Method for making a homogeneous mixture of polyolefin solids and organic peroxides

Abstract

A method for producing a homogeneous mixture of polyolefin solids and an organic peroxide without melting the polyolefin solids during production, the method comprising applying acoustic energy at a frequency of 20 to 100 hertz to a heterogeneous mixture comprising polyolefin solids and an organic peroxide for a period of time sufficient to substantially mix the polyolefin solids and the organic peroxide together, while maintaining the temperature of the heterogeneous mixture below the melting temperature of the polyolefin solids, thereby producing the homogeneous mixture without melting the polyolefin solids.

Description

[Technical Field]

[0001] Mixture of polyolefins with additives.

[0002] Introduction Patents and published patent applications in or relating to this field include US6,565,784; US7,188,993 B1; US7,468,404 B2; US7,695,817 B2; US8,124,309 B2; US8,435,714 B2; US8,680,177 B2; US8,889,331 B2; US9,223,236 B2; US9,593,919 B2; US9,926,427 B2; US9,957,360 B2; and US10,513,625 B2. Non-patent publications in or related to this field include G. Sanchez-Olivares et al., Assessment of extrusion-sonication process on flame retardant polypropylene by rheological characterization (AIMS Materials Science, 2016; vol. 3, no. 2, pp. 620-633) and K. Tarverdi et al., Enhanced Dispersion of Particulate Additive into Polymers Using Twin Screw Extrusion with Ultrasound Assistance (SPE ANTEC Anaheim 2017, pp. 1058-1062).

[0003] Traditional methods for mixing polyolefins with additives rely on mechanical blending of flowing melts (e.g., in a twin-screw extruder device). This process can be harmful to organic peroxides, which rapidly degrade or decompose at the temperatures of such flowing melts (e.g., 180°C to 220°C for polyethylene). Instead, a flowing melt of polyolefin is blended with additives other than peroxides, and the resulting mixture is pelletized to obtain pellets at ambient temperature. The pellets are then heated to a soaking temperature, and the heated pellets are immersed in a melt of liquid organic peroxide or a low-melting-point organic peroxide (a passive process). The soaking temperature for the liquid organic peroxide can be 30°C to 110°C. The solid organic peroxide used in the soaking method can have a melting point of 30°C to 100°C, and the soaking temperature is from above the melting point of the solid organic peroxide to 110°C. For example, dicumyl peroxide melts at 39-41°C, and the soaking temperature can be about 50-90°C, typically 60-80°C. In commercial plants, pellets are placed in large bins and soaked in the organic peroxide, which takes 10-16 hours to fully wet the polyolefin solids with the organic peroxide. Summary of the Invention

[0004] We have discovered a method for producing a homogeneous mixture of polyolefin solids and an organic peroxide without melting the polyolefin solids during production. The method involves applying acoustic energy at a frequency of 20 to 100 hertz to a heterogeneous mixture comprising polyolefin solids and an organic peroxide for a period of time sufficient to substantially mix the polyolefin solids and the organic peroxide together, while maintaining the temperature of the heterogeneous mixture (and, for that matter, the temperature of a homogeneous mixture produced therefrom) below the melting temperature of the polyolefin solids, thereby producing a homogeneous mixture without melting the polyolefin solids.

[0005] The present method achieves thorough mixing of the polyolefin solids with the organic peroxide without mechanically blending or melting the polyolefin solids, and does so more quickly than dipping methods. DETAILED DESCRIPTION OF THE INVENTION

[0006] A method for producing a homogeneous mixture of polyolefin solids and an organic peroxide without melting the polyolefin solids during production. The method comprises applying acoustic energy at a frequency of 20 to 100 hertz to a heterogeneous mixture comprising polyolefin solids and an organic peroxide for a period of time sufficient to substantially mix the polyolefin solids and the organic peroxide together, while maintaining the temperature of the heterogeneous mixture (and, for that matter, the temperature of the homogeneous mixture produced therefrom) below the melting temperature of the polyolefin solids, thereby producing a homogeneous mixture without melting the polyolefin solids. The method includes a mixing step consisting essentially of applying acoustic energy. This means that the method achieves thorough mixing of the polyolefin solids and the organic peroxide without mechanically blending or melting the polyolefin solids, and does so quickly, e.g., in less than 10 minutes, compared to immersion.

[0007] Additional inventive aspects follow, some of which are numbered below for ease of reference.

[0008] Aspect 1. A method for producing a homogeneous mixture of polyolefin solids and an organic peroxide without melting the polyolefin solids during production, comprising applying acoustic energy at a frequency of 20 to 100 hertz (Hz) to a heterogeneous mixture comprising (A) polyolefin solids and (B) organic peroxide for a period of time sufficient to substantially mix (thoroughly or completely homogenize) the (A) polyolefin solids and (B) organic peroxide together, while maintaining the temperature of the heterogeneous mixture (and, for that matter, the temperature of the homogeneous mixture produced therefrom) below the melting temperature of the (A) polyolefin solids, thereby producing the homogeneous mixture without melting the (A) polyolefin solids, wherein the (A) polyolefin solids and the (B) organic peroxide are 95.0 to 99.9 weight percent (wt %) and 0.1 to 5.0 wt %, respectively, of the combined weight of components (A) and (B). The heterogeneous mixture, and the homogeneous mixture produced therefrom by applying acoustic energy, may contain zero, one, two, or more optional additives. The total weight of all components of the heterogeneous mixture, including optional additives, is 100.0 wt.%, and the total weight of all components of the homogeneous mixture, including optional additives, is 100.0 wt.%. The method may further include the restriction that the heterogeneous mixture is not mechanically agitated (mixed by mechanical means) during the step of applying acoustic energy. The method may further include the restriction that the organic peroxide is not decomposed or degraded (as indicated by cure and / or mechanical properties) during the acoustic mixing step.

[0009] Aspect 2. The step of applying acoustic energy may be performed within the scope of any one of the following limitations (i) to (v): (i) the frequency is from 50 to 70 Hz, alternatively from 55 to 65 Hz, alternatively from 58 to 62 Hz, alternatively from 59 to 61 Hz; (ii) the duration is from 0.5 minutes to 4 hours, alternatively from 0.5 minutes to 2 hours, alternatively from 1 minute to 60 minutes, alternatively from 1 minute to 10 minutes; (iii) both (i) and (ii); (iv) maintaining the temperature of the heterogeneous mixture below the melting temperature of (A) the polyolefin solid. The method of embodiment 1, characterized by any one of (v), (iv), and (i)-(iii), including maintaining the temperature of the heterogeneous mixture (and, for that matter, the temperature of the homogeneous mixture made therefrom) between -20°C and 109°C, alternatively between 10°C and 109°C, alternatively between 15°C and 99°C, alternatively between -20°C and 50.0°C, alternatively between 20.0°C and 39.9°C, alternatively between 20.0°C and 29.9°C (e.g., 25°C ± 3°C). The temperature may be ambient outdoor temperature. The intensity is sufficient to move the materials with sufficient amplitude to be effective for mixing without mechanical agitation. The step of applying acoustic energy can be performed using an acoustic mixer device, the frequency being set by an operator of the acoustic mixer device.

[0010] Embodiment 3. The method of embodiment 1 or 2, wherein (A) the polyolefin solid is characterized by a physical form (i.e., solid particulate form) that is a powder, granules, pellets, or a blend of any two or more thereof, and a melting temperature that is 61°C to 180°C, alternatively 90°C to 180°C, alternatively 110°C to 174°C, alternatively 120°C to 180°C, and (B) the organic peroxide is a liquid organic peroxide or a solid organic peroxide. The solid organic peroxide may be in the form of a powder or granules and may have a melting temperature that is 24°C to 120°C, alternatively 35°C to 120°C.

[0011] Aspect 4. The method of any one of Aspects 1-3, wherein the polyolefin of the (A) polyolefin solid consists essentially of one or more ethylene-based polymers, each ethylene-based polymer being a low-density polyethylene (LDPE) polymer or a combination of an LDPE polymer and a polyolefin selected from the group consisting of a second LDPE polymer, a linear low-density polyethylene (LLDPE) polymer, and a high-density polyethylene (HDPE) polymer. In other embodiments, the polyolefin of the (A) polyolefin solid consists essentially of LDPE and a polypropylene (PP) polymer.

[0012] Aspect 5. The method of any one of Aspects 1-7, wherein the organic peroxide is a solid organic peroxide. In some embodiments, the solid organic peroxide is selected from dicumyl peroxide, dilauryl peroxide, dibenzoyl peroxide, and di-2-tert-butylperoxyisopropylbenzene, and α,α-bis(t-butylperoxy)diisopropylbenzene. In some embodiments, (B) the organic peroxide has a melting point T s is a solid organic peroxide having the formula T s is higher than 35°C, and the temperatures of the heterogeneous mixture and the homogeneous mixture are independently between -20°C and <T s , alternatively 10℃~ <T s , alternatively 15℃~ <T s , alternatively 20.0℃~ <T s In some embodiments, the (B) organic peroxide has a melting point T s is a solid organic peroxide having the formula T s is less than 109°C, and the temperatures of the heterogeneous mixture and the homogeneous mixture are independently >T s ~109℃, alternatively >T s ~99℃, alternatively >T s ~79°C, alternatively >T s ~50°C, alternatively >T s ~38℃.

