MXPA99005388A - Cable resistant to a - Google Patents

Abstract

A composition comprising: (i) polyethylene and, based on 100 parts by weight of component (i), (ii) about 0.3 to 0.6 parts by weight of 4,4-thiobis (2-methyl-6-t) -butylphenol), 4,4-thiobis (2-t-butyl-5-methylphenol), 2,2-thiobis (6-t-butyl-4-methylphenol), or a mixture of these compounds and (iii) about 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the approximate range of 1000 to 100.0

Description

CABLE RESISTENTEALAGUA Technical Field This invention relates to an insulated electrical power cable with a polyethylene composition, which has improved resistance to "water trees". BACKGROUND INFORMATION A typical electric power cable comprises one or more conductors in a cable core, which is surrounded by several layers of polymeric material, including a first semiconductive protective layer, an insulating layer, a second semiconductive protective layer, a protective tape or metallic wire, and a wrap. These isolated cables are known to suffer from shortened life when installed in an environment where the insulation is exposed to water, for example, underground cables or in high humidity locations. The shortened life has been attributed to the formation of "water trees", which occur when an organic polymeric material is subjected to an electric field for a prolonged period of time, in the presence of water, in liquid or vapor form. The formation of water trees is thought to be caused by the complex interaction of an electric field of alternating current (AC), humidity, time and the presence of ions. The net result is a reduction in the dielectric strength of the insulation. Many solutions have been proposed to increase the resistance of organic insulating materials to degradation by the formation of water trees. One solution involves the addition of polyethylene glycol, as a water tree growth inhibitor, to a low density polyethylene, as described in U.S. Patent No. 4,305,849. An improvement in electrical performance is provided by U.S. Patent No. 4,440,671. The combined teachings of these patents, however, leave room for improvements in processability, for example, in scorch resistance and in transpiration.

Disclosure of the Invention Therefore, it is an object of this invention to provide a polyethylene composition, which demonstrates an exemplary process capability in converting it to a cable insulation, in terms of resistance to scorching and transpiration, and supplying a resistance, commercially acceptable, to the formation of water trees and to the aging by heat. Other objects and advantages will become evident later.

In accordance with the invention, a composition has been discovered which complies with the above object. This composition comprises: (i) polyethylene and, based on 100 parts in that of component (i), (ii) about 0.3 to 0.6 parts by weight of 4,4'-thiobis (2-methyl-6-t) -butylphenol), 4,4'-thiobis (2-t-butyl-5-methylphenol); 2,2'-thiobis (6-t-butyl-4-methylphenol); or a mixture of these compounds and (i) about 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the range of about 1000 to 100,000.

Description of Preferred Modality (s) Polyethylene, according to that term used herein, refers to an ethylene homopolymer or a copolymer of ethylene and a minor proportion of one or more α-olefins, which have from 3 to 12 carbon atoms and preferably from 4 to 8 carbon atoms and, optionally, a diene, or a mixture of such homopolymers and copolymers. The mixture can be a mechanical mixture or a mixture in situ.

Examples of α-olefins are propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.

The polyethylene can be homogeneous or heterogeneous. The homogeneous polyethylenes usually have a polydispersity (Mw / Mn) (weight average molecular weight / number average molecular weight) of about 1.5 to 3.5 and an essentially uniform comonomer distribution, and are characterized by simple and relatively low melting points by the DSC (Differential Scanning Calorimetry). On the other hand, heterogeneous polyethylenes have a polydispersity (Mw / Mn) greater than 3.5 and do not have a distribution comonomer uniform. The Mw is defined as the weight average molecular weight and the Mn is defined as the number average molecular weight. The polyethylenes can also have a density in the range of 0.860 to 0.950 grams per cubic centimeter and preferably have a density in the range of about 0.870 to 0.930 grams per cubic centimeter. They can also have a melt index in the approximate range of 0.1 to 50 grams per 10 minutes. Polyethylenes can be produced by processes at low or high pressure. They are preferably produced in the gas phase, but can also be produced in the liquid phase in solutions or aqueous pastes by conventional techniques. Low pressure processes are typically carried out at pressures below 70 kg / cm2, while high pressure processes are typically carried out at pressures above 1050 kg / cm2. Typical catalytic systems that can be used to prepare these polyethylenes are the catalyst systems based on magnesium / titanium, which can be exemplified by the catalyst system described in U.S. Patent No. 4,302,565 (heterogeneous polyethylenes); vanadium-based catalyst systems, such as those described in U.S. Patent Nos. 4,508,842 (heterogeneous polyethylenes) and 5,332,793; 5,342,907 and 5,410,003 (homogeneous polyethylenes); a chromium-based catalyst system, such as that described in U.S. Patent No. 4,101,445; a metallocene catalyst system, such as that described in U.S. Patent Nos. 4,937,299 and 5,317,036 (homogeneous polyethylenes); or other transition metal catalyst systems. Many of these catalyst systems are often referred to as Ziegler-Natta catalyst systems or Phillips catalyst systems. Catalyst systems using chromium or molybdenum oxides on silica-alumina supports can be included here. Typical processes for preparing polyethylenes are also described in the aforementioned patents.

