Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C08L23/0853—Vinylacetate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/001—Conductive additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
  • C08K3/041—Carbon nanotubes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/08—Metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L15/00—Compositions of rubber derivatives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/10—Polyamides derived from aromatically bound amino and carboxyl groups of amino-carboxylic acids or of polyamines and polycarboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
  • C08L81/06—Polysulfones; Polyethersulfones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber

Definitions

• This invention relates to power cable compositions. Specifically, it relates to semiconductive power cable compositions, articles (such as a semiconductive cable layer and power cable constructions) prepared from the semiconductive compositions, and processes for preparing the semiconductive compositions and related articles. Power cables, rated for a conductor operating temperatme of 90-degree
• Centigrade or higher are commonly prepared by extruding chemically-crosslinkable polymer materials around the conductor. Following extrusion, the chemically- crosslinkable polymeric materials are crosslinked to resist material deformation at the rated cable operating temperature and related overload conditions. For medium- and high- voltage cable designs, the chemically-crosslinkable polymeric materials commonly contain conductive fillers to render the resulting cable layer semiconductive.
• the chemically-crosslinkable polymeric materials are extruded to prepare an electrical stress control layer between the metallic conductor and a polymer-dielectric insulation layer and may also be used as an electrical stress control layer between the polymer dielectric layer and grounding wires or tapes.
• the various layers are typically co-extruded and subsequently, simultaneously crosslinked.
• some cable constructions can include protective sheaths, moisture barriers, or protective jackets.
• Co-extrusion and simultaneous crosslinking are generally desirable because the resulting cable layers are closely bonded. Close bonding prevents partial delamination of the layers and precludes void forming between the layers, thereby preventing premature cable failure. Delamination and void formation can result from flexure and/or heat during the normal use of the cable. Unfortunately, close bonding as a result of co-extrusion and simultaneous crosslinking is not free of disadvantages. Notably, the method of manufacture presents problems for applications in which stripping the outermost electrical stress control layer (or semiconductive layer) from the polymer-dielectric insulation layer is desirable. (It is believed that crosslinking bond occ across the interface between the electrical stress control layer and the polymer-dielectric insulation layer.
• the chemically-crosslinkable polymeric materials often contain polar polymers to reduce their melt miscibility with insulation materials, which generally contain non-polar polyolefinic polymers.
• the chemically- crosslinkable polymer materials are based upon ethylene vinyl acetate copolymers, having a vinyl acetate comonomer content of greater than 28% by weight.
• a disadvantage of these high-polarity copolymers is that they tend to yield compounds prone to agglomeration. It is desirable to avoid the problem of agglomeration.
• the present invention is a semiconductive power cable composition
• a semiconductive power cable composition comprising (a) a mixture of a high-temperatme polymer and a soft polymer, and (b) a conductive filler, wherein a semiconductive cable layer prepared from the composition strippably adheres to a second cable layer.
• the invention also includes a semiconductive cable layer prepared from the semiconductive power cable composition as well as a power cable construction prepared by applying the semiconductive cable layer over a wire or cable.
• the present invention includes a process for preparing the semiconductive power cable composition comprising the step of blending a mixtme of a high-temperatme polymer, a soft polymer, and a conductive filler.
• the process comprises the steps of (a) reactively-coupling a mixture of a hightemperature polymer, a soft polymer, and a first coupling agent, in the presence of a conductive filler and wherein the resulting mixture having a reduced curative level, and (b) admixing a second coupling agent, wherein the second coupling agent does not substantially affect the curative level of the resulting mixtme.
• the present invention also includes a process for preparing a power cable comprising the steps of (a) extruding a power cable semiconductive composition over a metallic conductor to yield a semiconductive cable layer over the metallic conductor, (b) extruding a chemically-crosslinkable insulation composition over the semiconductive cable layer, (c) extruding a second semiconductive power cable composition over the polymer-dielectric insulation to yield a second semiconductive cable layer, and (d) crosslinking the chemically-crosslinkable insulation composition to yield a crosslinked, polymer-dielectric insulation.
• the invented semiconductive power cable composition comprises (a) a mixture of a high-temperature polymer and a soft polymer and (b) a conductive filler, wherein a semiconductive cable layer prepared from the composition strippably adheres to a second cable layer.
• the resulting semiconductive cable layer with have a heat resistance of less than 100% as measured by a Hot Creep test at a testing temperatme of 150 degrees Centigrade (Test Method described in ICEA T-28- 562, and referenced in ANSI/ICEA Standards S-94-649 and S-97-682).
