AU2014204538A1 - Improved Lead-Free Insulation Compositions Containing Metallocene Polymers - Google Patents

Abstract

Novel additive systems for lead-free filled cable insulation are disclosed. These systems provide improved electrical and mechanical properties. The base polymer may be metallocene based, non metallocene based or combinations thereof The additives may contain one or more hindered amine light stabilizers, mercapto compounds, and optionally, amine antioxidants. 5576815_1 (GHMatters) P77809.AU.2 MCAMP

Description

IMPROVED LEAD-FREE INSULATION COMPOSITIONS CONTAINING METALLOCENE POLYMERS [0001] This claims priority under 35 U.S.C. §119(e) to Ser. No. 60/729,735, filed October 25, 2005. FIELD OF THE INVENTION [0002] The invention relates to lead-free insulation compositions for electric power cables. BACKGROUND OF THE INVENTION [0003] Typical power cables generally have one or more conductors in a core that is surrounded by several layers that can include: a first polymeric semiconducting shield layer, a polymeric insulating layer, a second polymeric semiconducting shield layer, a metallic tape shield and a polymeric jacket. [0004] Polymeric materials have been utilized in the past as electrical insulating and semiconducting shield materials for power cables. In services or products requiring long-term performance of an electrical cable, such polymeric materials, in addition to having suitable dielectric properties, must be durable. For example, polymeric insulation utilized in building wire, electrical motor or machinery power wires, or underground power transmitting cables, must be durable for safety and economic necessities and practicalities. 1 5576815_1 (GHMatters) P77809.AU.2 MCAMP 100051 One major type of failure that polymeric power cable insulation can undergo is the phenomenon known as treeing, Treeing generally progresses through a dielectric section under electrical stress so that, if visible, its path looks something like a tree. Treeing may occur and progress slowly by periodic partial discharge. It may also occur slowly in the presence of moisture without any partial discharge, with moisture and discharge, or it may occur rapidly as the result of an impulse voltage. Trees may form at the site of a high electrical stress such as contaminants or voids in the body' of the insulation-seniconductive screen interface. in solid organic dielectrics, treeing is the most likely mechanism of electrical failures, which do not occur catastrophically, but rather appear to be the result of a more lengthy process. In the past, extending the service life of polymeric insulation has been achieved by modifying the polymeric materials by blending, grafting, or copolymerization of silane-based molecules or other additives so that either trees are initiated only at higher 'voltages than usual or grow more slowly once initiated. '0006] There are two kinds of treeing known as electrical treeing and water treeing. Electrical treeing results from internal electrical discharges that decompose the dielectric. High voltage impulses can produce electrical trees. The damage, which results from the application of moderate alternating current voltages to the electrode/insulation interfaces, which can contain irperfections, is commercially significant. In this case, very high, localized stress gradients can exist and with sufficient time can lead to initiation and growth of trees. An example of this is a high voltage power cable or connector with a rough interface between the conductor or conductor shield and the primary insulator. The failure mechanism involves actal breakdown of the modular structure of the dielectric material, perhaps by electron bombardment, In the past much of the art has been concerned with the inhibition of electrical trees, 2 [0007} In contrast to electrical treeing, which results from internal electrical discharges that decompose the dielectri, water treeing is the deterioration of a solid dielectric material, which is simultaneously exposed to liquid or vapor and an electric field, Buried power cables are especially vulnerable to water treeing. Water trees initiate from sites of high electrical stress such as rough interfaces, protruding conductive points, voids, or inibedded contaminants, but at lower voltages than that required for electrical trees. In contrast to electrical trees, water trees have the following distinguishing characteristics; (a) the presence of water is essential for their growth; (b) no partial discharge is nonnally detected during their initiation; (c) they can grow for years before reaching a size that may contribute to a breakdown; (d) although slow growing, they are initiated and grow in much lower electrical fields than those required for the development of electrical trees. [0008] Electrical insulation applications are generally divided into low voltage insulation (less than I K volts), medium voltage insulation (ranging from I K volts to 65 K volts), and high voltage insulation (above 65 K volts). In low to medium voltage applications, for example, electrical cables and applications in the automotive industry, electrical treeing is generally not a pervasive problem and is far less common than water treeing, which frequently is a problem. For medium-voltage applications, the most common polymeric insulators are made from either polyethylene homopolymers or ethylene-propylene elastomers, otherwise known as ethylene propylene-rubber (EPR) or ethylene-propylene-diene ter-polymer (EPDM). [00091 Polyethylene is generally used neat (without a filler) as an electrical insulation material. Polyethylenes have very good dielectric properties, especially dielectric constants and power factors (Tangent Delta). The dielectric constant of polyethylene is in the range of about 2.2 to 2.3. The power factor, which is a function of electrical energy dissipated and lost and should be 3 as low as possible, is around 0,0002 at room temperature, a very desirable value. The mechanical properties of polyethylene polymers are also adequate for utilization in many application as medi-voltage insulation although they are prone to deformation at high temperatures. However, polyethylene homopolymers are very prone to water treeing, especially toward the upper end of the mediunm-voltage range. [00101 There have been attempts to make polyethylene-based polymers that would have long tern electrical stability. For example, when dicurnyl peroxide is used as a crosslinking agent for polyethylene, the peroxide residue functions as a tree inhibitor for some time after curing However, these residues are eventually lost at most temperatures where electrical power cable is used. U.S. Pat, No. 4,144,202 issued Mar. 13, 1979 to Ashoraft, et a. discloses the incorporation into poiyethylenes of at least one epoxy containing organo-silane as a treeing inhibitor. However, a need still exists for a polymeric insulator having improved treeing resistance over such silane containing polyethylenes. 