CA1060769A - Strippable composite of polymeric materials for use in insulated electrical conductors, a method of forming the same and products thereof - Google Patents
Strippable composite of polymeric materials for use in insulated electrical conductors, a method of forming the same and products thereofInfo
- Publication number
- CA1060769A CA1060769A CA224,706A CA224706A CA1060769A CA 1060769 A CA1060769 A CA 1060769A CA 224706 A CA224706 A CA 224706A CA 1060769 A CA1060769 A CA 1060769A
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- Prior art keywords
- ethylene
- propylene
- copolymer
- polymeric materials
- cured
- Prior art date
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B9/00—Power cables
- H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
- H01B9/027—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients composed of semi-conducting layers
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/20—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for coatings strippable as coherent films, e.g. temporary coatings strippable as coherent films
-
- 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
-
- 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
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Organic Insulating Materials (AREA)
- Conductive Materials (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A composite of polymeric materials which are adheringly joined to each other and which can be easily and cleanly separated by stripping apart with a low pulling force whereupon the contacting surfaces of their interface separate cleanly without retention of any residue on one from the other, and which comprises the combination of a previously cured body of a copolymer of ethylene and propylene adjoined to a subsequently cured body of an elastomeric blond of a co-polymer of ethylene and propylene admixed with chlorosulfonated polyethylene. The combination of materials is especially advantageous when used in electrically conducting wire and cable constructions as a composite of an electrical insulation and an overlying strippable semiconductive layer.
A composite of polymeric materials which are adheringly joined to each other and which can be easily and cleanly separated by stripping apart with a low pulling force whereupon the contacting surfaces of their interface separate cleanly without retention of any residue on one from the other, and which comprises the combination of a previously cured body of a copolymer of ethylene and propylene adjoined to a subsequently cured body of an elastomeric blond of a co-polymer of ethylene and propylene admixed with chlorosulfonated polyethylene. The combination of materials is especially advantageous when used in electrically conducting wire and cable constructions as a composite of an electrical insulation and an overlying strippable semiconductive layer.
Description
l~t~
A common type of construction for electrical wires or cables designed for medium-to-high voltage applications, for example about 15 to 69 KV, as well as other classes of electrical service, comprises combinations of one or more insulating layers and semiconductive layers. In a typical cable structure, for instance, the metallic conductor may be provided with an organic polymeric insulation such as a crosslinked polymer comprising ethylene, and an overlying body of semiconducting material comprising an organic polymeric material which has been rendered electroconductive by the inclusion therein of electrical conductivity imparting agents or fillers such as carbon black. Although these cable con-structions may vary in certain elements, and often include t intermediate components disposed between the metallic conductor and the primary body of dielectric insulation, such as a layer of separating tape and/or inner layer of semiconductive material, or the overall cable assembly is enclosed within a -covering sheath, all such cable constructions conventionally include therein at least a body of primary dielectric in-sulation surrounding the conductor and an overlying body of semiconducting material in physical contact with the ins~
ation. However, this arrangement of a layer of insulation with a superimposed layer of semiconductive material thereover incurs certain handicaps.
For example, to prevent the occurrence of ion-ization or corona ormation resulting from internal voids or pockets within the cable construction and consequent ultimate ~-breakdown of the insulation, it is necessary to eliminate the presence or possible occurrence of any free space or voids within or resulting from the interface between the adjoining surfaces of the body of the insulation and the body of semiconducting material. U.S. Patents Nos. 3,541,228-Lombardi - issued November 17, 1970 and 3,677,849 - Lombardi -' ;
7tit3 issued July 18, 1972 eal with this problem of intermediate void spaces at the interface of the insulation and semiconductive material by applying a heat treatment to the assembled product to induce a shrinkage of the semiconductive materials tightly about the insulation. U.S. Patent No, 3,259,688 - Towne, et al -~
issued July 5, 1966 proposes a different solution to this problem comprising a distinctive construction and an irradiation treatment. ~-Further, the insulation layer for electrical cable can be formed concurrently about the wire or metal conductor by means of a continuous simultaneous extrusion process with one extruder, such as shown in U.S. Patent No. 3,646,248 -Ling, et al - issued February 29, 1972, or these layers can be formed in ssquence employing tandem extruders such as shown in U.S. Patent ~o. 3,569,610 - Garner, et al - issued March 9, 1971, and both layers are thereafter cured at the same time in a single operation and unit to minimize manufacturing steps and apparatus. Elowever, the simultaneous curing of both layers together, or even the curing of only one layer alone while it is in a contiguous arrangement with the other layer, can result in the apparent formation of crosslinking bonds bridging across the interface between the adjoining surfaces of each phase as noted in U.S. Patents Nos. 3,569,610 and 3,792,1g2 -Rye - issued February 12, 1974. This occurrence of such crosslinking bonds bridging the interface between the surfaces of the phases can render their subsequent separation very difficult, such as during removal of a portion of the body of semiconductive material from about the insulation by stripping for the purpose of making splices or terminal connections.
The separation of these layers often requires the application of great force, and, upon being stripped or peeled l(t~';'ti~
off, the semiconductive material often is prone to leave a substantial residue of its mass firmly adhering to the other surface or the insulation. As is known in the art, it i9 necessary when splicing and treating cable ends that the semi-conductive material be cleanly stripped or completely removed from the terminal section of the cable end without any damage or material loss to the underlying surface of the insulation, and consequently the separation of these phases can require an appreciable amount of added labor time and costs when the semiconductive material is difficult to remove by stripping and/or a residue thereof is retained tenaciously adhering to the surface of the insulation. A solution to the difficulties of this aspect of such cable constructions is the subject of U.S. Patent No. 3,684,821 - Miyauchi, et al - issued August 15, 1972.
Other recent U.S. patents addressed to the foregoing problem comprise the following: U.S. Patent No. 3,643,004 -McKean - issued February 15, 1972 relates to a cable construction wherein the semiconducting layer is adhering but unbonded-to the insulating layer; No. 3,787,255 - Carini, et al - issued January 22, 1974 which teaches attaching sulfonate groups to the surface of the polyolefin insulation to deter migration of the curing agent from the semiconductive layer across the interface to the insulation and as a result thereof their tenacious interlocking; and ~o. 3,793,476 - Misiura, et al -issued February 19, 1974 which proposes a semiconductive composition comprising a novel blend of ethylene-propylene rubber and chlorine-containing polymers which forms a controlled bonding upon curing with the underlying insulation of ethylene-containing polymer.
