefins and one or more antioxidants but does not contain peroxides and multi-alkenyl crosslinking aids with one or more multi-alkenyl crosslinking aids ("aid(s)"), or (b) a pellet / aid (plural possible) / organic peroxide (plural possible) premix prepared by contacting solid pellets of an intermediate compound that initially contains one or more thermoplastic polyolefins and one or more antioxidants but does not contain peroxides and multi-alkenyl crosslinking aids with a combination of curable additives including one or more multi-alkenyl crosslinking aids ("aid(s)") and one or more organic peroxides ("organic peroxide(s)"), or (c) solid pellets of an intermediate compound that initially contains one or more thermoplastic polyolefins and one or more antioxidants but does not contain peroxides and multi-alkenyl crosslinking aids and wherein material (c) does not contain curable additives, supplying any one of them; melting and first mixing one or more thermoplastic polyolefins with the other components of material (a), (b), or (c) for 15 to 35 seconds to obtain their initial melt mixture in the melting / mixing zone.Moving the initial molten mixture to the ultra-high temperature mixing zone of a melt compounding apparatus (e.g., an extruder); and optionally, injecting one or more multi-alkenyl crosslinking aids and / or one or more organic peroxides (collectively referred to as "curable additive(s)") into the initial melt in the ultra-high temperature mixing zone, wherein when material (a) is supplied, one or more organic peroxides are injected (not optional), and when material (c) is supplied, one or more multi-alkenyl crosslinking aids and / or one or more organic peroxides are injected (not optional); secondarily mixing the material (a), (b) or (c) and the injected curable additive(s) in the ultra-high temperature mixing zone for 10 to 20 seconds; discharging the obtained crosslinkable compound composition from the melt compounding apparatus (e.g., an extruder), the total residence time of the material (a) (e.g., in FIG. 4), the material (b) (e.g., in FIG. 5) or the material (c) (e.g., in FIG. 6) in the melt compounding apparatus (e.g., an extruder) being 25 to 55 seconds, and the total residence time of the injected curable additive(s) in the melt compounding apparatus (e.g., an extruder) being 10 to 30 seconds, or 10 to 20 seconds. The injected curable additive(s) is directly injected into the injection location (14) of FIGS. 1 to 3 or into the "ultra-high temperature mixing zone" of FIGS. 4 to 6. In some embodiments, the discharging step includes conveying the crosslinkable compound composition to a post-compounding apparatus (e.g., a pelletizer, or an extruder, or a system including a melt pump, a melt screen, and a pelletizer or an extruder). The residence time in the melt compounding apparatus does not include the residence time in the post-compounding apparatus, even if it exists. When used, the post-compounding apparatus is different from the melt compounding apparatus and is downstream of the melt compounding apparatus.

[0010] The above method may include an embodiment in which the material (a) is supplied and one or more organic peroxides and optionally one or more additional multi-alkenyl crosslinking aids are injected into the initial melt in the ultra-high temperature mixing zone of a melt compounding apparatus (e.g., an extruder), and the second mixing step includes mixing the material (a) and the injected curable additive. In some embodiments, one or more additional multi-alkenyl crosslinking aids are not injected. In other embodiments, at least one additional multi-alkenyl crosslinking aid is injected. This embodiment is shown in FIG. 4.

[0011] In FIG. 4, the melt compounding apparatus 2 includes a melting and mixing zone 34, an ultra-high temperature mixing zone 37, and a discharge zone 38. The melt compounding apparatus 2 may or may not be configured to have an optional in-line pre-blender 32. The feed material (a) 30 includes at least one thermoplastic polyolefin (TPO) polymer and at least one multi-alkenyl crosslinking aid, but does not include an organic peroxide. In one embodiment using the in-line pre-blender 32, the feed material (a) 30 is fed (31) to the in-line pre-blender 32 where it is pre-blended, and the resulting pre-blend is fed (33a) to the melting and mixing zone 34 of the melt compounding apparatus 2. In another embodiment without using the in-line pre-blender 32, the feed material (a) 30 is directly fed (33b) to the melting and mixing zone 34 of the melt compounding apparatus 2. The material passes through the melt compounding apparatus 2 in the left-to-right flow direction indicated by the arrow 60. After being processed in melting and mixing in zone 34 in any embodiment, the resulting material is passed through the ultra-high temperature mixing zone 37, and at the same time, one or more organic peroxides 35 are injected (36) into the material passing through the ultra-high temperature mixing zone 37. Each of the one or more organic peroxides may be injected (36) separately or as a mixture thereof. After the ultra-high temperature mixing according to the present invention, the resulting material containing the injected organic peroxide(s) is passed through the discharge zone 38 and then discharged (39) from the melt compounding apparatus 2.

[0012] One or more multi-alkenyl crosslinking aids of material (a) do not include α-methylstyrene dimer ("AMSD"), because AMSD has only one alkenyl group per molecule as shown by its structure:

[0013] [Chemical formula]

[0014] Alternatively, the above method (paragraph

[0015] ) may include an embodiment in which material (b) is supplied, no injection is performed, the second mixing step includes mixing material (b), and no additional curable additive is injected. This embodiment is shown in Figure 5.

[0015] ​In FIG. 5, the melt compounding apparatus 2 includes a melting and mixing zone 34, an ultra-high temperature mixing zone 37, and a discharging zone 38. The melt compounding apparatus 2 may or may not be configured to have an optional in-line pre-blender 32. The feedstock (b) 40 includes at least one thermoplastic polyolefin (TPO) polymer, at least one antioxidant, at least one multi-alkenyl crosslinking aid, and at least one organic peroxide. In one embodiment using the in-line pre-blender 32, the feedstock (b) 40 is fed (41) to the in-line pre-blender 22 where a preliminary blend is performed, and the resulting pre-blend is fed (43a) to the melting and mixing zone 34 of the melt compounding apparatus 2. The fed materials pass through the melt compounding apparatus 2 in the left-to-right flow direction indicated by the arrow 60. In another embodiment without using the in-line pre-blender 32, the feedstock (b) 40 is directly fed (43b) to the melting and mixing zone 34 of the melt compounding apparatus 2. After subjecting the resulting material to the treatment in melting and mixing in zone 34 in any embodiment, the resulting material is passed through the ultra-high temperature mixing zone 37, and at the same time, optionally and optionally, one or more additional additives 45 selected from one or more organic peroxides and / or one or more additional multi-alkenyl crosslinking aids are injected (46) into the material passing through the ultra-high temperature mixing zone 37. Each of the one or more additional organic peroxides (if present) and / or one or more additional multi-alkenyl crosslinking aids (if present) can be injected (46) separately or as a mixture thereof, or if three or more are injected (46), some can be injected (46) separately and some as a mixture. After the ultra-high temperature mixing according to the present invention, the resulting material, which may optionally contain the additionally injected additives, is passed through the discharging zone 38 and then discharged (39) from the melt compounding apparatus 2.

[0016] In some embodiments, one or more of the multi-alkenyl crosslinking aids of material (b) is vinyl-D4 and the organic peroxide of material (b) is dicumyl peroxide.

[0017] The above method (paragraph

[0015] ) may include an embodiment in which the material (b) is supplied and an injection step is performed, including injecting one or more additional multi-alkenyl crosslinking aids and / or one or more additional organic peroxides into the initial melt in the ultra-high temperature mixing zone of a melt compounding apparatus (e.g., an extruder). The second mixing step includes mixing the material (b) and the injected curable additive. In some embodiments, at least one additional multi-alkenyl crosslinking aid is injected, but no additional organic peroxide is injected. In other embodiments, at least one additional organic peroxide is injected, but no additional multi-alkenyl crosslinking aid is injected. In other embodiments, at least one additional multi-alkenyl crosslinking aid is injected and at least one additional organic peroxide is injected. This embodiment is shown in FIG. 5. In some embodiments, one or more multi-alkenyl crosslinking aids of the material (b) are vinyl-D4, the organic peroxide of the material (b) is dicumyl peroxide, and the injection step includes injecting an additional multi-alkenyl crosslinking aid that is triallyl isocyanurate (TAIC).

[0018] The above method (paragraph

[0015] ) may include the manner in which the material (c) is supplied. The method includes supplying pellets of an intermediate compound to a melting / mixing zone of a melt compounding apparatus (e.g., an extruder) to obtain a melt of an intermediate compound that includes one or more thermoplastic polyolefins and one or more antioxidants but does not include a peroxide and a multi-alkenyl crosslinking aid. The melt of the intermediate compound is at a melting temperature of 150.1 °C to 180.0 °C, or 155 °C to 174 °C, or 159 °C to 172 °C, or 162 °C to 171 °C; a step of injecting a combination of curable additives including one or more organic peroxides and one or more multi-alkenyl crosslinking aids into the melt of the intermediate compound; and a step of mixing the combination of curable additives with the melt of the intermediate compound to form a crosslinkable compound composition in the form of a melt containing a homogeneous mixture, wherein the homogeneous mixture is formed within 20 seconds or more and less than 60 seconds after completion of the injection step. When the mixing step ends in less than 20 seconds, the mixture may not be completely homogeneous. When the mixing step is extended beyond 60 seconds, the homogeneous mixture may scorch. This embodiment is shown in FIG. 6.

[0019] In FIG. 6, the melt compounding apparatus 2 includes a melting and mixing zone 34, an ultra-high temperature mixing zone 37, and a discharging zone 38. The melt compounding apparatus 2 may or may not be configured with an optional in-line pre-blender 32. The feedstock (c) 50 includes at least one thermoplastic polyolefin (TPO) polymer and at least one antioxidant, but does not include a multi-alkenyl crosslinking aid or an organic peroxide. In one embodiment using the in-line pre-blender 32, the feedstock (c) 50 is fed (51) to the in-line pre-blender 32, where a preliminary blend is performed, and the resulting pre-blend is fed (53a) to the melting and mixing zone 34 of the melt compounding apparatus 2. In another embodiment without using the in-line pre-blender 32, the feedstock (c) 50 is directly fed (53b) to the melting and mixing zone 34 of the melt compounding apparatus 2. The material passes through the melt compounding apparatus 2 in the left-to-right flow direction indicated by arrow 60. After subjecting the material to the treatment in melting and mixing in zone 34 in any embodiment, the resulting material is passed through the ultra-high temperature mixing zone 37, and simultaneously, a combination of curable additives 55 including one or more organic peroxides and one or more multi-alkenyl crosslinking aids is injected (56) into the material passing through the ultra-high temperature mixing zone 37. Each of the one or more organic peroxides and the one or more multi-alkenyl crosslinking aids can be injected (56) separately or as a mixture thereof, or if three or more are injected (56), some can be injected (56) separately and some in the mixture. After the ultra-high temperature mixing according to the present invention, the resulting material containing the injected combination of curable additives 55 is passed through the discharging zone 38 and then discharged (39) from the melt compounding apparatus 2.

[0020] The above method (paragraph

[0019] ) may include embodiments adapted to a melt compounding apparatus which may be a screw extruder, or a single-screw or twin-screw extruder. The melt compounding apparatus defines a conveyance path therethrough and, in series along the conveyance path, at least the following zones, namely, a melt / compounding zone configured to heat the thermoplastic polyolefin above its melting temperature and blend an antioxidant therein, and having at least one supply port (also known as a supply point) for supplying one or more materials (e.g., pellets containing a thermoplastic polyolefin and an antioxidant, or antioxidant-free pellets containing a thermoplastic polyolefin and separate sources of antioxidant) to the melt / compounding zone (e.g., from an external hopper, external supply line, or external storage tank); a mixing zone configured to rapidly incorporate a curable additive into the polymer melt and having at least one injection port (also known as an injection point) therebetween for injecting one or more materials containing the curable additive into the mixing zone (e.g., from an external storage tank or supply line); and a discharge zone for discharging a melt stream of the compounded material from the melt compounding apparatus to a post-compounding apparatus (e.g., a pelletizer or extruder, or a system including a melt pump, melt screen, and pelletizer or extruder). The method includes: (A) supplying a melt of an intermediate compound to the melt / compounding zone, or forming a melt of the intermediate compound in the melt / compounding zone; (B) conveying the melt of the intermediate compound to the mixing zone; (C) injecting a combination of curable additives including one or more organic peroxides and one or more multi-alkenyl crosslinking aids into the melt of the intermediate compound through at least one of the at least one injection port of the mixing zone; (D) mixing the combination of curable additives and the melt of the intermediate compound in the mixing zone to form a melt of a crosslinkable compound composition containing a homogeneous mixture, the homogeneous mixture being formed within 20.0 to 60.0 seconds after completion of the injection step; and (E) conveying the melt of the crosslinkable compound composition to the discharge zone.