100111 Unlike polyethylene, which can be utilized neat, another common medium-voltage insulator, EPR, typically contains a high level of filler in order to improve thennal properties and reduce cost. When utilized as a mediui-voltage insulator, EPR will generally contain about 20 to about 50 weight percent filler, usually calcined clay, and is preferably crosslinked with peroxides, The presence of the filler gives EPR a high resistance against the propagation of trees. EPR also has mechanical properties which are superior to polyethylene at elevated temperatures. [00 121 Unfortunately, while the fillers utilized in EPR may help prevent treeing, the filled EPR will generally have poorer dielectric properties, i.e. a poorer dielectric constant and a poor power factor. The dielectric constant of filled EPR is in the range of about 2.3 to about 2.8. Its 4 power factor is on the order of about 0.002 to about 0.005 at room temperature, which is approximately an order of magnitude worse than polyethylene. [0013] Thus, both polyethylenes and EPR have serious limitations as an electrical insulator in cable applications, Although polyethylene polymers have good electric properties, they have poor water tree resistance. While filled EPR has good treeing resistance and good mechanical properties, it has dielectric properties inferior to polyethylene polymers. [0014] Power factor increases with temperature. in addition it may continue to increase with time at high temperatures. Under writers Labs MvfV105 rated cables must be able to survive 21 days at an emergency circuit overload temperature of 140'C with less th an a 10% increase in Dissipation factor. Filled EPR insulations are usually used in these applications. [00151 Another class of polymers is described in EP-A-0 341 644 published Nov. 15, 1989. This reference describes linear polyethylenes produced by a traditional Ziegler-Natta catalyst system. They generally have a broad molecular Weight distribution similar to linear low density polyethylene and at low enough densities can show better tree retardancy. However, these linear-type polymers in the wire and cable industry have poor melt flow characteristics and poor processability. in order to achieve a good mix in an extruder, linear polymers must be processed at a temperature at which the peroxides present in the polymer prematurely crosslink the polymers, a phenomenon conunonly referred to as scorch. If the processing temperatare is held low enough to avoid scorch, incomplete melting occurs because of the higher melting species in linear polymers having a broad molecular weight distribution. This phenomenon results in poor mixing, surging extruder pressures, and other poor results, [00161 Newer metallocene polyethylene co-polymers are more flexible and have been proposed for use as cable insulation but they also have generally poorer thermal stability, and 5 may deform when exposed to high heat. They also suffer from higher electrical loss with AC current which may be measured by a factor called tan delta. [0017] Polyethylene is the lowest cost insulation polymer for power cables but is the least flexible, Flexibility is desirable for installing cables in confined or limited spaces such as underground ducts, tunnels, manholes and in complex switching stations and transfonner banks. EPR and EPDM are the most flexible insulation polymers but are higher in cost. Metallocene EPR, BPDM, ethylene-octenes, and ethylene-butenes have the desired flexibility at a lower cost. 10018) 1,2-dihydro-2-2-4 trimethylquinolines or "TMQs" are preferred antioxidants for filled LV, NMV or BV cable insulations because of their good thermal degradation protection, low interference with the widely used peroxide cure systems and low cost. TMQs are not used in polyethylene insulation because of their propensity to cause staining. [00191 Hindered amine light stabilizers or "HALS" are primarily ucd in clear plastic film, sheets or coatings to prevent degradation by light, HALS are used in unfilled polyethylene insulations. They are thought to prevent degradation caused by light emitted by tiny electrical discharges. U.S. Patent No. 5,719,218 discloses an optically transparent polyethylene insulation formulation with a HAL in combination 'with a hydrolyzed ethylene vinyl acetate terpolyner. The compositions disclosed are stated to be useful for the prevention of degradation of the insulation by water trees, [00201 EPDM type insulations have excellent resistance to water trees and have been used for over 30 years in AC cable insulations exposed to wet environments. In wet enviromnents the dielectric loss characteristics of an insulation material may be more important to the end user than thermal stability properties. EPDM type insulation are also proven to perform in high 6 temperature service in urban power networks. In these environments thennal stability may be most important to the end user. Filled insulations are opaque so they do not suffer from degradation caused by light emitted by tiny electrical discharges. (00211 -Metallocene polymers have shown much higher resistance to water trees than polyethylene but are not widely used as medium or high voltage AC cable insulation due to their higher AC loss, generally poorer thermal degradation resistance and higher cost than polyethylene. Metallocene polymers do have good acceptance of fillers and can be used for flexible, low temperature, low