This invention comprises a combination of specific organic polymeric materials coupled with a curing sequence .: . :- - . - .'- , ;.
- ' ' ' , ' ' ~ t~7~p whereby an elastomeric blend, which may comprise a body of semiconductive material, can be adheringly united to a contacting surface of a body of a copolymer of ethylene and propylene having an ethylene content of not more than about 50%
by weight of the copolymer, a conventional material for dielectric insulations. The materials and curing sequence of this invention provide a substantially continuous and secure union of their contacting surfaces extending over their common interface and thereby effectively obviating the occurrence of intermediate void spaces, while at the same time providing an interface union between the phases which is easily separated with a relatively small pulling force where-upon the components part from each other with clean surfaces each free of any residue from the other.
The invention includes the combination of a first body of a copolymer of ethylene and propylene of approximately equal parts by weight of copolymerized ethylene and propylene, adheringly joined with a second body composed of an elasto-meric blend of a minor portion of ethylene-propylene rubber admixed with a major portion of chlorosulfonated polyethylene, wherein said second body of an elastomeric blend is in a uncured condition and is applied to the first body of the copolymer in a cured condition and said uncured second body of the elastomeric blend is cured while a surface thereof is in physical contact with a surface of the cured first body of copolymer.
The compositions and their attributes of this combination are uniquely suitable and advantageous for use in the construction of electrical wires and cables in the function of a composite of an insulation of ethylene-propylene co-polymer or terpolymer with an easily and cleanly strippable semiconductive material superimposed over the insulation if~
when the polymeric material comprising the elastomeric blend is rendered suitably electroconductive by appropriate filling with a typical &lectrical-conductivity-imparting agent or filler such as carbon black dispersed therethrough, or some other electrically conductive particulate material such as silicon carbide, iron, aluminum, and the like, in such amounts so as to impart the desired degree of conductivity.
It is a primary object of this invention to provide polymeric materials that can be joined in a contiguous relationship with their interfacial surfaces adheringly united together so as to eliminate the presence of any occurrence of intermediate void spaces therebetween, and which thereafter -can be separated by the application of a low pulling force with the interfacial surfaces of the bodies cleaving cleanly ~;
and free of any adhering residual material.
It is also a primary object of this invention to provide electrical conductors or wire, and a method of manufacturing same, with coverings including a combination of bodies of organic polymeric materials comprising a first layer of insulation with a surface thereof adheringly joined to a surface of a second layer which may be of any suitable thickness down to less than about one millimeter, and wherein the second layer of the polymeric material is easily and cleanly strippable from the first layer of insulation with a low peeling effort of preferably about 2 to 18 pounds pulling force per one half inch wide strip of material, leaving the separated surface of each layer intact, and clean and free of any residue.
It is an additional and specific object of thig invention to provide an electrical wire or cable, and method of manufacturing same, having a multi-layered covering about a metallic conductor comprising a combination of cured polymeric materials consisting of an insulation and an overlying semiconductive shield which is free of intermediate voids or spaces at the interface of said materials, and wherein the material consisting of the semiconductive shield comprises a polymeric carrier or matrix for particulate conductive filler material dispersed therethrough can be peeled or stripped off the underlying insulation with little effort or pulling force and it separates or parts cleanly from the surface of the insulation leaving it intact and without adhering material.
It is a further object of this invention to provide a method of joining polymeric materials in a contiguous re-lationship with their interfacial surfaces adheringly united so as to eliminate the presence or accurrence of intermediate void spaces therebetween, and which thereafter can be separated by the application of a low pulling force with the interfacial surfaces of the bodies cleaving cleanly and free of any adhering residual material.
FIGURE 1 comprises a perspective view of a portion of an insulated condcutor having a semiconductive shield thereon;
and, FIGURE 2 comprises a cross-sectional view of the insulation and overlying semi-conductive layer about a portion of metallic conductor.
This invention is hereinafter described in relation to its principal field of application and utility, the construction of electrical wire and cable, although other areas of application are contemplated.
The invention specifically consists of a novel combination of given polymeric materials, or combined bodies composed thereof, coupled with a sequence of curing and combining such polymeric materials, for adheringly joining 7~,ja3 them together with unique interfacial characteristics at their mutual contiguous surfaces.
Polymeric materials of the invention comprise for the one phase, a body or unit of a copolymer or terpolymer of ethylene and propylene having an ethylene content of not more than about 50% by weight of the polymerized material, and preferably copolymers comprising approximately equal parts by weight of ethylene and propylene, and for the other phase or unit an elastomeric blend of about 20 to about 40 parts by weight of a copolymer or terpolymer of ehtylene and propylene admixed with about 60 to about 80 parts by -weight of chlorosulfonated polyethylene. Accordingly for the purposes of this disclosure and the claims,-the term copolymers of ethylene and propylene includes terpolymers comprising such monomers.
The terpolymers of ethylene-propylene suitable for this invention include commercially available rubbers produced by the copolymerization of ethylene and propylene together with minor proportions of dienes such as ethylidiene non~
bornene, dicyclopentadiene or 1,4-hexadiene or combinations thereoif. The terpolymers of ethylene-propylene with dienes, as is well known in the art, give greater latitude in the available curing systems in relation to the copolymers of only ethylene and propylene. Specifically, the copolymers require a free radical curing mechanism as provided by a per- -~
oxide compound, whereas the unsaturated phase of the terpoly-mers enables curing with a conventional suIfur-accelerator curing system, as well as with a peroxide free radical system. -An essential aspect of this invention comprises the curing, by conventional means such as curing agents, of the first phase or body of the copolymer of ethylene and pro-pylene prior to the physical combining or joining together of the first and second phases or bodies, and the curing, by conventional means such as curing agents, of the second phase or body of the elastomer blend while in physical contact with the previously cured first phase or body. Thus the curing and adjoining sequence required to achieve the advant- -ages and benefits of the invention, comprises applying the body or mass of the elastomeric blend while in an uncured condition to the body or mass of the copolymer of ethylene and propylene in a cured condition, and thereafter curing the body or mass of elastomeric blend while a surface thereof is in adjoining physical contact with a surface of the cured copolymer of ethylene and propylene. This sequence of curing and adjoining the respective polymeric components is necessary to prevent formation of a tenacious union and bonding between -~
the interface of the polymeric components which can only be separated with the application of very high pulling forces, and does not separate cleanly with each unit free of residue of the other.