[0021] The above method (paragraphs

[0019] or

[0020] ) includes embodiments adapted to a pellet manufacturing machine configured to have a strand die (e.g., a multi-strand die), cooling means (e.g., a water bath), and a cutting device (e.g., a rotary knife blade). The post-discharge zone process includes a step of transporting a melt of the crosslinkable compound composition from the discharge zone of the melt compounding device to the pellet manufacturing machine, a step of extruding the strands of the crosslinkable compound composition, a step of cooling the strands, and a step of cutting the strands to produce solid pellets of the crosslinkable compound composition.

[0022] The above method (paragraphs

[0019] or

[0020] ) may include embodiments adapted to an insulator extruder configured to have an annular die for extruding coating a filament. The post-discharge zone process includes transporting a melt of the crosslinkable compound composition from the discharge zone of the melt compounding device to the insulator extruder, extruding a layer of the crosslinkable compound composition onto a conductor to produce a coated conductor, and curing the crosslinkable compound composition of the insulating layer to produce a cable. In some embodiments, the conductor includes one or more conductive wires, one or more light-transmissive glass fibers ("optical fibers"), or a combination thereof, and the insulating layer includes a crosslinked polyolefin product.

[0023] The above method (paragraphs

[0019] to

[0022] ) may include embodiments in which a restriction (i) or restriction (ii) is imposed on the injection process: (i) the injection process consists of injecting a combination of curable additives together as a mixture thereof, or (ii) the injection process consists of injecting at least one, or all but one, or each of the curable additives separately from the other curable additives.

[0024] The above method involves one or more thermoplastic polyolefins being selected for manufacturing the insulation layer of the cable at high temperature / low scorch with a low scorch and high production speed. For such one or more thermoplastic polyolefins, there are restrictions (i) to (iii): (i) one or more thermoplastic polyolefins are present, and at least one of the one or more thermoplastic polyolefins, or each of the one or more thermoplastic polyolefins, independently has a density of 0.870 to 0.940 g / cm 3 measured according to ASTM D792, Method B, and a melt index (I2) of 1 to 20 g / 10 min measured at 190 °C and 2.16 kg according to ASTM D1238, or (ii) one or more thermoplastic polyolefins are present, and each is independently selected from the group consisting of polyethylene homopolymer, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, and ethylene / 1-octene copolymer, or (iii) a combination of restrictions (i) and (ii). It can include an embodiment where any one of the restrictions is imposed.

[0025] The above method can include an embodiment where additives are selected for manufacturing the insulation layer of the cable at high temperature / low scorch. For such additives, there are restrictions (i) to (v): (i) one or more antioxidants include thio-based antioxidants, or a mixture of two or more thio-based antioxidants, or two or more antioxidants including lauryl thiodipropionate and stearyl thiodipropionate, or (ii) one or more multi-alkenyl crosslinking aids have the formula (I): [R 1 ,R 2 SiO 2 / 2 n (I) (where the subscript n is an integer of 3 or more) and contains an alkenyl group-containing monocyclic organosiloxane. Each R 1 is independently (C2-C4) alkenyl or H2C=C(R 1a )-C(=O)-O-(CH2) m -, where R 1a is H or methyl, the subscript m is an integer of 1 to 4, and each R 2 ​is independently H, (C1-C4)alkyl, phenyl, or R 1 or is 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-tetracyclosiloxane, or (iii) a combination of limitations (i) and (ii), (iv) one or more organic peroxides include dicumyl peroxide or a peroxide containing a cumyl group, or include dicumyl peroxide, or (v) a combination of limitation (iv) with any one of limitations (i)-(iii), and any one of the limitations is imposed.

[0026] The above method may include aspects in which the crosslinkable compound composition is formulated to produce a crosslinkable insulating layer of a cable at high temperature / low scorch. For such a crosslinkable compound composition, limitations (i)-(iii): (i) The scorch time (ts1) at 140 °C, reported as the time required at 140 °C to increase by 1 pound-force inch (lbf·in) or 1.13 decinewton meters (dN·m) from the minimum torque (''ML''), determined by a test moving a rheometer (MDR) in accordance with ASTM procedure D5289, is at least 63 minutes, or at least 79 minutes, and the maximum torque (MH) at 182 °C, determined by a test moving a rheometer (MDR) in accordance with ASTM procedure D5289, is at least 1.67 decinewton meters (dN·m; equal to at least 1.48 lbf·in) higher than the minimum torque (ML) at 182 °C, or MH is at least 1.72 dN·m (at least 1.52 lbf·in) higher than ML at 182 °C, and MH at 182 °C is at least 1.79 dN·m (1.58 lbf·in), or at least 1.83 dN·m (1.62 lbf·in), or (ii) the high-temperature creep elongation at 200 °C of the crosslinkable compound composition is less than 130%, or less than 100%, when tested in accordance with ICEA T-28-562a, or (iii) a combination of limitations (i) and (ii), and may include aspects in which any one of the limitations is imposed.

[0027] The above method can be further defined as described below.

[0028] When supplying material (a) or material (b), if desired, a solid blender can be used to premix solid pellets with either one or more multi-alkenyl crosslinking aids of material (a) or one or more multi-alkenyl crosslinking aids and one or more organic peroxides of material (b) to obtain respective premixed mixtures, and then supply these to the melt / mixing zone of an extruder.

[0029] This method. Without being bound by theory, the method of the present invention is considered to produce a crosslinkable compound composition essentially having ts1 at 140°C and maximum torque (MH) at 182°C within the aforementioned temperature range. This is evidence of the ultra-high temperature, low scorch, and crosslinkability characteristics of the method of the present invention. Without being bound by theory, a melt compounding temperature of 150.1°C to 180.0°C is considered to be extremely high to achieve these characteristics.

[0030] The method of the present invention, which injects an organic peroxide and one or more multi-alkenyl crosslinking aids into the melt stream of an intermediate compound and mixes them rapidly (in less than 60 seconds), supplies a crosslinkable compound composition rapidly even before being cooled from the treatment.

[0031] Although not bound by theory, embodiments of a method that involves feeding a material (a) that includes an intermediate compound and one or more multi-alkenyl crosslinking aids but no organic peroxide to a melting and mixing zone and then injecting all of one or more organic peroxides (if plural) into an ultra-high temperature mixing zone are considered to be superior to embodiments of a method that involves feeding a material (c) that includes an intermediate compound but no curable additives to a melting and mixing zone and then injecting all of the curable additives into an ultra-high temperature mixing zone. This is because the multi-alkenyl crosslinking aid(s) can have an anti-scorch effect, and the anti-scorch effect is maximized by the former method embodiment in which the material (a) is fed and the multi-alkenyl crosslinking aid is premixed in and throughout the initial melt before the initial melt is injected with the organic peroxide(s). In contrast, the latter method embodiment of feeding only the material (c) and later injecting both the multi-alkenyl crosslinking aid and the organic peroxide into the initial melt can have portions that may come into contact with the organic peroxide before coming into contact with the aid.

[0032] Similarly, for similar reasons, the inventors consider embodiments of the present method that involve feeding a material (b) that includes an intermediate compound and at least one multi-alkenyl crosslinking aid and at least one organic peroxide to a melting and mixing zone and then optionally injecting additional aid(s) and / or additional organic peroxide(s) (if plural) into an ultra-high temperature mixing zone to also be effective in manufacturing a crosslinkable compound composition and potentially superior to embodiments of a method that involves feeding the material (c).

[0033] Therefore, embodiments of a method that involves feeding the material (c) may be less effective in suppressing scorch of the crosslinkable compound composition than embodiments of a method that involves feeding the material (a) or (b). Thus, embodiments of the former method are described, and examples are provided showing that these method embodiments function, and accordingly, embodiments of a method that involves feeding the material (a) or (b) also function.

[0034] Injecting the curable additive during the melt compounding process eliminates the need for a melt cooling process or an immersion process after compounding to produce the crosslinkable compound composition. The method of the present invention consistently provides a fully formulated crosslinkable compound composition without using a melt cooling process or immersing the thermoplastic polyolefin in a crosslinking initiator. The homogeneous mixture produced by this method contains a fully incorporated organic peroxide and a crosslinking aid as soon as the mixing process is complete. In contrast, a comparative crosslinkable compound composition produced by immersing the curable additive in pellets of the intermediate compound may not be homogeneous and may have a concentration gradient of the curable additive that is higher at the surface of the pellets and decreases towards the center of the pellets.

[0035] Preparation step. The preparation step may be adapted for use with pressurization and / or melt screening of the melt of the intermediate compound prior to the injection step. In some embodiments of the method as described above, the method comprises, prior to the injection step, pumping the melt of the intermediate compound through a first melt pump upstream of the mixing zone of the melt compounding apparatus to produce a pressurized melt stream of the intermediate compound, and melt screening the pressurized melt stream of the intermediate compound through a melt screen located upstream of all of the injection ports at one or more locations in the mixing zone of the melt compounding apparatus such that the melt of the intermediate compound in the mixing zone is melt screened.

[0036] The preparation process can be adapted to control the overall melting temperature of the molten stream of the intermediate compound. These embodiments of the method involve adding a solid feed of a second polymer downstream of the primary solid feed of the thermoplastic polyolefin polymer, for example, at any point adjacent to the upstream or the most upstream injection point of all injection points, and melt compounding the second feed. Since the second polymer is in solid form, it is essentially at a temperature lower than the temperature of the molten stream of the intermediate compound. By introducing a controlled amount of the second polymer, for example, with a weight ratio of the second polymer feed to the initial polymer feed of 1:1 to 1:4, or 1:2 to 1:4, the overall melting temperature of the molten stream of the intermediate compound and the resulting crosslinkable compound can be significantly reduced without dropping below 150 °C. The molten stream of the intermediate compound is at a temperature sufficient to melt the second polymer solid and achieve improved temperature control over the molten stream, i.e., to lower the melting temperature or maintain it within the range of 150 °C to 180 °C.

[0037] Injection process. The injection process can be adapted to the use of injection ports of various types and arrangements, regardless of the presence or absence of melt screening. In some embodiments, the injection points for injecting the curable additive are (i) at the distribution mixing or kneading section at the downstream end of the melt compounding device and (ii) at the injection point downstream of the melt formation of the melt compounding device itself, both (i) at the distribution mixing or kneading section at the downstream end of the melt compounding device and (iii) downstream of the melt screen located upstream of another melt pump but downstream of the melt compounding device, both (i) at the distribution mixing or kneading section at the downstream end of the melt compounding device and (iv) upstream of the second melt pump located at a point downstream of both the other melt pump and the melt screen in (iii), (ii) at the injection point downstream of the melt formation in the melt compounding device itself and (iii) downstream of the melt screen located upstream of another melt pump but downstream of the melt compounding device, both (ii) at the injection point downstream of the melt formation in the melt compounding device itself and (iv) upstream of the second melt pump located at a point downstream of both the other melt pump and the melt screen in (iii), or both (iii) downstream of the melt screen located downstream of the melt compounding device but upstream of another melt pump and (iv) upstream of the second melt pump located at a point downstream of both the other melt pump and the melt screen in (iii). In some embodiments, the injection points for injecting the curable additive can include any three of injection points (i)-(iv), or each of (i)-(iv).