[0013] Aspect 6. The method of any one of Aspects 1-5, wherein the heterogeneous mixture further comprises one or more additives that are not (A) polyolefin solids or (B) organic peroxides, and wherein the step of applying acoustic energy comprises applying acoustic energy at a frequency of 20-100 Hertz (Hz) to the heterogeneous mixture comprising (A) polyolefin solids, (B) organic peroxides, and the one or more additives that are not peroxide-free, for a period of time sufficient to substantially mix together (thoroughly or completely homogenize) the (A) polyolefin solids, (B) organic peroxides, and the one or more additives, while maintaining the temperature of the heterogeneous mixture (and, for that matter, the temperature of a homogeneous mixture made therefrom) below the melting temperature of the (A) polyolefin solids, thereby producing a homogeneous mixture further comprising the one or more additives without melting the (A) polyolefin solids. In some embodiments, the one or more additives are separate components in the heterogeneous mixture and are not included in the (A) polyolefin solids. In other embodiments, at least one of the one or more additives is pre-blended into the (A) polyolefin solid by melt mixing and pelletizing, such that the heterogeneous mixture comprises (B) an organic peroxide and a composite solid (e.g., pellets) comprising (A) a polyolefin mixed with one or more additives.

[0014] Aspect 7. The method of Aspect 6, wherein at least one, alternatively all but one, alternatively each of the one or more additives that are not components (A) or (B) is independently a liquid or particulate solid additive independently selected from additives (C)-(D): a liquid or particulate solid (C) antioxidant, and a liquid or particulate solid (D) stabilizer for stabilizing the homogeneous mixture against the effects of ultraviolet light and / or heat. In some embodiments, the one or more additives may further comprise at least one of a colorant, a crosslinking coagent for increasing crosslink density in the crosslinked homogeneous mixture produced by heating the homogeneous mixture, a processing aid, a flame retardant, and a solid filler.

[0015] Embodiment 8. The method of embodiment 7, wherein the one or more additives comprise one or more of a solid antioxidant (C)-1: tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione (“TMTT”), a solid antioxidant (C)-2: distearyl thiodipropionate (“DSTDP”), and a solid stabilizer (D)-1: N,N′-bisformyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (“BBHMDA”).

[0016] Embodiment 9. The method of any one of embodiments 1-8, further comprising, prior to the step of applying acoustic energy, the steps of melting (A) a polyolefin solid to form a melt thereof, mechanically blending the melt of (A) with (B) one or more additives that are not organic peroxides to obtain a (B) organic peroxide-free molten mixture, shaping the molten mixture to obtain a shaped molten mixture, cooling the shaped molten mixture to obtain the (A) polyolefin solid including the one or more additives, and combining the (A) polyolefin solid including the one or more additives with the (B) organic peroxide to obtain a heterogeneous mixture. The shaping step can include extruding the molten mixture as a coating (e.g., a coating composition) onto a conductive core (e.g., a wire, an optical fiber, or both) and solidifying the coating to produce a coated (e.g., coated) conductor comprising a conductive core and a solid in the form of a coating at least partially covering (e.g., coating) the conductive core.

[0017] Embodiment 10. The method of any one of embodiments 1-9, further comprising curing the homogeneous mixture (e.g., by heating the mixture to a temperature of 180°C to 220°C) to obtain a crosslinked homogeneous product.

[0018] The method includes a mixing step consisting essentially of applying acoustic energy. This means that the method achieves thorough mixing of the polyolefin solids and the organic peroxide without mechanically blending or melting the polyolefin solids, and does so quickly compared to immersion, e.g., in less than 10 minutes. Embodiments of the method do not immerse the polyolefin solids in the organic peroxide because the step of applying acoustic energy begins immediately after contacting the polyolefin solids and the organic peroxide together, e.g., within 0 to 10 minutes, alternatively within 0.1 to 5 minutes, alternatively within 0.1 to 1 minute of contact.

[0019] Embodiments of the present method may further include one, two, or more additives in the heterogeneous mixture, and thus in the homogeneous mixture produced therefrom by the step of applying acoustic energy, such as one or more liquid and / or solid additives, such as liquid or particulate solid (C) antioxidant(s) and / or liquid or particulate solid (D) stabilizer. Such embodiments have the added advantage of producing a homogeneous mixture comprising (A) polyolefin solids, (B) organic peroxide, and (A) one, two, or more additives without mechanically blending or melting the polyolefin solids. That is, the (A) polyolefin solids of the inventive homogeneous mixtures have improved (reduced) heat exposure compared to the comparative heat exposure of the (A) polyolefin solids of comparative homogeneous mixtures that have been made by a comparative method comprising melt blending the (A) polyolefin solids with one, two, or more additives to obtain a melt blend, extruding / pelletizing the melt blend to obtain solid pellets comprising a homogeneous mixture of the (A) polyolefin solids and the one, two, or more additives, and (B) impregnating the pellets with an organic peroxide. These inventive embodiments also have the additional advantage that the comparative methods produce the inventive homogeneous mixtures much more quickly than do the comparative homogeneous mixtures (e.g., within 10 minutes versus hours, respectively).

[0020] The present method solves the problem of mixing polyolefin solids with organic peroxides without melting the polyolefin solids, without immersing the organic peroxide in the polyolefin solids, and optionally without using mechanical mixing means. The step of applying acoustic energy can achieve such thorough and rapid mixing without melting the polyolefin solids. If desired, the method may be carried out without mechanical mixing.

[0021] The step of applying acoustic energy allows for and is effective in thoroughly and rapidly mixing (A) the polyolefin solids and (B) the organic peroxide without melting the polyolefin solids during mixing. This combination of benefits of thoroughness of mixing, mixing speed, and minimized heat exposure is described below. Embodiments of the present method that omit mechanical mixing advantageously avoid the use of expensive mechanical mixing equipment and simplify manufacturing operations.

[0022] The mixing in the step of applying acoustic energy is thorough because it achieves and creates a homogeneous mixture. In practical terms, achieving homogeneity can be recognized by visual inspection or by sampling the mixture and measuring the sample's properties as it transitions from a heterogeneous state to a homogeneous state. For example, homogeneity is achieved when the sampling error in the measurement is negligibly small or identical compared to the total error in the measurement. All other things being equal, (i) the greater the acoustic energy, the shorter the period required to achieve homogeneity, and vice versa; and (ii) the closer the frequency resonating with the polymer solid, the shorter the period required to achieve homogeneity, and vice versa.

[0023] Mixing in the step of applying acoustic energy is rapid, as complete mixing can be achieved in a matter of seconds or minutes, e.g., 0.5 minutes to 10 minutes, alternatively 1.0 minutes to 5.0 minutes, alternatively 2 minutes to 4 minutes.

[0024] The step of applying acoustic energy converts the heterogeneous mixture into a homogeneous mixture without melting the (A) polyolefin solid, thereby minimizing heat exposure of the homogeneous mixture. Indeed, if desired, it can be advantageously carried out at temperatures much lower than the melting temperature of the (A) polyolefin solid. For example, the step of applying acoustic energy may be carried out at a temperature between 0°C and 39°C, alternatively between 10°C and 34°C, or alternatively between 20°C and 30°C.

[0025] Because the step of applying acoustic energy can be carried out at temperatures much lower than the melting temperature of the (A) polyolefin solid, embodiments of the step can be advantageously carried out in an oxygen-containing atmosphere, such as air. Oxygen-containing atmospheres can be detrimental to conventional melt mixing or melt compounding operations, where exposing a melt of the (A) polyolefin solid, including the (B) organic peroxide and optional additives, to air at elevated temperatures, such as 140°C to 200°C, can undesirably cause scorch (premature curing) or oxidative and / or thermal degradation of the (A) polyolefin solid and / or additives. Thus, the step of applying acoustic energy beneficially maintains the temperature of the (A) polyolefin solid, as well as other components of heterogeneous mixtures containing it and homogeneous mixtures made therefrom, below the melting temperature of the (A) polyolefin solid.

[0026] Even in embodiments of the process further comprising melting and extruding the homogeneous mixture to obtain a shaped article, the homogeneous mixture has a lower thermal exposure than a comparable homogeneous mixture made by melt mixing or melt compounding a heterogeneous mixture, due to the avoidance of melt mixing / melt compounding exposure times that would otherwise impose exposure to temperatures of 140° C. or greater for 10 minutes or more.

