A method of making a polymeric composition including organopolysiloxane

Abstract

A method of forming a polymeric composition includes the steps of heating an ethylene-based polymer in a batch mixer to a temperature of 120ºC to 180ºC, adding an organopolysiloxane to the batch mixer, and mixing the organopolysiloxane and the ethylene-based polymer while the ethylene-based polymer is at a temperature of 120ºC to 180ºC to form the polymeric composition.

Description

[0001] A METHOD OF MAKING A POLYMERIC COMPOSITION INCLUDING ORGANOPOLYSILOXANE

[0002] BACKGROUND

[0003] Field of the disclosure

[0004] The present disclosure relates to a method of making a polymeric composition, and more specifically to a method of making a polymeric composition comprising organopolysiloxane.

[0005] Introduction

[0006] Silicone, such as organopolysiloxane and polydimethylsiloxane (“PDMS”), is well known to be used in ethylene-based polymers to reduce the coefficient of friction (“COF”) of the resulting polymeric composition. The reduction in COF of the polymeric composition is advantageous for various application such as wire and cable, film, fiber, and molded parts. However, ethylene-based polymers and silicones are immiscible within each other, and the COF benefits will not materialize if the dispersion of the silicones is not fine and homogenous. The formation of a homogeneous dispersion of silicone in an ethylene-based polymer is traditionally accomplished through a continuous mixing process under high peak shear rate (i.e., 500 1 / s or greater) and high temperature (e.g., 200°C or greater) to overcome the immiscibility of the silicone and the ethylene-based polymer. Low temperature processes are believed to result in the silicone simply sliding along the mixing elements and not mixing within the polyethylene. In practice, the traditional mixing is accomplished by utilizing a gear pump to inject the molten silicone at high pressures into a continuous twin screw extruder at temperatures above 200°C. For example, United States patent number 9,527,988 B2, which is directed to the production of a blend of polyolefin and organopolysiloxane, uses a gear pump to move melted silicone gum into a co-rotative twin screw extruder at a temperature of 200°C to 230°C in order to produce its inventive examples 1 and 2. The gear pump is used because it can generate pressures sufficiently high to overcome the pressure of the high shear rate twin extruder.

[0007] The traditional method described above suffers from several drawbacks though. First, the high pressure required by the gear pump to overcome the shear rate of the twin screw means that minor weight percents (e.g., less than 25 weight percent or less of silicone) cannot be added to the ethylene-based polymer. Rather, the resulting mixture often has 25 weight percent or more of the silicone. Such a high concentration of the silicone (i.e., “overloading”) leads an unconfined yield strength sufficiently high to causing pellets formed from the composition to agglomerate and block feed ports of machines used to process the pellets. An unconfined yield strength of about 4000 Pa or greater for pellets is sufficient to cause blocking. Secondly, an additional manufacturing step is required to address the issues created by the pellet agglomeration of the first issue. For example, the mixture needs to be re-blended with more polyolefin in a second step in order to lower the silicone content to a level that will not result in pellet blocking. Such an additional step adds additional manufacturing cost and complexity.

[0008] In view of the foregoing, it would be surprising to discover a process for making a polymeric composition comprising organopolysiloxane at a temperature of less than 200°C yet produces pellets with an unconfined yield strength of less than 4000 Pa.

[0009] SUMMARY OF THE DISCLOSURE

[0010] The inventors of the present application have found a process for making a polymeric composition comprising organopolysiloxane at a temperature of less than 200°C yet produces pellets with an unconfined yield strength of less than 4000 Pa.

[0011] The invention is the result of discovering that a batch mixer can make polymeric compositions having a low dosage of organopolysiloxane dispersed in an ethylene-based polymer in a one-step process at a melt temperature of less than 200°C. Without being bound by theory, it is believed that by mixing the organopolysiloxane and the ethylene-based polymer at a temperature of less than 200°C, the silicone remains solid enough that it does not simply slip along the mixing blades and can be incorporated whereas at temperature of 200°C and above it is sufficiently liquid. This allows low shear rate batch mixers to be used which overcomes the organopolysiloxane overloading issue and therefore the resulting polymeric composition has the target organopolysiloxane concentration and a second step of adding more ethylene-based polymer is not needed.

[0012] According to a first feature of the disclosure, a method of forming a polymeric composition comprising the steps of heating an ethylene-based polymer in a batch mixer to a temperature of 120°C to 180°C; adding an organopolysiloxane to the batch mixer; and mixing the organopolysiloxane and the ethylene-based polymer while the ethylene -based polymer is at a temperature of 120°C to 180°C to form the polymeric composition.

