EP2255364A1 - Isolation de conducteur résistant à l'écrasement - Google Patents

Isolation de conducteur résistant à l'écrasement

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Publication number
EP2255364A1
EP2255364A1 EP09721438A EP09721438A EP2255364A1 EP 2255364 A1 EP2255364 A1 EP 2255364A1 EP 09721438 A EP09721438 A EP 09721438A EP 09721438 A EP09721438 A EP 09721438A EP 2255364 A1 EP2255364 A1 EP 2255364A1
Authority
EP
European Patent Office
Prior art keywords
polymer
insulation
conductors
peaks
valleys
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.)
Withdrawn
Application number
EP09721438A
Other languages
German (de)
English (en)
Inventor
Gary Thuot
Robert Thomas Young
John L. Netta
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.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
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 EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Publication of EP2255364A1 publication Critical patent/EP2255364A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/02—Disposition of insulation
    • H01B7/0275—Disposition of insulation comprising one or more extruded layers of insulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/14—Insulating conductors or cables by extrusion
    • H01B13/142—Insulating conductors or cables by extrusion of cellular material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/14—Insulating conductors or cables by extrusion
    • H01B13/143—Insulating conductors or cables by extrusion with a special opening of the extrusion head
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/02—Disposition of insulation
    • H01B7/0233—Cables with a predominant gas dielectric

Definitions

  • the present invention relates to a crush resistant conductor insulation. More particularly, the present invention relates to a crush resistant polymer insulated conductor twinning process or cable where the polymer insulation is foamed or unfoamed, has peaks and valleys, and maintains the electrical and mechanical properties of a typical cylindrical polymer insulated conductor.
  • Twisted pair communications cable is used for high frequency signal transmission, typically in plenum areas of buildings.
  • the cable is composed of typically multiple twisted pairs of polymer-insulated conductors, covered by a polymer jacket.
  • the individual insulated conductors are typically twisted into pairs, and four pairs are cabled together and jacketed to make the cable.
  • Each pair is twisted at a different lay (conventionally measured in inches/turn) to reduce electrical coupling between adjacent twisted pairs (i.e. crosstalk).
  • the twisting together compresses (i.e. crushes) the polymer insulation. The shorter the lay, the tighter the twist and the greater the crush or compression of the polymer insulation (whether foamed or unfoamed).
  • the twisted pairs are typically designed to have 100 ohms impedance.
  • the center to center spacing of the conductors within the pair is a key factor affecting impedance. Therefore, because increased compression brings the conductors closer, additional insulation thickness is needed to maintain the desired impedance as the length of twist becomes shorter.
  • the problem with increasing the amount of polymer insulation used is that there is an increase in cable weight and cable size. It is thus desirable to have a polymer insulation that maintains the desired impedance and other electrical and mechanical properties without increasing the weight of the insulation material.
  • Il discloses a primary conductor of wire (solid or strands) that are enclosed by a coating of solid insulation with radially outward extending ribs.
  • the insulated ribs of a first insulated conductor are located adjacent to a second insulated conductor in which the outermost end of the first and second insulated conductor ribs abut.
  • the abutting ribs of the first and second insulated conductors define air spaces which are between the ribs and increase the distance between conductors from each other, thereby reducing the capacitance of the cable assembly.
  • a process of twinning a pair of polymer- insulated conductors to form a twisted pair each of said polymer-insulated conductors being formed by extruding a uniform thickness of said polymer onto said conductors, wherein said polymer-insulated conductors have a cylindrical exterior surface
  • the improvement comprising: improving impedance efficiency for said twisted pair as compared to polymer insulation of said uniform thickness of the same weight of said polymer by: (i) carrying out said extruding to form longitudinally running peaks and valleys in the exterior surface of each of said polymer-insulated conductors of said twisted pair of polymer-insulated conductors; and
  • a pair of conductors each having polymer insulation thereon the polymer insulation on each of said conductors having an exterior surface comprising: peaks and valleys alternating longitudinally along said exterior surface, said pair of conductors each having said polymer insulation thereon being twisted together to form a twisted pair wherein at least one of said peaks in the exterior surface of said polymer insulation on one of said conductors is nested in one of said valleys in the exterior surface of said polymer insulation on the other of said conductors to provide an improved impedance efficiency as compared to polymer insulation of the same weight but of uniform thickness, i.e. greater impedance per lb/1000 ft of polymer insulation.