[0027] Thus, without being bound by theory, it is believed that the homogeneous mixtures of the present invention may have improved cure properties (e.g., lower ML, higher MH, and / or higher MH-ML as measured by the cure property test methods described below), improved mechanical properties (e.g., higher tensile strength, lower elongation at break) as measured by the mechanical property test methods described below, and / or improved heat aging performance compared to comparative homogeneous mixtures.

[0028] These cure and mechanical property characteristics demonstrate that the inventive homogeneous mixtures can be prepared rapidly (less than 10 minutes, e.g., 3 minutes) at moderate temperatures (e.g., <30°C, e.g., 23-26°C) and achieve the (B) organic peroxide loading levels typically used in polyolefin curing. Furthermore, the inventive homogeneous mixtures can be cured to achieve improved cure and mechanical properties compared to those obtained from comparative examples made by a conventional two-stage process involving melt blending polyolefin solids with all additives (except the organic peroxide) at 120°C to obtain an intermediate blend, followed by extrusion and pelletizing of strands at 150°C / 170°C / 190°C / 195°C, and soaking the pellets in the organic peroxide at elevated temperatures (70°C) for extended periods of time (typically 8-10 hours). Indeed, it can be concluded that the acoustic mixing method of the present invention reduces organic peroxide decomposition during the preparation of the inventive homogeneous mixtures compared to the comparative melt-blended / dipped mixtures, as evidenced by the lower starting ML and final MH values ​​and higher MH-ML values ​​obtained by curing the inventive homogeneous mixtures using a moving die rheometer. Consequently, it can also be seen that a higher degree of crosslinking is achieved in the inventive homogeneous mixtures compared to the comparative melt-blended / dipped mixtures. This advantage of the present invention is also reflected in the inventive cured products, which have lower elongation-to-break values ​​(i.e., higher crosslinking) than the comparative cured products.

[0029] A technical explanation of how the step of applying acoustic energy creates a homogeneous mixture from a heterogeneous mixture without mechanical mixing is not necessary. Nevertheless, without being bound by theory, it is believed that applying acoustic energy at a frequency of 20 to 100 Hz generates sound waves that rapidly vibrate the (A) polyolefin solid and (B) organic peroxide. They experience relatively large physical displacements, the magnitude and speed of which are believed to be a function of the frequency and acoustic intensity. This vibration of the (A) polyolefin solid and (B) organic peroxide results in their rapid mixing, forming a homogeneous mixture. Thus, the homogeneous mixture is created without melting the (A) polyolefin solid, and, optionally, without mechanical mixing of either the (A) polyolefin solid and the (B) organic peroxide. Therefore, the method of the present invention differs from previous mixing methods that rely on mechanical blending of the polyolefin and (B) organic peroxide as solids (e.g., in a stirred tank device) or melts (e.g., in a twin-screw extruder device).

[0030] Sound with a frequency below 20 hertz (Hz) is referred to as "infrasound," 20 Hz to 20 kilohertz (KHz) is referred to as "acoustic," and above 20 KHz (up to 200 megahertz (MHz) or higher) is referred to as "ultrasound." Without being bound by theory, infrasound and ultrasound and acoustic above 100 Hz cannot, by themselves, rapidly vibrate (A) polyolefin solid or (B) organic peroxide in a heterogeneous mixture to cause relatively large physical changes, thereby resulting in a homogeneous mixture. The application of acoustic energy at frequencies between 20 and 100 Hz is referred to herein as "acoustic mixing."

[0031] To apply effective acoustic energy by practical means, the present method can create a homogenous mixture in an acoustic mixer device. Such a device may be free of components that may impede or attenuate the acoustic energy of the acoustic energy application step. Acoustic mixer devices are commercially available for use at various scales, from lab bench to commercial production, such as the resonant acoustic mixer from Resodyn Acoustic Mixers of Butte, Montana, USA.

[0032] The method may further include the restriction that the heterogeneous mixture is not mechanically agitated (moved by mechanical means) during the step of applying acoustic energy. Mechanically moving means initiating motion by direct contact forces, either manually or through a machine, where a physical object (e.g., a stirrer paddle, screw, plunger, or blender) makes contact and thereby moves the material. Examples of mechanically moving include stirring, screw mixing, plunger mixing, blender mixing, and other direct physical contact. Contact forces do not include electromagnetic forces, gravity, acoustic forces, or convection forces.

[0033] In addition to applying acoustic energy, some embodiments of the method may further include one or more optional steps. Typically, the optional steps are not performed simultaneously with the applying acoustic energy step. As described herein, the optional steps may be performed before the applying acoustic energy step or after the acoustic energy step.

[0034] The method may further include, after the step of applying acoustic energy, subsequent steps of melting and shaping the homogeneous mixture produced by the step of applying acoustic energy and cooling the shaped homogeneous mixture to produce an article comprising the shaped homogeneous mixture.

[0035] After applying acoustic energy, the method may further include melting the (A) polyolefin solids of the homogeneous mixture to form a homogeneous molten mixture containing (B) the organic peroxide, one or more additives, if present, and a melt of the (A) polyolefin solids; shaping the homogeneous molten mixture to form a shaped molten mixture; and cooling the shaped molten mixture to form a shaped solid. The melting and shaping may be performed without or alternatively with mechanical stirring. The shaping may include coating, extrusion, molding, pelletizing, or extrusion and pelletizing. In some embodiments, the shaping includes extruding the homogeneous molten mixture and pelletizing the extrudate to form pellets of the homogeneous mixture. The shaped solid may be useful as a product. The product may be a coating layer for a coated conductor, such as a telecommunications or power cable.

[0036] The method may further include the optional step of curing (crosslinking) the solid in coating form to obtain a coated conductor comprising a conductive core and a cured product in coating form at least partially covering the conductive core. This aspect can be used to make products including power cables, such as low voltage power cables.

[0037] The method may further include an optional step of forming a heterogeneous mixture prior to the step of applying acoustic energy. The heterogeneous mixture may be formed by contacting (A) polyolefin solids with (B) organic peroxide, and optionally one or more additives, to form a heterogeneous mixture containing components (A) and (B), and, if present, one or more additives. The contacting step is performed in the absence of acoustic energy, ideally without melting the (A) polyolefin solids.

[0038] The contacting of components (A) and (B), and optionally one or more additives, to create the heterogeneous mixture can be done simultaneously (all at once) or sequentially, or a combination of some all at once and others sequentially (stepwise). Simultaneous contacting can include combining components (A), (B), and any one or more additives together in a vessel at the same time to create the heterogeneous mixture.

[0039] The stepwise contacting can include different embodiments. In some embodiments, the sequential contacting can include contacting (B) an organic peroxide with at least one of the one or more additives to obtain a first pre-contacted batch that does not include (A), and then contacting (A) a polyolefin solid with the first pre-contacted batch to produce an embodiment of a heterogeneous mixture that includes (A), (B), and one or more additives.

[0040] Alternatively, the sequential contacting may include contacting (A) polyolefin solids with at least one of the one or more additives to obtain a second pre-contacted batch free of (B), and then contacting (B) organic peroxide with the second pre-contacted batch to produce an embodiment of a heterogeneous mixture of (A), (B), and one or more additives.

[0041] Alternatively, a combination of the above two sequential embodiments may be performed by making a first pre-contact batch using a first additive, making a second pre-contact batch using a second additive (where the first and second additives are the same or different), and then contacting the first and second pre-contact batches together to make an embodiment of a heterogeneous mixture comprising (A), (B), and one or more additives.

[0042] Prior to the contacting step, the (A) polyolefin solids used to create the heterogeneous mixture embodiment may be free of the (B) organic peroxide, or vice versa. Alternatively, in some embodiments, a masterbatch may be pre-formed containing a higher than final loading of the (B) organic peroxide dispersed in a portion of the (A) polyolefin solids, and the masterbatch may then be contacted with the remaining portion of the (A) polyolefin solids to create the heterogeneous mixture embodiment. The same or a different masterbatch may contain one or more additives and may be contacted with the remaining portion of the (A) polyolefin solids and the (B) organic peroxide to create the heterogeneous mixture embodiment. The masterbatch may be formed by acoustic mixing or conventional melt mixing.

[0043] The (A) polyolefin solids used in the contacting step to make the heterogeneous mixture may be free of one or more additives (e.g., the (A) polyolefin solids may consist of virgin polyolefin resin granules or pellets). Alternatively, the (A) polyolefin solids used in the contacting step to make the heterogeneous mixture may include some or all of one or more additives, such as one or more antioxidants and heat stabilizers. These additives may be premixed into virgin polyolefin resin granules or pellets by melt mixing or melt compounding the virgin resin to make the (A) polyolefin solids containing one or more antioxidants and heat stabilizers.