[0013] According to another feature of the disclosure, the method further comprises the step of pelletizing the polymeric composition, wherein no additional ethylene-based polymer is added to the polymeric composition after the mixing step and before pelletizing the polymeric composition. According to another feature of the disclosure, the ethylene-based polymer has a density of 0.980 g / cc or less as measured according to ASTM D792.

[0014] According to another feature of the disclosure, the ethylene-based polymer has a melt index (I2) of 1.0 g / lOmin or less as measured according to ASTM D1238.

[0015] According to another feature of the disclosure, the organopolysiloxane is polydimethylsiloxane.

[0016] According to another feature of the disclosure, the organopolysiloxane has a weight average molecular weight of 400,000 g / mol to 750,000 g / mol as measured according to Gel Permeation Chromatography.

[0017] According to another feature of the disclosure, the pelletized polymeric composition comprises 0.1 wt% to 30 wt% of the organopolysiloxane based on the total weight of the pelletized polymeric composition.

[0018] According to another feature of the disclosure, the pelletized polymeric composition comprises 0.1 wt% to 5 wt% of the organopolysiloxane based on the total weight of the pelletized polymeric composition.

[0019] According to another feature of the disclosure, the step of mixing the organopolysiloxane and the ethylene-based polymer is performed at a peak shear rate of 500 1 / s or less.

[0020] According to another feature of the disclosure, the step of mixing the organopolysiloxane and the ethylene-based polymer is performed at a peak shear rate of 300 1 / s or less.

[0021] DETAILED DESCRIPTION

[0022] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0023] All ranges include endpoints unless otherwise stated.

[0024] Test methods refer to the most recent test method as of the priority date of this document unless a date is indicated with the test method number as a hyphenated two-digit number. References to test methods contain both a reference to the testing society and the test method number. Test method organizations are referenced by one of the following abbreviations: ASTM refers to ASTM International (formerly known as American Society for Testing and Materials); IEC refers to International Electrotechnical Commission; EN refers to European Norm; DIN refers to Deutsches Institut fur Normung; and ISO refers to International Organization for Standards.

[0025] As used herein, the term weight percent (“wt%”) designates the percentage by weight a component is of a total weight of the polymeric composition unless otherwise specified.

[0026] Melt index (I2) values herein refer to values determined according to ASTM method DI 238 at 190 degrees Celsius (°C) with 2.16 Kilogram (kg) mass and are provided in units of grams eluted per ten minutes (“g / 10 min”).

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

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

[0029] Method

[0030] The present disclosure is generally directed to a method of making a polymeric composition. Although separate steps of the method are detailed below, the steps may be performed in any order or simultaneously without departing from the teachings provided herein. The method may begin with a step of heating an ethylene-based polymer in a batch mixer at a temperature of 120°C to 180°C. As used herein, the term “batch mixer” means a mechanical apparatus having a heated mixing vessel inside which one or more mixing blades are rotated. The batch mixer is configured to melt and mix a polymeric material, and optionally other ingredients, within the vessel as a single batch and then discharge the entire batch. As such, the mixer is non-continuous because it does not continuously mix and discharge the polymeric composition, but rather each batch must be melted, mixed and discharged separately from each other.

[0031] The ethylene-based polymer may be heated to a temperature of 120°C or greater, or 130°C or greater, or 140°C or greater, or 150°C or greater, or 160°C or greater, or 170°C or greater, while at the same time, 180°C or less, or 170°C or less, or 160°C or less, or 150°C or less, or 140°C or less, or 130°C or less. The ethylene-based polymer may be added to the batch mixer at ambient temperature, at an elevated temperature, or at a temperature where it is already molten. The step of heating the ethylene-based polymer encompasses both heating the ethylene-based polymer to cause melting and to keep an already molten ethylene-based polymer in its molten state.

[0032] Next, a step of adding an organopolysiloxane to the batch mixer is performed. The organopolysiloxane may be added to the batch mixer while the ethylene-based polymer is at a temperature of 120°C to 180°C or it may be added to the batch mixer with the ethylene-based polymer and heated to 120°C to 180°C. The organopolysiloxane may be added in a single drop, or may be divided and added over time.