The organic polymeric materials of each phase of the combination of this invention, both the copolymer of ethylene and propylene and the elastomeric blend, are typically cured to a substantially thermoset condition by crosslinking with a free radical forming peroxide according to conventional -~
practices such as described in U.S. Patents Nos. 2,888,424-Precopio, et al - issued May 26, 1959 and 3,079,370 - Precopio, et al - issued February 26, 1963, and in subsequent relevant prior art. However, other curing systems or means known to the art or prescribed by the polymer manufacturers or suppliers can be applied, such as the use of sulfur-based systems with terpolymers comprising ethylene and propylene.
For service in electrical applications such as a semiconductive component in cable for medium to high voltage l(~bO7~
service, the elastomeric blends can be easily rendered electroconductive to any appropriate degree d0sired by the filling or inclusion therethroughout of a suitable amount of an electrical conductivity imparting agent such as about 15 to about 75 parts of carbon black or metal particles by weight of the polymeric ingredients according to conventional practices. When aptly rendered electroconductive with a suitable amount of a conductive material, dispersed there-~ ughout, the elastomeric blend can fulfill the required electrical functions of a semiconducting material in elec-trical cable, and when combined with an ethylene-propylene copolymer insulation and cured in accordance with the sequence of this invention, the combination provides the unique inter-facial properties which effectively eliminate the occurrence - -of intermediate void spaces between the interface surfaces of insulation and semiconductive material and also enables an easy and clean separation of the semiconductive material from the insulation.
Referring to the drawing, a typical cable of medium-to-high voltage capacity of the type to which this invention is especially applicable and advantageous, is shown in perspective in Figure 1, and a short portion of such a cable is also shown with the insulation and semiconductive layer in longitudinal cross sec~ion about the conductor~in Figure 2. The overall cable product 10, primarily comprises a metallic conductor 12, a relatively thick first body of dielectric insulation 14 surrounding the conductor, and overlying the insulation is a second body or layer of semi- ~ -conductive material 16. Other components can be included in the cable structure following known designs. For example, separating paper or tape can be provided on the conductor -or a semiconductive layer can be located between the metallic 7~
conductor 12 and the primary insulation 14, such as shown in the aforementioned U.S. Patents Nos. 3,259,688 and 3,684,821, and the means of this invention apply thereto with its atten-dant advantages whenever the insulation abuts the semiconductive component as is conventional in medium-to-high voltage capacity cables. Upon combining and curing the components in the essential sequence of this invention as set forth herein-above, the insulation and semiconductive material covering the insulation become adheringly joined to each other, producing ~-a united interface 18 of unique attributes which eliminates intermediate voids, and upon the application of a small pulling force of only a few pounds, the surfaces at the interface separate cleanly leaving each surface free of adherents from the other.
The following comprise specific examples of suitable and preferred polymeric materials for the application of this invention in the construction of high-voltage cable comprising a body of ethylene-propylene copolymer insulation combined with an overlying body of semiconductive material of a polymeric carrier or matrix comprising an elastomeric blend filled with particulate conductive material. -The ethylene-propylene copolymer insulating com-position of the following examples consisted of the following ingredients, in parts by weight:
Parts Bv Weiqht Ethylene-Pr~pylene Copolymer t50% wt. ethylene) 100.0 Vistalon~404, Exxon Chemical Co.
Antioxidant - Flecto~ H, Monsanto 2.0 A polytrimethyldihydroquinoline Zinc Oxide 3.0 Lead Dioxide 2.0 Polybutadiene homopolymer - Ricon 150 5.0 Clay 96.0 Petrolatum 5.0 -Vinyl Silane 1.5 Dicumyl ~eroxide Curing A~ent 6.0 Di Cu ~40 KE, Hercules -These ingradients of the dielectric insulation were compounded in a suitable mixer, a Banbury mixer, until -substantially homogeneously dispersed. However, pursuant to conventional practices, all ingredients except the peroxide curing agent were first admixed with the temperature of the mixing ingredients maintained below about 400F. To prevent precuring the peroxide curing agent was added to the admixed ingredients while at a temperature of below about 200F. The --compound was then ready for forming to a given shape and curing to a thermoset condi~ion by the application of heat.
The elastomeric blend semiconductive composition of the following examples consisted of the following ingred- -ients, including an electrically conductive carbon black, in parts by weight:
-. .. , - . ..
Parts BY Weiqht Chlorosulfo~ated Polyethylene 65.0 Hypalo~40S, duPont A Ethylene-P~opylene Terpolymer 35.0 Nordel~1320, duPont Conducting Carbon Black 45.0 Vulcan XC-72 Litharge (90$ in EPDM) 20.0 Naphthenic Oil 17.0 Circosol 4240 Oil Crystalline ~ydrocarbon Wax 2.0 Sunocd~Anti-Chek Antioxidant-Agerit~ Resin D, R.T. Vanderbuilt 0.5 Polymerized dihydrotrimethylquinoline Trimethyl Propane Trimethacrylate 2.0 Dicumyl Pero~ide Curing Agent 2.5 Di Cu~ R, Hercules The foregoing ingredients of the semiconductive 20 cOmpQsitiOn were also compounded in a Banbury mixer until substantially homogeneously dispersed. Also according to conventional practice, all ingredients except the peroxide curing agent were fixst admixed with the temperature of the mixing ingredients maintained below about 250F. To prevent precuring the peroxide curing agent was added to the admixed ingredients while at a temperature of below about 200F.
The compounded elastomeric blend was then ready for forming to shape and curing to a thermoset condition by activating the curing agent ~ith heat.