[0044] The heterogeneous mixture used in the step of applying acoustic energy can be freshly prepared by such a contacting step. By "freshly prepared" it is meant that the time between the contacting step and the start of the step of applying acoustic energy can be less than 30 minutes, alternatively less than 15 minutes, alternatively less than 10 minutes, or alternatively less than 5 minutes. Alternatively, the heterogeneous mixture used in the step of applying acoustic energy can be pre-aged. By "pre-aged" it is meant that the time between the contacting step and the start of the step of applying acoustic energy can be at least 30 minutes, alternatively more than 60 minutes, or alternatively more than 120 minutes.

[0045] A homogeneous mixture is produced by the step of applying acoustic energy in the present method. The homogeneous mixture can be characterized as described above. Without being bound by theory, the product of that step can be characterized as homogeneous in that the (B) organic peroxide is substantially homogeneously adsorbed onto the exterior and accessible interior surfaces of the (A) polyolefin solid. "Substantially homogeneously adsorbed" means that at least some (B) organic peroxide is adsorbed onto substantially all accessible surfaces of the (A) polyolefin solid, although the amount of adsorbed (B) organic peroxide may vary across the surface. Once adsorbed onto the surface of the (A) polyolefin solid, the (B) organic peroxide may remain there until the (A) polyolefin solid is melted in an optional subsequent step.

[0046] When the heterogeneous mixture and the homogeneous mixtures made therefrom contain one or more additives, the (A) polyolefin solids can be 50 to 99.8 weight percent (wt%), the (B) organic peroxide can be 0.1 to 5.0 wt%, and the total weight of the one or more additives can be 0.1 to 45 wt% (all based on the weight of the homogeneous mixture and the homogeneous mixture, respectively). The total weight of all components of the heterogeneous mixture is 100.0 wt%, and the total weight of all components of the homogeneous mixture is 100.0 wt%.

[0047] Without being bound by theory, it is believed that the total weight of the homogeneous mixture is equal to the total weight of the heterogeneous mixture from which it is created, i.e., the step of applying acoustic energy does not result in a significant loss or gain of weight in going from a heterogeneous mixture to a homogeneous mixture.

[0048] (A) Polyolefin Solid A finely divided solid material comprised of polyolefin polymers independently containing at least 5, alternatively 10 to 200,000 constitutional units derived from the polymerization of one or more olefin-functional monomers.

[0049] Polyolefins can be homopolymers or copolymers. Homopolymers are made by polymerizing only one olefin monomer. Copolymers are made by polymerizing at least two different olefin monomers. Copolymers can be bipolymers, made by polymerizing two different olefin monomers, terpolymers, made by polymerizing three different olefin monomers, or tetrapolymers, made by polymerizing four different olefin monomers. Polyolefin copolymers can be block copolymers or random copolymers.

[0050] (A) Polyolefins Examples of olefin-functional monomers used to make the polyolefin(s) of the solid are ethylene, propene, (C4-C 20 ) alpha-olefins, cyclic alkenes (e.g., norbornene), dienes (e.g., 1,3-butadiene), unsaturated carboxylic acid esters, and olefin-functional hydrolyzable silanes. (C4-C 20 Examples of alpha-olefins are (4-C8) alpha-olefins such as 1-butene, 1-hexene, or 1-octene, and (C 10 -C 20) alpha-olefins. An example of a diene is 1,3-butadiene. Examples of unsaturated carboxylic acid esters are alkyl acrylates, alkyl methacrylates, and vinyl carboxylates (e.g., vinyl acetate). Examples of olefin-functional hydrolyzable silanes are vinyltrialkoxysilanes, vinyltris(dialkylamino)silanes, and vinyl(trioximo)silanes.

[0051] Examples of such polyolefins are polyethylene homopolymers, ethylene / alpha-olefin copolymers, (hydrolyzable silyl group)-functionalized polyethylene copolymers (HSG-FP copolymers), ethylene / unsaturated carboxylic acid ester copolymers (e.g., ethylene / vinyl acetate (EVA) copolymers or ethylene / alkyl (meth)acrylate (EAA or EAM) copolymers), halogenated polyolefins (e.g., chlorinated polyolefins such as poly(vinyl chloride) polymers), and combinations of any two or more thereof.

[0052] In some embodiments, the polyolefin of the (A) polyolefin solid is an ethylene-based polymer. The ethylene-based polymer contains 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 alternatively two, olefin-functional monomers (comonomers). The comonomers include propylene, (C4-C 20 ) alpha-olefins, and 1,3-butadiene. (C4-C 20 The alpha-olefin may be a (C4-C8) alpha-olefin such as 1-butene, 1-hexene, or 1-octene.

[0053] Examples of suitable ethylene-based polymers include polyethylene homopolymers, ethylene / (C4-C 20) alpha-olefin copolymers, ethylene / propylene copolymers, ethylene / propylene / diene monomer (EPDM) copolymers, such as ethylene / propylene / 1,3-butadiene terpolymers, and ethylene / 1-butene / styrene copolymers. Suitable ethylene / (C4-C 20 Examples of alpha-olefin copolymers are ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, and ethylene / 1-octene copolymer. The ethylene-based polymer can be ultra-low density polyethylene (ULDPE), very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or very high density polyethylene (HDPE). Many ethylene-based polymers are sold by The Dow Chemical Company under trade names such as AFFINITY, ATTANE, DOWLEX, ENGAGE, FLEXOMER, or INFUSE. Other ethylene-based polymers are sold by other suppliers under trade names such as TAFMER, EXCEED, and EXACT.

[0054] In some embodiments, the (A) polyolefin solids consist of solids of only one ethylene-based polymer (e.g., only LLDPE, or only LDPE, or only MDPE, or only HDPE).

[0055] In other embodiments, the (A) polyolefin solids comprise two or more different ethylene-based polymers. In some such embodiments, the (A) polyolefin solids comprise a first solid that is a first linear low-density polyethylene (first LLDPE) and at least one of a second solid that is a medium-density polyethylene (MDPE) and a third solid that is a second LLDPE different from the first LLDPE. In some embodiments, the particle blend comprises the first LLDPE and MDPE, alternatively the first LLDPE and second LLDPE, or alternatively each of the first LLDPE, MDPE, and second LLDPE.

[0056] In some embodiments, the halogen- and silicon-free ethylene-based polymer is a polyethylene homopolymer, a poly(ethylene-co-1-butene) copolymer, a poly(ethylene-co-1-hexene) copolymer, a poly(ethylene-co-1-octene) copolymer, or a combination of any two or more thereof. In some such embodiments, the polyolefin is a low-density polyethylene ("LDPE"), a linear low-density polyethylene ("LLDPE"), a medium-density polyethylene (MDPE), a high-density polyethylene (HDPE), or a combination of any two or more thereof (e.g., a combination of one LLDPE and one MDPE, or a combination of two LLDPEs and one MDPE).

[0057] In some embodiments, the ethylene-based polymer is a low density polyethylene (LDPE) having a density of 0.915 to 0.924 g / cc and a melt index (I2, 190° C., 2.16 kg) of 1.5 to 2.4 g / 10 min.

[0058] The (A) polyolefin solid may consist essentially of only one polyolefin.

[0059] In some embodiments, the (A) polyolefin solid consists essentially of two or three different polyolefins. Such embodiments of the (A) polyolefin solid can consist essentially of the solid, with each particle of the solid comprising a polymer blend of two or more different polyolefins. Other such embodiments can include a particle blend of a first solid consisting essentially of a first polyolefin, a second solid consisting essentially of a second polyolefin, and, optionally, a third solid consisting essentially of a third polyolefin. The first and second polyolefins, and the third polyolefin, if present, are different from each other. Still other embodiments can include a particle blend of a first solid consisting essentially of a first polyolefin and a second solid consisting essentially of a polymer blend of a second polyolefin and a third polyolefin. The first and second polyolefins are different from each other, and the first and third polyolefins are the same or different.

[0060] In some embodiments, the polyolefin of the (A) polyolefin solid does not contain halogen and / or silicon atoms. In some embodiments, the polyolefin also does not contain oxygen and / or nitrogen atoms. In some embodiments, the ethylene-based polymer also does not contain halogen and / or silicon atoms. In some embodiments, the ethylene-based polymer also does not contain oxygen and / or nitrogen atoms. In other embodiments, the ethylene-based polymer does not contain halogen and / or silicon atoms, and does not contain oxygen and / or nitrogen atoms derived from oxygen- and / or nitrogen-containing olefin monomers, but does contain crosslinks containing oxygen and / or nitrogen atoms derived from oxygen- and / or nitrogen-containing crosslinking coagents (e.g., triallyl isocyanurate or 2,4,6-tris(diallylamino)-1,3,5-triazine).

[0061] In some embodiments, the polyolefin of the (A) polyolefin solid comprises 51 to 100 wt. % propylene units derived from the polymerization of propylene and 49 to 0 wt. % comonomer units (selected from ethylene; (C4-C8) alpha-olefins such as 1-butene, 1-hexene, 1-octene, etc.) derived from the polymerization of one, alternatively two, olefin-functional monomers (comonomers).