  • less weight of polymer insulation can be used to achieve the same impedance as with conventional polymer insulation (uniform thickness).
  • the polymer insulation on the conductors is unfoamed or foamed.
  • a coaxial cable comprising a central conductor, polymer insulation encasing said central conductor, and an outer conductor encasing said polymer insulation, said polymer insulation having an exterior surface comprising longitudinally running peaks and valleys, said outer conductor bridging said valleys.
  • the polymer insulation can be unfoamed or foamed.
  • Figure 1 is an enlarged isometric view of a back twisted pair of polymer-insulated conductors of the present invention, showing the constitution of the radially outward polymer insulation with helically wound peaks and valleys.
  • Figure 2 is an enlarged cross-sectional view of the twisted pair of the present invention of Figure 1 along section 2-2, showing a foamed polymer insulation embodiment.
  • Figure 3 is an enlarged perspective view of an embodiment of an indeterminate length of an as extruded foamed polymer-insulated conductor of the present invention.
  • Figure 4 is a graphical illustration of the difference in insulation weight between the present invention and conventional insulated conductors with a 0.3 inch twist length (lay) at the same impedance.
  • Figure 5A shows a cross-sectional view of a conventional foamed 5 polymer coaxial cable.
  • Figure 5B shows a cross-sectional view of a foamed polymer coaxial cable of the present invention with a scalloped profile.
  • Figure 6 shows a cross-sectional view of an embodiment of a solid (i.e. unfoamed) embodiment of the present invention.
  • Figure 7 shows a cross-sectional view of another embodiment of a solid (i.e. unfoamed) embodiment of the present invention. While the present invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
  • a preferred embodiment for the insulation shape around the conductor produced from an extrusion process is a series of arches (e.g. scalloped) around the outer circumference of the insulation. This process 1) reduces the tension through the twinning machine by decreasing the contact surface area of the insulation with the machine components; 2) increases the crush resistance of the insulation layer; 3) increases the conductor center to center distance in the twisted pair with less total insulation weight than conventional round insulation; and 4) increases the insulation to insulation surface contact area.
  • Figure 1 shows a twisted pair 2 of polymer insulated conductors 4 and 6, each consisting of a central conductor 8 and 10, respectively, such as of copper, and polymer insulation 12 and 14, respectively.
  • the twinning process to form the twisted pair 2 is a conventional operation, causing the corrugated or shaped exposed exterior surfaces of insulation 12 and 14 to be forced together such as at contact points 16 and 17.
  • the surface of the polymer insulation of the present invention contains peaks and valleys forming a corrugated exterior surface.
  • the polymer insulation can be foamed or unfoamed.
  • the voids providing the foamed aspect of the polymer insulation 12, 14 are approximately spherical in shape and are shown in Figure 3 as small circles 7 within the polymer insulation.
  • Another embodiment would be to extrude or mold a solid skin on the foamed polymer insulation.
  • the solid skin typically has a thickness of about 1- 2 mils.
  • Figure 2 shows a cross-sectional view of the twisted pair of Figure 1 along section 2-2.
  • Figure 2 shows a foamed polymer insulated conductor embodiment.
  • the foamed polymer insulation 12, 14 encasing conductor 8, 10 has multiple peaks 18, 19 and valleys 20, 21.
  • the tops of the peaks 22, 23 are rounded in this embodiment for a scalloped type of peak profile.
  • This embodiment shows an outer diameter (circumference) represented by phantom line 24, 26.
  • the inner diameter of the polymer insulation is defined by the circle whose circumference coincides with the bottom (i.e. depth) of the valleys 20, 21.
