CA1151255A - Electrical insulated wire with flexibility and abrasion-resistant layer - Google Patents

Electrical insulated wire with flexibility and abrasion-resistant layer

Info

Publication number
CA1151255A
CA1151255A CA000364141A CA364141A CA1151255A CA 1151255 A CA1151255 A CA 1151255A CA 000364141 A CA000364141 A CA 000364141A CA 364141 A CA364141 A CA 364141A CA 1151255 A CA1151255 A CA 1151255A
Authority
CA
Canada
Prior art keywords
layer
crosslinked
inner layer
insulated wire
skin layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000364141A
Other languages
French (fr)
Inventor
Eric P. Marsden
John A. Checkland
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nordx CDT Inc
Original Assignee
Northern Telecom Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northern Telecom Ltd filed Critical Northern Telecom Ltd
Priority to CA000364141A priority Critical patent/CA1151255A/en
Application granted granted Critical
Publication of CA1151255A publication Critical patent/CA1151255A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30Insulators 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
    • H01B3/44Insulators 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
    • H01B3/443Insulators 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 vinylhalogenides or other halogenoethylenic compounds
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00Insulated conductors or cables characterised by their form
    • H01B7/02Disposition of insulation
    • H01B7/0275Disposition of insulation comprising one or more extruded layers of insulation

Abstract

ELECTRICAL INSULATED WIRE WITH
FLEXIBILITY AND ABRASION-RESISTANT LAYER

Abstract of the Disclosure Electrically insulated wire with an inner layer of non-crosslinked and non-crosslinkable polymeric material and a skin layer of irradiation crosslinked material compatible with the inner layer. The inner layer provides desirable flexibility and electrical insulating properties suitable for telecommunications cable and appliance wiring. The skin layer gives abrasion resistance suitable for the above purpose and heat resistance and fire retardance properties suitable for building wiring. The polymeric material of both layers is preferably of a polyvinylchloride composition.

- i -

Description

~5~55 This invention relates to electrically insulated wire.
Problems exist in the use of electrically insulated wires having electrical conductors with a maximum size possibly around 19 gauge but normally in the region of 22 to 26 gauge. For instance, in telecommunications cable, the insulated wires essentially are flexible to enable them to be bent into tortuous paths for instance in switchboard or main frame installations. Many cables are used in such installations and they must remain flexible to enable them to be flexed into different positions during changing of other cables during repair or maintenance procedures. Electrical wires to be used for connecting within and hooking up electrical appliances need to be flexible for similar reasons. A problem which exists with electrically insulated wires in which flexibility to this degree is provided, is that the wires are lacking in abrasion resistance when brought into contact with or are drawn along frame members.
Further, where wires are to be soldered together or to terminals, the insulation is crosslinked to give it the short term heat resistance required when being touched momentarily by a hot soldering iron. While crosslinking also makes the insulation abrasion resistant, it detracts from its electrical insulating properties and increases its rigidity to render it too inflexible to be used without difficulty in small spaces where bending of the wire is required.
Small gauge electrically insulated wiring is also used for house and other building wiring. Such wiring requires that the finished cable containing such wiring should pass current overload and fire resistance tests. Polyvinylchloride insulation will soften and flow in overload tests in which temperatures at the insulation surface ' ~5~;~5S

reach 200C. These may lead to exposure of conductors. Hence, as an alternative insulating material for building wire, 612 nylon is being used. This has certain disadvantages. For instance, nylons absorb water which, if it is converted to steam during extrusion of insulating layers, causes pinholes in the insulation. Nylon is also expensive and extremely flammable. The use of nylon also makes it difficult to use fastening push clips to attach wires to supporting surfaces as the hardness of the nylon resists surface piercing by the clips during attachment. There is also the problem that the nylon tends to separate from any material lying beneath it when it is subjected to compression as during attachment of push clips or even bending of wires along their desired paths.
The present invention provides an electrically insulated wire which has the required flexibility to eanble it to be used as telecommunications cable and for electrical appliances. While retaining its insulating properties, the insulation also has improved abrasion resistance and short term high temperature resistance. These latter properties also render the flexible wire suitable for building wiring and where soldering is required.
According to the present invention, an electrically insulated wire is provided comprising a conductor covered by two layers of insulation, said two layers consisting of an inner layer of non-crosslinked and non-crosslinkable polymeric material and an irradiated crosslinked polymeric skin layer compatible with the inner layer and surrounding the inner layer.
In the above defined wire according to the invention, the desired flexibility and electrical insulating characteristics are 5~55 provided by the inner non-crosslinked layer while the abrasion resistance and short term heat resistance is afforded by the skin layer. The materials of the two layers are a matter of choice and depend upon particular requirements. For instance, the inner layer may be chosen from materials including polyvinylchloride, polyolefins and polyethylene. In a preferred construction, the layers are made from a compound incorporating polyvinylchloride. It is essential that the inner layer is non-crosslinkable. As already stated, the inner layer provides desirable electrical insulating characteristics. The addition of cross-linking materials to the inner layer would detract from these desirable characteristics. Also, as there is no intention of cross-linking the inner layer, the addition of cross-linking materials should be avoided as in the non-crosslinked material they would be free to migrate through the insulation thus appearing at the surface of the outer layer to render the wire tacky. A tacky surface presents problems during the life of a wire such as adhesion to insulation on other wires and to switchboard and main frame installations. Such migration would also soften the outer layer and thus detract from the abrasion and short term heat resistance of the outer layer.
The invention also includes a method of making an electrically insulated wire in which a conductor covered with an inner layer of non-crosslinkable and non-crosslinked polymeric material is fed through an extruder to form a skin layer of crosslinkable polymeric material, compatible with the inner layer, around the inner layer, and the skin layer is then irradiated to crosslink it.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-.