[0062] The (A) polyolefin solids may be porous or non-porous. The (A) polyolefin solids may comprise powders, granules, or pellets.

[0063] The (A) polyolefin solid may have a melting temperature, at which melting begins or commences, of 60° C. or higher, alternatively greater than 100° C., alternatively greater than 110° C. The (A) polyolefin solid may have a melting temperature, at which melting ends or is complete, of up to 220° C., alternatively maximum 180° C., alternatively maximum 150° C.

[0064] The (A) polyolefin solids of the heterogeneous mixture may be characterized by an average particle size, as measured by count, of 10 to 500 particles per gram (ppg), alternatively 11 to 80 ppg, alternatively 20 to 40 ppg.

[0065] (B) Organic peroxide. A molecule, or assembly of such molecules, containing carbon, hydrogen, and two or more oxygen atoms and having at least one -OO- group, provided that if more than one -OO- group is present, each -OO- group is indirectly bonded to another -OO- group through one or more carbon atoms. The (B) organic peroxide can be used to cure the homogeneous mixture of the present invention by heating the homogeneous mixture to a temperature at or above the decomposition temperature of the (B) organic peroxide.

[0066] (B) Organic peroxides are represented by the formula R O -OOR O wherein each R O are independently (C1-C 20) alkyl group or (C6-C 20 ) aryl group. Each (C1-C 20 ) alkyl groups are independently unsubstituted or contain one or two (C-C 12 ) substituted with an aryl group. 20 The aryl group is unsubstituted or contains one to four (C-C 10 ) substituted with an alkyl group.

[0067] Alternatively, (B) can be a compound of formula R O -OOROOR O wherein R is a diperoxide of (C-C 10 ) alkylene, (C3-C 10 ) a divalent hydrocarbon group such as cycloalkylene or phenylene, and each R O is as defined above. (D) Organic peroxides include 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-butylperoxybenzoic acid, di-tert-amyl peroxide ("DTAP"), bis(α-t-butylperoxybenzoate), methylperoxide ("DTAP"). (B) The organic peroxide may be dicumyl peroxide.

[0068] In some embodiments, only a blend of two or more (B) organic peroxides is used, such as a 20:80 (w / w) blend of t-butylcumyl peroxide and bis(t-butylperoxyisopropyl)benzene (e.g., LUPEROX D446B, commercially available from Arkema). In some embodiments, at least one, alternatively each (B) organic peroxide contains one -OO- group.

[0069] The (B) organic peroxide can be at least one liquid organic peroxide (e.g., tert-butyl peroxyacetate). Alternatively, the (B) organic peroxide can be at least one solid organic peroxide (e.g., dicumyl peroxide). Alternatively, the (B) organic peroxide can be a combination of two liquid organic peroxides, two solid organic peroxides, or one liquid organic peroxide and one solid organic peroxide.

[0070] The liquid organic peroxide embodiment of (B) is an amorphous state of matter at ambient temperature (e.g., 23° C.) of formula R that is intermediate between gas and solid and has a stable volume but no definite shape. O -OOR O or formula R O -OOROOR O In some embodiments, the liquid organic peroxide is tert-butyl peroxyacetate.

[0071] The solid organic peroxide embodiment of (B) has a state of matter at ambient temperature (e.g., 23°C) with a stable volume and well-defined shape, and has the formula R O -OOR O or formula R O -OOROOR OThe solid organic peroxide may be amorphous, crystalline, or semi-crystalline. In some embodiments, the solid organic peroxide is selected from dicumyl peroxide, dilauryl peroxide, dibenzoyl peroxide, and di-2-tert-butylperoxyisopropylbenzene and α,α-bis(t-butylperoxy)diisopropylbenzene.

[0072] (B) The organic peroxide can be from 0.05 to 3.0 wt %, alternatively from 0.1 to 3 wt %, alternatively from 0.5 to 2.5 wt % of the heterogeneous mixture and homogeneous mixtures made therefrom.

[0073] and one or more optional additives, other than (A) a polyolefin solid or (B) an organic peroxide, that are added to the heterogeneous mixture to improve one or more properties of the homogeneous mixture produced therefrom. Without being bound by theory, it is believed that the step of applying acoustic energy in the method does not decompose any additives, and therefore, if the heterogeneous mixture contains an additive, the additive will also be present in the homogeneous mixture produced therefrom.

[0074] In some embodiments, the heterogeneous mixture, and the homogeneous mixtures made therefrom, do not contain any additives. In other embodiments, the heterogeneous mixture, and the homogeneous mixtures made therefrom, contain one or more additives.

[0075] The homogeneous mixture may further comprise one or more additional additives that were not present in the heterogeneous mixture from which it was created, but that are added to the homogeneous mixture after the step of applying acoustic energy. The method of adding such additional additives may involve melting the (A) polyolefin solid, as in a melt-mixing or melt-compounding operation. Alternatively, the method of adding such additional additives may involve a melt-free operation, such as passively immersing or imbibing such additional additives into the homogeneous mixture at a temperature between 20°C and 90°C (e.g., between 50°C and 80°C). Liquid additives and particulate solid additives having melting points below 90°C are useful for such imbibing or imbibing methods.

[0076] In some embodiments, the heterogeneous mixture, and the homogeneous mixtures produced therefrom, comprise one or more additives, alternatively two or more additives, alternatively three or more additives, alternatively four or more additives, or alternatively five or more additives. In some embodiments, the heterogeneous mixture, and the homogeneous mixtures produced therefrom, comprise no more than 10 additives in total, alternatively nine or less additives in total, alternatively eight or less additives in total, alternatively seven or less additives in total, or alternatively six or less additives in total.

[0077] In some embodiments, at least one, alternatively all but one, alternatively each of the one or more additives that are not component (A) or (B) is independently a liquid or particulate solid selected from a liquid or particulate solid (C) antioxidant and a liquid or particulate solid (D) stabilizer for stabilizing the homogeneous mixture against the effects of ultraviolet light and / or heat. In some embodiments, the one or more additives may include a colorant (e.g., carbon black or TiO), a crosslinking coagent (e.g., triallyl isocyanurate (TAIC)), a processing aid (e.g., a fluoropolymer or polydimethylsiloxane), a flame retardant (alumina), and / or a filler (e.g., fumed silica). Each additive may independently be a liquid additive or a particulate solid additive. In some embodiments, the heterogeneous mixture, and the homogeneous mixture from which it is made, includes at least one particulate solid additive, alternatively at least one liquid additive, or alternatively at least one particulate solid additive and at least one liquid additive.

[0078] Each particulate solid additive may independently have a melting point that is lower than, the same as, or higher than the melting point of the (A) polyolefin solid.

[0079] (C) antioxidants are optional liquid or particulate solid additives: organic molecules or aggregates of such molecules that inhibit oxidation. (C) antioxidants are compositionally distinct from (D) stabilizers, meaning that when a heterogeneous or homogeneous mixture contains both (C) and (D), the compound used as (C) is different from the compound used as (D). (C) antioxidants function to provide antioxidant properties to the heterogeneous or homogeneous mixture and / or the cured polymer product made by curing the homogeneous mixture.Examples of suitable (C) include bis(4-(1-methyl-1-phenylethyl)phenyl)amine (e.g., NAUGARD 445), 2,2'-methylene-bis(4-methyl-6-t-butylphenol) (e.g., VANOX MBPC), 2,2'-thiobis(2-t-butyl-5-methylphenol) (CAS No. 90-66-4, 4,4'-thiobis(2-t-butyl-5-methylphenol) (also known as 4,4'-thiobis(6-tert-butyl-m-cresol), CAS No. 96-69-5, commercially available LOWINOX TBM-6), 2,2'-thiobis(6-t-butyl-4-methylphenol) (CAS No. 90-66-4, commercially available LOWINOX TBM-6), and 2,2'-thiobis(6-tert-butyl-4-methylphenol) (CAS No. 90-66-4, commercially available LOWINOX TBM-6). TBP-6), tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione (e.g., CYANOX 1790), pentaerythritol tetrakis(3-(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)propionate (e.g., IRGANOX 1010, CAS No. 6683-19-8), 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid 2,2'-thiodiethanediyl ester (e.g., IRGANOX 1035, CAS No. 41484-35-9), distearyl thiodipropionate ("DSTDP"), dilauryl thiodipropionate (e.g., IRGANOX PS 800), stearyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (e.g., IRGANOX 1076), 2,4-bis(dodecylthiomethyl)-6-methylphenol (IRGANOX 1726), 4,6-bis(octylthiomethyl)-o-cresol (e.g., IRGANOX 1520), and 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide (IRGANOX 1024).(C) is 4,4'-thiobis(2-t-butyl-5-methylphenol) (also known as 4,4'-thiobis(6-tert-butyl-m-cresol)), 2,2'-thiobis(6-t-butyl-4-methylphenol, tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, distearyl thiodipropionate, or dilauryl thiodipropionate, or derivatives thereof. Any two or more of these may be combined. A combination may be tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione and distearyl thiodipropionate. The heterogeneous and / or homogeneous mixture may not contain (C). When present, the (C) antioxidant may be present in an amount of 0.01 to 1.5 wt %, alternatively 0.1 to 1.0 wt %, of the total weight of the heterogeneous and / or homogeneous mixture.