Typical polyethylene mixtures in situ and processes and catalyst systems for supplying them are described in U.S. Patent Nos. 5,371,145 and 5,405,901. The various polyethylenes can include ethylene low density homopolymers, obtained by high pressure processes (HP-LDPE), linear low density polyethylenes (LLDPE), very low density polyethylenes (VLDPE), medium density polyethylenes. (MDPE) and high density polyethylenes (HDPE) that have a density greater than 0.940 grams per cubic centimeter. The last four polyethylenes are generally obtained by low pressure processes. A conventional high pressure process is described in Introduction to Polymer Chemistry, by Stille, ile and Sons, New York, 1962, pages 149 to 151. High pressure processes are typically polymerizations initiated by free radical, conducted in a reactor tubular or in a shaking autoclave. In this agitated autoclave, the pressure is in the approximate range of 700 to 2100 kg / cm2 and the temperatures are in the approximate range of 175 to 250SC, and in the tubular reactor, the pressure is in the approximate range of 1750 to 3150 kg / cm2 and temperatures are in the approximate range of 200 to 3502C.

The VLDPE can be a copolymer of ethylene and one or more α-olefins having from 3 to 12 carbon atoms and preferably from 3 to 8 carbon atoms. The density of the VLDPE can be in the range of 0.870 to 0.915 grams per cubic centimeter. It may be produced, for example, in the presence of (i) a catalyst containing chromium and titanium, (ii) a catalyst containing magnesium, titanium, a halogen and an eron donor; or (iii) a vanadium containing catalyst, an eron donor, an alkyl aluminum halide modifier and a halocarbon promoter. Catalysts and processes for obtaining the VLDPE are described, respectively, in the patents of the United States of America Nos. 4,101,445, 4,302,565 and 4,508,842. The VLDPE melt index may be in the approximate range of 0.1 to 20 grams per 10 minutes and is preferably in the approximate range of 0.3 to 5 grams per 10 minutes. The portion of the VLDPE attributed to the comonomers, in addition to the ethylene, may be in the range of about 1 to 49 weight percent, based on the weight of the copolymer and is preferably in the approximate range of 15 to 40 weight percent . A third comonomer may be included, for example another α-olefin or a diene, such as ethylidene norbornene, butadiene, 1,4-hexadiene, or a dicyclopentadiene. Copolymers of ethylene / propylene and ethylene / propylene / diene terpolymers are generally referred to as EPR and the terpolymer is generally referred to as EPDM. The third comonomer may be present in an amount of about 1 to 15 weight percent, based on the weight of the copolymer and is preferably present in an amount of about 1 to 10 weight percent. It is preferred that the copolymer contains two or three comonomers, including ethylene. LLDPE may include VLDPE and MDPE, which are also linear, but generally have a density in the range of 0.916 to 0.925 grams per cubic centimeter. It may be a copolymer of ethylene and one or more α-olefins having from 3 to 12 carbon atoms and preferably from 3 to 8 carbon atoms. The melt index may be in the range of approximately 1 to 20 grams per 10 minutes, and is preferably in the range of approximately 3 to 8 grams per 10 minutes. The α-olefins may be the same as mentioned above, and the catalysts and processes are also the same, subject to the variations necessary to obtain the desired densities and melt indexes. As mentioned, ethylene homopolymers obtained by a conventional high pressure process are included in the definition of polyethylene. The homopolymer preferably has a density in the range of 0.910 to 0.930 grams per cubic centimeter. The homopolymer can also have a melt index in the range of approximately 1 to 5 grams per 10 minutes, and preferably has a melt index in the approximate range of 0.75 to 3 grams per 10 minutes. The melt index was determined according to ASTM D-1238, Condition E. It was measured at 190ac and is 2160 grams. Component (ii) is 4,4'-thiobis (2-methyl-6-t-butylphenol); 4,4'-thiobis- (2-t-butyl-5-methylphenol); 2,2'-thiobis) 6-t-butyl-4-methylphenol); or a mixture of these compounds. The amount of component (ii) that may be in the composition of the invention is in the range of about 0.3 to 0.6 parts by weight, based on 100 parts by weight of component (i). It should be noted that this amount is the total amount of component (ii), regardless of whether it is a single compound or a mixture of two or more compounds. Generally, polyethylene glycol is defined by its molecular weight, which may be in the range of about 1000 to 100,000, and preferably is in the range of about 5000 to 35,000. The optimum molecular weight is 20.00 (before the process). Those skilled in the art will understand that the polyethylene glycol process reduces its molecular weight by one-third to one-half. It will also be understood that polyethylene glycol can be in the form of, for example, a copolymer of ethylene glycol and ethylene or in any other form, compound or polymer, which provides the same functionality as polyethylene glycol. Polyethylene glycol is a polar compound, which can be represented by any of the formulas HOCH2 (CH2OCH2) nCH20H or HO (C2H0) nH, where, for example, n can be from 225 to 680. This is transferred in a molecular weight in the approximate range of 10,000 to 35,000. The amount of the polyethylene glycol that may be in the composition is in the approximate range of? 4 to 1 part by weight, based on 100 parts by weight of component (i). It should be understood that, if one or more additional resins are introduced into the composition, the amounts of the components (ii) and (iii) will be based on 100 parts by weight of the total resins in the composition. These resins can be various polyethylenes or polypropylenes or other polymer additives commonly used in wires and cables. Conventional additives, which can be introduced into the polyethylene formulation, are exemplified by antioxidants, coupling agents, ultraviolet absorbers or stabilizers, antistatic agents, pigments, dyes, nucleating agents, reinforcing fillers or polymer additives, slip agents, plasticizers, process aids, lubricants, viscosity control agents, tackifiers, anti-blocking agents, surfactants, diluting oils, metal deactivators, voltage stabilizers, fillers and flame retardant additives, crosslinking agents, agents of impulse and catalysts, and agents that suppress smoke. Fillers and additives can be added in amounts ranging from less than about 0.1 to more than about 200 parts by weight per 100 parts by weight of the base resin, in this case, polyethylene. Examples of antioxidants are clogged phenols, such as tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, bis [(beta- (3,5-diterc.