voltage or DC insulations, Unfilled polyethylene compositions such as those disclosed in U.S. Patent No, 5,719,218 are prone to staining when certain additives such as TMQ are present, as discussed above. WO 02/29829 uses the unfilled polyethylene composition disclosed in U.S. Patent No. 5,719,218 in an unfilled strippable insulation composition which contains a tetramethylpiperidine hindered amine light stabilizer additive. [00221 Therefore, a need exists in the electrical cable industry for an additive system that improves tie performance of filled insulation compositions including those using metallocene polyners as a base polymer or component of the base polymer. [00231 The inventions disclosed and claimed in conimonly assigned U.S, Patent No. 6,825,253, make use of lead containing fillers. European Patent Specification EP 1192624B1 discloses the well known concept that lead compounds are added to the insulating compositions for electric cables to prevent water trees, while also acknowledging the need to provide substantially lead-free insulation compositions for electric cables. EP 1192624B1 proposes the use of a specific elastomer terpolymer containing 5-yinyl-2-norbornene to provide an 7 insulation composition substantially free of lead or its derivatives with satisfactory stability of dielectric strength over time along with resistance to the formation of water trees. [0024] A need exists in the electrical cable industry for an additive system that improves the performance of lead-free filled insulation composition including those using metallocene polymers as a base polymer or component of the base polymer, without the use of special or custom polymers such as elastomer terpolymer containing 5-vinyl-2-norbornene as the base resin. SUMMARY OF THE INVENTION [0025] One aspect of the invention provides a lead-free insulation composition for electric cable comprising: (a) a base polymer comprising 20% to 99% by weight of a metallocene polymer and 1% to 80% by weight of a non-metallocene polymer; (b) a filler; and, (c) an additive comprising (i) an antioxidant, and (ii) a hindered amine light stabilizer; wherein no ingredients containing substantial amounts of lead have been added to said composition. [0025a] Another aspect of the invention provides a lead-free insulation composition for electric cable comprising: (a) a base polymer comprising 20% to 99% by weight of a metallocene polymer and 1% to 80% by weight of a non-metallocene polymer; (b) a filler; and, (c) at least one hindered amine light stabilizer; wherein no ingredients containing substantial amounts of lead have been added to said composition. [0026] In a third aspect, the invention provides a lead-free insulation composition for electric cable comprising a base polymer comprising (a) a base polymer comprising either (i) at least one metallocene polymer, or (ii) at least one non-metallocene polymer or (iii) a combination thereof; (b) a filler; and (c) an additive comprising either (i) at least one hindered amine light stabilizer, or (ii) at least one mercapto compound, or (iii) a combination thereof; wherein no ingredients containing substantial amounts of lead have been added to said composition. In one embodiment amine antioxidant may also be added to the composition of the invention as a further additive. [0027] Thus in an embodiment of the third aspect of the invention the base polymer may comprise at least one non-metallocene polymer. In other embodiments of the third aspect of the invention, the insulation composition base polymer may comprise at least one metallocene polymer. In further embodiments of the third aspect of the invention, the base polymer may comprise at least one non-metallocene polymer and at least one metallocene polymer. In further embodiments of the third aspect of the invention, the base polymer may comprise .20% to 99% 8 5576815_1 (GHMatters) P77809.AU.2 MCAMP by weight metallocene polymer and 1 % to 80% by weight non-metallocene polymer, and the additive may be from about 0.25% to about 2.5% by weight of said insulation composition, preferably from about 0.5% to about 1.5% by weight of said insulation composition. [0027a] In yet another aspect of the invention there is provided a lead-free insulation composition for electric cable comprising: (a) a base polymer; and (b) a filler; (c) at least one mercapto compound; wherein no ingredients containing substantial amounts of lead have been added to said composition. [0027b] In yet another aspect of the invention there is provided a lead-free insulation composition for electric cable comprising: (a) a base polymer; and (b) a filler; (c) at least one mercapto compound; wherein no ingredients containing substantial amounts of lead have been added to said composition, and said base polymer comprises at least one metallocene polymer selected from the group consisting of metallocene EP, metallocene EPDM, metallocene ethylene-butene and metallocene ethylene-octene, and mixtures thereof BRIEF DESCRIPTION OF THE DRAWINGS [0028] Figure 1 shows IRK Values for a composition according to the invention in comparison to a composition not in accordance with the invention. [0029] Figure 2 shows SIC values for a composition according to the invention in comparison to a composition not in accordance with the invention. DETAILED DESCRIPTION OF THE INVENTION [0030] The invention particularly relates to polymeric compositions utilizing polyolefins, which compositions have a unique combination of good mechanical properties, good dielectric properties, and good water treeing resistance, as well as a lower melt temperature for improved processability when the compositions include peroxide-containing compounds. The products are extremely useful as lead-free insulation compositions for electric power cables. [0031] In this description the expression "lead-free" can be considered synonymous with "substantially lead-free" and means that lead-containing substances are not added to the compositions and/or insulations of the invention or the cables that use them. The reality must be recognized, however, that trace or negligible amounts of lead or its derivatives or compounds may be present in the constituent materials that