SS

Figure 1 is a cross-section through an electrically insulated wire; and Figure 2 is a diagrammatic illustration of a means for producing the wire of Figure 1.
In a first embodiment, an electrically insulated wire, as illustrated in Figure 1, comprises a copper electrical conductor 10, having formed thereon an inner insulating layer 11 of a non-crosslinked and non-crosslinkable polyvinylchloride composition, and an irradiation crosslinked polyvinylchloride composition skin layer 12.
The two polyvinylchloride compositions are essentially the same but for the skin layer, methacry1ate and acrylate monomers are incorporated into the compositon at ~he dry blending stage. By subsequently exposing the insulation coated wire to an electron beam readiation, the skin 7ayer is crosslinked.
The above described wire is useful for a variety of purposes. For instance, it may be used as a wire in a cable pair in telecommunications cable. The inner layer 11 of insulation, of non-crosslinked polyvinylchloride is extremely flexible and may enable the wire to be bent without difficulty for main frame wiring or switchboard installations. Also, because of the lack of curing action, the electrical insulating properties of the polyvinylchloride are retained. The thickness of the layer 11 is, in fact, consistent with providing the required electrical insulating properties and for a conductor thickness from 19 - 26 gauge, the inner layer 11 may be around 0.010 inches thick. For the above reasons, the wire is also useful for electrical appliance wiring.

ss The outer or skin layer, because it is crosslinked, becomes harder to provide abrasion resistant properties useful for all applications and also has flame retardant and heat resistance properties. Thus, the skin layer protects the inner layer and makes the wire useful where conductor soldering is required as the skin layer will resist short term high temperature treatment by momentarily being touched by a hot soldering iron. While crosslinking of the skin layer detracts from its electrical insulation properties, this is important, as these properties are provided by the inner layer 11.
The wire is also useful for building wire and is capable of withstanding the standard electrical overload tests and the skin layer makes it fire retardant. While the overload tests could tend to soften the material of layer 11, the skin layer 12 remains unaffected by the heat thereby preventing softened material of layer 11 from flowing away to expose the conductor. The flexibility of the wire also is of assistance for use as building wire because it is easier to position than conventional building wire.
Further, because of the layer 11 being non-crosslinked, it is softer than the skin layer. Hence, it is a relatively simple operation to apply push clips against the wire to hold it to supporting structures as the skin layer is deformable by plastic displacement of the inner layer by a compressive force applied by the clips.
Separation between the layers does not take place during this deformability as the materials of the layers are compatible.
The wire remains flexible down to quite low tempertures, for example down to -30C. It therefore satisfactorily replaces present nylon insulated building wires while being cheaper and avoiding the flammability and tendency for having pinholes of nylon.