-butyl-4-hydroxybenzyl) ) -methylcarboxyethyl)] sulfide and thiodiethylene-bis (3,5-di-tert-butyl-4-hydroxy) hydrocinnamate; phosphites and phosphonites, such as tris (2,4-di-tert-butylphenyl) phosphite and di-tert.-butylphenylphosphonite; standard compounds, such as dilaurylthiopropionate, dimyristylthiodipropionate and distearylthiodipropionate; several siloxanes; and various amines, such as 2,2,4-trimethyl-1,2-dihydroquinoline and polymerized diphenylamines. The antioxidants can be used in amounts of about 0.1 to 5 parts by weight per 100 parts by weight of the polyethylene. The resin, ie the component (i), can be entangled by the addition of an interlacing agent to the composition or making the resin hydrolyzable, which is achieved by adding hydrolyzable groups, such as -Si (0R) 4, where R it is a hydrocarbyl radical, to the resin structure, through the graft. It is preferred that the resin be entangled and interlaced with an organic peroxide. The entanglement of polymers with free radical initiators, such as organic peroxides, is well known. In general, the organic peroxide is incorporated into the polymer by mixing in molten form in a roller mill, a biaxial screw kneader extruder, or a Banbury ™ or Brabender ™ mixer, at a lower temperature than the initial one, for a decomposition significant peroxide. The peroxides are judged by the decomposition based on the half-life temperatures, as described in the manual Plastic Additives Handbook, Gachter et al, 1985, pages 546 to 649. An alternative method for the incorporation of the organic peroxide into a polymeric compound is mix the liquid peroxide and the polymer pellets in a mixing device, such as the Henschel ™ mixer or a soaking device, such as a simple tumbler, which is maintained at temperatures above the freezing point of the organic peroxide and below of the decomposition temperature of the organic peroxide and the melting temperature of the polymer. Following the incorporation of the organic peroxide, the polymer / organic peroxide mixture is then, for example, introduced in an extruder, where it is extruded around an electrical conductor, at a temperature lower than the decomposition temperature of the organic peroxide, for form a cable. The cable is then exposed to higher temperatures at which the organic peroxide decomposes, to supply free radicals, which intertwine with the polymer. Suitable crosslinking agents are organic peroxides, such as dicumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; t-butyl-cumyl peroxide; and 2,5-dimethyl-2,5-di (t-butylperoxy) hexan-3. Dicumyl peroxide is preferred. Hydrolyzable groups can be added, for example, by grafting an ethylenically unsaturated compound, having one or more Si (OR) 3 groups, such as vinyltrimethoxysilane, vinyltriethoxysilane, and gamma-methacryloxypropyltrimethoxy-silane, to the homopolymer, in the presence of the organic peroxides mentioned above. The hydrolysable resins are then entangled by moisture, in the presence of a silanol condensation catalyst, such as dibutyltin dilaurate, dioctyl tin maleate, dibutyltin diacetate, stannous acetate, lead naphthenate and caprylate. zinc. Dibutyl tin dilaurate is preferred. Examples of hydrolysable grafted copolymers are the ethylene homopolymer grafted with vinyltrimethoxy-silane, ... ethylene homopolymer grafted with vinyltriethoxy-silane, and ethylene homopolymer grafted with vinyl-taxhoxy-silane .... A cable, which uses the composition of the invention can be prepared in various types of extruders, for example of single or double screw types. The composition can be made in the extruder or before extrusion, in a conventional mixer, such as a Brabender ™ mixer or a Banbury ™ mixer. A description of a conventional extruder can be found in U.S. Patent No. 4,857,600. A typical extruder has a hopper at its upstream end and a die at its downstream end. The hopper feeds into a cylinder, which contains a screw. At the downstream end, between the end of the screw and the die, is a screen package and a rupture plate. The screw portion of the extruder is considered to be divided into three sections, the feeding section, the compression section and the dosing section, and two zones, the rear heat zone and the front heat zone, the sections and the zones they go from the upstream end to the downstream end. In the alternative, there may be multiple heating zones (more than two) along the axis running from the upstream end to the downstream end. If there is more than one cylinder, these cylinders are connected in series. The ratio of the length to the diameter of each cylinder is in the approximate range of 15: 1 to 30: 1. In a wire coating, where the material is interlaced with an organic peroxide after extrusion, the crosshead die feeds directly into a heating zone, and this zone can be maintained at a temperature in the approximate range of 130 to 2602C and preferably in the approximate range of 170 to 220sc. The advantages of the invention lie in the improved processing capacity of the composition in a cable, in terms of resistance to scorching and reduction in perspiration. In addition, heat aging and resistance to the growth of water trees are as good as or better than commercially available materials.