Samples of both of the foregoing insulating and semiconducting compounds were sheeted out on separate roll mills and applied as follows. In the hereinafter described Example I, strip specimens of each sheeted sample of uncured insulation and uncured semiconducting material were combined by super-imposing specimens of one sample sheet upon the other and both cured together as a laminate in adjoining Ot~
physical contact in a press at 310F for 45 minutes. After cooling to room temperature and conditioning for at least 16 hours at room temperature, 1/2 by 4 inch strips of the simul-taneously cured laminated samples were tested for strippability.
The results are given hereinafter.
Like samples of both of the same foregoing insulating ~`
and semiconducting compounds sheeted out on separate mill rolls were applied as follows in accordance with this invention for comparison. In Example II, the strip specimens of the sheeted `
insulating composition of ethylene-propylene copolymer were first cured at 350F for 15 minutes in a mold. After cooling to room temperature and conditioning for at least 16 hours at room temperature, the precured strip specimens of the in-sulating compound were combined with like sheeted specimens of the uncured semiconducting compound by superimposing one sheeted specimen on the other providing a laminate. The semiconductive compound was thereafter cured as a laminate while in adjoining physical contact with the precured insulat-ing compound, at 310F for 45 minutes in a press.
A common type of construction for electrical wires or cables designed for medium-to-high voltage applications, for example about 15 to 69 KV, as well as other classes of electrical service, comprises combinations of one or more insulating layers and semiconductive layers. In a typical cable structure, for instance, the metallic conductor may be provided with an organic polymeric insulation such as a crosslinked polymer comprising ethylene, and an overlying body of semiconducting material comprising an organic polymeric material which has been rendered electroconductive by the inclusion therein of electrical conductivity imparting agents or fillers such as carbon black. Although these cable con-structions may vary in certain elements, and often include t intermediate components disposed between the metallic conductor and the primary body of dielectric insulation, such as a layer of separating tape and/or inner layer of semiconductive material, or the overall cable assembly is enclosed within a -covering sheath, all such cable constructions conventionally include therein at least a body of primary dielectric in-sulation surrounding the conductor and an overlying body of semiconducting material in physical contact with the ins~
ation. However, this arrangement of a layer of insulation with a superimposed layer of semiconductive material thereover incurs certain handicaps.
For example, to prevent the occurrence of ion-ization or corona ormation resulting from internal voids or pockets within the cable construction and consequent ultimate ~-breakdown of the insulation, it is necessary to eliminate the presence or possible occurrence of any free space or voids within or resulting from the interface between the adjoining surfaces of the body of the insulation and the body of semiconducting material. U.S. Patents Nos. 3,541,228-Lombardi - issued November 17, 1970 and 3,677,849 - Lombardi -' ;
7tit3 issued July 18, 1972 eal with this problem of intermediate void spaces at the interface of the insulation and semiconductive material by applying a heat treatment to the assembled product to induce a shrinkage of the semiconductive materials tightly about the insulation. U.S. Patent No, 3,259,688 - Towne, et al -~
issued July 5, 1966 proposes a different solution to this problem comprising a distinctive construction and an irradiation treatment. ~-Further, the insulation layer for electrical cable can be formed concurrently about the wire or metal conductor by means of a continuous simultaneous extrusion process with one extruder, such as shown in U.S. Patent No. 3,646,248 -Ling, et al - issued February 29, 1972, or these layers can be formed in ssquence employing tandem extruders such as shown in U.S. Patent ~o. 3,569,610 - Garner, et al - issued March 9, 1971, and both layers are thereafter cured at the same time in a single operation and unit to minimize manufacturing steps and apparatus. Elowever, the simultaneous curing of both layers together, or even the curing of only one layer alone while it is in a contiguous arrangement with the other layer, can result in the apparent formation of crosslinking bonds bridging across the interface between the adjoining surfaces of each phase as noted in U.S. Patents Nos. 3,569,610 and 3,792,1g2 -Rye - issued February 12, 1974. This occurrence of such crosslinking bonds bridging the interface between the surfaces of the phases can render their subsequent separation very difficult, such as during removal of a portion of the body of semiconductive material from about the insulation by stripping for the purpose of making splices or terminal connections.
The separation of these layers often requires the application of great force, and, upon being stripped or peeled l(t~';'ti~
off, the semiconductive material often is prone to leave a substantial residue of its mass firmly adhering to the other surface or the insulation. As is known in the art, it i9 necessary when splicing and treating cable ends that the semi-conductive material be cleanly stripped or completely removed from the terminal section of the cable end without any damage or material loss to the underlying surface of the insulation, and consequently the separation of these phases can require an appreciable amount of added labor time and costs when the semiconductive material is difficult to remove by stripping and/or a residue thereof is retained tenaciously adhering to the surface of the insulation. A solution to the difficulties of this aspect of such cable constructions is the subject of U.S. Patent No. 3,684,821 - Miyauchi, et al - issued August 15, 1972.
Other recent U.S. patents addressed to the foregoing problem comprise the following: U.S. Patent No. 3,643,004 -McKean - issued February 15, 1972 relates to a cable construction wherein the semiconducting layer is adhering but unbonded-to the insulating layer; No. 3,787,255 - Carini, et al - issued January 22, 1974 which teaches attaching sulfonate groups to the surface of the polyolefin insulation to deter migration of the curing agent from the semiconductive layer across the interface to the insulation and as a result thereof their tenacious interlocking; and ~o. 3,793,476 - Misiura, et al -issued February 19, 1974 which proposes a semiconductive composition comprising a novel blend of ethylene-propylene rubber and chlorine-containing polymers which forms a controlled bonding upon curing with the underlying insulation of ethylene-containing polymer.
This invention comprises a combination of specific organic polymeric materials coupled with a curing sequence .: . :- - . - .'- , ;.
- ' ' ' , ' ' ~ t~7~p whereby an elastomeric blend, which may comprise a body of semiconductive material, can be adheringly united to a contacting surface of a body of a copolymer of ethylene and propylene having an ethylene content of not more than about 50%
by weight of the copolymer, a conventional material for dielectric insulations. The materials and curing sequence of this invention provide a substantially continuous and secure union of their contacting surfaces extending over their common interface and thereby effectively obviating the occurrence of intermediate void spaces, while at the same time providing an interface union between the phases which is easily separated with a relatively small pulling force where-upon the components part from each other with clean surfaces each free of any residue from the other.