make up the insulation composition and the terms "lead-free" and "substantially lead-free" do not exclude this possible presence of 9 5576815_1 (GHMatters) P77809.AU.2 MCAMP trace or negligible amounts. In any event, "lead-free" and "substantially lead-free" can be taken to mean no more than 500 ppm lead in the insulation composition. [00321 The polymers utilized in the protective jacketing, insulating, conducting or semiconducting layers of the inventive cables of the invention may be made by any suitable process which allows for the yield of the desired polymer with the desired physical strength properties, electrical properties, tree retardancy, and melt temperature for processability. [00331 The base polymer in accordance with the invention may comprises either at least one non-metallocene polymer, at least one metallocene polymer or at least one non-metallocene polymer and at least one metallocene polymer. [00341 Metallocene polymers are produced using a class of highly active olefin catalysts Known as metallocenes, which for the purposes of this application are generally defined to contain one or more cyclopentadienyl moiety. The manufacture of metallocene polymers is described in U.S. Patent No. 6,270,856 to Hendewerk, et al, the disclosure of which is incorporated by reference in its entirety. 100351 Metallocenes are well known especially in the preparation of polyethylene and copolyethylene-alpha-olefins. These catalysts, particularly those based on group IV transition metals, zirconium, titanium and hafnium, show extremely high activity in ethylene polymerization. Various fonns of the catalyst system of the metallocene type may be used for polymerization to prepare the polymers used in this invention, including but not limited to those of the homogeneous, supported catalyst type, wherein the catalyst and cocatalyst are together supported or reacted together onto an inert support for polymerization by a gas phase process, high pressure process, or a slarry, solution polymerization process. The metallocene catalysts are also highly flexible in that, by manipulation of the catalyst composition and 10 reaction conditions, they can be made to provide polyolefins with controllable molecular weights from as low as about 200 (useful in. applications such as lube-oil additives) to about I million or higher, as for example in ultra-high molecular weight linear polyethylene. At the same tine, the MWD of the polymers can be controlled from extremely narrow (as in a polydispersity of about 2), to broad (as in a polydispersity of about 8). [00361 Exemplary of the development of these netallocene catalysts for the polymerization of ethylene are U.S. Pat. No, 4,937,299 and EP-A-0 129 368 to Ewen, et al, U.S, Pat. No, 4,808,561 to Weiborn, Jr., and U.S. Pat. No. 4,814,310 to Chang, which are all hereby are fully incorporated by reference. Among other things, Ewen, et al. teaches that the stature of the netallocene catalyst includes an ahunoxane, fored when water reacts with tialkyl aluminum. The alumnoxane complexes with the metallocene compound to form the catalyst. Welbon, Jr, teaches a method of polymerization of ethylene with alpha-oiefins and/or diolefins. Chang teaches a method of making a metallocene alunoxane catalyst system utilizing the absorbed water in a silica gel catalyst support. Specific methods for making ethylene/alpha-olefin copolyners, and ethylenefalpha-olefin/diene terpolymers are taught in U.S. Pat Nos. 4,871,705 (issued Oct 3, 1989) and 5,001,205 (issued Mar. 19, 1991) to Hoel, et al., and in EP-A-0 347 129 published Apr. 8& 1992, respectively, all of which are hereby fully incorporated by reference. [00371 Other cocatalysts may be used with metallocenes, such as trialkylaluminum compounds or ionizing ionic activators, such as tri(n-butyl)anmonium tetra(pentafluorophenyl) boron, which ionize the neutral metallocene compound. Such ionizing compounds may contain an active proton or some other cation such as carbonium, which ionizing the metallocene on contact, forms a metailocene cation associated with (but not coordinated or only loosely 11 coordinated with) the remaining ion of the ionizing ionic compound. Such compounds are described in EP-A-0 277 003 and EP-A-0 277 004, both published Aug. 3, 1988, and are herein filly incorporated by reference. Also, the polymers useful in this invention can be a metallocene catalyst component that is a ionocylopentadienyl compound, which is activated by either an alumoxane or an ionic activator to form an active polymerization catalyst system. Catalyst systems of this type are shown by POT International Publication WO92/00333, published Jan, 9, 1992, U.S. Pat. Nos. 5,096,867 and 5,055,438, EP-A-0 420 436 and WO91/04257 all of which are fully incorporated herein by reference. The catalyst systems described above may be optionally prepolymerized or used in conjunction with an additive component to enhance catalytic productivity. [00381 As previously stated, metallocene catalysts are particularly attractive in making tailored ultra-uniform and super-random specialty copolymers. For example, if a lower density copolymer is being made with a metallocene catalyst such as very low density polyethylene, (VLDPE), an ultra-uniform and super random copolymerization will occur, as contrasted to the polymer produced by copolymerization using a conventional Ziegler-Natta catalyst. in view of the ongoing need for electrical cables having improved mechanical and dielectric properties and improved water treeing, resistance, as well as the need to process these materials at temperatures low enough to allow scorch free processing, it would be desirable to provide products utilizing the high quality characteristics of polyolefins prepared with metallocene catalysts. [0039] The base polymer utilized in the insulation composition for electric cable in accordance with the invention may also be selected from the group of polymers consisting of ethylene polyinerized with at least one comonomer selected from the group consisting of C3 to Co 12 alpha-olefins and C 3 to C 20 polyenes. Generally, the alpha-olefins suitable for use in the invention contain in the range of about 3 to about 20 carbon