  • peaks 18, 19 When the peaks 18, 19 are subjected to a crushing force, they tend to reduce the outer diameter 24, 26 of the foamed polymer insulation 12, 14 towards an intermediate diameter between the inner and outer polymer insulation diameter. In contrast, when the polymer insulation is of uniform thickness and has an intermediate diameter as the outer diameter the same crushing force tends to reduce the intermediate diameter towards the inner diameter, thereby reducing the effective thickness of the insulation as compared to when the peaks and valleys are present.
  • a solid polymer insulation for the present invention responds similarly to that described above with regard to foamed insulation, however, the compression affect on the solid or unfoamed polymer from the crushing force is less than that on a foamed polymer insulation.
  • the inner diameter of the polymer insulation of the present invention is less than the diameter of the polymer insulation obtained by extruding the same weight of the polymer but in uniform thickness (conventional insulation) onto the conductors.
  • the thickness 24, 26 of the polymer insulation of the present invention is 4-100 mils and even up to 125 mils (3.1 mm), preferably 4-20 mils (0.1 - 0.5 mm), more preferably 6-14 mils (0.15-0.36 mm).
  • the thickness of the insulation of the present invention on coaxial cable is typically 4 - 100 mils (0.1-2.5 mm) and even up to 125 mils (3.1 mm).
  • Each of the polymer insulated conductors of the present invention is formed by extruding polymer onto the conductors.
  • the polymer is extruded forming longitudinally running peaks and valleys on the exterior surface of each of the insulated conductors as shown in Figure 3.
  • the resultant polymer- insulated conductors are twisted to nest at least one of the peaks 30 of the exterior surface of one of the polymer insulated conductors in a valley 31 of the exterior surface of the other polymer-insulated conductor of the twisted pair as shown in Figure 2.
  • This twinning of polymer insulated conductors to nest in the valley of the other polymer insulated conductor provides the improved impedance efficiency by using a lesser amount of polymer by weight (lbs/1000 feet is the customary unit) than used in a typical non-corrugated insulation.
  • the polymer insulated conductors of the present invention are separate from one another prior to twinning a pair of conductors.
  • An embodiment of the present invention of the pair of conductors with polymer insulation is shown in Figure 2 as a cross- sectional shape of peaks that form 25 a scalloped edge profile.
  • the cross-sectional shape of Figure 2 shows the nesting embodiment between the twisted polymer insulated conductors 4, 6 of Figure 1.
  • the twinning process of the present invention is such that the peaks have a smaller or lesser width than the valleys or, alternatively, the peaks have a greater width than the valleys.
  • the nesting peak 30 of the one polymer-insulated conductor of a twisted pairs does not fill up the valley 31 of the other polymer-insulated conductors of the twisted pairs.
  • the peaks and valleys could also be of equal width in the present invention for nesting.
  • Two or more twisted pairs can be enclosed or encased in a polymer jacket to form a twisted pair cable.
  • the polymer insulated conductor 6 comprises a conductor 10 and polymer insulation 14 encasing the conductor 10.
  • the conductor 10 is centered within the polymer insulation 14.
  • the exterior surface of the polymer insulation 14 is composed of peaks 18 and valleys 20 running along the length of the polymer insulated conductor 6.
  • the peaks 18 and valleys 20 alternate with one another, i.e. the valleys separate adjacent peaks from one to another.
  • the number of peaks and intervening valleys, and the width of the peaks (measured at their base) and of the valleys vary according to the communications or other wire and cabling applications intended for the polymer-insulated conductor 6.
  • the peaks and valleys are continuous along the entire length of the insulation and are parallel to the conductor as extruded as shown in Figure 3.
  • the polymer- insulated conductors are twinned to form a twisted pair.
  • the individual polymer-insulated conductors are first back twisted by the twinning machine, followed by the insulated conductors being twisted together.
  • the effect of the back twisting changes the disposition of the peaks and valleys on the insulation exterior surface, from parallel to helical.