• strippably adheres means that the semiconductive layer adheres to a second layer (usually, an insulation layer) under normal operating conditions of the power cable while having the property of being easily strippable from the second layer (i.e., delaminating/separating the semiconductive layer from the second layer without substantially damaging the second layer) on demand.
• strip tension the term “strippably adheres” means a strip tension between 3 and 24 pounds per 0.5 inch wide strip (1.3 to 10.9 kilograms per 13 millimeter wide strip). This test method is also is also referenced in ANSI/ICEA Standards S-94-649 and S-97-682.
• a high-temperatme polymer means a polymer having suitable heat resistance for the semiconductive cable layer but lacking other desirable properties.
• the high-temperatme polymer may not have desirable processing characteristics or other material properties.
• Suitable high- temperatme polymers include polypropylenes, polyesters, nylons, polysulfones, and polyaramides.
• Preferred high-temperature polymers are polypropylenes.
• the high temperatme polymer is preferably in the composition in an amount less than 50 weight percent. More preferably, the high temperatme polymer is present in an amount between 10 and 40 weight percent. Most preferably, it is present in an amount between 20 and 30 weight percent.
• a soft polymer as that term is used herein, means a polymer that enhances the processing characteristics of the high-temperature polymer and provides a networking source as the soft polymer is coupled to the high-temperature polymer for additional heat resistance.
• Suitable soft polymers include polyethylenes, polypropylenes, polyesters, and rubbers.
• Preferred soft polymers are polyethylenes.
• Polyethylenes include homopolymers of ethylene and copolymers of ethylene and one or more alpha-olefins, and, optionally, a diene.
• the polyethylene can also be a copolymer of ethylene and an unsaturated ester such as a vinyl ester (e.g., vinyl acetate or an acrylic or methacrylic acid ester), a copolymer of ethylene and an unsaturated acid such as acrylic or methacrylic acid, or a copolymer of ethylene and a vinyl silane (e.g., vinyltrimethoxysilane and vinyltriethoxysilane) as well as interpolymers of any of these comonomers.
• Post-modified polyethylenes of any other of the above are considered within the scope of this invention as well as blends thereof.
• Preferred polyethylenes are homopolymers of ethylene, copolymers of ethylene and one or more alpha-olefins, and a copolymer of ethylene and an unsaturated ester. More preferred polyethylenes for soft polymers are copolymers of a polar monomer and a nonpolar comonomer. Most preferred polyethylenes are copolymers of ethylene and an unsaturated ester.
• Suitable polypropylenes include homopolymers of propylene, copolymers of propylene and other olef s, and terpolymers of propylene, ethylene, and dienes.
• Suitable polyesters include thermoplastic resins comprising a saturated dicarboxylic acid and a saturated difunctional alcohol. Specific examples include polyethylene terephthalate, polypropylene terephthalate (or trimethylene terephthalate), polybutylene terephthalate, polytetramethylene terephthalate, polyhexamethylene terephthalate, polycyclohexane-l,4-dimethylol terephthalate, and polyneopentyl terephthalate.
• Preferred polyesters are polyethylene terephthalate, polypropylene terephthalate (or trimethylene terephthalate), and polybutylene terephthalate.
• Suitable nylons include nylon 6, nylon 6,6, and nylons based upon longer chain-length diamines. Preferred nylons are nylon 6 and nylon 6,6.
• Suitable rubbers include thermoplastic rubbers, ethylene propylene diene rubber, styrene-butadiene block copolymers, styrene-butadiene rubber, polybutadiene rubbers, isoprene rubbers, nitrile rubbers, polychloroprene rubbers, hydrogenated styrene-butadiene block copolymers, methacrylate butadiene styrene rubber, acrylic elastomers (such ethylene methylacrylate), fluor ⁇ elastomers, and thermoplastic elastomers (such as thermoplastic methanes, polyamids, and polyester ethers).
• Suitable conductive fillers include carbon blacks, carbon fibers, carbon nanotubes, graphite particles, metals, and metal-coated particles.
• Preferred conductive fillers are carbon blacks.
• the conductive filler will be present in the composition in an amount sufficient to impart a volume resistivity of less than 50,000 ohm-cm for a semiconductive cable layer prepared therefrom, as measmed by the methods described in ICEA S-66-524.
• a curing agent may be present in the semiconductive composition.
• Suitable curing agents include organic peroxides, azides, organofunctional silanes, maleated polyolefins, phenols, and sulfur vulcanizing agents.
• Suitable organic peroxides include aromatic diacyl peroxides, aliphatic diacyl peroxides, dibasic acid peroxides, ketone peroxides, alkyl peroxyesters, and alkyl hydroperoxides.