atoms. Preferably, the alpha oIefins contain in the range of about 3 to about 16 carbon atoms, most preferably in the range of about 3 to about 8 carbon atoms. Illustrative non-limiting examples of such alpha-olefins are propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-dodecene, 100401 Preferably, the polymers utilized in the cables of the invention are either ethylene/alpha-oefin copolymers or ethylene/aipha-olefin/diene terpolyners. The polyene utilized in the invention generally has about 3 to about 20 carbon atoms, Preferably, the polyene has in the range of about 4 to about 20 carbon atoms, most preferably in the range of about 4 to about 15 carbon atoms. Preferably, the polyene is a diene, which can be a straight chain, branched chain, or cyclic hydrocarbon diene. Most preferably the diene is a non conjugated diene. Examples of suitable dienes are straight chain acyclic dienes such as: 1,3 butadiene, 1,4-hexadiene and 1,6-octadiene; branched chain acyclic dienes such as: 5-methyl 1,4-hexadiene, 3,7-dimethyl 6-octadiene, 3,7 -dimethy-1,7-octadiene and mixed isomers of dihydro myricene and dihydroocinene; single ring alicyclic dienes such as: 1,3 cyclopentadiene, 1,4-cylcohexadiene, 1,5-cyclooctadiene and 1,5-cyclododecadiene; and multi ring. alicyclic fused and bridged ring dienes such as: tetrahydroindene, methyl tetrahydroindene, dicyloopentadieno, bicyclo-(22, 1)-hepta-2-5-diene; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as 5-methylene-2morbomene (MNB), 5 prop enyl-2-norbornene, 5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene, 5cyclohexydene-2-norborene, and norbornene. Of the dienes typically used to prepare EPIR's, the particularly preferred dienes are I,4-hexadiene, 5-ethylidene-2-norbomene, 5-vinyllidene 13 2-norbomene, 5-nethylene-2-riorbornene and dicyclopentadiene. The especially preferred dienes are 5-ethyiidene-2-norbomene and 1,4-hexadiene. [0041] In preferred embodiments of the invention, the base polymer comprises metallocene EP, which is an EPR, an EPDM polymer, ethylene-butene, or ethylene-octene, all of which are prepared with metallocene catalysts. In further preferred embodiments of the invention, the base polymer may be rnetallocene EP alone, rmetaliocene EP and at least one other metallocene polymer, or metallocene EP and at least one non-metallocene polymer as described below, in other preferred embodiments of the invention, a metallocene base polymer with at least one hindered amine light stabilizer and an amine antioxidant achieves the objects of the invention, As stated above, however, combinations of factors such as cost and availability of raw materials, -especially metallocene base polymers, and end user requirements for certain environments may dictate certain compositions or cause certain embodimers to be preferred in certain circumstances which under other circumstances they might not be. [00421 As an additional polymer in the base polymer composition, a non-metallocene base polymer may be used having the strutural formula of any of the polyolefins or polyolefin coolymers described above. Ethylene-propylene rubber (EPR), polyethylene, polypropylene or ethylene vinyl acetates having a range of vinyl acetate content of from about 10% to about 40% may all be used in combination with the metallocene polymers in the base polymer to give other desired properties in the base polymer. [0043] in embodiments of the invention, the insulation composition base polymer comprises 20% to 99%by weight metallocene polymer or polymers and 1% to 80% by weight non metallocene polymer or polymers. The additive is present in amounts from about 0.25% to 14 about 2.5% by weight of said composition, preferably from about 0,5% to about 1.5% by weight of said composition. [00441 As described above, the additive in accordance with the invention may comprise at least one hindered amine light stabilizer, and optionally, an amine antioxidant. In further embodiments of the invention, the additive in accordance with the invention comprises at least two hindered amine light stabilizers. In further embodiments of the invention, the additive in accordance with the invention comprises at least two hindered amine light stabilizers and an am ine antioxidant. [00451 Any suitable hindered amine light stabilizer may be used in accordance with the invention, for example, Bis (2,2,6,6 -tetramethyl-4-piperidyl) sebaceate (tinuvin 770); Bis (1,2,2,6,6 -tetramethyl-4-piperidyi) sebaceate + methyl l,2,2,6,6-tetramethy 4-piperidyI sebaceate (tinnvin 765); 1,6-Hexanediamine, N, N' -Bis (2,2,6,6 Atetramethyl-4-piperidyl) polymer with 2,4,6 trichloro-1,3,5-triazine, reaction products with N-butyl 2,2,6,6-tetranethyl 4-piperidinamine (Chimassorb 2020); Decanedioic acid, Bis (2,2,6,6 -tetramethyl--(octyoxy) 4-piperidyl)ester, reaction products with 1,1 -dimethyiethylhydroperoxide and octane (Tinuvin 123); Triazine derivatives (tinuvin NOR 371); Butanedioic acid, dimrethylester. 4 hydroxy 2,2,6,6 -tetramnethyl-piperidine ethanol (Tinuvin 622), 1,3,5-Trazine-2,4,6-tiamine,N,N"1,2 ethane-diyl-bis [4,6-bis-[butyl(1,2,2,6,6pentanethyl-4-piperdinyl)amino]-1,3,5-triazine-2-yl) imnino]-3,1-propanediyl]] bis [N'N" -* dibuty-N',N" bis(2,2,6,6-tetramethy-4-piperidyl) (Chiassorb 119). Chimassorb 944 LD and Tinuvin 622 LD are preferred hindered amine light stabilizers. [00461 As stated above, optionally, any suitable amine antioxidant may be used in accordance with the invention, for example, 1,2-dihydro-2-2-4, trimethylquinoline(Agerite MA , Agerite 15 D, Flectol TMQ), octylated diphenylamine(Agerite Stelite), diphenyl-p-phenylene diamine(Agerite DPPD) , 4,4tdi(1, 1-dimethylbenzyl)-diphenylamine(Naugard 445), ethoxy 1,2-dihydro-2-2-4 trimethylquinoline(Santaflex AW), p,p'-dioctyldiphenylamine(Vanox 12), 2-tert-butylhydroquinone(Eastian TenoxTBHiQ), N-(l,3-dimethyl butyl)-N'-phenyl-p phenylene diamine(Vulcanox 4020), N-phenyi-N'isopropyL-p-phenylene diaaine(Vulcanox 4010), p-phenylene diamine(Wingstay 100), 1,2-dihydro-2-2-4, Trimethylquinoline and diphenylamine-acetone reaction products are preferred amine antioxidants. [00471 As described above, the composition in accordance with the invention may comprise at least mercapto compound either