[0038] One injection point or multiple injection points can be located downstream of a melt screen that is itself located downstream of a melt pump. The melt compounding apparatus can comprise an arrangement of twin melt pumps further comprising a second downstream melt pump and a melt screening apparatus disposed between the melt pump and the second downstream melt pump. The two melt pumps are located before and after the melt screen. In the case of twin melt pumps, injecting a combination of curable additives involves melt pumping the melt stream of the intermediate compound to create a pressurized melt stream, melt screening the pressurized melt stream of the intermediate compound, and injecting the combination of curable additives into the melt stream at an injection point downstream of the melt screen, which can be in or immediately upstream of the second downstream melt pump.

[0039] Mixing step. The mixing step is configured to quickly create a homogeneous mixture of the crosslinkable compound composition. This is achieved by continuously performing melt compounding at or downstream of the downstream end of the melt compounding apparatus, thereby immediately, quickly, and completely (homogeneously) blending the injected curable additives into the melt of the intermediate compound in 20 to 60 seconds. The method can be operated at an ultra-high temperature of 150.1 °C to 180.0 °C and uses a melt compounding apparatus described below that enables such quick and complete mixing in less than 60 seconds.

[0040] Apparatus that cannot achieve quick and complete blending in the mixing step are excluded from the method. Such excluded apparatus include any of a rolling mill, a rolling drum, a ball mill, a hand mixer, and other mixing / blending apparatus with a long residence time, for example, a batch mixer, which cannot completely melt the essentially thermoplastic polyolefin and cannot mix all components of the crosslinkable compound composition in less than 60 seconds as described herein.

[0041] Embodiments of the continuous and batch processes of the present method. The present method is adaptable to embodiments of batch processing or continuous processing. As used herein, "batch processing" means that, depending on the size of the apparatus, at discreet, short intervals, e.g., every few minutes or every few hours, with a temporal interruption and / or an interruption in the flow of material through the production line, so that the intermediate materials and the final product are produced in discreet time and discontinuous batches, and / or with an interruption in the flow of material through the production line, it means an embodiment of the method of intermittently producing a crosslinkable compound composition.

[0042] "Continuous processing" means an embodiment of the method of continuously producing a crosslinkable compound composition without interruption time or interruption in the flow of material through the production line so that the final product is produced without interruption. Theoretically, a continuous process can run permanently, but in practice, it can be run for 12 hours or more, or 24 hours or more, or 7 days or more, and can be stopped irregularly for equipment cleaning, etc., when the supply of raw materials is interrupted (e.g., due to a shipping delay), or when the equipment is switched to produce different final products. Continuous embodiments produce the crosslinkable compound composition in a continuous stream produced at a production rate that is advantageously high enough (e.g., at least 10 kilograms, or at least 50 kg / hour, or at least 100 kg / hour of crosslinkable compound composition produced per hour) to continuously supply the freshly made crosslinkable compound composition to a pelletizing device or a cable coating device of a commercial cable production line in a few seconds. In some embodiments, the method is a continuous process that includes continuous embodiments of a preparation step, an injection step, and a mixing step.

[0043] Optional additional steps of the present method. The present method is not particularly limited in including additional steps, provided that the additional steps do not invalidate the preparation step, the injection step, and the mixing step.

[0044] Optional preliminary steps preceding the preparation step. In order to produce the intermediate compound in a uniform form and in a continuous process, the primary feed of the thermoplastic polyolefin polymer and one or more antioxidants are melt compounded or melt blended in a melt compounding apparatus to create a primary stream of the melt of the intermediate compound. Typically, in practice, the method includes the step of melting the thermoplastic polyolefin polymer. However, other embodiments are also contemplated where the melt of the thermoplastic polyolefin polymer is produced directly (i.e., not from a solid), such as a polymerization reaction in solution and / or at a temperature higher than the melting temperature of the polymer to polymerize olefin monomers. In some embodiments, the method includes the following additional steps: prior to the preparation step, introducing a solid form (e.g., pellets) of the intermediate compound into the melt / compounding zone through one of the feed ports in the melt / compounding zone and melting the introduced intermediate compound in the melt / compounding zone of the screw extruder, including at least one of these steps. Alternatively, prior to the preparation step, introducing a solid form of one or more thermoplastic polyolefins through one of the feed ports of the melt / compounding zone, introducing one or more antioxidants into the melt / compounding zone, melting the one or more thermoplastic polyolefins in the melt / compounding zone of the screw extruder, and melt compounding the one or more antioxidants into the melt of the one or more thermoplastic polyolefins to produce a melt of the intermediate compound. The melt of the one or more thermoplastic polyolefins or the melt of the intermediate compound can be melt screened prior to the preparation step.

[0045] Optional steps after the mixing process. The method is not particularly limited in including additional steps, provided that the additional steps do not invalidate the preparation step, the injection step, and the mixing step. For example, the method does not allow a step of delaying the mixing step beyond 60 seconds or a step that prevents the mixing step from achieving the uniformity of the mixture. In some embodiments, the method does not include any steps before the preparation step, while in other embodiments, the method includes at least one additional step before the preparation step, such as a step of producing a melt of an intermediate compound. In some embodiments, the method does not include any steps after the mixing step, while in other embodiments, the method includes at least one additional step after the mixing step, such as a pelletizing step or a coating step. In some embodiments, the method does not include any steps between the preparation step and the injection step, while in other embodiments, the method includes at least one step between the preparation step and the mixing step, such as a step of supplying a second polymer to the melt of the intermediate compound. The method does not include any steps between the injection step and the mixing step, but may include an additional step during the injection step, such as a step of injecting a combination of curable additives and simultaneously injecting one or more non-curable additives.

[0046] In some embodiments, the method includes one or more additional steps after the mixing step that are adapted to produce an insulating layer (commonly referred to as an "insulated conductor") of a power cable or a communication cable. An insulated conductor typically includes a conductor covered by an insulating layer. The conductor can be solid or stranded (e.g., a bundle of wires). Some insulated conductors may also contain one or more additional elements such as a semiconductive layer and / or a protective jacket (e.g., a winding, tape, or sheath). Examples include coated metal wires and power cables for use in power cables and their power transmission / distribution applications at low voltage (low voltage, "LV", >0 to <5 kilovolts (kV)), medium voltage (medium voltage, "MV", 5 to <69 kV), high voltage (high voltage, "HV", 69 to 230 kV), and extra-high voltage (extra-high voltage, "EHV", >230 kV).

[0047] Melt screening and pressurization process. The process of any method using a polymer melt is adaptable to melt screening and / or pressurization. Devices useful for such melt screening and / or pressurization are described below.

[0048] Optional devices for melt compounding equipment and production lines.

[0049] This method can be carried out without hindrance by any device capable of performing a preparation step, an injection step, and a mixing step. An example of such a device is the melt compounding device described above. Some embodiments of the method may include one or more additional devices selected from the group consisting of a melt pump, a melt screen (e.g., a filtration unit containing a melt screen), and a pelletizing device. In some embodiments, the method may further include a coating device for coating a crosslinkable compound composition onto a wire or optical fiber, as in the manufacture of power cables or communication cables.

[0050] Suitable apparatus for making a homogeneous mixture of the intermediate compound and the crosslinkable compound composition includes segments in a distributive mixing device or extruder, or high-intensity mixers such as mixing rotors, toothed mixing elements (TME, ZME, etc.) and kneading blocks (forward, neutral, or reverse pumping), gear mixers, melt pumps, gear pumps, or kneading blocks such as blister elements when combined with downstream mixing elements. Such melt compounding devices include, for example, co-rotating intermeshing twin-screw extruders (e.g., the Coperion ZSK-30 twin-screw extruder with an inner diameter of 30 millimeters (mm) used in Examples CE1 and IE1 - IE4 later, or the Coperion ZSK-26 twin-screw extruder with an inner diameter of 26 mm, which may be used in future examples), counter-rotating, high-intensity, non-intermeshing twin rotor mixers (e.g., the FCM from Farrell), or suitable mixing devices such as single-screw extruders equipped with a Maddock-type mixing section (having a Maddock-type mixer device). When the method of the present invention includes delivering the molten stream of the intermediate compound to a melt pump and melt screening the pressurized molten stream upstream of any injection point, i.e., the location for injecting the combination of curable additives into the molten stream, a wider selection of compounding devices can be used. In such cases, the melt compounding device may include any of the compounders, co-rotating intermeshing twin-screw extruders, or counter-rotating high-intensity non-intermeshing twin-screw compounding mixers listed above. When there is not a sufficiently rapid and complete incorporation of the curing agent into the melt by the means described, the resulting composition exhibited severe scorch or decomposition of the organic peroxide. For example, experiments in a Banbury mixer of a comparative example discharged at a melt temperature of 155°C with the combination of curable additives added downstream resulted in severe scorch and rendered the compound unusable.

[0051] In the screening process, pressure is required to extrude the melt through a screen, or in the pelletizing process, to extrude it through a die. Some melt compounding devices that can be used in aspects of the present method generate sufficient pressure to perform screening or pelletizing (i.e., they "generate sufficient pressure"). Other melt compounding devices that can be used in aspects of the present method do not generate sufficient pressure for screening and / or pelletizing (i.e., they generate insufficient pressure). In such aspects, a melt pump or a single screw extruder can also be used to generate sufficient pressure. Thus, a melt compounding device may or may not be able to generate sufficient pressure for melt screening or pelletizing.

[0052] Examples of melt compounding devices that generate sufficient pressure for screening or pelletizing are single screw extruders and some twin screw extruders. Examples of melt compounding devices that do not generate sufficient pressure for screening or pelletizing and are thus used in combination with a melt pump or a single screw extruder are some twin screw extruders, co-rotating intermeshing twin screw extruders not configured to generate sufficient pressure for melt screening or pelletizing, and counter-rotating high-intensity non-intermeshing twin screw extruders (e.g., FCM and LCM manufactured by Farrel, LCM manufactured by Kobe Steel, Continuous Intensive Mixer (CIM) or CIMP manufactured by Japan Steel Works (JSW)), or a suitable mixing device, such as a single screw extruder equipped with a Maddock type mixing section.

[0053] A suitable production line moves from upstream to downstream of the melt stream and includes at least one melt compounding device, and further includes (i) a distribution mixing element in the melt compounding device such as a gear mixer or a gear mixing element, or (ii) a distribution mixing element as a melt pump located downstream of the melt compounding device, or (iii) both of the distribution mixing elements, and further includes a melt screening unit. The melt mixing device may further include a pelletizer or a pelletizing die. The melt mixing device may be provided with two melt pumps, one disposed upstream of the melt screen and the other disposed downstream of the melt screen.

[0054] A melt screening device suitable for use according to the method of the present invention may include, for example, a continuous plate, a rotary screen changer, a slide plate screen changer, a dual bolt or chamber screen changer, or any candle, pleated candle, disk, cylinder, or flat plate filter element having a filter medium of woven or non-woven fabric capable of stopping particles in the size range of 25 μm to 500 μm such as a polymer gel, etc., including continuous screening or filtration techniques.

[0055] Suitable melt pumps for use in the method of the present invention may include any known in the art, for example, those manufactured by MAAG, Farrel-Pomini, gear mixers, or twin gear pressure generating melt pumps appropriately modified to promote mixing.

[0056] In an example of an extruder, a single-screw or twin-screw extruder has a feeder, a melt screw section, and a downstream mixing section, for example, a kneading block or a gear mixer. A thermoplastic polyolefin polymer feed consisting of LDPE and an antioxidant may be supplied through a feeder at the upstream end of the extruder barrel. The curable additive may be injected at any of various injection locations upstream of the downstream mixing section.

[0057] Figures 1, 2, and 3 show versions of a melt compounding apparatus and production line that can be used in embodiments of the present method. Figures 4, 5, and 6 show process flow diagrams of embodiments of a method of supplying material (a) (Figure 4), material (b) (Figure 5), or material (c) (Figure 6) to the melt / mixing zone of a melt compounding apparatus (e.g., an extruder).