• Suitable azide c ing agents include alkyl azide, aryl azides, acyl azides, azidoformates, phosphoryl azides, phosphinic azides, silyl azides, and polyfunctional azides.
• Suitable silanes include unsaturated silanes that comprise an ethylenically unsaturated hydrocarbyl group, such as a vinyl, allyl, isopropenyl, butenyl, cyclohexenyl or ⁇ - (meth)acryloxy allyl group, and a hydrolyzable group, such as, for example, a hydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group.
• Preferred curing agents are organic peroxides.
• the semiconductive power cable composition may further comprise a coupling agent.
• the term "coupling agent,” as used herein, means a compound or mixtme of compounds used for the purposes of coupling or grafting a polymer or polymer blend.
• the coupling agent may be present in an amount sufficient to reduce the amount of a cming agent required to impart heat resistance to the semiconductive cable layer.
• the coupling agent may be the same compound as the c ing agent..
• Suitable coupling agents include organic peroxides, azides, organofunctional silanes, maleated polyolefins, phenols, and sulfur vulcanizing agents.
• Suitable organic peroxides include aromatic diacyl peroxides, aliphatic diacyl peroxides, dibasic acid peroxides, ketone peroxides, alkyl peroxyesters, and alkyl hydroperoxides.
• Suitable azide coupling agents include alkyl azide, aryl azides, acyl azides, azidoformates, phosphoryl azides, phosphinic azides, silyl azides, and polyfunctional azides.
• Suitable silanes include unsaturated silanes that comprise an ethylenically unsaturated hydrocarbyl group, such as a vinyl, allyl, isopropenyl, butenyl, cyclohexenyl or ⁇ -(meth)acryloxy allyl group, and a hydrolyzable group, such as, for example, a hydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group.
• Preferred coupling agents are organic peroxides.
• the semiconductive power cable composition may further comprise a compatibilizing polymer.
• a compatibilizing polymer includes those polymers having an affinity for both the high-temperature polymer and the soft polymer.
• Preferred compatibilizing polymer are copolymers (such as ethylene-alpha-olef ⁇ n copolymers) and functionalized polymers (such as maleated polyolefins and glycidil-functional polyolefins). Based on the selection of the high-temperatme and soft polymers, a person skilled in the art can readily identify other suitable compatibilizing polymers.
• the present invention is a semiconductive power cable composition
• a semiconductive power cable composition comprising (a) a mixtme of a high-temperatme polymer and a soft polymer and (b) a conductive filler, wherein a semiconductive cable layer prepared from the composition strippably adheres to a second cable layer.
• the high- temperatme polymer and the soft polymer may have different heat resistance.
• the semiconductive cable layer has a heat resistance of less than 100%) as measured by a Hot Creep test at a testing temperature of 150 degrees Centigrade.
• the second cable layer is a chemically-crosslinked layer.
• a semiconductive cable layer is prepared from the semiconductive power cable composition.
• a power cable construction is prepared by applying the semiconductive cable layer over a wire or cable.
• the present invention is a process for preparing a semiconductive power cable composition
• a process for preparing a semiconductive power cable composition comprising the step of blending a mixtme of a high-temperature polymer, a soft polymer, and a conductive filler, wherein a semiconductive cable layer prepared from the composition strippably adheres to a second cable layer.
• the mixtme may further comprise a coupling agent.
• the coupling agent reduces the amount of a curing agent required to impart heat resistance to a semiconductive cable layer prepared from a mixtme of the high-temperature polymer, the soft polymer, and the conductive filler in the absence of the coupling agent.
• the invention is a process for preparing a semiconductive power cable composition
• a process for preparing a semiconductive power cable composition comprising the steps of (a) reactively- coupling a mixtme of a high-temperatme polymer, a soft polymer, and a coupling agent, in the presence of a conductive filler, and (b) admixing a cming agent, wherein a semiconductive cable layer prepared from the composition strippably adheres to a second cable layer.
• the coupling agent reduces the amount of the cming agent required to impart heat resistance to a semiconductive cable layer prepared from a mixtme of the high-temperatme polymer, the soft polymer, and the conductive filler in the absence of the coupling agent.
• the invention is a process for preparing a power cable comprising the steps of (a) extruding a semiconductive power cable composition comprising a mixture of a high-temperatme polymer, a soft polymer, and a conductive filler, over a metallic conductor to yield a semiconductive cable layer over the metallic conductor, and (b) extruding a polymer-dielectric insulation over the semiconductive cable layer.
• This embodiment may further comprise the step of (c) extruding a second semiconductive power cable composition over the polymer-dielectric insulation to yield a second semiconductive cable layer.