[0080] Optional liquid or particulate solid additive (D): a stabilizer (UV stabilizer) for stabilizing heterogeneous and / or homogeneous mixtures against ultraviolet light. (D) stabilizers are compositionally distinct from (C) antioxidants, meaning that when a mixture contains both (C) and (D), the compound used as (C) will be different from the compound used as (D). Examples include hindered amine light stabilizers (HALS), benzophenones, or benzotriazoles. (D) UV stabilizers can be molecules or aggregates of molecules containing a basic nitrogen atom bonded to at least one sterically bulky organic group, which acts as an inhibitor of degradation or decomposition. HALS are compounds with sterically hindered amino functional groups that inhibit oxidative degradation and can also extend the shelf life of homogeneous mixtures containing (B) organic peroxides. Examples of suitable (D) compounds are butanedioic acid dimethyl ester, a polymer containing 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (CAS No. 65447-77-0, commercially available as LOWILITE 62), and N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (CAS No. 124172-53-8, commercially available as Uvinul 4050 H). The heterogeneous and / or homogeneous mixtures may be free of (D). When present, the (D) UV stabilizer may be present in an amount of 0.001 to 1.5 wt. %, alternatively 0.002 to 1.0 wt. %, or alternatively 0.05 to 0.1 wt. % of the heterogeneous and / or homogeneous mixture.

[0081] Articles. Articles made from the homogeneous mixture may include formed forms thereof. Examples include coatings on substrates, tapes, films, layers of laminates, foams, and pipes.

[0082] Coated conductor. The product can be a coated conductor including a conductive core and a polymer layer at least partially surrounding the conductive core, wherein at least a portion of the polymer layer comprises the homogeneous mixture or a cured polymer product obtained by curing the homogeneous mixture. The entire polymer layer, or only a portion of the layer, can comprise the cured polymer product.

[0083] The conductive core may be linear (e.g., wire-like) having a length and proximal and distal ends spaced apart by the length of the linear shape, and the polymer layer may surround the conductive core except for the proximal and distal ends.

[0084] The coated conductor may further include one or more additional polymer layers, which may or may not independently include a cured polymer product, and / or an outer shielding layer (e.g., a metal sheath or sleeve). The coated conductor may include one or two insulating layers, at least one of which includes a cured polymer product, and alternatively or additionally, one or two semiconducting layers, at least one of which includes a cured polymer product that includes carbon black, and alternatively or additionally, an outer shielding layer including a cured polymer product.

[0085] High density polyethylene or HDPE. 0.940-0.980 g / cm3 measured according to ASTM D792-13 3 Polyethylene homopolymer or poly(ethylene-co-1-alkene) copolymer having a density of 1-1-2-3, 1-2-3, 1-3-4, 1-4-5, 1-5-6, 1-6-7, 1-7-8, 1-8-9, 1-9-10, 1-11, 1-12, 1-13, 1-14, 1-15, 1-16, 1-17, 1-18, 1-19, 1-20, 1-21, 1-22, 1-23, 1-24, 1-25, 1-26, 1-27, 1-28, 1-29 ... 20 ) 1-alkene.

[0086] Low-density polyethylene or LDPE, 0.871 to 0.930 grams per cubic centimeter (g / cm), measured according to ASTM D792-13 3 Poly(ethylene-co-1-alkene) copolymers having a density less than 1000C and a significantly lower amount of short chain branches per 1,000 carbon atoms (SCB / 1000C) than LLDPE. SCB / 1000C is determined according to the GPC and SCB test methods described below, and the 1-alkene comonomer is a (C4-C8) 1-alkene such as 1-butene, 1-hexene, or 1-octene. 20 ) 1-alkene.

[0087] Linear low density polyethylene or LLDPE. 0.871-0.930 g / cm, measured according to ASTM D792-13 3 Poly(ethylene-co-1-alkene) copolymers having a density less than 1000 and a significant amount of short chain branching per 1,000 carbon atoms (SCB / 1000C), where SCB / 1000C is determined according to the GPC and SCB test methods described below, and the 1-alkene comonomer is a (C4-C8) 1-alkene, such as 1-butene, 1-hexene, or 1-octene. 20 ) 1-alkene.

[0088] LLDPE is made using process conditions different from those used to make LDPE. It differs compositionally from LDPE and has certain superior properties that have led it to replace LDPE in many commercial applications. These include coatings, films, sheets, and injection-molded articles. LLDPE coatings include the insulation layer of telecommunication cables. LLDPE film and sheet are used in packaging and non-packaging applications. Examples include agricultural films, food packaging, garment bags, grocery bags, heavy-duty sacks, industrial sheeting, pallets, and shrink wrap and shrink bags. LLDPE injection-molded articles include buckets, freezer containers, lids, and toys.

[0089] Liquid refers to an amorphous state of matter at ambient temperature (eg, 23° C.) that is intermediate between a gas and a solid and has a stable volume but no definite shape.

[0090] Liquid additive is used to describe the state of matter of the additive at the temperature of the heterogeneous mixture during the step of applying acoustic energy; if the temperature of the heterogeneous mixture during the step of applying acoustic energy is higher than ambient temperature, the additive is not necessarily liquid at ambient temperature (e.g., 23°C). In some embodiments, the liquid additive is liquid at ambient temperature (e.g., 23°C). Solvents are not examples of liquid additives because they are used only to dissolve the solid or liquid additive for contact with (A) the polyolefin solid and / or (B) the organic peroxide and are intended to be removed from the heterogeneous mixture after the contacting step or to be subsequently removed from the homogeneous mixture before the homogeneous mixture is used to make a molded article.

[0091] Maintaining the temperature of the material below a threshold. Any passive or active means that prevents the material from heating or cooling by raising the material to a threshold. Passive maintaining means may include placing the material in a container (e.g., in an acoustic mixer device) where the temperature of the container is below the threshold and the container and its contents are not exposed to a heat source. Active maintaining means may include insulating the container or placing the container in effective cooling contact with a heat exchanger device through which a cooling fluid is circulated.

[0092] Medium Density Polyethylene or MDPE. 0.930-0.940 g / cm3 measured according to ASTM D792-13 3 Poly(ethylene-co-1-alkene) copolymers having a density less than 1. The alkene comonomer is a (C4-C8) 1-alkene such as 1-butene, 1-hexene, or 1-octene. 20 ) 1-alkene

[0093] Melting refers to the process of changing a substance from a solid to a liquid state. Usually, melting refers to the completion of the change so that the liquid state contains no unmelted solid forms of the material. The temperature at which a material can be characterized as a solid or liquid is 20°C.

[0094] Polyolefin refers to any polymer, or mixture of polymers, containing constitutional units derived from the polymerization of an olefin-functional monomer or the copolymerization of at least two olefin-functional monomers. Polyolefins can be amorphous (i.e., have a glass transition temperature in differential scanning calorimetry (DSC) but no melting point) or semi-crystalline (i.e., have a glass transition temperature and a melting point in DSC).

[0095] Solid means a state of matter at ambient temperature (e.g., 23°C) that has a stable volume and definite shape. It may be amorphous, crystalline, or semi-crystalline.

[0096] Any compound, composition, formulation, material, mixture, or reaction product herein may be free of any one of the chemical elements selected from the group consisting of H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, lanthanides, and actinides, except that chemical elements essentially required by the compound, composition, formulation, material, mixture, or reaction product (e.g., C and H required by polyethylene, or C, H, and O required by alcohol) are not excluded.

[0097] Alternatively, different embodiments are preceded. ANSI is the American National Standards Institute, headquartered in Washington, DC, USA. ASME is the American Society of Mechanical Engineers, headquartered in New York City, New York, USA. ASTM is the standardization organization ASTM International, West Conshohocken, Pennsylvania, USA. Any comparative examples are used for illustrative purposes only and are not prior art. Not containing or lacking means completely absent, alternatively undetectable. IUPAC 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 May 1, 2018, edition of IUPAC. May is not required and allows for choice. Operative means functionally capable or effective. Optional(ly) means absent (or excluded), alternatively present (or included). Properties can be measured using standard tests and conditions. Ranges include endpoints, subranges, and integer and / or fractional values ​​subsumed therein, but integer ranges do not include fractional values. Room temperature: 23°±1°C.