  • the twinning is carried out with the helical longitudinally running peaks and valleys of the two polymer-insulated conductors being disposed in the same direction as shown in Figure 1.
  • the twinning of the longitudinally running helical peaks and valleys thus results in a peak from one insulation nesting within a valley of the other insulation of the twisted pair.
  • the polymer insulation has a corrugated surface created by the longitudinally running peaks and valleys.
  • the number of peaks present depends on the diameter of the polymer insulation. As the diameter increases, so does the circumference, which means that the peak width chosen for a small diameter polymer insulation, if used on a larger diameter polymer insulation, will require more peaks. Alternatively, the peak widths could be increased.
  • the peaks are not tall and thin, because such configuration does not improve crush resistance. Such peaks tend to fold over upon themselves upon being subjected to crushing.
  • the peaks used in the present invention have sufficient width relative to height that they do not fold during crushing.
  • Preferred quantitative characterizations of the peaks are independently as follows: (i) the height of the peaks is no greater than about 150% of the width of said peaks, (ii) the peaks cover at least about 30% of the exterior surface (valley circumference) of the polymer insulation (this defines the foot print of the peaks), and (iii) the peaks have a height that is at least about 50% of the width of the peaks. As the width of the peaks decrease the number of peaks increased to provide equivalent improvement. For the very small size (diameter) communications cable, such as wherein the overall thickness of insulation is about 6 to 14 mils (0.150 to 0.360 mm), and the height of the peaks is at least about 25% of said overall thickness.
  • Overall thickness is the thickness of the insulation from the conductor surface to the top of the peaks.
  • the width of the peaks is the distance across the base of the peaks where they intersect with the valleys.
  • the height of the peaks is measured from the circumference defined by the valleys (valley circumference) to the top of the peaks.
  • the peaks are rounded to facilitate nesting.
  • a jacket is applied over either the twisted pair or coaxial constructions to complete the communications cable. Multiple twisted pairs can be bundled together in a single jacket.
  • the height of the peaks is preferably at least 25% of the thickness of the overall polymer insulation, more preferably at least 30%, and even more preferably, at least 40 % thereof.
  • folding of the peaks during crushing is avoided if the height of the peaks is no more than 150% of the width of the peaks, preferably no more than 125%, and more preferably no more than 100% thereof.
  • the peaks are also wide enough that they do not fold upon crushing, which is generally obtained when the width of the peaks range from 75% or 100% of the peak height to 200% of the peak height.
  • Another indication of the peak width is the coverage of the peaks on the circumference of the polymer insulated cable, the circumference in this case meaning the inner diameter of the foamed polymer insulation represented by the surface (floor) of the valleys.
  • the peaks cover up to about 90% of the circumference (valley surface), preferably at least 35% of such circumference.
  • the peaks are prominent in the surface of the insulation, e.g. for the 4 to 20 mil (0.1 to 0.5 mm) and 6 to 14 mil (0.15 to 0.35 mm) overall thickness ranges for the insulation, the peak height preferably ranges from 3 to 7 mils (0.075 to 0.175 mm), preferably 4 to 6 or 7 mils (0.1 to 0.15 or 0.175 mm).
  • the peak height will preferably be from 3 to 20 mils (0.076 to 0.5 mm).
  • the peak width will preferably be in the range of 75 to 200% of the peak height.
  • the present invention extrusion and twinning described above maintains the desired impedance performance for the twisted pair while maintaining or reducing the amount of polymer used in insulating the conductors (i.e. impedance efficiency).
  • the polymer material for the insulation can be foamed or unfoamed.
  • unfoamed means solid or that under a magnification of 4Ox, virtually no voids are visible in the regions at the interior and exterior surfaces of the foamed polymer.
  • the desired impedance performance for a twisted pair is 100 ohms.
  • Figure 4 shows a graphical illustration of impedance (Z 0 ) as a function of the amount of insulation (lbs/1000 ft) on the insulated conductor of the present invention compared to conventional insulation for solid insulation twisted pair with a 0.3 inch twist length (i.e. lay).