with or without at least one hindered amine light stabilizer, and optionally, with an amine antioxidant. Quite surprisingly the mercapto compounds function in manner similar to a HAL in that the electrical and mechanical properties of no-lead insulation compositions in accordance with the invention are dramatically improved by their presence. it has quite surpisingly been discovered that mercapto compounds do not show such positive results in the presence of lead, only in its absence. {00481 Examples of mercapto compounds are methylmnercaptobenzimidazole, Zinc 2 methylmercaptobenzimidazole (Vanderbilt Vanox ZMTI), zinc salts of 2 methylmercaptabenzimnidazole, methyl-2- methylmercaptobenzimidazole, 2 naercaptotolulimidazole (Vanderbilt Vanox MT1), blends of 4 and 5 methylnercaptobenzirnidazole (Bayer Vulcanox MB2), and blends of 4 and 5 zinc methyhnercaptobenzimidazoie (Bayer Vulcanox ZMB2). [00491 The insulating composition of the invention is filled. An illustrativeexample of a suitable filler is olay, talc (aluminum silicate or magnesium silicate), magnesium aliminuin silicate, magnesium calcium silicate, calcium carbonate, magnesium calcium carbonate, silica, 16 ATH, magnesium hydroxide, sodium borate, calcium borate, kaolin clay, glass fibers, glass p articles, or mixtures thereof In accordance with the invention, the weight percent range for fillers is from about 10 percent to about 60 percent, preferably from about 20 to about 50 weight percent filler, [00501 Other additives commonly employed in the polyolefin compositions utilized in the invention can include, for example, crosslinking agents, antioxidants, processing aids, pigments, dyes, colorants, metal deactivators, oil extenders, stabilizers, and lubricants. [0051] All of the components of the compositions utilized in the invention are usually blended or comounded together rior to their introduction into an extrusion device from which they are to be extruded onto an electrical conductor. The polymer and the other additives and filers may be blended together by any of the techniques used in the art to blend and compound such mixtures to homogeneous masses. For instance, the components may be fluxed on a variety of appsratus including multi-roll mills, screw mills, continuous mixers, compounding extruders and Banbury mixers. [0052] After the various components of the composition are uniformly adnixed and blended together, they are further processed to fabricate the cables of the invention. Prior art methods for fabricating polymer insulated cable .nd wire are well known, and fabrication of the cable of the invention may generally be accomplished any of the various extrusion methods. {00531 In a typical extrusion method, an optionally heated conducting core to be coated is pulled through a heated extrusion die, generally a cross-head die, in which a layer of melted polymer is applied to the conducting core. Upon exiting the die, the conducting core with the applied polymer layer is passed through a heated vulcanizing section, or continuous vulcanizing section and then a cooling section, generally an elongated cooling bath, to cool. 17 Multiple polymer layers may be appnled by consecutive extrusion steps in which an additional layer is added in each step, or with the proper type of die, multiple polymer layers may be applied simultaneously. r0054] The conductor of the invention may generally comprise any suitable electrically conducting material, although generally electrically conducting metals are utilized, Preferably, the metals utilized are copper or alaninum. TFEST PROCEDURES AND SAMPLE PREPARATION [00551 Square 14 gauge copper conductor wires with 30 mils of insulation were extruded with a 20:1 LD Davis standard extruder and a crosshead die and cured in steam at 4004F Eight to ten 25 inch samples of these insulated square conductor wires were placed in a 75*C water bath and energized with 7500 volts. Time to short circuit was recorded. [0056] The purpose of the square conductor is to create an electrical stress concentration at each corner and accelerate time to failure. [0057] Square 14 gauge copper conductor wires with 30 mils of insulation were extruded with a 20:1 LD Davis standard extruder and a crosshead die and cured in steam at 4004P. The wires were prepared and tested in accordance with (ICEA) standard T-22-294. The purpose of this test is to monitor electrical stability over time on insulated wires immersed in water. [0058] The following materials were used: Antioxidants Agerite TM4QJ, Polymerized 1,2-dihydro-2,2,4-rimethylquinoline, Antioxidant, R,.. Vanderbilt Company, Inc, Norwalk, CT. Agerite Superflex, Diphenyiamine-acetone reaction product, R.T. Vanderbilt Company, Inc., Norwalk, CT. is Mercapto Compound Vulcanox ZMB2, zinc nethylmercaptobenzinidazole, Bayer Corp., Akron, OH. Vanox DSTDP, Distearyl thiodipropionate, Secondary Antioxidant, R.T. Vanderbilt TAH) Santovar TAHQ, 2 ,5-Di(tert-amyl)hydroquinone, A, Flexsys Amerikca L.P., Akron, OH HALS Chimassorb 81, 2 -Hydroxy-4-n-octoxybenzophenone, Ciba Specialty Chemicals Corp., Tarrytown, NY Chimassorb 944 LD, Poly[[6-[(1,1,3,3-totramethylbutyl)amino]-.1,3,5-txiazine-2,4-diyli, Ciba Specialty Chemicals Corp., Tarrytown, NY Tinuvin 622 LDI Dinethyl succinate polymer w/ 4 -hydroxy-2,2,6,6,-tertramethyl-

I