[0058] Figure 1 shows the method and apparatus of the present invention for manufacturing a conductor or cable insulator composition. The melt compounding line (2) moves from left to right from upstream to downstream and comprises a melt compounding apparatus (4), in this case a twin-screw extruder, a melt pump (6), a melt screen (8), and a pelletizing die (10). The melt compounding apparatus (4) melts and mixes a base thermoplastic polyolefin (ethylene polymer) feed (12) comprising an antioxidant additive and optionally a combination of curable additives. The melt pump (6) helps to increase the pressure upstream of the melt screen (8), and the melt screen itself promotes the distribution of the curable additives and improves the cleanliness of the crosslinkable compound product. The pelletizing die (10) pelletizes the formulation into an immediately usable form. The melt compounding apparatus (4) can be a twin-screw extruder, a counter-rotating twin rotor mixer (e.g., FCM manufactured by Farrel), or a single-screw extruder. Along the melt compounding line (2), the curable additives can be injected i) into the melt compounding apparatus (4) in or above a distributive mixing section (not shown), ii) at the transition between the melt compounding apparatus (4) and the melt pump (6), or iii) directly into the melt pump (6) or any injection location (14) such as a combination thereof. A plurality of injection locations (14) each containing a portion of the combination of curable additives can be used to inject the desired total amount of curable additives.

[0059] Figure 2 shows another method and apparatus of the present invention for manufacturing a conductor or cable insulator composition. The melt compounding line (2) moves from left to right from upstream to downstream and comprises a melt compounding apparatus (4), in this case a twin-screw extruder, two melt pumps (6) located before and after a melt screen (8), and a pelletizing die (10). The melt compounding apparatus (4) melts and mixes a base thermoplastic polyolefin (ethylene polymer) feed (12) that also includes an antioxidant additive and optionally a combination of curable additives. The upstream (left) melt pump (6) helps to increase the pressure upstream of the melt screen (8), and the melt screen itself improves the cleanliness of the crosslinkable compound product. The downstream (right) melt pump (6) disperses the curable additives into the intermediate compound. The pelletizing die (10) pelletizes the formulation into an immediately usable form. The melt compounding apparatus (4) can be a co-rotating intermeshing twin-screw extruder, a counter-rotating twin-screw compounding mixer (e.g., FCM manufactured by Farrel), or a single-screw extruder. The curable additives can be injected at one or more injection locations (14) such as i) the transfer line between the melt screen (8) and the downstream melt pump (6), or ii) directly into the downstream melt pump (6). Both injection locations (14) may be used such that a plurality of injectors (not shown) can inject a combined amount that totals the desired amount of curable additives.

[0060] Figure 3 shows an experimental melt compounding line (2) used in a part of the examples, moving from left to right from upstream to downstream and comprising an extruder (20), a polymer feed location (12), an injection location (14) for a combination of curable additives, a melt screen (8), and a pelletizing die (10).

[0061] Figure 4 shows a process flow diagram of an embodiment of a method for supplying material (a) to the melting / mixing zone of a melt compounding apparatus (e.g., an extruder). In Figure 4, material (a) includes at least one thermoplastic polyolefin polymer (“TPO polymer”), at least one antioxidant, and at least one multi-alkenyl crosslinking aid (“aid”), but does not include peroxide. Material (a) is continuously supplied to the melting and mixing zone of the extruder, where the TPO polymer is continuously and rapidly melted as described above to obtain an initial melt. The initial melt is continuously conveyed to an ultra-high temperature mixing zone (“ultra-high temperature mixing zone”), where it continuously receives the injection of one or more organic peroxides. The one or more organic peroxides are rapidly and completely mixed into the initial melt to form a melt of a crosslinkable compound composition, which melt is discharged from the melt compounding apparatus. Figure 4 assumes that the crosslinkable compound composition is discharged to a post-compounding apparatus (e.g., a pelletizer) not shown.

[0062] Figure 5 shows a process flow diagram of an embodiment of the present method for supplying material (b) to the melting / mixing zone of a melt compounding apparatus (e.g., an extruder). In Figure 5, material (b) comprises at least one thermoplastic polyolefin polymer (“TPO polymer”), at least one antioxidant, at least one multi-alkenyl crosslinking aid (“aid”), and at least one organic peroxide. Material (b) is continuously supplied to the melting and mixing zone of the extruder, where the TPO polymer is continuously and rapidly melted as described above to obtain an initial melt. The initial melt is continuously supplied to an ultra-high temperature mixing zone (“ultra-high temperature mixing zone”), where it either does not receive an injection of a curable additive or continuously receives an injection of at least one additional organic peroxide, at least one additional multi-alkenyl crosslinking aid, or both. The injected additional organic peroxide(s) and / or aid(s) are rapidly and completely mixed into the initial melt to create a melt of a crosslinkable compound composition, which melt is discharged from the melt compounding apparatus. Figure 5 assumes that the crosslinkable compound composition is discharged to a post-compounding apparatus (e.g., a pelletizer) not shown.

[0063] Figure 6 shows a process flow diagram of an embodiment of a method for supplying material (c) to the melting / mixing zone of a melt compounding apparatus (e.g., an extruder). In Figure 6, material (c) includes at least one thermoplastic polyolefin polymer (“TPO polymer”) and at least one antioxidant, but does not include a multi-alkenyl crosslinking aid (“aid”) or a peroxide. Material (c) is continuously supplied to the melting and mixing zone of the extruder, where the TPO polymer is continuously and rapidly melted as described above to obtain an initial melt. The initial melt is continuously conveyed to an ultra-high temperature mixing zone (“ultra-high temperature mixing zone”), where it continuously receives the injection of a curable additive containing one or more multi-alkenyl crosslinking aids and one or more organic peroxides. The curable additives can be injected as their premix or can be injected individually and separately. The injected curable additives are rapidly and completely mixed into the initial melt to create a melt of the crosslinkable compound composition, which is discharged from the melt compounding apparatus. Figure 6 assumes that the crosslinkable compound composition is discharged to a post-compounding apparatus (e.g., a pelletizer) not shown.

[0064] Extruded articles. The crosslinkable compound composition made by this method can be extruded into products. These extruded articles include pellets, coatings, films, laminates, pipes, conduits, etc., including the crosslinkable compound composition. The extruded articles can include a polyolefin-based layer of a coated conductor, such as a semi-conductive layer (including carbon black), an insulating layer, or both. The extruded articles may be exposed to high temperatures during use, for example, due to heating to which the insulating layer will be exposed during operation of MV, HV, or EHV power cables.

[0065] Crosslinkable compound composition. The crosslinkable compound composition is inventive depending on how it is manufactured by the method of the present invention. The method of the present invention is manufactured from the same amount of the same components, but is manufactured by a passive method of incorporating one or more organic peroxides into a thermoplastic polyolefin, and compared to the characteristics of the compound composition of the same comparative example otherwise identical, it can result in an essential difference in at least one characteristic. Examples of such passive methods are dipping or absorption. In some embodiments, the passive method may not achieve the characteristics of the present invention.

[0066] For example, the thermal history of the crosslinkable compound composition of the present invention is different from the thermal history of the compound composition of the comparative example by different methods of manufacturing it. Therefore, as a result of different thermal histories, the crosslinkable compound composition of the present invention may differ from the compound composition of the comparative example in at least one aspect selected from the group consisting of the ratio of components, the concentration of components, melt rheology properties, and mechanical properties.

[0067] The crosslinkable compound composition is stable during storage. This enables subsequent separate in-line article production, i.e., separate extrusion and molding into manufactured articles such as cable insulators, batch stability, and even crosslinkability after melt compounding.

[0068] This crosslinkable compound composition is resistant to scorch and has excellent curability. In some embodiments, for the present method and the composition produced thereby, the following limitations (i)-(iii) apply: (i) the time to scorch (scorch time) ts1 at 140 °C is at least 95 minutes, (ii) the minimum torque (ML) at 182 °C is 0.10 to 0.14 decinewton meters (dN·m), or (iii) a combination of limitations (i) and (ii). Some embodiments can include aspects where any one of these limitations is imposed. In some embodiments, the crosslinkable compound composition has a scorch time (ts1) at 140 °C, reported as the time required at 140 °C to increase by 1 pound-force inch (lbf·in) or 1.13 decinewton meters (dN·m) from the minimum torque (“ML”) as determined by a test moving a rheometer (MDR) according to ASTM procedure D5289, of at least 63 minutes, or at least 79 minutes, and the crosslinkable compound composition has a maximum torque (MH) at 182 °C, as determined by a test moving a rheometer (MDR) according to ASTM procedure D5289, that is at least 1.67 decinewton meters (dN·m; equivalent to at least 1.48 lbf·in) higher than the minimum torque (ML) at 182 °C, or MH is at least 1.72 dN·m (at least 1.52 lbf·in) higher than ML at 182 °C, and MH at 182 °C is at least 1.79 dN·m (1.58 lbf·in), or at least 1.83 dN·m (1.62 lbf·in). If the scorch time (ts1) of the crosslinkable compound composition is too short (i.e., less than 63 minutes), the crosslinkable compound composition may undergo excessive scorch and may not be of sufficient quality to produce extruded articles. The longer the measured scorch time (ts1) exceeds 63 minutes, the less premature crosslinking of the crosslinkable compound composition occurs. If the MH at 182 °C of the crosslinkable compound composition is too small (i.e., less than 1.6 dN·m), the crosslinkable compound composition may not be curable or may have defects such as gels.If the MH of the crosslinkable compound composition at 182 °C is too large (i.e., exceeding 4 dN·m), the crosslinkable compound composition may take too much time to cure completely.

[0069] The crosslinkable compound composition has excellent extrudability as indicated by its rheological properties. In some embodiments, for the method and the composition produced thereby, the following restrictions (i)-(iii) apply: (i) the melt index I at 120 °C and 10.0 kg 10 is 4.0 to 5.7 g / 10 min, (ii) the viscosity at 135 °C under a shear rate of 0.1 radian per second (rad / s) is 1.7 to 2.7 kilopascal seconds (kPa·s) (1700 to 2700 Pa·s), or (iii) a combination of (i) and (ii). Embodiments can include any one of these restrictions. The I of the crosslinkable compound composition at 120 °C 10 or the viscosity at 135 °C / 0.1 rad / s is too low (i.e., less than 4 g / 10 min or less than 1.7 kPa·s, respectively), the crosslinkable compound composition does not have sufficient melt extrudability and may cause defects such as cracks, voids, or gels in the extruded article. The I of the crosslinkable compound composition at 120 °C 10 or the viscosity at 135 °C / 0.1 rad / s is too high (i.e., more than 6 g / 10 min or more than 2.7 kPa·s, respectively), the extruded article made from the crosslinked product may not have sufficient creep resistance when exposed to heat. In some embodiments, the viscosity of the crosslinkable compound composition at 135 °C / 0.1 rad / s is 2.05 to 2.65 kPa·s.

[0070] The crosslinkable compound composition has excellent mechanical properties as exhibited by at least one of its tensile strength, resistance to elongation, and resistance to high-temperature creep. In some embodiments, for the present method and the composition produced thereby, there are limitations (i)-(v): (i) the tensile strength exceeds 17.20 megapascals (MPa); (ii) the elongation at break exceeds 500.0%; (iii) the combination of (i) and (ii); (iv) the high-temperature creep at 200 °C is less than 80.0%; or (v) the combination of (iv) and any one of (i)-(iii). If the tensile strength and / or elongation at break are too low, the extruded article produced from the crosslinked product may have insufficient mechanical strength for its intended use. If the tensile strength and / or elongation at break are too high, the extruded article produced from the crosslinked product may break prematurely during use. If the high-temperature creep of the crosslinkable compound composition at 200 °C is too high (i.e., exceeds 80%), the extruded article made from the crosslinked product may not have sufficient creep resistance when exposed to heat.

[0071] Intermediate compounds and their melts (including the primary flow).