  • the present invention has a polymer weight of about 0.815 lbs/1000 ft in contrast to the conventional weight of about 0.905 lbs/1000 ft.
  • the present invention is shown by a solid line and the conventional is shown by a dashed line in Figure 4. This shows that less polymer weight is required to maintain 100 ohms impedance in the present invention than in the conventional case.
  • the present invention graphically represented in Figure 4 is for an unfoamed or solid twisted pair and the conventional representation is for a solid twisted pair.
  • any method for foaming the polymer to form the foamed regions of the polymer insulation of the present invention can be used. It is preferred, however, that the method used will obtain cells (voids) that are both small and uniform for the best combination of electrical properties, such as low return loss and high signal transmission velocity.
  • the cells are preferably about 50 micrometers in diameter or less and the average void content is about 10 to 70%, preferably about 20 to 50%, more preferably about 20 to 35%.
  • Average void content is determined by capacitance measurement on the insulated conductor. It is preferable for twisted pair that the average void content is between 0-35% and more preferably 10-35%.
  • the average void content is preferably 10-70%.
  • Average void content is determined by comparing the weight of the foamed insulation with the weight of unfoamed insulation (same polymer) of the same dimensions according to the following equation;
  • Void content (vol%) 100(1-[foamed wt/unfoamed wt]).
  • Figures 6 and 7 show embodiments of two unfoamed polymer insulated conductors of the present invention with twelve (12) peaks.
  • the unfoamed polymer insulation 50 encasing the conductor 52 has longitudinally running peaks 54 and valleys 56.
  • the peaks 54 are rounded at their tops.
  • the unfoamed polymer insulation 60 encasing the conductor 62 has the same number of longitudinally running peaks 64 and valleys 66 as in Fig. 6, but the peaks 64 are wide enough that the valleys 66 have little to no width.
  • the valleys 66 are simply the location of the intersection (interconnection) of adjacent peaks 64.
  • the tops of peaks 64 are rounded.
  • the polymer insulation for the present invention can be any thermoplastic polymer that can be used to coat a conductor (preferably by extrusion) that has the electrical, physical, and thermal properties desired for the particular communications or other cabling application.
  • the most common such polymer insulations are polyolefin and fluoropolymer.
  • Non-fluorinated polymer other than polyolefin can also be used.
  • the fluoropolymer used in the present invention is preferably a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). In these copolymers, the HFP content is typically about 6-17 wt%, preferably 9-17 wt% (calculated from HFPI x 3.2).
  • HFPI HFP Index
  • IR infrared radiation
  • the TFE/HFP copolymer includes a small amount of additional comonomer to improve properties.
  • the preferred TFE/HFP copolymer is TFE/HFP/perfluoro(alkyl vinyl ether) (PAVE), wherein the alkyl group contains 1 to 4 carbon atoms.
  • PAVE monomers are perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE).
  • Preferred TFE/HFP copolymers containing the additional comonomer have an HFP content of about 6-17 wt%, preferably 9-17 wt% and PAVE content, preferably PEVE, of about 0.2 to 3 wt%, with the remainder of the copolymer being TFE to total 100 wt% of the copolymer.
  • FEP compositions are those disclosed in U.S. Patents 4,029,868 (Carlson), 5,677,404 (Blair), and 6,541 ,588 (Kaulbach et al.) and in U.S. Statutory Invention Registration H130.
  • the FEP is partially crystalline, that is, it is not an elastomer.
  • partially crystalline is meant that the polymers have some crystallinity and are characterized by a detectable melting point measured according to ASTM D 3418, and a melting endotherm of at least about 3 J/g.
  • fluoropolymers can be used, i.e. polymers containing at least 35 wt% fluorine, that are melt fabricable so as to be melt extrudable, but FEP is preferred because of its high speed extrudability and relatively low cost.