[0033] Next, a step of mixing the organopolysiloxane and the ethylene-based polymer while the ethylene-based polymer is at a temperature of 120°C to 180°C to form the polymeric composition is performed. As noted above, by mixing the organopolysiloxane and the ethylenebased polymer at a temperature below about 200°C, the organopolysiloxane is efficiently mixed and the overloading problem is avoided. The mixing step occurs at a temperature of from 120°C or greater, or 130°C or greater, or 140°C or greater, or 150°C or greater, or 160°C or greater, or 170°C or greater, while at the same time, 180°C or less, or 170°C or less, or 160°C or less, or 150°C or less, or 140°C or less, or 130°C or less.

[0034] The step of mixing the organopolysiloxane and the ethylene-based polymer may be performed at a peak shear rate of 500 1 / s or less. In mixing, shear rate is the rate of change in velocity at which one layer of fluid passes over an adjacent layer. As highlighted above, the prior art typically requires that the organopolysiloxane be in liquid form (i.e., at a temperature of over 200°C) such that a gear pump can be used to overcome the high shear rates of twin screw extruders. The mixing of the organopolysiloxane and the ethylene-based polymer may be performed at a shear rate of 500 1 / s or less, or 450 1 / s or less, or 400 1 / s or less, or 350 1 / s or less, or 300 1 / s or less, or 250 1 / s or less, or 200 1 / s or less, or 150 1 / s or less, or 100 1 / s or less.

[0035] The method may further comprise a step of pelletizing the polymeric composition. Pelletizing of the polymeric composition may be accomplished in a variety of manners such as through hot die cutting, water ring pelletizing, underwater pelletizing, strand pelletizing, belt conveyor pelletizing, twin-screw extruder pelletizing, drop pelletizing and other methods. As highlighted above, an advantage of the presently disclosed method is that the organopolysiloxane overloading issue is not present and therefore no additional ethylene-based polymer needs to be added to the polymeric composition after the mixing step and before pelletizing the polymeric composition. As used herein, the phrase “no additional ethylenebased polymer” means that any additional polymer added between the mixing and pelletizing step is not added to purposely reduce the organopolysiloxane content and if it does the overall organopoly siloxane in the polymeric composition is not reduced by greater than 10 wt% based on the total weight of the polymeric composition.

[0036] Ethylene-based polymer

[0037] As noted above, the polymeric composition comprises the ethylene-based polymer. The ethylene-based polymer may be a linear low-density polyethylene (“LLDPE”), a low-density polyethylene (“LDPE”), a medium-density polyethylene (“MDPE”) or a high-density polyethylene (“HDPE”). As used herein, a “linear” ethylene-based polymer is defined as an ethylene / a-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C3-C10 a-olefin comonomer or at least one C4-C8 a-olefin comonomer, or at least one C6-C8 a-olefin comonomer. Linear polymers are characterized by little, if any, long chain branching, in contrast to polyethylene (co)polymers made in a high-pressure process.

[0038] As used herein, “ethylene-based” polymers are polymers in which greater than 50 wt% of the monomers are ethylene though other co-monomers may also be employed. Ethylenebased polymers include ethylene and one or more C3-C20 a-olefin comonomers such as propylene, 1 -butene, 1 pentene, 4-methyl-l -pentene, 1 -hexene, and 1 -octene. The ethylenebased polymer may be produced in a gas phase polymerization reactor or in a solution or slurry phase reactor.

[0039] The ethylene-based polymer may comprise 50 wt% or greater, 60 wt% or greater, 70 wt% or greater, 80 wt% or greater, 85 wt% or greater, 90 wt% or greater, or 91 wt% or greater, or 92 wt% or greater, or 93 wt% or greater, or 94 wt% or greater, or 95 wt% or greater, or 96 wt% or greater, or 97 wt% or greater, or 97.5 wt% or greater, or 98 wt% or greater, or 99 wt% or greater, while at the same time, 99.5 wt% or less, or 99 wt% or less, or 98 wt% or less, or

[0040] 97 wt% or less, or 96 wt% or less, or 95 wt% or less, or 94 wt% or less, or 93 wt% or less, or

[0041] 92 wt% or less, or 91 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or

[0042] 70 wt% or less, or 60 wt% or less of ethylene monomers as measured using Nuclear Magnetic

[0043] Resonance (NMR) or Fourier-Transform Infrared (FTIR) Spectroscopy.