[0098] Unless otherwise stated, definitions of terms used herein are taken from the IUPAC Compendium of Chemical Technology ("Gold Book"), Edition 2.3.3, dated February 24, 2014. For convenience, some definitions are provided below.

[0099] Density: Measured in accordance with ASTM D792-13, Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement, Method B (for testing solid plastics in liquids other than water, e.g., liquid 2-propanol). Units are grams per cubic centimeter (g / cm 3 ).

[0100] Melt Index "I2": Measured in accordance with ASTM D1238-13 using the 190°C / 2.16 kg condition, formerly known as "Condition E." Units: grams per 10 minutes (g / 10 min). [Example]

[0101] Additional inventive embodiments are the aspects described above and claims described below that describe process condition ranges and / or material property ranges, in which the endpoints of the process condition ranges and / or the endpoints of the material property ranges are modified to any one example process condition value and / or any one example material property value, respectively, described below in this section for any one example of the invention.

[0102] Polyolefin solid (A)-1: A low-density poly(ethylene-co-1-hexene) copolymer ("LDPE-1, 2MI") having a unimodal molecular weight distribution, a density of 0.92 g / cc, and a melt index of 2 g / 100 min (I2, 190°C, 2.16 kg). Used in the form of dry pellets.

[0103] Polyolefin solid (A)-2 (hypothetical example): A low-density poly(ethylene-co-1-hexene) copolymer (LDPE-2) with a density of 0.92 g / cc and a melt index of 0.6-0.8 g / 10 min (I2, 190°C, 2.16 kg). Used in the form of dry pellets.

[0104] Polyolefin Solid (A)-3 (Hypothetical Example) Low-density poly(ethylene-co-1-hexene) copolymer (LDPE-3) with a density of 0.922-0.924 g / cc and a melt index of 20 g / 10 min (I2, 190°C, 2.16 kg). Used in pellet form.

[0105] Polyolefin Solid (A)-4 (Hypothetical Example): Linear low-density polyethylene (LLDPE-1), a poly(ethylene-co-1-butene) copolymer with a unimodal molecular weight distribution, a density of 0.92 g / cc, and a melt index of 0.6 to 0.8 g / 10 min (I2, 190°C, 2.16 kg). It can be used in the form of dried pellets or dried granules. Granules can be obtained from a gas-phase polymerization reactor. Pellets are made from reactor granules and are available from The Dow Chemical Company as DFDA-7530 NT. Pellets can be converted to granules by prilling. Granules were used in Examples IE1 to IE4 (Table 1 below), and pellets were used in Hypothetical Example IE9 (Table 2 below).

[0106] Polyolefin Solid (A)-5 (Hypothetical Example): Medium-density polyethylene (MDPE-1), a poly(ethylene-co-1-hexene) copolymer with a unimodal molecular weight distribution, a density of 0.930 to 0.940 g / cc, and a melt index of 0.7 to 0.9 g / 10 min (I2, 190°C, 2.16 kg). DFH-3580 from The Dow Chemical Company. Used in dry pellet form.

[0107] Organic peroxide (B)-1: Dicumyl peroxide Solid antioxidant (C)-1: Tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione (“TMTT”).

[0108] Solid antioxidant (C)-2: Distearyl thiodipropionate ("DSTDP") Solid stabilizer (D)-1: A solid heat stabilizer which is N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine ("BBHMDA").

[0109] Comparative Example 1 (CE1): Sample prepared by melt mixing (melt compounding). In a conventional mixing process, the sample was prepared by first creating an intermediate blend containing only the components polyolefin solid (A)-1, antioxidant (C)-1, antioxidant (C)-2, and heat stabilizer (D)-1. The experiment was conducted in a Brabender model Prep Mixer / Measuring Head laboratory electric batch mixer equipped with a cam blade. The components were fluxed at 120°C for 3 minutes. The resulting mixture was then flattened, cooled, and chopped into strips. These were then fed into a single-screw extruder to produce wire strands, which were then chopped into pellets. The unit consisted of a BRABENDER 1.9 cm (3 / 4 inch) extruder with variable speed drive, a 24:1 Maddock mixing head screw, a BRABENDER strand die, a laboratory water-cooled trough with air wipes, a laser micrometer, and a variable speed puller. The samples were extruded at a screw speed of 40 revolutions per minute (rpm) and a take-up speed of approximately 2.4 meters (8 feet) per minute. Strands were produced using a set temperature profile of 150°C / 170°C / 190°C / 195°C (across Zone 1, Zone 2, Zone 3, and the head / die) followed by pelletization at room temperature (e.g., 23°C). Organic peroxide (B)-1 was removed from a freeze-sealed glass bottle, placed in a polyethylene bag, and placed in a 60°C water bath. Sample pellets were preheated in a large glass jar at 70°C for 4 hours. After the pellet preheating step, the specified amount of organic peroxide (B)-1 was pre-weighed and applied to the pellets using a syringe. The pellet jar was tightly capped and placed on a ceramic tumbler set at 30 rpm. After tumbling for 5 minutes, the jar was removed and manually shaken to loosen the pellets from the sides of the jar. The organic peroxide soaking process continued at 70°C for 8-10 hours. The formulation of CE1 is reported later in Table 1.

[0110] Comparative Example 2 (CE2): Prepared by physical blending. A total of 150 g of polyethylene granules (A)-1 was contacted with the organic peroxide (B)-1 (removed from a frozen, sealed glass bottle) and additives antioxidant (C)-1, antioxidant (C)-2, and heat stabilizer (D)-1 in the amounts shown in Table 1 and rapidly physically blended to prepare CE2, a physical blend of (A)-1, (B)-1, (C)-1, (C)-2, and (D)-1. CE2 was rapidly tested for cure properties, the results of which are also shown in Table 1. The cure properties indicated that the physical blend of CE2 was unable to undergo crosslinking, i.e., lacked crosslinking. Because no crosslinking was observed, there was no reason to perform mechanical testing on CE2.

[0111] Inventive Example 1 (IE1): An inventive example was prepared by acoustic mixing. A total of 150 g of polyethylene granules (A)-1 was contacted with the amounts shown in Table 1 of organic peroxide (B)-1 and additives antioxidant (C)-1, antioxidant (C)-2, and heat stabilizer (D)-1 removed from a frozen, sealed glass bottle to prepare a heterogeneous mixture of IE1. A homogeneous mixture of IE1 was prepared separately by applying acoustic energy to the heterogeneous mixture in the glass bottle at a frequency of 60 hertz (Hz) using a Resodyn™ Acoustic Mixer (LabRAM Mixer) for 3 minutes at 23°C to 26°C. Multiple batches of the homogeneous mixture were prepared and extruded onto wire for full material property testing. The inventive homogeneous mixtures were separately extruded using a 1.9 cm (¾ inch) Brabender extruder, 25-1 L / D, equipped with a Maddox mixing head screw using a strand die. The temperature profile of the extruder was set at 150°C / 170°C / 180°C / 190°C, and the screw speed was 40 rpm. The strands were pelletized at room temperature for further processing, obtaining a homogeneous mixture of IE1 as pellets separately. The formulation is reported later in Table 1.

[0112] Cure Characterization Test Method: Moving die rheometer analysis was performed on IE1 and CE1 samples using an Alpha Technologies Rheometer MDR Model 2000 unit. Testing was based on ASTM D5289-12, Standard Test Method for Rubber Properties - Vulcanization Using a Rotorless Cure Meter. MDR analysis was performed using 4-5 grams of material. Samples were tested at 182°C for 15 minutes with a 0.5-degree arc oscillation while monitoring the torque change. The minimum torque value measured is designated as "ML," expressed in deciNewton meters (dN-m). As curing or crosslinking progresses, the measured torque value increases, eventually reaching a maximum torque value. The maximum or highest measured torque value is designated as "MH," expressed in dN-m. All other things being equal, the higher the MH torque value, the greater the degree of crosslinking. The total amount of crosslinking is determined as the difference between MH and ML (MH-ML). The greater the MH-ML difference, the greater the amount of crosslinking. It is measured in pounds-inches (lb.-in.) and converted to newton-meters (Nm), where 1.00 lb.-in. = 0.113 Nm.