  • FEP ethylene/tetrafluoroethylene
  • perfluoropolymers are preferred, these including copolymers of tetrafluoroethylene (TFE) and perfluoro(alkyl vinyl ether) (PAVE), commonly known as PFA, and in certain cases MFA.
  • PAVE monomers include perfluoro(ethyl vinyl ether) (PEVE), perfluoro(methyl vinyl ether) (PMVE), and perfluoro(propyl vinyl ether) (PPVE).
  • PEVE perfluoro(ethyl vinyl ether)
  • PMVE perfluoro(methyl vinyl ether)
  • PPVE perfluoro(propyl vinyl ether)
  • TFE/PEVE and TFE/PPVE are preferred PFAs.
  • MFA is TFE/PPVE/PMVE copolymer.
  • FEP is the most preferred polymer.
  • the fluoropolymers used in the present invention are also melt-fabricable, i.e. the polymer is sufficiently flowable in the molten state that it can be fabricated by melt processing such as extrusion, to produce wire insulation having sufficient strength so as to be useful.
  • the melt flow rate (MFR) of the perfluoropolymers used in the present invention is preferably in the range of about 5 g/10 min to about 50 g/10 min, preferably at least 20 g/10 min, and more preferably at least 25 g/10 min.
  • MFR is typically controlled by varying initiator feed during polymerization as disclosed in U.S. Patent 7,122,609 (Chapman). The higher the initiator concentration in the polymerization medium for given polymerization conditions and copolymer composition, the lower the molecular weight, and the higher the MFR. MFR may also be controlled by use of chain transfer agents (CTA). MFR is measured according to ASTM D-1238 using a 5 kg weight on the molten polymer and at the melt temperature of 372°C as set forth in ASTM D 2116-91a (for FEP), ASTM D 3307-93 (PFA), and ASTM D 3159-91a (for ETFE, which is measured at 297°C).
  • CTA chain transfer agents
  • fluoropolymers are stabilized to replace substantially all of the unstable end groups by stable end groups.
  • the preferred methods of stabilization are exposure of the perfluoropolymer to steam or fluorine at high temperature. Exposure of the perfluoropolymer to steam is disclosed in U.S. Patent 3,085,083 (Schreyer). Exposure of the perfluoropolymer to fluorine is disclosed in U.S. Patent 4,742,122 (Buckmaster et al.) and U.S. Patent 4,743,658 (Imbalzano et al.). These processes can be used in the present invention. The analysis of end groups is described in these patents.
  • the presence of the -CF3 stable end group (the product of fluorination) is deduced from the absence of unstable end groups existing after the fluorine treatment, and this is the preferred stable end group, providing reduced dissipation factor as compared to the - CF 2 H end group stabilized perfluoropolymer the product of steam treatment.
  • the total number of unstable end groups constitute no more than about 80 such end groups per 10 6 carbon atoms, preferably no more than about 40 such end groups per 10 6 carbon atoms, and most preferably, no greater than about 20 such end groups per 10 6 carbon atoms.
  • non-fluorinated thermoplastic polymers include polyolefins, polyamides, polyesters, and polyaryleneetherketones, such as polyetherketone (PEK), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK).
  • Polyolefins may also be used as insulation according to the present invention.
  • polyolefins include polypropylene, e.g. isotactic polypropylene, linear polyethylenes such as high density polyethylenes (HDPE), linear low density polyethylenes (LLDPE), e.g. having a specific gravity of 0.89 to 0.92.
  • linear low density polyethylenes made by the INSITE® catalyst technology of Dow Chemical Company and the EXACT® polyethylenes available from Exxon Chemical Company can be used in the present invention; these resins are generically called (mLLDPE).
  • mLLDPE linear low density polyethylenes
  • These linear low density polyethylenes are copolymers of ethylene with small proportions of higher alpha monoolefins, e.g. containing 4 to 8 carbon atoms, typically butene or octene. Any of these thermoplastic polymers can be a single polymer or a blend of polymers.
  • the EXACT® polyethylenes are often a blend of polyethylenes of different molecular weights.