;,-~.~Sl;~55 The thickness of the skin layer should be chosen to provide sufficient abrasion, heat resistance and fire retardance properties while not detracting unduly from the flexibility character-istics of the wire. Thus, the skin layer should be as thin as possible while providing the required properties to the wire. Hence, in a wire with conductor up to 19 gauge thickness and an inner layer of around 0.020 inches thickness, the skin layer may have a thickness of around 0.003 inches.
Four compounds suitable for the skin layer 12 with varying qualities of heat resistant and good flame retardation are:-phr phr phr phr _ 2 3 4 Polyvinylchloride (Kvalue 65) 100 100 100 100 Tribase (stabilizer) 7 7 - 7 Santonox R 0.15 0.15 0.15 0.15 Mark 1900 - - 1.5 TFGDM = Difunctional methacrylate monomer TMPTM = Trifunctional methacrylate monomer TOTM = Trioctyl Trimaletate - plasticizer Mark 1900 = Methyltin stabllizer.
Figure 2 illustrates diagrammatically a process for the production of the wire of Figure 1. The conductor, for example a copper wire 14, is fed off a reel 15. The wire 14 is often of a diameter larger than the desired diameter of the conductor and in this ~s~ss case is fed through a drawing machine 16 which reduces the wire size to form the conductor 10. The conductor is then fed through an annealing furnace 17 and then through two extruders 18, 19 in tandem where the polyvinylchloride inner PVC layer 11 is applied in extruder 18 and the polyvinylchloride crosslinkable layer 12 is app7ied in extruder 19. A
transfer tube 20 connects the extruders 18 and 19 and initially this may be heated, but this is not necessary after the process has run for a short time. The transfer tube maintains the first layer of insulation at a temperature which assists in the second layer bonding to the first layer. From the extruder 19 the coated conductor passes through a cooling region 21 and then through an irradiation apparatus 22.
Irradiation causes crosslinking in the skin of the insulation for the whole or part of its depth to produce the skin thickness required.
In a second embodiment, a wire is of similar cross-section to that shown in Figure 1 and is produced by the process described for the first embodiment. The electrically insulated wire of the second embodiment is different, however, in that its inner layer 10 if formed of a non-crosslinked and non-crosslinkable polyethylene composition and the skin layer is formed of a crosslinked polyethylene composition.

.

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electrically insulated wire comprising a conductor covered by two layers of insulation, said two layers consisting of an inner layer of non-crosslinked and non-crosslinkable polymeric material and an irradiated crosslinked skin layer compatible with the inner layer and surrounding the inner layer.
2. An electrically insulated wire according to claim 1 wherein the inner layer is non-crosslinked polyvinylchloride composition and the skin layer is irradiation crosslinked polyvinyl-chloride composition.
3. A method of making an electrically insulated wire in which a conductor is covered with a first layer of non-crosslinked and non-crosslinkable polymeric material comprising:-feeding the conductor with its covering layer through an extruder to form a skin layer of cross-linkable polymeric material, compatible with the first layer, around the first layer, and irradiating the skin layer to crosslink it.
4. A method according to claim 3 wherein the first layer is extruded onto the conductor before extrusion of the skin layer.
5. A method according to claim 3 wherein the first layer is a non-crosslinkable polyvinylchloride compositon and the skin layer is extruded as an irradiation crosslinkable composition.
CA000364141A 1980-11-06 1980-11-06 Electrical insulated wire with flexibility and abrasion-resistant layer Expired CA1151255A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA000364141A CA1151255A (en) 1980-11-06 1980-11-06 Electrical insulated wire with flexibility and abrasion-resistant layer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA000364141A CA1151255A (en) 1980-11-06 1980-11-06 Electrical insulated wire with flexibility and abrasion-resistant layer

Publications (1)

Publication Number Publication Date
CA1151255A true CA1151255A (en) 1983-08-02

Family

ID=4118367

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000364141A Expired CA1151255A (en) 1980-11-06 1980-11-06 Electrical insulated wire with flexibility and abrasion-resistant layer

Country Status (1)

Country Link
CA (1) CA1151255A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0222507A1 (en) * 1985-10-11 1987-05-20 RAYCHEM CORPORATION (a Delaware corporation) Shaped articles of crosslinked polymers
US5059483A (en) * 1985-10-11 1991-10-22 Raychem Corporation An electrical conductor insulated with meit-processed, cross-linked fluorocarbon polymers
WO2009138971A2 (en) * 2008-05-14 2009-11-19 Nexans Skin cured ptfe wire and cable
CN108794930A (en) * 2018-06-29 2018-11-13 重庆文理学院 Non-crosslinked PVC material

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0222507A1 (en) * 1985-10-11 1987-05-20 RAYCHEM CORPORATION (a Delaware corporation) Shaped articles of crosslinked polymers
US5059483A (en) * 1985-10-11 1991-10-22 Raychem Corporation An electrical conductor insulated with meit-processed, cross-linked fluorocarbon polymers
WO2009138971A2 (en) * 2008-05-14 2009-11-19 Nexans Skin cured ptfe wire and cable
WO2009138971A3 (en) * 2008-05-14 2010-02-25 Nexans Skin cured ptfe wire and cable
US8884163B2 (en) 2008-05-14 2014-11-11 Nexans Skin cured PTFE wire and cable
CN108794930A (en) * 2018-06-29 2018-11-13 重庆文理学院 Non-crosslinked PVC material

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