The invention includes the combination of a first body of a copolymer of ethylene and propylene of approximately equal parts by weight of copolymerized ethylene and propylene, adheringly joined with a second body composed of an elasto-meric blend of a minor portion of ethylene-propylene rubber admixed with a major portion of chlorosulfonated polyethylene, wherein said second body of an elastomeric blend is in a uncured condition and is applied to the first body of the copolymer in a cured condition and said uncured second body of the elastomeric blend is cured while a surface thereof is in physical contact with a surface of the cured first body of copolymer.
The compositions and their attributes of this combination are uniquely suitable and advantageous for use in the construction of electrical wires and cables in the function of a composite of an insulation of ethylene-propylene co-polymer or terpolymer with an easily and cleanly strippable semiconductive material superimposed over the insulation if~
when the polymeric material comprising the elastomeric blend is rendered suitably electroconductive by appropriate filling with a typical &lectrical-conductivity-imparting agent or filler such as carbon black dispersed therethrough, or some other electrically conductive particulate material such as silicon carbide, iron, aluminum, and the like, in such amounts so as to impart the desired degree of conductivity.
It is a primary object of this invention to provide polymeric materials that can be joined in a contiguous relationship with their interfacial surfaces adheringly united together so as to eliminate the presence of any occurrence of intermediate void spaces therebetween, and which thereafter -can be separated by the application of a low pulling force with the interfacial surfaces of the bodies cleaving cleanly ~;
and free of any adhering residual material.
It is also a primary object of this invention to provide electrical conductors or wire, and a method of manufacturing same, with coverings including a combination of bodies of organic polymeric materials comprising a first layer of insulation with a surface thereof adheringly joined to a surface of a second layer which may be of any suitable thickness down to less than about one millimeter, and wherein the second layer of the polymeric material is easily and cleanly strippable from the first layer of insulation with a low peeling effort of preferably about 2 to 18 pounds pulling force per one half inch wide strip of material, leaving the separated surface of each layer intact, and clean and free of any residue.
It is an additional and specific object of thig invention to provide an electrical wire or cable, and method of manufacturing same, having a multi-layered covering about a metallic conductor comprising a combination of cured polymeric materials consisting of an insulation and an overlying semiconductive shield which is free of intermediate voids or spaces at the interface of said materials, and wherein the material consisting of the semiconductive shield comprises a polymeric carrier or matrix for particulate conductive filler material dispersed therethrough can be peeled or stripped off the underlying insulation with little effort or pulling force and it separates or parts cleanly from the surface of the insulation leaving it intact and without adhering material.
It is a further object of this invention to provide a method of joining polymeric materials in a contiguous re-lationship with their interfacial surfaces adheringly united so as to eliminate the presence or accurrence of intermediate void spaces therebetween, and which thereafter can be separated by the application of a low pulling force with the interfacial surfaces of the bodies cleaving cleanly and free of any adhering residual material.
FIGURE 1 comprises a perspective view of a portion of an insulated condcutor having a semiconductive shield thereon;
and, FIGURE 2 comprises a cross-sectional view of the insulation and overlying semi-conductive layer about a portion of metallic conductor.
This invention is hereinafter described in relation to its principal field of application and utility, the construction of electrical wire and cable, although other areas of application are contemplated.
The invention specifically consists of a novel combination of given polymeric materials, or combined bodies composed thereof, coupled with a sequence of curing and combining such polymeric materials, for adheringly joining 7~,ja3 them together with unique interfacial characteristics at their mutual contiguous surfaces.
Polymeric materials of the invention comprise for the one phase, a body or unit of a copolymer or terpolymer of ethylene and propylene having an ethylene content of not more than about 50% by weight of the polymerized material, and preferably copolymers comprising approximately equal parts by weight of ethylene and propylene, and for the other phase or unit an elastomeric blend of about 20 to about 40 parts by weight of a copolymer or terpolymer of ehtylene and propylene admixed with about 60 to about 80 parts by -weight of chlorosulfonated polyethylene. Accordingly for the purposes of this disclosure and the claims,-the term copolymers of ethylene and propylene includes terpolymers comprising such monomers.
The terpolymers of ethylene-propylene suitable for this invention include commercially available rubbers produced by the copolymerization of ethylene and propylene together with minor proportions of dienes such as ethylidiene non~
bornene, dicyclopentadiene or 1,4-hexadiene or combinations thereoif. The terpolymers of ethylene-propylene with dienes, as is well known in the art, give greater latitude in the available curing systems in relation to the copolymers of only ethylene and propylene. Specifically, the copolymers require a free radical curing mechanism as provided by a per- -~
oxide compound, whereas the unsaturated phase of the terpoly-mers enables curing with a conventional suIfur-accelerator curing system, as well as with a peroxide free radical system. -An essential aspect of this invention comprises the curing, by conventional means such as curing agents, of the first phase or body of the copolymer of ethylene and pro-pylene prior to the physical combining or joining together of the first and second phases or bodies, and the curing, by conventional means such as curing agents, of the second phase or body of the elastomer blend while in physical contact with the previously cured first phase or body. Thus the curing and adjoining sequence required to achieve the advant- -ages and benefits of the invention, comprises applying the body or mass of the elastomeric blend while in an uncured condition to the body or mass of the copolymer of ethylene and propylene in a cured condition, and thereafter curing the body or mass of elastomeric blend while a surface thereof is in adjoining physical contact with a surface of the cured copolymer of ethylene and propylene. This sequence of curing and adjoining the respective polymeric components is necessary to prevent formation of a tenacious union and bonding between -~
the interface of the polymeric components which can only be separated with the application of very high pulling forces, and does not separate cleanly with each unit free of residue of the other.
The organic polymeric materials of each phase of the combination of this invention, both the copolymer of ethylene and propylene and the elastomeric blend, are typically cured to a substantially thermoset condition by crosslinking with a free radical forming peroxide according to conventional -~
practices such as described in U.S. Patents Nos. 2,888,424-Precopio, et al - issued May 26, 1959 and 3,079,370 - Precopio, et al - issued February 26, 1963, and in subsequent relevant prior art. However, other curing systems or means known to the art or prescribed by the polymer manufacturers or suppliers can be applied, such as the use of sulfur-based systems with terpolymers comprising ethylene and propylene.