[0072] The intermediate compound is adapted for use in the present method. For example, one or more thermoplastic polyolefins (TPOs) have a sufficiently high overall initial melt index value (I2) such that after the mixing step, even if the crosslinkable compound composition undergoes minimal premature crosslinking (scorch), it has a melt rheology that allows subsequent extrusion of the composition into an extruded article. For example, in some embodiments, one or more thermoplastic polyolefins have an overall melt index (I2) of 1 to 20 g / 10 min, or 2 to 10 g / 10 min, or 3 to 10 g / 10 min, or 3 to 5 g / 10 min as determined according to ASTM D1238 at 190 °C and 2.16 kg. If the overall I2 of one or more TPOs is too low (i.e., less than 1 g / 10 min), after minimal scorch, the crosslinkable compound composition does not have sufficient melt extrudability and may result in defects such as cracks, voids, or gels in the extruded article. If the overall I2 of one or more TPOs is too high (i.e., greater than 20 g / 10 min), the extruded article produced from the crosslinked product may not have sufficient creep resistance when exposed to heat.

[0073] The intermediate compound can be produced by any process or series of steps, and as far as the present method is concerned, how the intermediate compound is produced is not particularly important. In some embodiments of the present method as described above, prior to the preparation step, (a1) supplying one or more antioxidants and one or more thermoplastic polyolefins through one or more supply ports to a melt / compounding zone to create a primary stream containing one or more antioxidants and one or more thermoplastic polyolefins (collectively, the components of the primary stream), but not containing peroxide and multi-alkenyl crosslinking aids and added solids of the second polymer; (a2) in the melt / compounding zone, melt-compounding the primary stream at a temperature of 155 °C to 174 °C to create a melt of the intermediate compound; (a3) cooling the melt of the intermediate compound to produce the intermediate compound in solid form, for example as pellets; and (a4) supplying the solid form of the intermediate compound to the melt / compounding zone of a screw extruder.

[0074] In some embodiments using the above melt compounding apparatus, a melt of one or more thermoplastic polyolefins and one or more antioxidants, which does not contain peroxide, multi-alkenyl crosslinking aids, and added solids of a second polymer, is herein referred to as the "primary stream". A primary stream that includes one or more antioxidants and one or more thermoplastic polyolefins (collectively, the components of the primary stream), but does not include one or more curable additives selected from the group consisting of organic peroxides and multi-alkenyl crosslinking aids, and the melt stream of the intermediate compound made therefrom (an intermediate compound that includes a mixture of one or more thermoplastic polyolefin polymers and one or more antioxidants (AO), but does not include one or more curable additives) does not contain other polymers. In such embodiments, the polymer component of the primary stream and the intermediate compound(s) made therefrom consist of one or more thermoplastic polyolefins. In such embodiments, the polymer component(s) of the crosslinkable compound composition produced by the method of the present invention consist of one or more thermoplastic polyolefins, and the polymer component(s) of the crosslinked compound composition produced by curing the crosslinkable compound composition independently consist of one or more thermoplastic polyolefins and / or crosslinked polyolefins produced by curing it.

[0075] In some embodiments, a primary stream that includes one or more antioxidants and one or more thermoplastic polyolefins (collectively, the components of the primary stream), but does not include one or more curable additives selected from the group consisting of organic peroxides and multi-alkenyl crosslinking aids, and a melt stream of an intermediate compound made therefrom (an intermediate compound that includes a mixture of one or more thermoplastic polyolefin polymers and one or more antioxidants (AO), but does not include one or more curable additives) also include the polyolefin that is the non-thermoplastic polymer described above. In such embodiments, the polymer component(s) of the primary stream and the intermediate compound made therefrom consist of one or more thermoplastic polyolefins and one or more ethylene / unsaturated carboxylic acid ester copolymers. The proportion of one or more ethylene / unsaturated carboxylic acid ester copolymers (if any) used in such embodiments of the primary stream can be 0.05 wt% to 20 wt%, or 0.10 to 15 wt%, or 0.10 to 5 wt% based on the total weight of the primary stream, and the proportion of one or more ethylene / unsaturated carboxylic acid ester copolymers (if any) used in such embodiments of the intermediate compound can independently be 0.05 wt% to 20 wt%, or 0.10 to 15 wt%, or 0.10 to 5 wt% based on the total weight of the intermediate compound. According to the method of the present invention, embodiments of the crosslinkable compound composition produced therefrom also contain one or more ethylene / unsaturated carboxylic acid ester copolymers (if any), and the crosslinkable compound composition produced by curing such embodiments contains the crosslinked product thereof.

[0076] Thermoplastic polyolefin (TPO). The crosslinkable compound composition includes a thermoplastic polyolefin (“TPO”). The terms “thermoplastic polyolefin” and “TPO” are used herein to refer to homopolymers produced by polymerizing a single unsaturated hydrocarbon monomer or copolymers produced by polymerizing two or more different unsaturated hydrocarbon monomers, each unsaturated hydrocarbon monomer consisting of carbon atoms and hydrogen atoms.

[0077] In some embodiments, the thermoplastic polyolefin is an ethylene-based polymer. The ethylene-based polymer comprises 51 to 100 wt% ethylene units derived from the polymerization of ethylene and 49 to 0 wt% comonomer units derived from the polymerization of one or two olefin-functional monomers (monomers and comonomers). The comonomer can be selected from propylene, (C4-C 20 ) alpha-olefin, and 1,3-butadiene. The (C4-C 20 ) alpha-olefin can be a (C4-C8) alpha-olefin such as 1-butene, 1-hexene, or 1-octene.

[0078] Ethylene-based polymer embodiments of the TPO can be selected from the group consisting of polyethylene homopolymers, ethylene / propylene copolymers, and ethylene / (C4-C 20 ) alpha-olefin copolymers. Examples of unsaturated hydrocarbon monomers are ethylene, propylene, (C4-C 20 ) alpha-olefin, and 1,3-butadiene. In some embodiments, the TPO is a polyethylene homopolymer or an ethylene / (C4-C 20 ) alpha-olefin copolymer. The (C4-C 20 ) alpha-olefin is a compound of the formula H2C=C(H)-(CH2) q CH3, where the subscript q is an integer from 1 to 17. In some embodiments, the (C4-C 20 ) alpha-olefin can be 1-butene, 1-hexene, or 1-octene, or 1-butene or 1-hexene, or 1-octene, or 1-hexene, or 1-butene.

[0079] When blends of ethylene polymers are used, the polymers can be blended by any in-reactor or post-reactor process.

[0080] The ethylene polymer can be selected from the group consisting of low-density polyethylene ("LDPE"), linear low-density polyethylene ("LLDPE"), very low-density polyethylene ("VLDPE"), and combinations of two or more thereof. LDPE is generally a highly branched ethylene homopolymer and can be prepared by a high-pressure process (i.e., HP-LDPE).

[0081] Suitable LDPE has a density in the range of 0.91 to 0.94 g / cm 3 or, for example, at least 0.915 g / cm 3 but less than 0.94, or a density less than 0.93 g / cm 3 The polymer density provided herein is determined according to ASTM method D792. Suitable LDPE for use herein may have a melt index (I2) of 1 to 20 g / 10 min, or 2 to 10 g / 10 min, or 3 to 10 g / 10 min, or 3 to 5 g / 10 min as determined at 190 °C and 2.16 kg according to ASTM method D1238.

[0082] Suitable LLDPE may have a non-uniform distribution of comonomers (e.g., α-olefin monomers) and be characterized by short-chain branches. For example, LLDPE can be a copolymer of ethylene and an α-olefin monomer having a density in the range of 0.916 to 0.925 g / cm 3 Suitable LLDPE for use herein may have the same melt index (I2) as LDPE.

[0083] Suitable VLDPE and ULDPE for use as TPO may have a non-uniform distribution of comonomers (e.g., α-olefin monomers) and be characterized by short-chain branches. For example, VLDPE can be a copolymer of ethylene and one or more of the above α-olefin monomers. Suitable VLDPE for use herein may have a density in the range of 0.87 to 0.915 g / cm 3 Suitable VLDPE for use herein may have the same melt index (I2) as LDPE.

[0084] The total weight of one or more thermoplastic polyolefins in the intermediate compound and / or crosslinkable compound composition can be 50 to 99.79% by weight, or 80.0 to 99.79% by weight, or 95 to 99% by weight, for example 98.0 to 98.9% by weight, and all weights are based on the total weight of the intermediate compound or crosslinkable compound composition, respectively. The weight percentages not attributable to one or more thermoplastic polyolefins, one or more antioxidants, and curable additives are attributable to one or more non-curable additives and / or a second polymer described hereinafter in this specification.

[0085] Thermoplastic polyolefins can be produced by methods known in the art. Conventional or hereafter discovered production methods for producing suitable ethylene polymers can be used to prepare ethylene-based polymer embodiments of thermoplastic polyolefins. Generally, the polymerization can be achieved under conditions known in the art for Ziegler-Natta polymerization reactions or Kaminsky-Sinn polymerization reactions, i.e., at a temperature of 0 to 250 °C, or 30 or 200 °C, and a pressure of 100 to 10,000 atmospheres (1,013 megapascals (“MPa”) or 500 to 10,000 atmospheres). In most polymerization reactions, the molar ratio of the polymerization catalyst to the monomer is in the range of -12 10 -1 :1 to 10 -9 10 -5 :1 to 10

[0086] Non-thermoplastic polyolefins are not included as embodiments of one or more thermoplastic polyolefins, but may be included as additional components that are non-thermoplastic polymers in certain embodiments of intermediate compounds and crosslinkable compound compositions made therefrom. Examples of such non-thermoplastic polymers are ethylene / unsaturated carboxylic acid ester copolymers. Examples of ethylene / unsaturated carboxylic acid ester copolymers that may be used are ethylene / alkyl acrylate (EAA) copolymers, ethylene / alkyl methacrylate (EAMA) copolymers, and ethylene / vinyl acetate (EVA) copolymers. Examples of ethylene / alkyl acrylate copolymers are ethylene / methyl acrylate (EMA) copolymers, ethylene / ethyl acrylate (EEA) copolymers, and ethylene / butyl acrylate (EBA) copolymers. Examples of ethylene / alkyl methacrylate copolymers are ethylene / methyl methacrylate (EMMA) copolymers, ethylene / ethyl methacrylate (EEMA) copolymers, and ethylene / butyl methacrylate (EBMA) copolymers. These polymers may be used as the second polymer in embodiments that include a second polymer.