piperidiicethanol. Ciba Specialty Chemicals Corp., Tarrytown, NY Tinuvin 783 FDL, 50% by wt Tinuvin 622 and 50% by wt Climassorb 944, Light Stabilizer, Ciba Specialty Chemicals Corp., Tarrytown, NY Polymers Vistalon 1703, Ethylene Propylene Diene Rubber, Polymer, .86 Mg/l, ExxonMobil Chemical Company, Houston, TX. Vistalon 722, Ethylene Propylene Rubber, Polymer, ,86 g'rnl, ExxonMobil Chemical Company, Houston, TX. Engage 8200, Copolyrmer of Ethylene and Octene-1, Polymer, 87 g/mi, Dupont Dow Elastomers L. L. C., Wilmington, DE, Exact 4006, Ethylene-Butene Copolymer, Polymer, .9 g/ln, ExxonMobil Chemical Company, Houston, TX. LDPE, Low-density Polyethylene, Polymer, .92 g/ml, Equistar Chemicals, LP, Houston, TX. Nordel! 37221P Ethylene Propylene Diene Rubber, Polymer, Dow Chemical, Midland, M.T Filler 19 Polyfil, Chemically Treated Anhydrous Aluminum Silicate, Filler, Huber Engineered Materials, Macon, GA Minor Ingredients Recco 140, Paraffin Wax, Processing Aid, R.E. Carroll Inc., Trenton, New Jersey (Silane) A172 - 50G, 50% Vinyl - tris (2 - methoxyethoxy) silane in a 50% elastomeric (EPDM), Coupling Agent, UA Rubber Specialty Chemical Sdn. Bhd., Bukit Mertajanm. Malaysia Zinc Oxide, Activator, U.S. Zinc Corp., Chicago, IL DI-Cup, Dicumyl Peroxide, Cross-Linker, Hercules Incorporated, Wilmington, DE 20 [00591 Lettered examples are comparative examples and numbered examples are examples in accordance with the invention, f0060] Figure I and Figure 2 show the results of the round wire test. The Insu nation Constant and Insulation Resistance remain stable for one year. Prior art formulations without lead would become unstable and short out on. test within 3 months. The Comparative Examples and Examples of the invention in Table I shov the improved heat resistance and electrical properties of the invention with Ethylene Propylene Diene Rubber and Ethylene Propylene Rubber. No Lead Filled Insulation Patent Data Tible I. 'FORMULATION A B 1 C D 3 4 5 6 1 8 9 Vistalon 1703 Zig 900 90.0 90.0 Natta EPDM LIPE DYNHI 1 2020 20 0 20 ,0 20.0 20.0 2 0 20.0 20.0 20 0 20. Polyethylene ------ 0 T i Polyfil WC Clay 50 50 0 50.0 50 50,0! 50.0 5 50.0 500 50 0 AAgrite ). TMQ 15 15 0.8 1_5 1.5 0.8 0 0.8 08[ 08! 0 08J Paraffin Wax 42 4,2 4,2 4._4 4.2 42 -- 2 4.2 42 A172 Silane 0 8 -a 08 0.81 0m O8 08 0. 0.8 0.8 0.8 TRD-90P Red 54 _Le,-ad Azo 66 Zinc 5.0 5.0 5 0 5.0 5.0 5.0 0 5.0 Oxide Vistalon 722 90.0 9o metaliocene EPR - - - Nordell 3722IP 90,0 90.0 90 0 90.0 90.0 900 90 0 Mvetauocene EPDM_____ ____ _ Chisorb228 ___ ______ ______ Chimnasorb 944 -08 8 Tiuvn 123 0__ 8 __ Tinuvin 783 _____ ____ __ _ 08 0.8 Tinivin 622LD _______ 0 81 ___ 0.8 0.8 0, 8__________ 1Dica Dicumyl 2.4 2.4! 2 4 2.4 2.4 2.4 2A 2.4 2A 2. 2.4 Parox de_____ ___.___ __ TOTAL______ 1793_ 168.9 174.0 17 9,3 173.9 174,3 174,0 169,0 169 0 .171 6 174,0 174.0 2r ---- -- ---- - -- 21- MIDR state of 14.0 12.0 22.0 21.0 22.0 19,0 17.0 20.0 120 17.0 17.0 P cure Long retained 7d 90.0 70.0 100.0 68.0 86.0 93.0 87,0 83,0 89,0 95,0 96.0 9 @ 140C Long retained 7d 50.0 Brttle 40,0 40.0 Brittle Brittle 6.0 5,0 10,0 Brittle Brittle Bri @ 150C Initial TD at 1,3 1.0 10 1.3 1,9 1A 2,0 1.4 1.4 1.3 1.3 140C 3 wk aged at 1.4 0.8 0.7 2.2 1,5 1.4 1.1 0.8 1.5 0,9 1 1400 TD [00611 The Comparative Examples and Examples of the invention in Table 2 show the improved heat resistance and electrical properties of the invention with Ethylene Octene and Ethylene Butene copolymers. [0062] The Comparative Examples and Examples of the invention in Table 3 show the improved heat resistance and electrical properties of another embodiment of the invention wi th Ethylene Propylene Diene Rubber and Ethylene Propylene Rubber. 22 Table 2 1 F G 10 11 12 13 gagp 8200 ethylene ctane co polym 90 90 90 90 LDPE 20 26- 20 20 0 20 20 1 PolyfillWC y filler 50 20 5 ___50 50 Parfinprocessaid 2 2 2 2 j 2 2 . 2 TRD90P 5.4 5.4 P (A172>-50 sila5 e s ___I____e0.8 0.8 0.8 0.8 0.8 0,8 0.8 Zinc oxide 3 )85 Agerite resn DTMQ LS LS 0--,8 1- 07 Tinuvin 622LD 9. 0s 0 75 Exact 4006 Ethylene butane copolymer 90 9 90 Chinasorb 944 FDL 1.5 0.8 Santavar TAHQ 0.3 D)Lcup Diumy tPerxide 2.4 2.4 2.4 2,4 2,4 241 2,4 TOTAL 178.6 177.1 166.8 166,8 166.7 1 166.8 167.05 MDR state of cure 6.6 10.7 12.41 13.99 10.45 11,16 11,16 Elong retained 7d @140C 105 97 92 S5 91 86 85 Long retained 7d @1 SOC 70 6 11 9 9 1 initial TD at 140C 36 1.25 118 1.6 16 1.54 1.6 3 wk aged at 140C TD 8.7 1.3 0.9 0.93 1.3 0.99 1 23 Table 3 D 1 14 15 LDyPE DYNy.0 20.0 20.0 20.0 PolyfilWC Clay 50.0 50.0 50- 50.0- Agerite D. TMQ , 4 L. 4 Paraffm wax 4,2 4,2 4.2 4,2 I TRD-90P Red Lead 5.4 54 - IM72 Silane 0,8 0.8 0.8 09 Azo 66 Zin Ox ide 5.0 5.0 5.0 5.0 Nordell 3722IP Metaloen5 PD 90 900 00 M Vistalon 722 metallocene EPR 90.0 1.0 10 LOD L5 Ageitesuerfex0.5 0.5 1.0 -__- Dicup Dieumyl Peroxide 2.4 24 2.4 - TOTAL 79.3 1 180,1 175, 173 5 MDR state of ure 16 13 10 1i Blong retained 7d @140C 65 85 100 100 Long retained 7d @150C 0 30 85 84 Initial TD at 140C L7 2 1.9 1.9 3 wk aged at 140C TD L5 1.7 L5 1 10063) The Comrparative Examples and Examples of the invention in Table 4 show the improved electical life of insulation mat rials of the invention with square wire test data..The purpose of the square conductor is to create an electrical stress concentration at each corner and acceleratetime to failure by water tree growth. Table 4 also shows that the state of cure (MDR) is ifinproved in the embodiments of the invention shown therein, in particular, the use of a mercapto compound in a lead free insulation composition without the use of one or more HALs 24 Table 4 Sqfuare Wire Time to Failure Data K L M N O0 16 V istalon 1703P ------- 45-------- - - - --------- Nordol 3722 - - 45 45 Vktaton 722 4 45 45 Ege24 90 45 45 45 Exact 4006 in bags 45 45 LDPE 20 20 20 20O00 20.00 20,00 20.00 Polyfill _ WC clyfiler 50 50 50 50.00 50.00 50.00 50.00 Parifm process aid 2 2 2 2,00 2.00 2, 200 TRUgMP 5.4 5.4 5.4 ,40 EF (A172)-50 silane 0 0.8 0.8 0,80 0.80 0.8G - M 80 nOxide 5, 5 5 5,0 5 0 5.0 5.0 Agerte resn D 0.8 15 1.5 15 0.8 O's Tinivum 622LD 0.8 ,.80 0.80 Diu2iuyAeod 2A 24 2.4 2.4 1 2.4 2,4 TOTAL 177 772 12. 17 177 ..1 17,l2 1718 -sampieH ED383 E BD383E Control KD6A EDj§§375B7' A43 4728A44 1 711 ^711 1397 110 142 1409 1248 2 769 1116 1463 161 1525 2542 3 1061 1242 1477 273 1662 2557 4 1068 1267 1640 1795 2557 5 1055 15 1 1943 1 L1958 j 5537 6 1242 1397 21841 2 11 4 5902 27 I I 2723 2301 5902 1397 2799 2543 5902 1691 1397 2799 ___-. . . 9 1753 1694 2871 235 6167 10 1875 1699 2898 - 3235 6 3 0 3 [00641 The following Tables list the data used in compiling Figures 1 and 2. 25 SIC Data for I 4723 A44 (80 v/mil) (Example 16 in accordance with the Invent.) SIC1 - SI-2 - 5- C AvgragSIG 8/11/2004 2 88 2.88 239 289 8/17/2004 3-04 M4 3,M 3.04 8/24/2004 1 13 3 2 311 8/31/2004 3.17 316 3,16 3.1 9/14/2004 3 17 3,16 1 3.17 10/5/2004 .2 3 23 3.22 3 2 322 11/2/2004 3.15 3.17 3," 316 1/30/2004 319 3.19 3 -17 12/28/2004 3,18 3,18 3.16 - 3 1 1/25/2005 3263

--