[0044] Other units of ethylene-based polymers may be derived from one or more polymerizable monomers including, but not limited to, polar monomers such as unsaturated esters. The unsaturated esters (i.e. polar monomers) may be alkyl acrylates, alkyl methacrylates, or vinyl carboxylates. The alkyl groups can have from 1 to 8 carbon atoms, or from 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8 carbon atoms, or from 2 to 5 carbon atoms. Examples of acrylates and methacrylates include, but are not limited to, ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, and 2 ethylhexyl acrylate. Examples of vinyl carboxylates include, but are not limited to, vinyl acetate, vinyl propionate, and vinyl butanoate. The ethylene-based polymer may have a polar comonomer content of 40 wt% or less, or 35 wt% or less, or 30 wt% or less, or 25 wt% or less, or 20 wt% or less, 15 wt% or less, or 10 wt% or less, or 5 wt% or less, or 3 wt% or less, or 1 wt% or less, or 0 wt% based on the total weight of the ethylene-based polymer as measured using Nuclear Magnetic Resonance (NMR) or Fourier-Transform Infrared (FTIR) Spectroscopy.

[0045] The ethylene-based polymer can have a unimodal or a bimodal molecular weight distribution and can be used alone or in combination with one or more other types of ethylenebased polymers (e.g., a blend of two or more ethylene-based polymers that differ from one another by monomer composition and content, catalytic method of preparation, molecular weight, molecular weight distributions, densities, etc.). If a blend of ethylene-based polymers is employed, the polymers can be blended by any in-reactor or post-reactor process. The term “multimodal polymer” refers to polymers that are characterized by having at least two distinct peaks in a gel permeation chromatography (GPC) chromatogram depicting the molecular weight distribution of the composition. Accordingly, the generic term multimodal polymer includes bimodal polymers, which have two primary fractions: a first fraction, which may be a low molecular weight fraction and / or component, and a second fraction, which may be a high molecular weight fraction and / or component.

[0046] The polymeric composition may comprise from 40 wt% to 99.9 wt% of the ethylenebased polymer based on a total weight of the polymeric composition. For example, the polymeric composition may comprise 40 wt% or greater, or 45 wt% or greater, or 50 wt% or greater, or 55 wt% or greater, or 60 wt% or greater, or 65 wt% or greater, or 70 wt% or greater, or 75 wt% or greater, or 80 wt% or greater, or 85 wt% or greater, or 90 wt% or greater, or 95 wt% or greater, or 99 wt% or greater, while at the same time, 99.9 wt% or less, or 95 wt% or less, or 90 wt% or less, or 85 wt% or less, or 80 wt% or less, or 75 wt% or less, or 70 wt% or less, or 65 wt% or less, or 60 wt% or less, or 55 wt% or less, or 50 wt% or less, or 45 wt% or less of the of the ethylene-based polymer based on a total weight of the polymeric composition.

[0047] The density of the ethylene-based polymer may be from 0.901 g / cc to 0.980 g / cc as measured according to ASTM D792. For example, the density of the ethylene-based polymer may be 0.901 g / cc or greater, or 0.905 g / cc or greater, or 0.910 g / cc or greater, or 0.915 g / cc or greater, or 0.920 g / cc or greater, 0.925 g / cc or greater, or 0.930 g / cc or greater, or 0.935 g / cc or greater, or 0.940 g / cc or greater, or 0.945 g / cc or greater, or 0.950 g / cc or greater, or 0.955 g / cc or greater, or 0.960 g / cc or greater, or 0.965 g / cc or greater, or 0.970 g / cc or greater, or 0.975 g / cc or greater, or while at the same time, or 0.980 g / cc or less, or 0.975 g / cc or less, or 0.970 g / cc or less, or 0.965 g / cc or less, or 0.960 g / cc or less, or 0.955 g / cc or less, or 0.950 g / cc or less, or 0.945 g / cc or less, 0.940 g / cc or less, or 0.935 g / cc or less, or 0.930 g / cc or less, or 0.925 g / cc or less, or 0.920 g / cc or less, or 0.915 g / cc or less, or 0.910 g / cc or less, or 0.905 g / cc or less as measured according to ASTM D792.