[0113] Mechanical Property Testing Method. Compression-molded plaques of the CE1 comparative blend and the IE1 homogeneous blend were prepared and used as specimens for ultimate tensile strength and elongation at break (T&E) testing. The pelletized homogeneous blends were separately compression-molded using a WABASH Genesis Steam press (with quench function) operated in manual mode. The press was preheated to 115°C ± 5°C. A total of 75 grams of pellets were pre-weighed and centered on a 1.9 mm (75 mil) stainless steel plaque between a die assembly composed of a Mylar sheet and an aluminum sheet. The resulting filled die was then placed in the press at 2.1 megapascals (Mpa, 300 pounds per square inch (psi)) for 3 minutes. After this initial press, the temperature was increased to 185°C ± 5°C for 2 minutes. The pressure was then increased to 17.2 Mpa (2,500 psi) for 15 minutes. The steam was switched to water 15 seconds before the end of the 15-minute period, and the samples were quenched for 5 minutes. The cooled samples were removed after reaching 35°C, resulting in compression-molded plaques (IE1 and CE1) with dimensions of 0.20 x 0.20 x 1.9 mm (8 x 8 x 75 mils). Three plaques were made from IE1 and three from CE1. Five Type IV dogbones were cut from the plaques and tensile-tested according to ASTM D638-03 after initial conditioning for 48 hours in a controlled air atmosphere at 23.0°C (73.4°F) and 50% relative humidity. Tensile strength and elongation-to-break tests were performed on an Instron Renew 4201 65 / 16 instrument using a 45-kilogram (kg, 100 lb) load cell and a jaw separation rate of 50.8 cm per minute (20 inches per minute). Mechanical property testing was performed on compression molded plaque specimens that were not heat aged and on specimens that had been heat aged. The higher the tensile strength value, the greater the maximum amount of stress the material can withstand without stretching or breaking. The lower the elongation at break value, the less stretch the test material can undergo before breaking. The data are reported in Table 1 below. [Table 1]

[0114] N / m: Not measured. N / a: Not applicable. N / r: Not reported.

[0115] As shown by comparing the data for IE1 in Table 1 with those for CE1, these cure and mechanical property characteristics demonstrate that the inventive homogeneous mixtures can be prepared rapidly (within 10 minutes, e.g., 3 minutes) at moderate temperatures (e.g., <30°C, e.g., 23-26°C) and achieve the (B) organic peroxide loading levels typically used in polyolefin curing. Furthermore, the inventive homogeneous mixtures can be cured to achieve improved cure and mechanical properties compared to those obtained from comparative examples made by a conventional two-stage process involving melt-blending polyolefin solids with all additives (except the organic peroxide) at 120°C to obtain an intermediate blend, followed by extrusion and pelletizing of the resulting strands at 150°C / 170°C / 190°C / 195°C, and soaking the pellets in the organic peroxide at elevated temperatures (70°C) for extended periods (typically 8-10 hours). Indeed, it can be concluded that the acoustic mixing method of the present invention reduces organic peroxide decomposition during the preparation of the inventive homogeneous mixtures compared to the comparative melt-blended / dipped mixtures, as evidenced by the lower starting ML and final MH values ​​and higher MH-ML values ​​obtained by curing the inventive homogeneous mixtures using a moving die rheometer. Consequently, it can also be seen that a higher degree of crosslinking is achieved in the inventive homogeneous mixtures compared to the comparative melt-blended / dipped mixtures. This advantage of the present invention is also reflected in the inventive cured products, which have lower elongation-to-break values ​​(i.e., higher crosslinking) than the comparative cured products.

[0116] Mechanical testing of CE2 was not performed because the cure characteristics of the sample indicated a lack of crosslinking, as shown by the data for CE2 in Table 1. This result for CE2 demonstrates that the comparative methods involving mechanical or physical mixing of (A) polyolefin solids and (B) organic peroxides without melting the (A) polyolefin solids or allowing time for the (B) organic peroxide to soak into the unmolten (A) polyolefin solids are problems solved by the method of the present invention, which involves applying acoustic energy to achieve acoustic mixing.

[0117] Hypothetical Example: Preparation of a Coated Conductor. A homogeneous mixture of pelletized IE1 of the present invention is introduced into a wire coating extrusion line to produce a coated wire having a coating consisting essentially of IE1 as a wire structure on a 14 AWG solid copper wire, or a crosslinked product produced by curing it. The wire coating extrusion line is composed of a BRABENDER 1.9 cm extruder with variable speed drive, a 25:1 standard PE screw, a BRABENDER crosshead wire die, a laboratory water-cooled trough with air wipes, a laser micrometer, and a variable speed wire puller. Samples are extruded to a wall thickness of 0.76 millimeters (mm, 30 mils) at a screw speed of 40 rpm. Wire is produced using a set temperature profile of 160°C / 170°C / 180°C / 190°C across Zone 1, Zone 2, Zone 3, and the head / die, respectively, with a take-up speed of 3.1 meters per minute (10 feet per minute). The coating on the wire consists essentially of the homogeneous mixture of IE1 and the crosslinked product thereof, which is obtained by curing the homogeneous mixture of IE1. If necessary, the wire can be passed through a vulcanizing tube set at a curing temperature of 220°C to sufficiently cure the homogeneous mixture to obtain a wire having a coating thereon, which coating consists essentially of the crosslinked product of IE1.

Claims

1. 1. A method for making a homogeneous mixture of polyolefin solids and an organic peroxide without melting the polyolefin solids during its preparation, comprising applying acoustic energy at a frequency of 20 to 100 Hertz (Hz) to a heterogeneous mixture comprising said (A) polyolefin solids and said (B) organic peroxide, while maintaining a temperature of said heterogeneous mixture (and, for that matter, a temperature of a homogeneous mixture made therefrom) below the melting temperature of said (A) polyolefin solids, for a period of time sufficient to substantially mix said (A) polyolefin solids and said (B) organic peroxide together, thereby making said homogeneous mixture without melting said (A) polyolefin solids, wherein said (A) polyolefin solids and said (B) organic peroxide are 95.0 to 99.9 weight percent (wt %) and 0.1 to 5.0 wt %, respectively, of the combined weight of components (A) and (B).

2. 2. The method of claim 1, wherein the step of applying acoustic energy is characterized by any one of limitations (i)-(v): (i) the frequency is 50-70 Hz; (ii) the duration is 0.5 minutes to 4 hours; (iii) both (i) and (ii); (iv) maintaining the temperature of the heterogeneous mixture below the melting temperature of the (A) polyolefin solid comprises maintaining the temperature of the heterogeneous mixture at -20°C to 109°C; and (v) both of (iv) and any one of (i)-(iii).

3. 3. The method of claim 1 or 2, wherein the (A) polyolefin solid is characterized by a physical form (i.e., solid particulate form) that is a powder, a granule, a pellet, or a blend of any two or more thereof, and a melting temperature that is from 61° C. to 180° C., and the (B) organic peroxide is a liquid organic peroxide or a solid organic peroxide.

4. 4. The method of any one of claims 1 to 3, wherein the polyolefin of the (A) polyolefin solid consists essentially of one or more ethylene-based polymers, each ethylene-based polymer being a low density polyethylene (LDPE) polymer or a combination of a LDPE polymer and a polyolefin selected from the group consisting of a second LDPE polymer, a linear low density polyethylene polymer, and a high density polyethylene polymer.

5. The method according to any one of claims 1 to 4, wherein the organic peroxide is a solid organic peroxide.

6. 6. The method of any one of claims 1 to 5, wherein the heterogeneous mixture further comprises one or more additives that are not the (A) polyolefin solid or the (B) organic peroxide, and the step of applying acoustic energy comprises applying acoustic energy at a frequency of 20 to 100 Hertz (Hz) to the heterogeneous mixture comprising the (A) polyolefin solid, the (B) organic peroxide, and the one or more additives that are not peroxide-free, for a period of time sufficient to substantially mix together (thoroughly or completely homogenize) the (A) polyolefin solid, the (B) organic peroxide, and the one or more additives, while maintaining a temperature of the heterogeneous mixture below the melting temperature of the (A) polyolefin solid, thereby creating the homogeneous mixture further comprising the one or more additives without melting the (A) polyolefin solid.

7. 7. The method of claim 6, wherein at least one of the one or more additives that is not component (A) or (B) is independently a liquid or particulate solid additive selected from additives (C)-(D): liquid or particulate solid (C) antioxidants, and liquid or particulate solid (D) stabilizers for stabilizing the homogeneous mixture against the effects of ultraviolet light and / or heat.

8. 8. The method of claim 7, wherein the one or more additives comprise one or more of solid antioxidant (C)-1: tris[(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)methyl]-1,3,5-triazine-2,4,6-trione, solid antioxidant (C)-2: distearyl thiodipropionate, and solid stabilizer (D)-1: N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine.

9. 9. The method of any one of claims 1 to 8, further comprising the steps of melting the (A) polyolefin solid to form a melt thereof, mechanically blending the melt of (A) with one or more additives that are not organic peroxides to obtain a (B) organic peroxide-free molten mixture prior to the step of applying acoustic energy, shaping the molten mixture to obtain a shaped molten mixture, cooling the shaped molten mixture to obtain an (A) polyolefin solid comprising one or more additives, and combining the (A) polyolefin solid comprising one or more additives with the (B) organic peroxide to obtain a heterogeneous mixture.

10. 10. The method of any one of claims 1 to 9, further comprising curing the homogeneous mixture to obtain a crosslinked homogeneous product.

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