For service in electrical applications such as a semiconductive component in cable for medium to high voltage l(~bO7~
service, the elastomeric blends can be easily rendered electroconductive to any appropriate degree d0sired by the filling or inclusion therethroughout of a suitable amount of an electrical conductivity imparting agent such as about 15 to about 75 parts of carbon black or metal particles by weight of the polymeric ingredients according to conventional practices. When aptly rendered electroconductive with a suitable amount of a conductive material, dispersed there-~ ughout, the elastomeric blend can fulfill the required electrical functions of a semiconducting material in elec-trical cable, and when combined with an ethylene-propylene copolymer insulation and cured in accordance with the sequence of this invention, the combination provides the unique inter-facial properties which effectively eliminate the occurrence - -of intermediate void spaces between the interface surfaces of insulation and semiconductive material and also enables an easy and clean separation of the semiconductive material from the insulation.
Referring to the drawing, a typical cable of medium-to-high voltage capacity of the type to which this invention is especially applicable and advantageous, is shown in perspective in Figure 1, and a short portion of such a cable is also shown with the insulation and semiconductive layer in longitudinal cross sec~ion about the conductor~in Figure 2. The overall cable product 10, primarily comprises a metallic conductor 12, a relatively thick first body of dielectric insulation 14 surrounding the conductor, and overlying the insulation is a second body or layer of semi- ~ -conductive material 16. Other components can be included in the cable structure following known designs. For example, separating paper or tape can be provided on the conductor -or a semiconductive layer can be located between the metallic 7~
conductor 12 and the primary insulation 14, such as shown in the aforementioned U.S. Patents Nos. 3,259,688 and 3,684,821, and the means of this invention apply thereto with its atten-dant advantages whenever the insulation abuts the semiconductive component as is conventional in medium-to-high voltage capacity cables. Upon combining and curing the components in the essential sequence of this invention as set forth herein-above, the insulation and semiconductive material covering the insulation become adheringly joined to each other, producing ~-a united interface 18 of unique attributes which eliminates intermediate voids, and upon the application of a small pulling force of only a few pounds, the surfaces at the interface separate cleanly leaving each surface free of adherents from the other.
The following comprise specific examples of suitable and preferred polymeric materials for the application of this invention in the construction of high-voltage cable comprising a body of ethylene-propylene copolymer insulation combined with an overlying body of semiconductive material of a polymeric carrier or matrix comprising an elastomeric blend filled with particulate conductive material. -The ethylene-propylene copolymer insulating com-position of the following examples consisted of the following ingredients, in parts by weight:
Parts Bv Weiqht Ethylene-Pr~pylene Copolymer t50% wt. ethylene) 100.0 Vistalon~404, Exxon Chemical Co.
Antioxidant - Flecto~ H, Monsanto 2.0 A polytrimethyldihydroquinoline Zinc Oxide 3.0 Lead Dioxide 2.0 Polybutadiene homopolymer - Ricon 150 5.0 Clay 96.0 Petrolatum 5.0 -Vinyl Silane 1.5 Dicumyl ~eroxide Curing A~ent 6.0 Di Cu ~40 KE, Hercules -These ingradients of the dielectric insulation were compounded in a suitable mixer, a Banbury mixer, until -substantially homogeneously dispersed. However, pursuant to conventional practices, all ingredients except the peroxide curing agent were first admixed with the temperature of the mixing ingredients maintained below about 400F. To prevent precuring the peroxide curing agent was added to the admixed ingredients while at a temperature of below about 200F. The --compound was then ready for forming to a given shape and curing to a thermoset condi~ion by the application of heat.
The elastomeric blend semiconductive composition of the following examples consisted of the following ingred- -ients, including an electrically conductive carbon black, in parts by weight:
-. .. , - . ..
Parts BY Weiqht Chlorosulfo~ated Polyethylene 65.0 Hypalo~40S, duPont A Ethylene-P~opylene Terpolymer 35.0 Nordel~1320, duPont Conducting Carbon Black 45.0 Vulcan XC-72 Litharge (90$ in EPDM) 20.0 Naphthenic Oil 17.0 Circosol 4240 Oil Crystalline ~ydrocarbon Wax 2.0 Sunocd~Anti-Chek Antioxidant-Agerit~ Resin D, R.T. Vanderbuilt 0.5 Polymerized dihydrotrimethylquinoline Trimethyl Propane Trimethacrylate 2.0 Dicumyl Pero~ide Curing Agent 2.5 Di Cu~ R, Hercules The foregoing ingredients of the semiconductive 20 cOmpQsitiOn were also compounded in a Banbury mixer until substantially homogeneously dispersed. Also according to conventional practice, all ingredients except the peroxide curing agent were fixst admixed with the temperature of the mixing ingredients maintained below about 250F. To prevent precuring the peroxide curing agent was added to the admixed ingredients while at a temperature of below about 200F.
The compounded elastomeric blend was then ready for forming to shape and curing to a thermoset condition by activating the curing agent ~ith heat.
Samples of both of the foregoing insulating and semiconducting compounds were sheeted out on separate roll mills and applied as follows. In the hereinafter described Example I, strip specimens of each sheeted sample of uncured insulation and uncured semiconducting material were combined by super-imposing specimens of one sample sheet upon the other and both cured together as a laminate in adjoining Ot~
physical contact in a press at 310F for 45 minutes. After cooling to room temperature and conditioning for at least 16 hours at room temperature, 1/2 by 4 inch strips of the simul-taneously cured laminated samples were tested for strippability.
The results are given hereinafter.
Like samples of both of the same foregoing insulating ~`
and semiconducting compounds sheeted out on separate mill rolls were applied as follows in accordance with this invention for comparison. In Example II, the strip specimens of the sheeted `
insulating composition of ethylene-propylene copolymer were first cured at 350F for 15 minutes in a mold. After cooling to room temperature and conditioning for at least 16 hours at room temperature, the precured strip specimens of the in-sulating compound were combined with like sheeted specimens of the uncured semiconducting compound by superimposing one sheeted specimen on the other providing a laminate. The semiconductive compound was thereafter cured as a laminate while in adjoining physical contact with the precured insulat-ing compound, at 310F for 45 minutes in a press.