[0048] The ethylene-based polymer may have a melt index (I2) of 0. 1 g / 10 min to 3.0 g / 10 min. as measured according to ASTM D1238. For example, the ethylene-hased polymer may have a melt index (I2) of 0.1 g / 10 min or greater, or 0.2 g / 10 min or greater, or 0.3 g / 10 min or greater, or 0.4 g / 10 min or greater, or 0.5 g / 10 min or greater, or 0.6 g / 10 min or greater, or 0.7 g / 10 min or greater, or 0.8 g / 10 min or greater, or 0.9 g / 10 min or greater, 1.0 g / 10 min or greater, or 1.1 g / 10 min or greater, or 1.2 g / 10 min or greater, or 1.3 g / 10 min or greater, or 1.4 g / 10 min or greater, or 1.5 g / 10 min or greater, or 1.6 g / 10 min or greater, or 1.7 g / 10 min or greater, or 1.8 g / 10 min or greater, or 1.9 g / 10 min or greater, or 2.0 g / 10 min or greater, or 2.1 g / 10 min or greater, or 2.2 g / 10 min or greater, or 2.3 g / 10 min or greater, or 2.4 g / 10 min or greater, or 2.5 g / 10 min or greater, or 2.6 g / 10 min or greater, or 2.7 g / 10 min or greater, or 2.8 g / 10 min or greater, or 2.9 g / 10 min or greater while at the same time, 3.0 g / 10 min or less, or 2.9 g / 10 min or less, or 2.8 g / 10 min or less, or 2.7 g / 10 min or less, or 2.6 g / 10 min or less, or

[0049] 2.5 g / 10 min or less, or 2.4 g / 10 min or less, or 2.3 g / 10 min or less, or 2.2 g / 10 min or less, or

[0050] 2.1 g / 10 min or less, or 2.0 g / 10 min or less, or 1.9 g / 10 min or less, or 1.8 g / 10 min or less, or

[0051] 1.7 g / 10 min or less, or 1.6 g / 10 min or less, or 1.5 g / 10 min or less, or 1.4 g / 10 min or less, or

[0052] 1.3 g / 10 min or less, or 1.2 g / 10 min or less, or 1.1 g / 10 min or less, or 1.0 g / 10 min or less, or

[0053] 0.5 g / 10 min or less as measured according to ASTM D1238.

[0054] Organopolysiloxane

[0055] The method includes adding an organopolysiloxane to the ethylene-based polymer to form the polymeric composition. The organopolysiloxane may be polydimethylsiloxane. The organopolysiloxane may be unsubstituted or substituted. In PDMS examples of the organopolysiloxane, a “substituted PDMS” is a PDMS in which at least one methyl group of the PDMS is substituted with a substituent. Nonlimiting examples of substituents include halogen atoms (such as chlorine, fluorine, bromine, and iodine); halogen atom-containing groups (such as chloromethyl groups, perfluorobutyl groups, trifluoroethyl groups, and nonafluorohexyl groups); oxygen atom-containing groups (such as hydroxy groups, alkoxy groups (such as methoxy groups and ethoxy groups), (meth)acrylic epoxy groups, and carboxyl groups); nitrogen atom-containing groups (such as amino-functional groups, amido-functional groups, and cyano-functional groups); sulphur atom-containing groups (such as mercapto groups); hydrogen; C2-C10 alkyl groups (such as an ethyl group); C2-C10 alkynyl groups; alkenyl groups (such as vinyl groups and hexenyl groups); aryl groups (such as phenyl groups and substituted phenyl groups); cycloalkyl groups (such as cyclohexane groups); and combinations thereof. The substituted methyl group may be a terminal methyl group or a nonterminal methyl group. Nonlimiting examples of suitable substituted PDMS include trialkylsilyl terminated PDMS wherein at least one alkyl is a C2-C10 alkyl; dialkylhydroxysilyl terminated PDMS; dialkylhydrogensilyl terminated PDMS; dialkylalkenyl silyl terminated PDMS; dialkylvinylsilyl terminated PDMS, dimethylhydroxysilyl terminated PDMS, and dimethylvinylsilyl terminated PDMS.

[0056] The organopolysiloxane has a weight average molecular weight of 400,000 g / mol to 750,000 g / mol as measured according to Gel Permeation Chromatography described in greater detail below. For example, the organopolysiloxane may have a weight average molecular weight of 400,000 g / mol or greater, or 450,000 g / mol or greater, or 500,000 g / mol or greater, or 550,000 g / mol or greater, or 560,000 g / mol or greater, or 570,000 g / mol or greater, or 580,000 g / mol or greater, or 590,000 g / mol or greater, or 600,000 g / mol or greater, or 610,000 g / mol or greater, or 620,000 g / mol or greater, or 630,000 g / mol or greater, or 640,000 g / mol or greater, or 650,000 g / mol or greater, or 660,000 g / mol or greater, or 670,000 g / mol or greater, or 680,000 g / mol or greater, or 690,000 g / mol or greater, or 700,000 g / mol or greater, or 710,000 g / mol or greater, or 720,000 g / mol or greater, or 730,000 g / mol or greater, or 740,000 g / mol or greater, while at the same time, 750,00 g / mol or less, or 700,000 g / mol or less, or 650,00 g / mol or less, or 640,000 g / mol or less, or 630,000 g / mol or less, or 620,000 g / mol or less, or 610,000 g / mol or less, or 600,000 g / mol or less, or 590,000 g / mol or less, or 580,000 g / mol or less, or 570,000 g / mol or less, or 550,000 g / mol or less, or 500,000 g / mol or less, or 450,000 g / mol or less as measured according to Gel Permeation Chromatography.