  • the polymer forming the insulation can also contain other additives that are commonly used in polymer insulation, such as pigments, extrusion aids, fillers, flame retardants, and antioxidants, depending on the identity of the polymer being used and properties to be enhanced.
  • the conductor used in the present invention is any material that is useful for transmitting signals as required for service in a communications cable. Such material can be in the form of a single strand or can be multiple strands twisted together or otherwise united to form a unitary strand. .
  • the most common such material is copper or copper containing.
  • a copper conductor may be plated with a different metal such as silver, tin or nickel.
  • the present invention is not only applicable to twisted pair applications as discussed above but also for coaxial cable.
  • a coaxial cable is a cable consisting of inner 35 and outer 45 conductors with an insulating layer 40, 41 there between as shown in Figures 5A and 5B.
  • the outer conductor 45 has a braid of conductive material such as copper wire strands and/or a metalized tape. These coaxial cables are produced to a set impedance of normally 50 to 75 ohms. The impedance is a function of the spacing between the inner 35 and outer 45 conductors and the dielectric constant of the insulating material 40, 41.
  • the insulating material though shown as foamed in Figures 5A, 5B can also be unfoamed.
  • the cable insulation can be made thinner or, a larger inner conductor can be used to reduce attenuation while still maintaining the same impedance.
  • the conductor used in the Examples unless otherwise indicated is copper single strand wire having a diameter of 22.6 mils (565 ⁇ m).
  • the polymer insulation of Examples 1 and 3 has a void content of 20 vol% unless otherwise specified.
  • the unfoamed layer at the inner surface of the insulation is observable by viewing a cross section of the polymer- insulated conductor under magnification.
  • Example 2 is for unfoamed polymer insulation.
  • the unfoamed exterior surface of the insulation is observable by the surface of the insulation being void free in appearance. Both the foamed and unfoamed polymer insulation encasing the conductors are formed by extruding.
  • the profile of a scalloped insulation surface is used for a foamed insulation coaxial cable as shown in
  • FIG. 5B In Table 1 below, the properties of a typical or conventional foamed coaxial cable (Figure 5A) are compared to the scalloped foamed insulation coaxial cable ( Figure 5B) of the present invention. As indicated in Table 1 the significant difference is the insulation weight. Capacitance, VP (velocity of propagation) and calculated impedance are virtually the same. The weight of the conventional foamed insulation is about 0.918 lb/1000 ft versus the reduced weight of 0.721 lb/1000 ft. This weight reduction in material while maintaining the electrical and mechanical properties of the coaxial cable provides a significant cost savings to the manufacturer.
  • Table 1 shows the electrical properties of the conventional foamed coaxial cable (Figure 5A) in comparison to the present invention of the scalloped foamed coaxial cable ( Figure 5B).
  • a twisted pair has a 0.3 inch (7.6 mm) lay and solid (unfoamed) polymer insulation about a conductor.
  • the lay 46 for the twisted pair is defined as the inches per complete twist which is shown in Figure 1.
  • the unfoamed polymer insulation of this Example resembles that of Fig. 6, wherein there are 12 peaks, each being 6 mils (0.150 mm) wide and 4 mils (0.1 mm) high. The peaks occupy about 62% of the inner circumference of the polymer insulation defined by the valleys.
  • the polymer insulation weight used to maintain a 100 ohm impedance is shown to decrease in weight from the conventional solid insulation, to the embodiment of the present invention shown in Figure 6.
  • the polymer insulation weight reduces from 0.905 lbs/1000 ft to 0.815 lbs/1000 ft.
  • Table 2 also shows a reduction in weight from the standard or conventional solid insulation when compared to the profile of the present invention in Figure 7.
  • the polymer insulation weight is reduced from 0.905 lbs/ 1000 ft. to 0.820 lbs/1000 ft, respectively.