2~ After cooling to room temperature, 1/2 by 4 inch strips of the dissimilarly cured specimens of Example II were tested for strippability in the same manner and conditions as the simultaneously cured specimens of Example I. The combined results were as follows: -Example I Example II
Specimens could not be stripped Specimens stripped with apart, semicon layer completely average pulling force of 2.32 bonded to insulation. lbs., and separated cleanly.
In the following examples illustrating the merits of this invention, the foregoing insulating and semiconducting compositions were combined under actual extrusion conditions simulating the manufacture of high-voltage electrical cable having a metallic conductor covered with a body or layer of dielectric insulation and an overlying body or layer of semi-conducting material. The cable construction consisted of a #2 AWG stranded metal core conductor, cpvered with a 0.150 inch thickness of the insulation and a 0.035 inch thickness of the semicon with a total outside diameter of about 0.680 inches, each applied by extrusion in a conventional manner.
In each example, the insulating composition was continuously formed on the core conductor by a first extrusion operation and thereafter continuously cured by passing at a rate of 14 feet per minute through a steam chamber 75 feet in length maintained at a pressure of about 255 psig (209C) for a swell period of about five minutes.
Following the continuous forming and curing of the insulation composition on the core conductor, an overlying covering of the semiconducting composition was continuously applied in each example by a second extrusion operation and thereafter continuously cured by passing at a rate of 15 feet per minute through a steam chamber 75 feet in length main-tained at a pressure of about 255 psig (209C) for a swell period of about five minutes.
The four examples prepared as described according to this invention were treated and tested for several properties in addition to strippability as set forth in the following table:
7~jc-~
Insulation Treatment Prior E X A M P L E S
To Semicon Extrusion III IV V VI Reauirements*
Insulation Ovenized ** No No Yes Yes Spica oil applied to inter-face ***Yes No No Yes PROPERTIES
Outer Semicon Results Tensile Strength, psi 16221615 19151858 Elongation, % 305327 295302 Seven Days Air Oven 121 C
Tensile Strength, psi ---1681 16261802 Elongation, % --- 223205193 100 minimum Conductivity Room Temperature - ohm-cm --- 525108 103 5000 maximum 90C - ohm-cm --- 2437055 50000maximum Strippabilitv Lbs. per 1/2 inch wide strip 4.755.75 5.38 5.64 4-minimum 18-maximum :
* IPCEA S-66-524 & AEIC 6-73 ** Ovenizing conditions - 51 hrs. at 115C
*** Spica oil applied to insulation surface prior to semicon extrusion to prevent nipple "plug-up".
Although the invention has been described with reference to certain specific embodiments thereof, numerous modifications are possible and it is desired to cover all modifications falling within the spirit and scope of the invention.
Specimens could not be stripped Specimens stripped with apart, semicon layer completely average pulling force of 2.32 bonded to insulation. lbs., and separated cleanly.
In the following examples illustrating the merits of this invention, the foregoing insulating and semiconducting compositions were combined under actual extrusion conditions simulating the manufacture of high-voltage electrical cable having a metallic conductor covered with a body or layer of dielectric insulation and an overlying body or layer of semi-conducting material. The cable construction consisted of a #2 AWG stranded metal core conductor, cpvered with a 0.150 inch thickness of the insulation and a 0.035 inch thickness of the semicon with a total outside diameter of about 0.680 inches, each applied by extrusion in a conventional manner.
In each example, the insulating composition was continuously formed on the core conductor by a first extrusion operation and thereafter continuously cured by passing at a rate of 14 feet per minute through a steam chamber 75 feet in length maintained at a pressure of about 255 psig (209C) for a swell period of about five minutes.
Following the continuous forming and curing of the insulation composition on the core conductor, an overlying covering of the semiconducting composition was continuously applied in each example by a second extrusion operation and thereafter continuously cured by passing at a rate of 15 feet per minute through a steam chamber 75 feet in length main-tained at a pressure of about 255 psig (209C) for a swell period of about five minutes.
The four examples prepared as described according to this invention were treated and tested for several properties in addition to strippability as set forth in the following table:
7~jc-~
Insulation Treatment Prior E X A M P L E S
To Semicon Extrusion III IV V VI Reauirements*
Insulation Ovenized ** No No Yes Yes Spica oil applied to inter-face ***Yes No No Yes PROPERTIES
Outer Semicon Results Tensile Strength, psi 16221615 19151858 Elongation, % 305327 295302 Seven Days Air Oven 121 C
Tensile Strength, psi ---1681 16261802 Elongation, % --- 223205193 100 minimum Conductivity Room Temperature - ohm-cm --- 525108 103 5000 maximum 90C - ohm-cm --- 2437055 50000maximum Strippabilitv Lbs. per 1/2 inch wide strip 4.755.75 5.38 5.64 4-minimum 18-maximum :
* IPCEA S-66-524 & AEIC 6-73 ** Ovenizing conditions - 51 hrs. at 115C
*** Spica oil applied to insulation surface prior to semicon extrusion to prevent nipple "plug-up".
Although the invention has been described with reference to certain specific embodiments thereof, numerous modifications are possible and it is desired to cover all modifications falling within the spirit and scope of the invention.
Claims (9)
1. An easily and cleanly strippable composite of cured polymeric materials comprising a body of a copolymer of ethylene and propylene having an ethylene content of not more than about 50% by weight with a surface adheringly joined to a contacting surface of a body comprising an elastomeric blend of a minor amount of a copolymer of ethylene and propylene admixed with a major amount of chlorosulfonated polyethylene, said contacting surfaces of the bodies of polymeric materials being adheringly joined at their contacting surfaces by applying the body of the elastomeric blend while in an uncured condition to the body of the copolymer of ethylene and propy-lene in a cured condition and thereafter curing said body of the elastomer blend while a surface thereof is in adjoining physical contact with a surface of the cured body of the copolymer of ethylene and propylene.
2. A composite of cured polymeric materials as claimed in claim 1 wherein said elastomeric blend comprises about 20 to about 40 parts by weight of a copolymer of ethylene and propylene admixed with about 60 to about 80 parts by weight of chlorosulfonated polyethylene.
3. A composite of cured polymeric materials as claimed in claim 2, wherein said elastomeric blend comprises about 35 parts by weight of copolymer of ethylene and propylene admixed with about 65 parts by weight of chlorosulfonated polyethylene.