[0057] The polymeric composition may comprise from 0.1 wt% to 30 wt% of the organopolysiloxane. For example, the polymeric composition may comprise 0.1 wt% or greater, or 0.5 wt% or greater, or 1 wt% or greater, or 2 wt% or greater, or 3 wt% or greater, or 4 wt% or greater, or 5 wt% or greater, or 10 wt% or greater, or 15 wt% or greater, or 20 wt% or greater, or 25 wt% or greater, while at the same time, 30 wt% or less, or 25 wt% or less, or 20 wt% or less, or 15 wt% or less, or 10 wt% or less, or 5 wt% or less, or 4 wt% or less, or 3 wt% or less, or 2 wt% or less, or 1 wt% or less, or 0.5 wt% or less of the organopolysiloxane based on the total weight of the polymeric composition. Additives

[0058] The polymeric composition may include one or more additives. Nonlimiting examples of suitable additives include antioxidants, colorants, corrosion inhibitors, lubricants, ultraviolet (UV) absorbers or stabilizers, anti-blocking agents, flame-retardants, coupling agents, compatibilizers, plasticizers, fillers, processing aids, and combinations thereof. The one or more additives may be combined with a polyethylene resin to form a masterbatch such that a portion or all of the additives may be introduced to the polymeric composition in one or more masterbatches.

[0059] The polymeric composition may include an antioxidant. Nonlimiting examples of suitable antioxidants include phenolic antioxidants, thio-based antioxidants, phosphate-based antioxidants, and hydrazine-based metal deactivators. Suitable phenolic antioxidants include high molecular weight hindered phenols, methyl-substituted phenol, phenols having substituents with primary or secondary carbonyls, and multifunctional phenols such as sulfur and phosphorous-containing phenol. Representative hindered phenols include 1,3,5-trimethyl- 2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene; pentaerythrityl tetrakis-3(3,5-di-tert- butyl-4-hydroxyphenyl)-propionate; n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)- propionate; 4,4'-methylenebis(2,6-tert-butyl-phenol); 4,4'-thiobis(6-tert-butyl-o-cresol); 2,6- di-tertbutylphenol;6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-l,3,5 triazine; di-n- octylthio)ethyl 3,5-di-tert-butyl-4-hydroxy-benzoate; and sorbitol hexa[3-(3,5-di-tert-butyl-4- hydroxy-phenyl)-propionate]. The polymeric composition may include pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), commercially available as Irganox™ 1010 from BASF. A nonlimiting example of a suitable methyl-substituted phenol is isobutylidenebis(4,6-dimethylphenol). A nonlimiting example of a suitable hydrazine-based metal deactivator is oxalyl bis(benzylidiene hydrazide). The polymeric composition may contain from 0 wt%, or 0.001 wt%, or 0.01 wt%, or 0.02 wt%, or 0.05 wt%, or 0.1 wt%, or 0.2 wt %, or 0.3 wt %, or 0.4 wt% to 0.5 wt%, or 0.6 wt %, or 0.7 wt%, or 0.8 wt %, or 1.0 wt %, or 2.0 wt%, or 2.5 wt%, or 3.0 wt% antioxidant, based on total weight of the polymeric composition.

[0060] The composition may include a processing aid. Nonlimiting examples of suitable processing aids include oils, organic acids (such as stearic acid), and metal salts of organic acids (such as zinc stearate). In an embodiment, the composition contains from 0 wt%, or 0.01 wt%, or 0.02 wt%, or 0.05 wt%, or 0.07 wt%, or 0. 1 wt%, or 0.2 wt %, or 0.3 wt %, or 0.4 wt% to 0.5 wt%, or 0.6 wt %, or 0.7 wt%, or 0.8 wt %, or 1.0 wt %, or 2.0 wt%, or 2.5 wt%, or 3.0 wt%, or 5.0 wt%, or 10.0 wt%, or 20.0 wt% processing aid, based on total weight of the composition.