In certain polyethylene compositions, 4,4'-thiobis (2-methyl-6-t-butyl-phenol) and 2,2 • thiobis (6-t-butyl-4-methylphenol) have been found to cause color problem, which, despite its scorch inhibition qualities, may be commercially unacceptable. This problem is solved by the addition of hydroquinone or a substituted hydroquinone, in an amount sufficient to inhibit color formation. Its details can be found in a patent application of the United States of America, filed on the same date as the present patent application, by Michael J. Keogh, for A Composition of Interlaced Polyolefin (D-17874), which carries the serial number . The term "surrounded" is applied to a substrate that is surrounded by an insulator composition, wrapping material or other cable layer, and is considered to include extrusion around the substrate; coating the substrate or wrap around the substrate, as is well known to those skilled in the art. The substrate may include, for example, a core including a conductor or a bundle of conductors, or several layers of underlying cables, as mentioned above. Any molecular weight mentioned in this specification refers to the weight-average molecular weight, unless indicated otherwise.

The patents, patent applications and publications mentioned in this specification are incorporated herein by reference. The invention is illustrated by the following examples.

Examples 1 to 17 In the examples, the remainder of each formulation, in percent by weight, is an ethylene homopolymer having a density of 0.92 gram per cubic centimeter and the melt index of 2 grams per 10 minutes, and is prepared by a high pressure process. All amounts are given in percentages by weight, based on the weight of the total formulation. PEG = polyethylene glycol, which has a molecular weight, before the process, of 20,000. Stabilizer A = 4,4'-thiobis- (2-tert-butyl-5-methyl-phenol).