4. The easily and cleanly strippable composite of cured polymeric materials of claim 2, wherein said polymeric material of the body of a copolymer of ethylene and propylene comprising approximately equal parts by weight of copolymerized ethylene and propylene.
5. A composite of cured polymeric materials as claimed in claim 1, 2 or 3 wherein a metallic electrical conductor is sur-rounded by said body of the copolymer of ethylene and propylene.
6. A method of preparing an easily and cleanly strippable composite of cured polymeric materials comprising a body of a copolymer of ethylene and propylene having an ethylene content of not more than about 50% by weight with a surface adheringly joined to a contacting surface of a body comprising an elastomeric blend of a minor amount of a copolymer of ethylene and propylene admixed with a major amount of chlorosulfonated polyethylene, comprising curing a body of said copolymer of ethylene and propylene, apply-ing to a surface of said cured body of copolymer of ethylene and propylene a body comprising said elastomeric blend in an uncured condition, and while the surfaces of said bodies of cured and uncured polymeric materials are in adjoining physical contact, curing said body of uncured elastomeric blend.
7. The method of preparing an easily and cleaning strippable composite of cured polymeric materials of claim 6, wherein said elastomeric blend comprises about 35 parts by weight of copolymer of ethylene and propylene admixed with about 65 parts by weight of chlorosulfonated polyethylene.
8. The method of preparing an easily and cleanly strippable composite of cured polymeric materials of claim 6, wherein the polymeric material of the body of a copolymer of ethylene and propylene comprising approximately equal parts by weight of copolymerized ethylene and propylene.
9. A method as claimed in claim 6, 7 or 8 wherein said body of said copolymer of ethylene and propylene surrounds a metallic electrical conductor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US468397A US3925597A (en) | 1974-05-09 | 1974-05-09 | Electrical conductors with strippable insulation and method of making the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1060769A true CA1060769A (en) | 1979-08-21 |
Family
ID=23859646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA224,706A Expired CA1060769A (en) | 1974-05-09 | 1975-04-14 | Strippable composite of polymeric materials for use in insulated electrical conductors, a method of forming the same and products thereof |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US3925597A (en) |
| JP (1) | JPS50150886A (en) |
| CA (1) | CA1060769A (en) |
| DE (1) | DE2510510A1 (en) |
| ES (1) | ES436350A1 (en) |
| FR (1) | FR2270285B1 (en) |
| HU (1) | HU173995B (en) |
| NL (1) | NL7504448A (en) |
| SE (1) | SE7505361L (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4075421A (en) * | 1975-12-23 | 1978-02-21 | General Electric Company | Direct current cable with resistivity graded insulation, and a method of transmitting direct current electrical energy |
| US4876440A (en) * | 1976-12-13 | 1989-10-24 | Raychem Corporation | Electrical devices comprising conductive polymer compositions |
| US4866253A (en) * | 1976-12-13 | 1989-09-12 | Raychem Corporation | Electrical devices comprising conductive polymer compositions |
| US4426339B1 (en) | 1976-12-13 | 1993-12-21 | Raychem Corp. | Method of making electrical devices comprising conductive polymer compositions |
| US4764664A (en) * | 1976-12-13 | 1988-08-16 | Raychem Corporation | Electrical devices comprising conductive polymer compositions |
| US4317001A (en) * | 1979-02-23 | 1982-02-23 | Pirelli Cable Corp. | Irradiation cross-linked polymeric insulated electric cable |
| JPS56132586A (en) * | 1980-03-19 | 1981-10-16 | Osaka Gas Co Ltd | Method of and conductor for long-sized material buried underground |
| US4384944A (en) * | 1980-09-18 | 1983-05-24 | Pirelli Cable Corporation | Carbon filled irradiation cross-linked polymeric insulation for electric cable |
| JPH04118402U (en) * | 1991-04-01 | 1992-10-22 | 芳子 澤内 | 21st century Japanese clothing |
| US5225635A (en) * | 1991-11-08 | 1993-07-06 | Cooper Industries, Inc. | Hermetic lead wire |
| GB9125417D0 (en) * | 1991-11-29 | 1992-01-29 | Bicc Plc | An improved communication cable |
| JP4554330B2 (en) * | 2004-10-21 | 2010-09-29 | 株式会社リコー | High durability heat insulating stamper structure |
| KR101106557B1 (en) * | 2004-12-28 | 2012-01-19 | 엘지디스플레이 주식회사 | IPS mode LCD apparatus |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3269862A (en) * | 1964-10-22 | 1966-08-30 | Raychem Corp | Crosslinked polyvinylidene fluoride over a crosslinked polyolefin |
| US3571490A (en) * | 1970-01-16 | 1971-03-16 | Anaconda Wire & Cable Co | Flame resistant electric cable |
| US3793476A (en) * | 1973-02-26 | 1974-02-19 | Gen Electric | Insulated conductor with a strippable layer |
-
1974
- 1974-05-09 US US468397A patent/US3925597A/en not_active Expired - Lifetime
-
1975
- 1975-03-11 DE DE19752510510 patent/DE2510510A1/en active Pending
- 1975-03-24 HU HU75GE972A patent/HU173995B/en unknown
- 1975-04-07 ES ES436350A patent/ES436350A1/en not_active Expired
- 1975-04-14 CA CA224,706A patent/CA1060769A/en not_active Expired
- 1975-04-15 NL NL7504448A patent/NL7504448A/en unknown
- 1975-05-07 JP JP50053943A patent/JPS50150886A/ja active Pending
- 1975-05-07 SE SE7505361A patent/SE7505361L/en unknown
- 1975-05-07 FR FR7514302A patent/FR2270285B1/fr not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SE7505361L (en) | 1975-11-10 |
| ES436350A1 (en) | 1977-04-16 |
| FR2270285A1 (en) | 1975-12-05 |
| FR2270285B1 (en) | 1982-03-05 |
| DE2510510A1 (en) | 1975-11-20 |
| US3925597A (en) | 1975-12-09 |
| JPS50150886A (en) | 1975-12-03 |
| NL7504448A (en) | 1975-11-11 |
| HU173995B (en) | 1979-10-28 |
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