[0061] Coated Conductor

[0062] The present disclosure is useful to form a coated conductor. The coated conductor includes a conductor and a coating on the conductor, the coating including the polymeric composition. The polymeric composition is at least partially disposed around the conductor to produce the coated conductor. The conductor may comprise a conductive metal or an optically transparent structure.

[0063] The process for producing a coated conductor includes mixing and heating the pelletized polymeric composition to at least the melting temperature of the polymeric components in an extruder to form a polymeric melt blend, and then coating the polymeric melt blend onto the conductor. The term "onto" includes direct contact or indirect contact between the polymeric melt blend and the conductor. The polymeric melt blend is in an extrudable state.

[0064] The polymeric composition is coupled to and / or around the conductor to form a coating. The coating may be one or more inner layers such as an insulating layer. The coating may wholly or partially cover or otherwise surround or encase the conductor. The coating may be the sole component surrounding the conductor. Alternatively, the coating may be one layer of a multilayer jacket or sheath encasing the conductor. The coating may directly contact the conductor. The coating may directly contact an insulation layer surrounding the conductor.

[0065] Examples

[0066] Materials

[0067] The following materials were used in the formation of the inventive examples (“IE”) and the comparative examples (“CE”).

[0068] EPl is an ethylene-based polymer having a density of 0.935 g / cc and a melt index (I ) of 0.7 dg / min. and is commercially available as AXELERON™ FO 6549 NT CPD from The Dow Chemical Company, Midland, Michigan.

[0069] EP2 is a linear low density ethylene-based polymer having a density of 0.92 g / cc and a melt index (b) of 0.65 dg / min and is commercially available as DFH-2065 GP from The Dow Chemical Company, Midland, Michigan.

[0070] SI is polydimethylsiloxane having a weight average molecular weight of 550,000 g / mol to 660,000 g / mol and is commercially available as XIAMETER™ RBG-0900 from The Dow Chemical Company, Midland, Michigan. PEG is polyethylene glycol having a weight average molecular weight of 20,000 g / mol, is used as a processing aid, and is commercially available as POLY GLYKOL™ 20000 P from Clariant Specialty Chemicals, Muttenz, Switzerland.

[0071] CBMB is a carbon black masterbatch comprising 45 wt% carbon black in an ethylenebased polymer and is commercially available as AXELERON™ GP A-0037 BK from The Dow Chemical Company, Midland, Michigan.

[0072] AO1 is an antioxidant blend commercially available as IRGANOX™ B225 from BASF, Ludwigshafen, Germany.

[0073] AO2 is a polymeric antioxidant commercially available as UVASORB™ HA10 from 3V Sigma USA, Georgetown, South Carolina, USA.

[0074] AO3 is an oligomeric stabilizer is sold under the tradename UVASORB™ HA88 from 3V Sigma USA, Georgetown, South Carolina, USA.

[0075] Test Methods

[0076] Density: Density was tested according to ASTM D792.

[0077] Unconfined Yield Strength: The blocking tendency of the pelletized polymeric composition was measured by the unconfined yield strength test. This test includes a sintering portion and a compression testing portion. The sintering portion is accomplished by placing 100 gram of pelletized polymeric composition sample into a cylindrical cell having an internal diameter of 5.08 cm and a height of 16.5 cm. A sheet of Polytetrafluoroethylene was added to the cell to prevent sticking of the pellets. A 2.7 kg weight was placed on top of the pellets in the cell and the combined cell and weight were sintered in an oven at 45 °C for 1 month. After the sintering time had elapsed, the cells were removed from the oven and allowed to condition in ambient temperatures for 24 hours. The samples were removed from the cells and an Instron compression tester was used to test the unconfined yield stress test. The reported unconfined yield stress is the stress required to initiates the breakup of agglomerate to the point where the same began to collapse. The reported values are the average of 5 duplicate sample tests.

[0078] Gel permeation chromatography: Weight average molecular of the organopolysiloxane is measured by GPC (Viscotek™ GPC Max) using a triple detection capability. The Viscotek™ TDA305 unit is equipped with a differential refractometer, an online differential pressure viscometer, and low angle light scattering (LALS: 7° and 90° angles of detection). The mobile phase is Toluene HPLC grade. The columns are two PL Gel Mixed C from Varian-(7.5*300 mm, 5 pm particle size) and a PL Gel Guard column from Varian-(7.5*300 mm) 5 fractom Injection volume with a flow of 1 mL / min and a run time of 37 min. The column and detector temperature is 40°C. The software used is Omnisec 4.6.1 (Viscotek™ ). The detectors are calibrated by injection of a narrow polystyrene standard (Mw 68,100 g / mol) of a known concentration.