[0087] Antioxidant. The intermediate compound contains one or more antioxidants. Suitable antioxidants (AO) can include tertiary amines, secondary or tertiary thiols, secondary or tertiary phenols, bisphenols, triphenols and tetraphenols, or combinations of two or more of these. Examples of suitable antioxidants include, for example, (4-(1-methyl-1-phenylethyl)phenyl)amine (e.g., NAUGARD 445, manufactured by Addivant USA, Danbury, Connecticut), 2,2-methylenebis(4-methyl-6-t-butylphenol) (e.g., VANOX MBPC, manufactured by Vanderbilt Chemicals, New York, New York), 2,2-thiobis(2-t-butyl-5-methylphenol) (CAS No. 90-66-4, also known as 4,4’-thiobis(2-t-butyl-5-methylphenol) and also known as 4,4’-thiobis(6-tert-butyl-m-cresol)), CAS No. 96-69-5, LOWINOX TBM-6, antioxidant, manufactured by Addivant), 2,2’-thiobis(6-t-butyl-4-methylphenol) (CAS No. 90-66-4, commercially available LOWINOX TBP-6), tris[((4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione (e.g., CYANOX 1790 antioxidant, manufactured by Solvay Chemicals, Syracuse, New York), pentaerythritol tetrakis(3-(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)propionate (e.g., IRGANOX 1010 antioxidant, CAS No. 6683-19-8), 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid 2,2’-thiodiethyl ester (e.g., IRGANOX 1035 antioxidant, CAS No. 41484-35-9, manufactured by BASF, Ludwigshafen, Germany), distearyl thiodipropionate (“DSTDP”), dilauryl thiodipropionate (e.g., IRGANOX PS800 antioxidant), stearyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (e.g., IRGANOX 1076), 2,4 - bis(dodecylthiomethyl)-6 - methylphenol (IRGANOX 1726 antioxidant), 4,6 - bis(octylthiomethyl)-o - cresol (e.g., IRGANOX 1520 antioxidant), and 2,3 - bis[[3 - [3,5 - di - tert - butyl - 4 - hydroxyphenyl]propionyl]]propionohydrazide (IRGANOX 1024 antioxidant) may be mentioned. In some embodiments, one or more antioxidants are 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 (e.g., Cyanox 2212), or a combination of any two or more thereof. In some embodiments, the antioxidant may be a combination of tris(4 - tert - butyl - 3 - hydroxy - 2,6 - dimethylphenyl)-1,3,5 - triazine - 2,4,6 - trione and distearyl thiodipropionate. The total amount of one or more antioxidants may be 0.01 - 5 wt%, or 0.05 - 3 wt%, or 0.10 - 0.30 wt%, and all weights are based on the total weight of the intermediate compound or crosslinkable compound composition, respectively.,

[0088] Organic peroxide. The curable additive includes one or more organic peroxides. As used herein, an organic peroxide is a molecule containing a carbon atom, a hydrogen atom, and two or more oxygen atoms and having at least one - O - O - group, provided that when more than one - O - O - group is present, each - O - O - group is indirectly bonded to another - O - O - group through one or more carbon atoms or is an aggregate of such molecules. The curable additive may independently include one or more organic peroxides that may be a monoperoxide of the formula R O -O - O - R O , wherein each R O is independently a (C1 - C 20 ) alkyl group or a (C6 - C 20) is an aryl group. Each (C1-C 20 ) alkyl group is independently unsubstituted or substituted with one or two (C6-C 12 ) aryl groups. Each (C6-C 20 ) aryl group is unsubstituted or substituted with 1 to 4 (C1-C 10 ) alkyl groups. Alternatively, the curable additive is independently of the formula R O -O-O-R-O-O-R O (wherein R is a divalent hydrocarbon group such as (C2-C 10 ) alkylene, (C3-C 10 ) cycloalkylene, or phenylene, and each R OIt may contain one or more organic peroxides that can be diperoxides as defined above. Alternatively, the curable additive may contain one or more monoperoxides and one or more diperoxides. Examples of suitable organic peroxides are 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(alpha-t-butyl-peroxyisopropyl) benzene ("BIPB"), isopropylcumyl t-butyl peroxide; t-butylcumyl peroxide; di-t-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, isopropylcumylcumyl peroxide; butyl 4,4-di(tert-butylperoxy)valerate, or di(isopropylcumyl) peroxide, or dicumyl peroxide. In some embodiments, the organic peroxide comprises or consists of dicumyl peroxide. In some aspects, a blend of two or more organic peroxides is used, for example, a 20:80 (wt / wt) blend of t-butylcumyl peroxide and bis(t-butylperoxyisopropyl) benzene (e.g., LUPEROX D446B commercially available from Arkema) is used. The total amount of one or more organic peroxides can be 0.1 to 5 wt%, or 0.2 to 3 wt%, or 0.3 to 0.8 wt%, and all weights are based on the total weight of the intermediate compound or crosslinkable compound composition, respectively.

[0089] Multi-alkenyl crosslinking aids. The curable additive contains one or more multi-alkenyl crosslinking aids. Suitable multi-alkenyl crosslinking aids include, for example, monocyclic organosiloxanes of formula (I): [R 1 ,R 2 SiO 2 / 2 n (I), wherein the subscript n is an integer of 3 or more, and each R 1 is independently (C2-C4) alkenyl or H2C=C(R 1a )-C(=O)-O-(CH2) m -, wherein R 1a is H or methyl, the subscript m is an integer from 1 to 4, and each R 2 is independently H, (C1-C4) alkyl, phenyl, or R 1 ​It is the same as. Suitable multi-alkenyl crosslinking aids for formula (I) include, for example, 2,4,6-trimethyl-2,4,6-trivinyl-cyclotrisiloxane ("vinyl-D3"), 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane ("vinyl-D4"), 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinyl-sidopentasiloxane ("vinyl-D5"), and mixtures thereof. Other suitable multi-alkenyl crosslinking aids may include polyfunctional monomers capable of copolymerizing with ethylene polymers, such as multi-allyl or multi-vinyl crosslinking aids. As used herein, "multi-allyl" means a compound having at least two pendant allyl functional groups, for example, a triallyl compound selected from the group consisting of triallyl isocyanurate ("TAIC"), triallyl cyanurate ("TAC"), triallyl trimellitate ("TATM"), and mixtures of two or more thereof. Examples of suitable multi-alkenyl crosslinking aids include multi-allyl crosslinking aids such as triallyl isocyanurate ("TAIC"), triallyl cyanurate ("TAC"), triallyl trimellitate ("TATM"), triethyl orthoformate, pentaerythritol triallyl ether, triallyl citrate, and triallyl aconitate, multi-acrylic crosslinking aids such as ethoxylated bisphenol A dimethacrylate, trimethylolpropane triacrylate ("TMPTA"), trimethylolpropane trimethylacrylate ("TMPTMA"), 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, and propoxylated glyceryl triacrylate, polybutadiene with a high 1,2-vinyl content, and trivinylcyclohexane ("TVCH"), and other multi-alkenyl crosslinking aids as described in U.S. Patent Nos. 5,346,961 and 4,018,852. Still other multi-alkenyl crosslinking aids may have at least one N,N-diallylamide functional group as disclosed in U.S. Patent No. 10,941,278(B2) to Cai et al.The multi-alkenyl crosslinking aid can be TAIC. Further examples of multi-alkenyl crosslinking aids are described in U.S. Patent No. 6,277,925 (e.g., allyl 2-allyl-phenyl ether, etc.) and U.S. Patent No. 6,143,822 (e.g., 1,1-diphenylethylene which may be unsubstituted or substituted).

[0090] The multi-alkenyl crosslinking aid can be a blend of two or more such aids. In some embodiments, the multi-alkenyl crosslinking aid is a blend of a monocyclic organosiloxane of formula (I) and a multi-allyl crosslinking aid. In some embodiments, the multi-alkenyl crosslinking aid is a blend of 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane (vinyl-D4) and triallyl isocyanurate (TAIC).

[0091] The amount of one or more multi-alkenyl crosslinking aids in the intermediate compound and / or crosslinkable compound composition can be 0.1 to 10% by weight, or 0.3 to 5% by weight, or 0.6 to 3% by weight, or 1.1 to 2.4% by weight, all weights being based on the total weight of the intermediate compound or crosslinkable compound composition, respectively.

[0092] In some embodiments, the combination of curable additives includes one organic peroxide and one or two multi-alkenyl crosslinking aids. In some embodiments, the method uses a crosslinkable compound composition, and the crosslinkable compound composition includes low-density polyethylene (LDPE), at least one antioxidant selected from distearyl thiodipropionate and dilauryl thiodipropionate, at least one organic peroxide selected from dicumyl peroxide, and at least one multi-alkenyl crosslinking aid selected from 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane (vinyl-D4) and triallyl isocyanurate (TAIC).

[0093] Optional non-curing additives. In some embodiments, the intermediate compound and crosslinkable compound composition contains one or more additional non-curing additives in addition to one or more antioxidants. The one or more additional non-curing additives can be additives known for use in the insulating layer of a power cable or a communication cable. Examples of such one or more additional non-curing additives are hindered amine stabilizers (HAS) such as hindered amine light stabilizers (HALS), inorganic fillers, flame retardants, anti-tracking agents, methyl radical scavengers, processing aids, colorants; lubricants; plasticizers, surfactants, and extender oils, scavengers, metal deactivators, or combinations of any two or more thereof.

[0094] Any compound, composition, formulation, material, mixture, or reaction product herein may not contain any one of the chemical elements selected from the group consisting of Li, Be, B, 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, lanthanoids, and actinoids, provided that the chemically essential elements are not excluded thereby.

[0095] Alternatively, it precedes different embodiments. ANSI is an organization, the American National Standards Institute, headquartered in Washington, D.C., USA. ASME is the American Society of Mechanical Engineers, headquartered in New York City, New York, USA. ASTM is the standards organization ASTM International, West Conshohocken, Pennsylvania, USA. Any comparative examples are used only for illustrative purposes and are not prior art. "Not including" or "lacking" means complete absence or undetectability. 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 the elements is the IUPAC version as of May 1, 2018. "May" is not mandatory and gives a permitted option. "Operative" means functionally possible or effective. "Optional (optionally)" means either non-existent (or excluded) or existent (or included). Properties can be measured using standard test methods and conditions. A range includes endpoints, sub-ranges, and integer and / or fractional values included therein, provided that an integer range does not include fractional values. Room temperature: 23°C ± 1°C.

[0096] Unless otherwise specified, the definitions of the terms used in this specification are obtained from the IUPAC Compendium of Chemical Technology ("Gold Book"), 2.3.3 edition, dated February 24, 2014.

[0097] Any one or more of the open-ended terms "comprising" or "comprises" may be replaced by the partially closed-ended phrases "consisting essentially of" or "consists essentially of", or the closed-ended phrases "consisting of" or "consists of". As used herein, the phrases "consisting essentially of" and "consists essentially of" mean that the method, intermediate compound, and crosslinkable compound composition do not include the excluded elements and steps. Examples of excluded steps are passively adding a curable additive to the intermediate compound and cooling the melt of the intermediate compound to less than 150 °C immediately prior to the injection step. In some embodiments, discontinuous manufacturing methods are excluded. Excluded elements include excluded devices such as immersion towers or excluded mixing devices, and excluded additives such as may be found in accidentally disclosed prior art. The phrases "consisting of" and "consists of" are closed-ended and exclude any element or feature not explicitly listed thereafter. The use of the term "comprises" or "comprising" when referring to the following materials or features does not negate the partially closed-ended nature of "consisting essentially of" or "consists essentially of", or the closed-ended nature of "consisting of" or "consists of", but rather allows for additional elements or steps not explicitly excluded by "consisting essentially of" or "consists essentially of".Predictive examples are embodiments of the present invention that are contemplated to be practiced in accordance with the present invention by the inventors, although not actually practiced.

[0098] Contemplated herein are any ranges formed by combining a preferred lower limit with any upper limit, or by combining a preferred upper limit with any lower limit, or by combining a measured value from any one of the examples of the present invention with any lower or upper limit.

[0099] Preparation of cured plaques: Pellets were pressed and cured using a WABASH™ GENESIS™ steam press having quenching ability. For the comparative example compound compositions, the dipped pellets were pressed and cured under pressure using a WABASH™ GENESIS™ steam press (manufactured by Wabash MPI, Wabash, Indiana) having quenching ability. The plaques were then subjected to the indicated tests. Curing for the high temperature creep test involved melting the pellets at 120° C. in a compression mold WABASH™ GENESIS™ steam press, the dimensions of the mold being 203 mm×203 mm (8 inches×8 inches)×1.3 mm (50 mils), compressing for 3 minutes under a low pressure of 3.5 MPa (500 psi) and then for a further 3 minutes under a high pressure of 17 MPa (2500 psi) at the same temperature, opening the mold, removing the plaque from the mold, and cutting the plaque into four small pieces of the same size. In the test, the four pieces were then rearranged, returned to the mold, melted at 120° C. under a low pressure of 3.5 MPa (500 psi) for 3 minutes, compressed for a further 3 minutes at the same temperature under a high pressure of 17 MPa (2500 psi), then raising the temperature of the press to 182° C. and holding for 12 minutes to cure the sample under high pressure. After curing, the mold was cooled to room temperature at 15° C. / minute under high pressure.