Stabilizer B = 4,4'-thiobis- (2-methyl-6-t-butylphenol). The dicumyl peroxide is present in the formulations of Examples 1 to 7 and 15 to 17, in an amount of 1.95 percent by weight. It is present in the formulation of the example 14 in an amount of 1.75 percent by weight. The resistance of the insulation compositions to the water trees was determined by the method described in U.S. Patent No. 4,144,202. This measurement leads to a value for resistance to water trees, in relation to the standard polyethylene insulation material. The term used for the value is the "water tree growth regime" (WTGR). It was found that this WTGR is at a commercially acceptable level. The homopolymer is composed of PEG in a two-roll mill, which operates at 24 revolutions per minute (rpm) on the front roller and at 36 rpm on the rear roller and at a temperature of 125 to 1302C, on the two rollers, around 10 minutes. The procedure involves preheating the resin to 70SC in an oven; melt the resin as quickly as possible in the two-roll mill (about 3 to 4 minutes); add PEG and 4,4'-thiobis- (2-tert-butyl-5-methyl-phenol) and flux for 3 to 4 additional minutes, and then add the peroxide and flux, peel and fold until well mixed . Sufficient dicumyl peroxide was introduced into each composition to supply an oscillating disc rheometer (an arc of 5 degrees at 1822C), with reading of 53 cm-kg. Each composition was then removed from the two-roll mill as a crepe and cubed and molded into 2.54-cm disks with a thickness of 6.35 mm, in a two-stage press: Initial Stage Final Stage Pressure (kg / cm2) 140 2800 Temperature (° C) 120 175 Residence Time (minutes) 9 15 to 20 Each plate was tested for the WTGR and the results were compared with the control polyethylene composition, which exhibits 100 percent of the WTGR. The variables and results are indicated in Table I.

Table I Example PEG 0.4 0.6 0.8 Stabilizer A 0.4 0.4 0.4 WTGR (%) 40 25 16 The following formulations were prepared in a twin-screw laboratory mixer, using a melt mixing temperature of 200SC, followed by the addition of peroxide, to effect entanglement. The interlaced material was then compression molded using the condition described in the sample preparation of WTGR) into a laboratory plate, from which specimens were prepared in the form of a dog tap, as described in ASTM D-638 . The property of the elongation of the samples was tested without aging and after aging for 2 weeks in an air circulating oven, at a temperature of 150 ° C, followed by ASTM D-638. The criterion of passing this test is to retain more than 75 percent of the elongation properties, after this aging protocol. As shown in Table II, the minimum level of 4,4'-thiobis- (2-tert.-butyl-5-methyl-phenol) necessary to meet this requirement is greater than 0.25 percent by weight. The data show that 0.375 weight percent of 4,4'-thiobis (2-tert-butyl-5-methyl-phenol) meets this criterion, with 0.4 to 0.6 weight percent of PEG. See Table II for variables and results Table II Example PEG 0.4 0.4 0.6 0.6 Stabilizer A 0.25 0.375 0.25 0.375 Retention of 35 95 4 88 Elongation (%) ** ** Retention of the elongation after aging in an oven with circulation of are, at 150 ° C, for 2 weeks.

To measure the singe resistance (prior curing during extrusion) of the ethylene homopolymer, as prepared in Examples 1 to 3, an instrument called the Mobile Die Rheometer (MDR) 2000, described in ASTM D-5289, and A Rubber Process Analyzer (RPA) 2000, manufactured by Alpha Technologies, was used here for illustration. The MDR Mh is the maximum torque that represents the total cure measured in a sample and is directly related to the total amount of active peroxide in the polymer formulations. For the exact comparison of the characteristics of scorching of the material, the MDR Mh must be comparable. The test conditions used to evaluate the total cure by the MDR are: 1822C; 0.5 degree arc; oscillation of 100 cycles per minute; 12 minute test time. The torsion was supplied in kilograms-centimeter. As seen in Table III, the total cure level of Examples 8 and 9 to 13 are approximately comparable. The RPA was used to evaluate the resistance of the material to singeing with the actual extrusion conditions. This test was conducted using 1502C conditions, 2.5 degree arc; oscillation of 200 cycles per minute; 30 minutes test time. The scorch resistance under these simulated extrusion conditions was calibrated by the TsL of the RPA, which is the time required for the torsion to reach 1152 kg-cm (1 lb-in) above the minimum torque. Under these test conditions, the higher the value of Tsl, the greater the resistance to scorching. As can be seen in Table III, formulations with 0.3 percent or more of stabilizer A or B result in a significant improvement in scorch resistance by 18 percent or more. The variables and results are indicated in Table III.