[0079] Peak shear rate: Peak shear rate is calculated according to equation 1 where D is rotor or screw diameter, rpm is the rotor or screw speed in revolutions per minute, h is the clearance between the tip of the rotor or screw and the barrel wall of the mixer.

[0080] Sample Preparation

[0081] CE1 and CE2 were prepared using a twin-screw extruder. The EPl was melted to a temperature of 238°C in the twin screw extruder and mixed at a rate of 360 revolutions per minute (“RPM”) for a shear rate of 1400 1 / s. A MAAG EXTREX™ Pump 70-3SP gear pump was used to mix the SI into the polyolefin of the samples. CE1 was then pelletized using a GALA™ underwater pelletizer at a temperature of 55°C.

[0082] IE1 was made in a type 01-38-000 BR AB ENDER™ batch mixer at a peak shear rate of 150 1 / s. For IE1, the ethylene polymer resin and additive were added to the batch mixer and melted at a temperature of 150°C. After the ethylene polymer resin and additives were completely melted, the silicone was fed into the melted resin. Residence time in the batch mixer was approximately 7 minutes. IE2-IE5 were made in a BANBURY™ batch mixer at 70 rpm and a peak shear rate of 258 1 / s. For IE2-IE5, the ethylene polymer resin and additives were added to the batch mixer and melted at a temperature of 135°C. After the ethylene polymer resin and additives were completely melted, the silicone was fed into the melted resin and the temperature was increased to 150°C. Residence time in the batch mixer was approximately 7 minutes. Results

[0083] Table 1 provides the example composition, and the unconfined yield strength for the associated example.

[0084] Table 1

[0085] Referring now to Table 1 , CE1 was prepared via the twin screw extruder and gear pump. During mixing, the organopolysiloxane melted before the resin and the mixture slipped without advancing through the extruder. CE2 performed as expected in that the pure ethylene-based polymer did not exhibit an unconfined yield strength meaning that the pellets were free flowing. Referring now to IE1-IE5, it is clear that the inventive process is capable of making a polymeric composition comprising organopolysiloxane at a temperature of less than 200°C yet produces pellets with an unconfined yield strength of less than 4000 Pa. IE1 demonstrates that high- density polyethylene may be used in the inventive process. IE1 and IE2 demonstrate that the inventive process is capable of producing compositions with high organopolysiloxane concentrations. IE3-IE5 demonstrate that the inventive process is also capable of making polymeric compositions with minor organopolysiloxane amounts (i.e., less than 5 wt%) without an additional ethylene-based polymer dilution step.

Claims

CLAIMSWhat is claimed is1. A method of forming a polymeric composition comprising the steps of: heating an ethylene-based polymer in a batch mixer to a temperature of 120°C to 180°C; adding an organopolysiloxane to the batch mixer; and mixing the organopolysiloxane and the ethylene-based polymer while the ethylenebased polymer is at a temperature of 120°C to 180°C to form the polymeric composition.

2. The method of claim 1, further comprising the step of: pelletizing the polymeric composition, wherein no additional ethylene-based polymer is added to the polymeric composition after the mixing step and before pelletizing the polymeric composition.

3. The method of any one of claims 1 and 2, wherein the ethylene-based polymer has a density of 0.980 g / cc or less as measured according to ASTM D792.

4. The method of any one of claims 1-3, wherein the ethylene-based polymer has a melt index (I2) of 1.0 g / lOmin or less as measured according to ASTM D1238.

5. The method of any one of claims 1-4, wherein the organopolysiloxane is polydimethylsiloxane.

6. The method of any one of claims 1-5, wherein the organopolysiloxane has a weight average molecular weight of 400,000 g / mol to 750,000 g / mol as measured according to Gel Permeation Chromatography.

7. The method of any one of claims 1-6, wherein the pelletized polymeric composition comprises 0.1 wt% to 30 wt% of the organopolysiloxane based on the total weight of the pelletized polymeric composition.

8. The method of claim 7, wherein the pelletized polymeric composition comprises 0.1 wt% to 5 wt% of the organopolysiloxane based on the total weight of the pelletized polymeric composition.

9. The method of any of claims 1-8, wherein the step of mixing the organopolysiloxane and the ethylene-based polymer is performed at a peak shear rate of 500 1 / s or less.

10. The method of claims 9, wherein the step of mixing the organopolysiloxane and the ethylene-based polymer is performed at a peak shear rate of 300 1 / s or less.

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