,21 12 3,24 2/22/2005 3.27 3.25 3 25 3/22/2005 3.17 3.17 314 __316 4/19/2005 3.26 3,23 319 3 5/17/2005 3.17 3.20 3.13 34/200q 3.18 3. 1'7 3,14 .16 7/12/2005 318 1 316 3.12 3 15 89/2005 3.17 3.16 3.10 3 14 26 MR Data for El 4728 A43 (Comparatdve Example 0) D IRI R2 IR3 Averge IR IRK 8112004 1900 1800 1800 1633 4723 8/17/2004 1700 1600 1600 1700 4379 8/24/2004 1700 1700 170 1700 4379 8/31/2004 1 1700 1700 1500 16 408 186____ 1 1633 46 9/14/2004 1800 1800 2200 1933 4961 9/21/2004 1600 1500 1500 1533 3950 9/28/2004 1400 1400 1 400 1400 3607 1 0/5/2004 1400 1400 1400 1400 3607 10/12/2004 1400 1400 1300 1367 3521 10/19/2004 1400 1300 1300 1333 3435 I 6i/2006 1300 1300 1200 1267 3263 11/2/2004 300 1200 1200 1 233 3177 11/9/2004 1200 1200 1200 1200 3091 11/16/2004 1200 1200 T 1100 1167 3005 11/23/2004 1300 1200 1200 1233 3177 11/30/2004 1000 1000 990 997 2568 12/7/2004 1100 1100 1 lo0 110 2634 12/114/2004 110 1 100 1000 106;7 48_ '21l2i1/204 1(100 1000 11,00 10 001 2576 100 1100 1100 1100 2734 12121200 V _ ____ 1100 1100__ _ __ 141205 1100 1 00 1100 1133 2920 ' 1/2005 00 1100 1100 1100 2634 8/2005 100 100 970 1023 23 1/25/2005 970 990 980 980 2525 1/2005 1000 950 920 957 2464 2/812005 1000 960 99 990 2550 2/115/200, f 000o 970 970- - 6 2525 2/22/2005 1000 1000 1000 1000 2576 3/1/2005 9597095 940 953 2456 3/6/2005 87S 900 870 880 2 3/15/2005 970 970 950 963 2482 3/22/2005 890 880 860 T77 2258 3900 1000 970 990 2553 4/5/2005 1100 1000 990 1030 2653 4/12/2005 1200 200- - 1200 1200 3091 4/19/2005 940- 960 930 943 2430 4/26/2005 1100 1200 1100 1133 1 2920 5/3/2005 1100 1200 1100 1133 2920 5/10/2005 1500 1500 1400 1467 3778 5/17/2005 H 1100 1100 1100 2834 5/24/2005 j400 1400 1400 1400 3607 5/31/2005 1100 1100 1100 1100 2834 6/7/2005 1300 1300 1300 !300 3349 61'4/205 930 970 940 947 2439 6;21/2005 1200 1200 1200 - 1200 3091 6282005 1300 1300 1300 1300 3349 7/52005 1300 1400 1300 333 3435 2005 [ 1300 1200 1200 1233 3177 7/1912005 1000 1000 90 993 2559 I7/ __0 - 1100 1100 1100 1100 2834 27 1200os 1100 101332920 8/9/2005 1000 100 6 9 2559 3/23/2005 ~ 1300 i 100 1 I200 1273263 28 IR Data for El 4728 A44 (Example 16 in accordance with the Invention) Date IRI IR2 IR3 Averae IR 8/11/2004 100 1100 1100 100 2634 8/11/2004 1100 1100 1100 1100 2634 8/24/2004 1200 1300 1400 1300 3349 8/31/2004 1200 1200 1200 1200 3091 9/14/2004 1500 1500 1600 1533 3950 9/21/2004 1 300 1400 1400 1367 3521 9/28/2004 1300 1300 1300 1300 3349 1015/2004 r 1400 1500 1500 1467 3778 10/12/2004 1400 1500 400 1433 1 3692 10119/2004 1400 1500 1500 1467 3776 10/26/2004 1600 1600 1700 1633 4208 1/2/2004 1600 1600 1600 1300 4122 11/9/2006 1500 1600 1600 1533 3950 11/16/2004 1400 1400 1400 3607 1/2312"'0 180_ 1800 1800 1800 46-7_ 11/3G/2004 500 1600 1600 1567 4036 12/7/2004 1700 1800 1800 ] 1767 4551 12/14/2004 1500 1500 1500 1 1500 3864 12/21/2004 1400 1400 1400 1400 307 12/28/2004 1400 j 1500 1500 1467 3776 1/4/2005 1600 1600 1600 1600 4122 1/11/2005 1700 1700 1600 1667 4294 1/18/2005 2000 2000 4500 2633 7299 1/25/2005 1700 13800 1800 1767 4551 2/1/2005 1700 1800 1800 1767 4551 2/8/2005 1900 1900 2000 1933 4981 2/15/2005 1800 1900 2000 1900 4895 2/22/2005 1800 1800 1900 1633 4723 3/1/2005 1800 1300 1800 1600 4637 318/2005 1600 1600 1700 1633 4208 /15/0 1700 1700 1800 1733 4465 3/22/2005 1500 1500 1700 1567 4036 3/29/2005 1700 1700 100 1733 4465 4/5/2005 1600 1700 1300 1 1700 4379 4/12/2005 1300 190 2000 1900 48 4/19/2005 1700 1800 1900 1300 4637 4/26/2005 2000 2000 2100 2033 5238 5/3/2005 2100 2100 2200 213 5496 5/10/2005 2000 2000 2100 2033 5236 5/17/2005 1900 2000 2100 2000 5152 5/24/2005 1700 1800 1900 1600 4637 5/31/2005 2100 2100 2200 2133 5496 6/72005 1900 2000 2100 2000 5152 /2i205 1900 1900 2000 1933 4961 6/21/2005 2100 2200 1 2200 2167 5582 6/28/2005 2100 2100 2200 2133 5496 7/5/2005 2000 2100 2200 2100 5410 7/12/2005 2100 2200 2300 2200 5667 7/19/2005 1800 1900 1900 1867 4809 7/26/2005 1700 1800 1900 1800 4837 29 8/2/2005 2000 2100 2300 2133 5496 8/9/2005 1900 2000 2100 2000 5152 8/16/2005 1800 1800 1900 1833 4723 8/23/2005 1800 1900 2100 1933 4961 SIC Data for El 4728 A43 (80 v/mil) (Comparative Example 0) Date SICI SIC2 SIC3 Average SIC 8/11/2004 2.90 2.87 2.92 2.90 8/17/2004 2.97 2.94 2.99 2.96 8/24/2004 3.02 2.99 3.04 3.01 8/31/2004 3.00 2.97 3.03 3.00 9/14/2004 2.96 2.92 2.99 2.96 10/5/2004 3.01 2.95 3.01 2.99 11/2/2004 2.95 2.90 2.97 2.94 11/30/2004 3.00 2.92 3.01 2.98 12/28/2004 2.99 2.93 3.02 2.98 1/25/2005 3.10 3.02 3.10 3.08 2/22/2005 3.13 3.06 3.11 3.10 3/22/2005 3.10 3.04 3.09 3.08 4/19/2005 3.17 3.09 3.16 3.14 5/17/2005 3.13 3.02 3.11 3.09 6/14/2005 3.18 3.06 3.15 3.13 7/12/2005 3.17 3.08 3.16 3.13 8/9/2005 3.18 3.08 3.15 3.14 [0065] While the present invention has been described and illustrated by reference to particular embodiments thereof, it will be appreciated by those of ordinary skill in the art that the invention lends itself to variations not necessarily illustrated herein. [0066] For this reason, then, reference should be made solely to the appended claims for the purposes of determining the true scope of this invention. [0067] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. [0068] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 30 2745657_1 (GHMatters) P77809.AU MCAMP

Claims (5)

1. A lead-free insulation composition for electric cable comprising: (a) a base polymer; and (b) a filler; (c) at least one mercapto compound; wherein no ingredients containing substantial amounts of lead have been added to said composition, and said base polymer comprises at least one metallocene polymer selected from the group consisting of metallocene EP, metallocene EPDM, metallocene ethylene-butene and metallocene ethylene-octene, and mixtures thereof.

2. A lead-free insulation composition according to claim 1, wherein said base polymer further comprises at least one non-metallocene polymer.

3. A lead-free insulation composition according to claim 2, wherein said base polymer comprises 20% to 99% by weight metallocene polymer and 1% to 80% by weight non metallocene polymer.

4. A lead-free insulation composition according to any one of the preceding claims, wherein said composition contains less than about 500 parts per million by weight of lead.

5. A lead-free insulation composition according to any one of the preceding claims wherein said composition further comprises an amine antioxidant. 31 5576815_1 (GHMatters) P77809.AU.2MCAMP