[0100] Preparation of Uncured Plaques: The dipped pellets were pressed using a Wabash (trademark) GENESIS (trademark) steam press having quenching ability. In the moving die rheometer test method described below, the pellets were first melted at 120 °C for 3 minutes under a low pressure of 3.5 MPa (500 psi) and further compressed at the same temperature under a high pressure of 17 MPa (2500 psi) for another 3 minutes. The mold was cooled from the high pressure to room temperature at 15 °C / min to form uncured plaques.

[0101] Density Test Method: Measured in accordance with ASTM D792-13, Method B of Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement (for Testing Solid Plastics in Liquids Other than Water, e.g., in Liquid 2-Propanol). The unit is grams per cubic centimeter (g / cm 3 )

[0102] Melt Index (I2) Test Method: I2 is measured using the conditions of 190 °C / 2.16 kilograms (kg) in accordance with ASTM D1238-04 (190 °C, 2.16 kg), Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Platometer. The unit is the equivalent in grams eluted per 10 minutes (g / 10 min) or decigrams per 1 minute (dg / 1 min), and 10.0 dg = 1.00 g.

[0103] Melt Index (I 10 ) Test Method: I 10 is measured using the conditions of 120 °C / 10.0 kilograms (kg) in accordance with ASTM D1238-04 (120 °C, 10.0 kg), Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Platometer. The unit is the equivalent in g / 10 min or dg / 1 min, and 10.0 dg = 1.00 g.

[0104] Stability test method: Samples of each crosslinkable compound composition produced by the method of the present invention were collected under the same processing conditions, and were collected at various time intervals after starting the injection of the curability additive into the melt flow of the intermediate compound, and were tested to demonstrate the product and process stability as indicated by the consistency of the product characteristics generated over a long continuous melt compounding operation. To demonstrate the ability of the method of the present invention operated as a continuous high-production process, an experiment was conducted as a long continuous melt compounding operation lasting 2 to 4 hours.

[0105] High-temperature creep test method: High-temperature creep measures the curing performance or degree of crosslinking of a crosslinkable compound and can also indicate the degree to which the compound has not yet been crosslinked. High-temperature creep refers to the elongation deformation under load of a cured specimen of a given crosslinkable compound and is measured in accordance with ICEA T-28-562. The high-temperature creep test was carried out on a 1.3 mm (50 mil) dogbone sample cut from a cured plaque using a die cutter in accordance with ASTM D412 type D, with a weight of 20 N / cm 2 attached to the lower end, marked with two fiducial lines (each line being 25.4 mm apart at the center of the sample), and carried out at 200 °C. The samples were placed in a preheated oven at 200 °C with a weight equal to the force of 20 N / cm 2 attached to the bottom of each sample. After 15 minutes, the elongation (distance between the fiducial lines) was measured and used to calculate the high-temperature creep. The weight was removed from the sample. Five minutes after being placed in the oven, the sample was taken out and left at room temperature for 24 hours. The elongation (distance between the fiducial lines) was measured again and this value was used to calculate the heat curing. Three samples were tested and the average of the high-temperature creep was reported. Acceptable high-temperature creep results are 100% or less. For high-temperature creep, the lower the elongation percentage, the more advanced the crosslinking of the material.

[0106] Moving Die Rheometer (MDR) Test Method: The Moving Die Rheometer (MDR) enables the measurement of the curing characteristics of crosslinkable compounds. The instrument measures the torque response of the material under deformation. As the crosslinking of the material progresses, the torque response increases and ultimately reaches a maximum torque ("MH") after the peroxide has reacted under the test conditions of time and temperature. The MH value indicates the crosslinking level of a given compound and must be high enough to produce a crosslinkable compound. The MDR test is performed in accordance with ASTM procedure D5289, "Standard Test Method for Rubber-Property Vulcanization Using Rotorless Cure Meters," using an Alpha Technologies Rheometer, MDR model 2000 unit (manufactured by Alpha Technologies, Hudson, Ohio), and measured under shear. For the test, a disk with a diameter of 2.56 cm (1 inch) was cut from an uncured plaque with a thickness of 1.905 mm (75 mils), and two 1.905 mm (75 mil) disks were stacked together. The two stacked 1.905 mm (75 mil) disks were tested at 182 °C for 12 minutes to obtain MH and at 140 °C (typical extrusion melt temperature) for various lengths of time to obtain ts1. Both tests were performed with an arc vibration of 0.5 degrees. MH is reported as the torque value when the curve becomes flat. Desirably, MH is higher than 2.26 dN·m or less than 2 lbf·in immediately after processing and does not change over time.

[0107] The scorch time or ts1 indicates a cure kinetics that is useful for evaluating the resistance to premature crosslinking (scorch). In the case of scorch time measurement, the reported value is the time required for the minimum torque ("ML") to increase by 1 unit (inch-lbf) or 1.13 decinewton meters (dN·m). The acceptable ts1 at 140 °C should be at least 51 minutes or more. The longer ts1 is, the better. Other scorch measurement criteria such as ts0.5, ts2, ts5, etc. can be used according to the same definition.

[0108] Tensile Strength and Elongation at Break Test Method: Measured on a 75-mil thick double-pass compression molded plaque cured at 182 °C using a tensile speed of 50.8 centimeters per minute (20 inches) and a load of 45.3 kilograms (kg, 100 pounds (lbs)).

[0109] Viscosity Test Method: (Oscillatory Shear Viscosity Test at Low Shear Rate of 0.1 radian per second): Using a TA Instruments "Advanced Rheometric Expansion System (ARES)" equipped with a 25 mm (diameter) parallel plate, frequency sweep at a constant temperature was performed under nitrogen purge. The sample was placed on the plate and melted at 135 °C for 5 minutes. Then, the plate was closed to a gap set at 1.5 mm, and the sample was trimmed (removing the excess sample extending beyond the circumference of the "25 mm diameter" plate), and then the test was started. This method incorporated an additional 5-minute delay to allow for temperature equilibration. The test was conducted at 135 °C over a frequency range of 0.1 radian per second (rad / s) to 100 rad / s at a constant strain amplitude of 25%.

Example

[0110] Low-Density Polyethylene (LDPE-1). LDPE-1 is a thermoplastic polyolefin having a density of 0.919 g / cm 3 and a melt index I2 of 3.9 g / 10 min. It is available from The Dow Chemical Company as AGILITY (trademark) EC 7000.

[0111] Antioxidant Blend 1: A combination of lauryl thiodipropionate and stearyl thiodipropionate. Available from Solvay Chemicals as Cyanox 2212.

[0112] Example of an Organic Peroxide: Dicumyl peroxide having the structure of the formula PhC(CH3)2-O-O-C(CH3)2Ph, where Ph is phenyl.

[0113] Crosslinking Aid Example 1: Triallyl isocyanurate ("TAIC").

[0114] Crosslinking Aid Example 2: 2,4,6,8 - Tetramethyl - 2,4,6,8 - tetravinyl - cyclotetrasiloxane ("vinyl - D4").

[0115] The same amounts of the above compounds (LDPE - 1, antioxidant blend 1, DiCup, TAIC, and vinyl - D4) were used in Comparative Example 1 and Examples 1 - 4 of the present invention below. However, the method used to prepare CE1 was the dipping method of the comparative examples described below, and the methods for preparing IE1 - IE4 included embodiments of the method of the present invention. The amounts are shown in Table 1 below.

[0116]

Table 1

[0117] Preparation of Intermediate Compound 1: It consisted of pellets of LDPE - 1 and antioxidant blend 1 in the relative amounts shown in Table 1. The pellets were prepared by melt - compounding LDPE - 1 and antioxidant blend 1 in a twin - screw extruder and then pelletizing using a Conair Model 304 strand pelletizer to obtain Intermediate Compound 1.

[0118] Comparative Example 1 (CE1): CE1 was prepared by a dipping method of a comparative example including obtaining preheated pellets by preheating 250 grams of pellets of Intermediate Compound 1 at 70° C. for at least 4 hours, adding to the preheated pellets a liquid mixture of the relative amounts of DiCup, TAIC, and Vinyl-D4 shown in Table 1 to obtain a combination of the preheated pellets and the liquid mixture, rolling the combination to uniformly distribute the liquid mixture over the preheated pellets, and heating the rolled pellet / liquid combination at 70° C. overnight (at least 12 hours) to obtain Comparative Example 1 in the form of dipped pellets composed of Intermediate Compound 1, DiCup, TAIC, and Vinyl-D4. The crosslinkable compound composition of the comparative example of CE1 was tested according to the above test method, and the data are reported below in Table 3.

[0119] Production Line Example 1: Used to implement the method of the present invention in Examples 1 to 4 (IE1 to IE4) of the present invention: a melt compounding apparatus and a post-compounding apparatus. The melt compounding apparatus is a ZSK-30 type twin-screw extruder of Coperion with an inner diameter of 30 millimeters (mm), which defines a conveying path therethrough, and along the conveying path in series, at least the following zones: a melt / compounding zone configured to heat the thermoplastic polyolefin above its melting temperature and blend the antioxidant therein, and having one or more supply ports (also known as supply points) for supplying one or more materials (for example, pellets containing a thermoplastic polyolefin and an antioxidant, or antioxidant-free pellets containing a thermoplastic polyolefin and a separate source of antioxidant) to the melt / compounding zone (for example, from an external hopper, an external supply line, or an external storage tank); a mixing zone configured for rapid mixing of the curable additive into the polymer melt of the melt compounding apparatus, and having one or more injection ports (also known as injection points) for injecting one or more materials containing the curable additive into the mixing zone (for example, from an external storage tank or a supply line) located therebetween; and a discharge zone for discharging the melt stream of the compounded material from the melt compounding apparatus to a post-compounding apparatus (for example, a pelletizer or an extruder, or a system including a melt pump, a melt screen, and a pelletizer or an extruder). The post-compounding apparatus was a pelletizing apparatus including a melt pump, a melt screen (accommodated in a filtration unit), and a pelletizing die.

[0120] Examples 1 to 4 (IE1 to IE4) of the present invention: IE1 to IE4 were prepared using the processing conditions of the method of the present invention shown in the above Production Line Example 1 and Table 2 below.

[0121]

Table 2

[0122] As shown in Table 2, a homogeneous mixture of the crosslinkable polymer composition of the present invention was produced in less than 60 seconds. Samples of the crosslinkable polymer composition were tested according to the above test method. The data are reported below in Table 3.

[0123] [Table 3]

[0124] In Table 3, the data reported for IE2 are the average of three test samples taken at approximately one-hour intervals during continuous operation. The individual high-temperature creep data for the samples of IE2 are 121% (2bk), 110% (1bk), and 102% (1bk), where 2bk means that two of the three samples were broken and 1bk means that one of the three samples was broken. STDEV means standard deviation. N / a means not applicable.

[0125] The data in Table 3 are the melt index I exhibited by CE1 using the dipping process of the comparative example (i.e., without modification by the high-temperature compounding step) 10 (120 °C, 10.0 kg) is 6.0 g / 10 min, and the ML at 182 °C is 0.1 lbf·in, which is low and indicates no premature scorch. IE1 to IE4 were produced by an embodiment of the ultra-high temperature low-scorch melt compounding method of the present invention and have a lower melt index I 10It exhibits values and shows the modification of the rheology of the thermoplastic polyolefin (LDPE-1 in the examples) due to the initial decomposition of a part of the organic peroxide (DiCup in the examples) during the ultra-high temperature compounding process. However, the obtained crosslinkable compound composition of the present invention retains an appropriate level of the combination of curing additives (DiCup, TAIC, and vinyl-D4 in the examples) and exhibits a sufficient level of crosslinking as indicated by the MH value at 182°C. The MH values at 182°C of IE1 to IE4 are surprisingly almost the same as the MH value at 182°C of the immersed crosslinkable compound composition of Comparative Example CE1. Table 3 also shows the results of the oscillatory shear viscosity test at a low shear rate of 0.1 radian per second. Relaxation spectrum data is available upon request.

[0126] The above detailed description teaches the method of the present invention, and the results of IE1 to IE4 demonstrate that the method and its advantages are achieved.