  • Table 2 also shows the reduction in polymer insulation weight for a 0.5 inch lay twisted pair, at a twinning rate of 2000 turns per minute, from the standard solid insulation (0.733 lbs/1000ft) when compared to the present invention profile (0.627 lbs/1000ft) of Fig. 6 and the profile (0.535 lbs/1000ft) of Fig. 7.
  • the present invention also shows a reduction in polymer insulation required for foam designs when compared to the standard polymer insulation under similar conditions.
  • the foamed polymer insulation of this Example resembles that of Fig. 2, wherein the 6 peaks are each 4 mils (0.1 mm) wide and 4 mils (0.1 mm) high and the overall insulation thickness is 11 mils (0.28 mm).
  • the thickness of the insulation at the inner circumference defined by he valleys is 8 mils (0.2 mm).
  • the diameter of the insulation from peak top to peak top is about 45 mils (1.143 mm).
  • the peaks occupy about 41% of the inner circumference of the polymer insulation defined by the valleys.
  • this polymer-insulated conductor is twinned with another of the same polymer-insulated conductors at a twinning rate of 2000 turns/min to form a lay of 0.3 in (7.6 mm) for the twisted pair, a peak of one insulation nests in a valley of the other insulation assisted by the back-twisting of the individual polymer-insulated conductors prior to twinning.
  • the impedance of the twisted pair is 100 ohms for both the conventional twisted pair of uniform thickness and the twisted pair of the present invention.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Communication Cables (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Processes Specially Adapted For Manufacturing Cables (AREA)

Abstract

L'invention concerne un procédé de pairage d'une paire de conducteurs isolés par un polymère afin de former une paire torsadée, lesdits conducteurs étant formés par extrusion d'un revêtement polymère d'épaisseur uniforme sur ces derniers. Une gaine polymère formant un câble renferme plus d'une paire torsadée. Pour obtenir une paire torsadée présentant une performance d'impédance moyenne désirée, on utilise une quantité limitée en poids de polymère formant les conducteurs isolés. Le procédé comprend les étapes : (i) d'extrusion pour former des crêtes et des creux s'étendant longitudinalement sur la surface extérieure de chaque conducteur de la paire de conducteurs isolés par un polymère et (ii) de pairage des conducteurs résultants isolés par un polymère afin d'emboîter au moins l'une des crêtes de la surface extérieure de l'un des conducteurs résultants dans au moins l'un des creux de la surface extérieure de l'autre conducteur de la paire de conducteurs isolés par un polymère.
EP09721438A 2008-03-17 2009-03-16 Isolation de conducteur résistant à l'écrasement Withdrawn EP2255364A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US3705508P 2008-03-17 2008-03-17
US3719208P 2008-03-17 2008-03-17
PCT/US2009/037213 WO2009117331A1 (fr) 2008-03-17 2009-03-16 Isolation de conducteur résistant à l'écrasement

Publications (1)

Publication Number Publication Date
EP2255364A1 true EP2255364A1 (fr) 2010-12-01

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EP09721438A Withdrawn EP2255364A1 (fr) 2008-03-17 2009-03-16 Isolation de conducteur résistant à l'écrasement

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EP (1) EP2255364A1 (fr)
JP (1) JP2011514649A (fr)
CN (1) CN101978433A (fr)
WO (1) WO2009117331A1 (fr)

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CN102157249B (zh) * 2011-04-13 2012-11-28 广东昌宝通讯电缆电线有限公司 一种低烟、高防火性能网络线的生产工艺
JP5811145B2 (ja) * 2013-06-17 2015-11-11 日立金属株式会社 同軸ケーブル
KR102483591B1 (ko) 2018-04-25 2023-01-03 다이킨 고교 가부시키가이샤 꼬인 전선 및 그 제조 방법
CN216618840U (zh) * 2021-05-31 2022-05-27 浙江科赛新材料科技有限公司 聚醚酮酮(pekk)挤出型材

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Also Published As

Publication number Publication date
CN101978433A (zh) 2011-02-16
WO2009117331A1 (fr) 2009-09-24
JP2011514649A (ja) 2011-05-06

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