T abla III Eiemolo 8 9 10 11 11 11 PEG 0 0.6 0.4 0.6 0.4 0.6 Stabilizer A 0.18 0.18 0.30 0.375 0 0 Stabilizer B 0 0 0 0 0.30 0.375 DCP * 1.70 1.85 1.90 1.90 2.05 2.20 MDR Mh 3.59 3.76 3.83 3.41 3.59 3.32 (kg-cm) RPA Tsl 9.48 8.19 29.49 33.86 34.28 38.79 (min) * DCP = dicumyl peroxide.

In order to test the perspiration of additives (which emerges on the surface of the pellet), which can cause extrusion problems, such as leakage or variation in diameter, a method involving washing 100 grams of pellets was used. with 100 milliliters of methanol for 1 minute. The methanol was decanted after filtering through a 1 miter polypropylene filter., and analyzed by High Pressure Liquid Chromatography (HPLC) for the concentration of 4,4-thiobis- (2-tert-butyl-4-methyl-phenol). As shown in the data, the presence of PEG helped to solubilize 4,4'-thiobis- (2-tert.-butyl-5-methyl-phenol) in the ethylene homopolymer, thus reducing its transpiration by two orders of magnitude, after conditioning at 50SC for 8 weeks. The variables and results are indicated in Table IV.

Table 4 Ej.emp | o - jg - - Stabilizer A 0.18 0.375 0.375 0.375 Transpiration (ppm) ** greater than 600 2 l l ** Stabilizer A perspiration concentration, after a temperature of 50 ° C for 8 weeks, in parts per million (ppm).

Claims (9)

1. CLAIMS 1. A composition comprising: (i) polyethylene and, based on 100 parts by weight of component (i), (ii) about 0.3 to 0.6 parts by weight of the 4,4'-thiobis (2-methyl-6-t-butylphenol), 4,4'-thiobis (2-t-butyl-5-methylphenol); 2,2'-thiobis (6-t-butyl-4-methylphenol); or a mixture of these compounds and (iii) about 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the range of about 1000 to 100,000.
2. 2. The composition defined in claim 1, wherein component (ii) is 4,4-thiobis (2-methyl-6-t-butylphenol).
3. 3. The composition defined in the claim 1, in which component (ii) is 4,4'-thiobis (2-t-butyl-5-methylphenol).
4. 4. The composition defined in claim 1, wherein component (ii) is 2,2'-thiobis (6-butyl-4-ethylphenol).
5. 5. The composition defined in claim 1, wherein the polyethylene glycol has a molecular weight in the range of about 5000 to 35,000.
6. 6. A composition comprising: (i) an ethylene homopolymer, obtained by a high pressure process, having a density in the range of 0.910 to 0.930 grams per cubic centimeter and a melt index in the range of approximately 1 to 5 grams for 10 minutes and, based on 100 parts by weight of component (i), (ii) about 0.3 to 0.6 parts by weight of 4,4'-thiobis (2-methyl-6-t-butylphenol); 4,4'-thiobis (2-t-butyl-5-metlfenol); 2,2'-thiobis (6-t-butyl-4-methylphenol); or a mixture of these compounds; and (iii) about 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the range of about 5000 to 35,000.
7. 7. A cable comprising one or more electrical conductors or a core of electrical conductors, each conductor or core is surrounded by a layer of a composition comprising: (i) the interlaced polyethylene, and, based on 100 parts by weight of the component (i), (ii) about 0.3 to 0.6 parts by weight of the 4,4'-thiobis (2-methyl-6-t-butylphenol), 4,4'-thiobis (2-t-butyl-5-methylphenol); 2,2'-thiobis (6-t-butyl-4-methylphenol); or a mixture of these compounds; and (iii) about 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the range of about 1000 to 100,000.
8. 8. The cable defined in claim 8, wherein the polyethylene glycol has a molecular weight in the range of approximately 5000 to 35,000.
9. 9. A cable comprising one or more electrical conductors or a core of electrical conductors, each conductor or core is surrounded by a layer comprising: (i) an interlaced ethylene homopolymer, obtained by a high pressure process, having a density in the range of 0.910 to 0.930 grams per cubic centimeter and a melt index in the range of approximately 1 to 5 grams per 10 minutes and , based on 100 parts by weight of component (i), (ii) about 0.3 to 0.6 parts by weight of 4,4'-thiobis (2-ethyl-6-t-butylphenol); 4,4-thiobis (2-t-butyl-5-metlfenol); 2,2'-thiobis (6-t-butyl-4-methylphenol); or a mixture of these compounds; and (i) approximately 0.4 to 1 part by weight of a polyethylene glycol, which has a molecular weight in the range of approximately 5000 to 35,000.