[0127]

Table 4

[0128]

Table 5

[0129]

Table 6

[0130] Comparative Example 2 (actual) and Examples 5 and 6 (IE5 and IE6) of the present invention (virtual) were prepared / are prepared using the processing conditions of the method of the present invention shown in Production Line Example 1 and Table 2.

[0131]

Table 7

[0132] As shown in Table 7, as expected, the scorch inhibitor AMSD provided CE2 with a scorch time TS1 at 140 °C exceeding 120 minutes (> 120 minutes). However, since AMSD has only one carbon-carbon double bond per molecule, it is not a multi-alkenyl crosslinking coagent and cannot function as a multi-alkenyl crosslinking coagent. Therefore, although CE2 was produced by an embodiment of the ultra-high temperature and low scorch melt compounding method of the present invention, it did not show the improvement of the present invention, with inferior MH and MH-ML at 182 °C, inferior high temperature creep at 200 °C, inferior tensile strength, and inferior elongation at break. CE2 indicates that the method of the comparative example without using a multi-alkenyl crosslinking coagent cannot achieve the improvement of the present invention.

[0133] In contrast, in Table 7, when IE5 and IE6 are carried out by an embodiment of the ultra-high temperature and low scorch melt compounding method of the present invention, they are predicted to show lower melt index I 10 values, which indicates the modification of the rheology of the thermoplastic polyolefin (LDPE-1 in the examples) due to the initial decomposition of part of the organic peroxide (DiCup in the examples) during the ultra-high temperature compounding process. However, the obtained crosslinkable compound composition of the present invention maintained an appropriate level of the combination of curing additives (either DiCup and either TAIC or vinyl-D4, but not both) and exhibited a sufficient level of crosslinking as shown by MH at 182 °C. IE5 and IE6 indicate that the embodiments of the method in which the combination of curing additives includes one or more organic peroxides and only one multi-alkenyl crosslinking coagent are expected to show the improvement of the present invention.

Claims

1. A method for producing a crosslinkable compound composition using ultra-high temperature and low scorch, wherein the crosslinkable compound composition comprises a homogeneous mixture of one or more thermoplastic polyolefins, one or more antioxidants, and a combination of a curing additive comprising one or more organic peroxides and one or more multi-alkenyl crosslinking aids, and the method is as follows: The process involves preparing a melt compounding apparatus having a solid transport section, a melting / mixing zone, and an ultra-high temperature mixing zone in sequence, wherein the temperature of the ultra-high temperature mixing zone is 150.1°C to 180.0°C. In the melting / mixing zone of the melting compounding apparatus, materials (a) to (c): Material (a) A pellet / auxiliary(multiple) premixture made by contacting solid pellets of an intermediate compound containing one or more thermoplastic polyolefins and one or more antioxidants at the start, but without peroxides and multialkenyl crosslinking aids, with one or more multialkenyl crosslinking aids ("auxiliary(multiple)"), or Material (b) An intermediate compound containing one or more thermoplastic polyolefins and one or more antioxidants at the start, but without peroxides and multialkenyl crosslinking aids A step of supplying one of the following materials: a pellet / additive / organic peroxide premixture made by contacting solid pellets of ound with a combination of one or more multi-alkenyl crosslinking aids ("additives (multiple)") and one or more organic peroxides ("organic peroxides (multiple)"), or a solid pellet of an intermediate compound containing one or more thermoplastic polyolefins and one or more antioxidants at the start of material (c), but without peroxides and multi-alkenyl crosslinking aids, and without curing additives; A step of melting and first mixing one or more of the thermoplastic polyolefins with other components of material (a), (b), or (c) for 15 to 35 seconds to obtain the initial molten mixture in the melting / mixing zone, A step of moving the initial molten mixture to the ultra-high temperature mixing zone of the molten compounding apparatus, A step of optionally injecting one or more multi-alkenyl crosslinking agents and / or one or more organic peroxides (collectively referred to as "curable additives (multiple possible)") into the initial molten material in the ultra-high temperature mixing zone, wherein when material (a) is supplied, the injection of one or more organic peroxides is performed (not optionally), and when material (c) is supplied, the injection of one or more multi-alkenyl crosslinking agents and / or one or more organic peroxides is performed (not optionally), A step of performing a second mixing of the material (a), (b), or (c) and the injected curable additive(s) in the ultra-high temperature mixing zone for 10 to 20 seconds, The process includes the step of discharging the obtained crosslinkable compound composition from the melt compounding apparatus, A method wherein the total residence time of material (a), material (b), or material (c) in the molten compounding apparatus is 25 to 55 seconds, and the total residence time of the injected curable additive(s) in the molten compounding apparatus is 10 to 30 seconds.

2. The method according to claim 1, wherein the material (a) is supplied, the injection is carried out by injecting the one or more organic peroxides and optionally one or more additional multialkenyl crosslinking aids into the initial molten material in the ultra-high temperature mixing zone of the melt compounding apparatus, and the second mixing step is to mix the material (a) with the injected curable additive.

3. The method according to claim 1, wherein the material (b) is supplied, the injection is not performed, and the second mixing step includes mixing the material (b), and no additional curing additive is injected.

4. The method according to claim 1, wherein the material (b) is supplied, the injection step is performed, and one or more additional multialkenyl crosslinking agents and / or one or more additional organic peroxides are injected into the initial molten material in the ultra-high temperature mixing zone of the melt compounding apparatus, the second mixing step comprising mixing the material (b) with the injected curable additive.

5. A method according to claim 1, comprising the steps of supplying material (c), supplying the pellets of the intermediate compound to the melting / mixing zone of the melting compounding apparatus to obtain a molten intermediate compound containing one or more thermoplastic polyolefins and one or more antioxidants, but free from peroxides and multialkenyl crosslinking aids, wherein the molten intermediate compound is at a melting temperature of 150.1°C to 180.0°C, A step of injecting the combination of the one or more organic peroxides and the one or more multi-alkenyl crosslinking agents into the molten intermediate compound, A method comprising the step of mixing the combination of curable additives with the molten intermediate compound to produce the crosslinkable compound composition in the form of a molten material containing the homogeneous mixture, wherein the homogeneous mixture is formed within 20 seconds or more but less than 60 seconds after the completion of the injection step.

6. The method according to claim 5, adapted to a melt compounding apparatus, the melt compounding apparatus comprising, defining a transport path through which it passes, and comprising, in series along the transport path, at least the following zones: a melt / compounding zone configured for heating thermoplastic polyolefins above their melting temperature and blending antioxidants therein, and having one or more supply ports for supplying one or more materials to the melt / compounding zone; a mixing zone configured for rapid blending of curable additives into a polymer molten mass, and having one or more injection ports positioned between them for injecting one or more materials containing the curable additives into the mixing zone; and a discharge zone for discharging a molten flow of compounded material from the melt compounding apparatus to a post-compounding apparatus, the method being, (A) A step of supplying the molten material of the intermediate compound to the melting / compounding zone, or creating the molten material of the intermediate compound within the melting / compounding zone, (B) A step of transporting the molten material of the intermediate compound to the mixing zone, (C) A step of injecting the combination of the one or more organic peroxides and the one or more multi-alkenyl crosslinking agents into the molten intermediate compound through at least one of the one or more injection ports in the mixing zone, (D) A step of mixing the combination of curable additives and the molten intermediate compound in the mixing zone to produce the molten crosslinkable compound composition containing the homogeneous mixture, wherein the homogeneous mixture is formed 20.0 to 60.0 seconds after the completion of the injection step, A method comprising (E) transporting the molten material of the crosslinkable compound composition to the discharge zone.

7. A method according to claim 5, comprising: a post-discharge zone step adapted to a pellet manufacturing machine having strand dies, cooling means, and a cutting device, the post-discharge zone step including transporting the molten material of the crosslinkable compound composition from the discharge zone of the molten compounding device to the pellet manufacturing machine; a step of extruding strands of the crosslinkable compound composition; a step of cooling the strands; and a step of cutting the strands to produce solid pellets of the crosslinkable compound composition.

8. A method according to claim 5, comprising: a post-discharge zone step adapted to an insulator extruder having an annular die for extruding and coating a filament, the post-discharge zone step including transporting the molten material of the crosslinkable compound composition from the discharge zone of the molten compounding apparatus to the insulator extruder; a step of extruding a layer of the crosslinkable compound composition onto a conductor to produce a coated conductor; and a step of curing the crosslinkable compound composition of the insulating layer to produce the cable.

9. The method according to claim 5, wherein the injection step is subject to restriction (i) or restriction (ii): (i) the injection step comprises injecting the combination of curable additives together as a mixture, or (ii) the injection step comprises injecting at least one of the curable additives, or all but one, or each separately from the other curable additives.

10. The method according to claim 1, wherein the one or more thermoplastic polyolefins are selected for producing the insulating layer of a cable at high temperature / low scorch rate with low scorch, and the following limitations apply to such one or more thermoplastic polyolefins: (i) If one or more thermoplastic polyolefins are present, and at least one or each of the one or more thermoplastic polyolefins is measured according to ASTM 792, Method B, the concentration is 0.870 to 0.940 g / cm³. ３ The density and, when determined according to ASTM D1238 at 190°C and 2.16 kg, the melt index (I) of 1 to 20 g / 10 min ２ It is low-density polyethylene having ) or (ii) One or more thermoplastic polyolefins are present, each independently selected from the group consisting of polyethylene homopolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, and ethylene / 1-octene copolymers, or (iii) A method that is subject to any one of the combinations of restrictions (i) and (ii).

11. A method according to claim 1, wherein the additive is selected for manufacturing the insulating layer of the cable at high temperature / low scorch, and such additive is limited to (i) to (v): (i) The one or more antioxidants include a thio-based antioxidant, or (ii) The above one or more multi-alkenyl crosslinking aids are of the formula (I): [R １ , R ２ SiO ２／２ ｎ (I) (where the subscript n is an integer of 3 or more) and contains an alkenyl group-containing monocyclic organosiloxane. Each R １ is independently (C ２ - C ４ ) alkenyl or H ２ C = C(R １ａ ) - C(=O) - O - (CH ２ ) ｍ - where R １ａ is H or methyl, the subscript m is an integer of 1 to 4, and each R ２ is independently H, (C １ - C ４ ) alkyl, phenyl, or R １ , or (iii) Restrictions (i) and combinations of (ii), (iv) The one or more organic peroxides include dicumyl peroxide or cumyl group-containing peroxides, (v) A method that is subject to any one of the following restrictions: (iv) a combination of restriction (iv) and any one of restrictions (i) to (iii).

12. A method according to any one of claims 1 to 11, wherein the crosslinkable compound composition is formulated for producing a crosslinkable insulating layer of a cable at high temperature / low scorch, and with respect to such a crosslinkable compound composition, limitations (i) to (iii): (i) The crosslinkable compound composition is The scorch time (ts1) at 140°C, reported as the time required at 140°C to increase the minimum torque ("ML") by 1 pound-inch (lbf·in) or 1.13 decinewton-meters (dN·m), as determined by a test moving the die rheometer (MDR) according to ASTM Procedure D5289, is at least 63 minutes or at least 79 minutes. Having a maximum torque (MH) at 182°C such that, as determined by a test moving the die rheometer (MDR) according to ASTM procedure D5289, the minimum torque (ML) at 182°C is at least 1.67 decinewton meters (dN·m; equal to at least 1.48 lbf·in), or the maximum torque (MH) at 182°C is at least 1.72 dN·m (at least 1.52 lbf·in) higher than the ML at 182°C, and the MH at 182°C is at least 1.79 dN·m (1.58 lbf·in), or at least 1.83 dN·m (1.62 lbf·in), or (ii) The crosslinkable compound composition has a high-temperature creep elongation at 200°C of less than 130% or less than 100% as determined by testing in accordance with ICEAT-28-562a, or (iii) A method that is subject to any one of the combinations of restrictions (i) and (ii).

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