• the invention is a process comprising the steps of (a) extruding a power cable semiconductive composition comprising a mixtme of a high-temperature polymer, a soft polymer, and a conductive filler, over a metallic conductor to yield a semiconductive cable layer over the metallic conductor, (b) extruding a chemically-crosslinkable insulation composition over the semiconductive cable layer, (c) extruding a second semiconductive power cable composition over the polymer-dielectric insulation to yield a second semiconductive cable layer, and (d) crosslinking the chemically-crosslinkable insulation composition to yield a crosslinked, polymer-dielectric insulation.
• Examples 1-7 In Comparative Examples 1, 6, and 7 and Examples 2, 4, and 5, the mixtures were combined in a lab-scale compounder to achieve a melt temperature of 190 degrees Centigrade for 5 minutes.
• Example 3 the mixtme of the high-temperature polymer, the soft polymer, and the conductive filler were combined in a lab-scale compounder to achieve a melt temperatme of 190 degrees Centigrade for 5 minutes and then allowed to cool; then the peroxide was added at 120 degrees Centigrade.
• Hot Creep performance was evaluated for Hot Creep performance and adhesion to a polyethylene-insulation substrate.
• the Hot Creep test specimens were evaluated for their resistance to thermal deformation under load conditions of 20 N/sq. cm. tensile stress for 15 minutes at 150 degrees Centigrade. Elongation and residual deformation were measured. Residual deformation is reported in Table I as % Hot Set.
• a polyethylene-insulation substrate was prepared from The Dow Chemical Company's commercially available HFDB-4202 crosslinkable polyethylene insulation at 120 degrees Centigrade. Subsequently, the test plaques and the polyethylene-insulation substrate were molded together under pressure at a temperature in excess of 180 degrees Centigrade for a length time sufficient for the substrate to cure. Next, the dual-layer specimens were conditioned at ambient temperatme overnight. A one-half inch wide strip was scored from the dual-layer specimen. A 90-degree peel test was performed in an INSTRONTM tensile machine at a peel rate of 20inches per minute.
• the polymeric materials for the exemplified formulations were added in the concentrations shown in Table I and include:
• each formulation contained 55 parts per hundred polymer (pphr) of carbon black.
• the peroxide used was TRIGANOX 101, and commercially available from Akzo Nobel.
• the peroxide was added in the amount of 0.4 pphr during the compounding.
• the peroxide was added in the amount of 0.4 pphr following the compounding.
• the formulation for Comparative Example 7 did not contain any peroxide.
• Comparative Example 1 was fully bonded to the polyethylene-insulation substrate.
• Table I shows that formulation exemplified as Example 2 had desirable Hot
• Example 3 formulation showed improved heat resistance, its test specimens became fully bonded to the polyethylene-insulation substrate.
• Examples 4 and 5 demonstrated formulations with improvements over the Example 2 formulation in heat resistance and strippability.
• Comparative Example 6 demonstrated excellent heat resistance, its unreacted peroxide (i.e., peroxide not consumed during compounding) did not sufficiently reduce the curative level of the mixture to prevent the test specimens from fully bonding to the polyethylene-insulation substrate.
• Comparative Example 7 which is a blend with no coupling agent, yielded test specimens with relatively poor heat resistance.
• Example 8 a mixture was combined in a lab-scale compounder to achieve a melt temperature of 190 degrees Centigrade for 5 minutes.
• the mixtme contained 65 parts of EVA-1, 35 parts of PP-1, 55 parts per hundred polymer (pphr) of Cabot Corporation CSX614 carbon black, and 0.4 pphr Akzo Nobel TRIGANOX 101 peroxide.
• the mixture was extruded as a semiconductive layer over a peroxide crosslinkable polyethylene insulation (HFDB- 4202).
• HFDB-4202 crosslinkable polyethylene insulation is available commercially from The Dow Chemical Company.
• the 15-kilovolt power cable design used a 1/0 AWG aluminum conductor, 15 mils of a crosslinkable semiconductive power cable compound, 175 mils of the crosslinkable polyethylene insulation, and 40 mils of the semiconductive power cable composition of Example 8.
• the extruded cable was passed through a hot, dry nitrogen tube (continuous vulcanization tube) wherein the thermal decomposition of organic peroxide initiates polymer crosslinking.
• the cured cable was then passed through a cooling water trough.
• the outer semiconductive power cable composition of Example 8 was found to strippably adhere to the crosslinked polyethylene cable insulation, having a strip tension of 11-12 pounds per 0.5 inches. It also had a Hot Creep elongation of 19%> when tested at 150 degrees Centigrade and 0.2 MPa of applied tensile stress.

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