CABLE, ESPECIALLY DATA TRANSFER CABLE, WIRE, AND METHOD FOR PRODUCING SUCH A WIRE

Abstract

A cable, especially a data transfer cable, has at least one wire having an inner conductor and a wire sheath which has been applied directly thereto. The wire sheath has a dielectric layer composed of a foamed uncrosslinked thermoplastic polymer, preferably polyethylene or polypropylene, and the dielectric layer is encased by an outer skin layer composed of unfoamed, chemically crosslinked polyethylene. The specific wire sheath leads to a distinct improvement in soldering properties. Additionally specified are a corresponding wire and a production process therefor.

Claims

1. A cable, comprising: at least one wire formed with an inner conductor and a wire sheath applied directly to said at least one wire; said wire sheath having a dielectric layer composed of a foamed uncrosslinked thermoplastic polymer; an outer skin layer composed of unfoamed, chemically crosslinked polyethylene encasing said dielectric layer.

2. The cable according to claim 1, wherein said thermoplastic polymer of said dielectric layer is a foamed polyethylene.

3. The cable according to claim 1, wherein said thermoplastic polymer of said dielectric layer is a foamed polypropylene.

4. The cable according to claim 1, wherein said outer skin layer has a thickness in a range from 70 to 150 m.

5. The cable according to claim 1, wherein said outer skin layer has a level of crosslinking G of greater than 50%.

6. The cable according to claim 1, wherein said outer skin layer consists of unfoamed, silane-crosslinked polyethylene.

7. The cable according to claim 1, wherein said wire sheath has an inner skin layer manufactured from polyethylene.

8. The cable according to claim 7, wherein said inner skin layer is a layer manufactured from a crosslinked polyethylene.

9. The cable according to claim 7, wherein said inner skin layer has a thickness in a range from 25 to 100 m.

10. The cable according to claim 1, being a coaxial cable having an outer conductor surrounding said inner conductor and being spaced apart therefrom by said dielectric layer, and having an outer shell surrounding said outer conductor.

11. The cable according to claim 1, being a symmetrical data cable having at least two wires each having an inner conductor, a wire sheath applied directly to said inner conductor and having a dielectric layer composed of a foamed uncrosslinked thermoplastic polymer, wherein the respective said dielectric layer is encased by an outer skin layer composed of unfoamed, chemically crosslinked polyethylene.

12. The cable according to claim 11, comprising a screening layer surrounding said at least two wires.

13. A wire for a cable according to claim 1, the wire comprising: an inner conductor and a wire sheath applied directly to said inner conductor; said wire sheath having a dielectric layer composed of a foamed uncrosslinked thermoplastic polymer, an outer skin layer composed of unfoamed, chemically crosslinked polyethylene encasing said dielectric layer, and an inner skin layer composed of unfoamed and uncrosslinked or chemically crosslinked polyethylene surrounded by said dielectric layer.

14. A method for producing an electrical wire, the method comprising: providing an inner conductor; guiding the inner conductor through a dielectric region and through an outer skin region of an extrusion head of an extrusion machine; applying a dielectric layer composed of a foamed thermoplastic polymer in the dielectric region of the extrusion head; and applying an outer skin layer composed of unfoamed, chemically crosslinked polyethylene in the outer skin region of the extrusion head; to form an electrical wire with an inner conductor and a wire sheath applied directly to the inner conductor and the outer skin layer encasing the dielectric layer.

15. The method according to claim 14, wherein the thermoplastic polymer of the dielectric layer is composed of foamed polyethylene.

16. The method according to claim 14, wherein the thermoplastic polymer of the dielectric layer is composed of foamed polypropylene.

17. The method according to claim 14, wherein the chemically crosslinked polyethylene of the outer skin layer is formed by mixing a silane-crosslinkable compound with a crosslinking activator to give a mixture and then, after the mixing, extruding the mixture.

18. The method according to claim 14, which comprises, prior to the guiding the inner conductor through the dielectric region: guiding the inner conductor through an inner skin region of the extrusion head and applying an inner skin layer composed of polyethylene in the inner skin region of the extrusion head.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0045] FIG. 1 is a cross section through an electrical wire according to the invention;

[0046] FIG. 2 is a cross section through cable in the form of a coaxial cable according to the invention; and

[0047] FIG. 3 is a cross section through a cable in the form of a symmetrical data cable according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0048] Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a wire 2 having an inner conductor 4 and a wire sheath 6. In the working example shown here, the latter has an inner skin layer 8 and a dielectric layer 10. In a variant which is not shown, the inner skin layer 8 is dispensed with and the dielectric layer 10 is applied directly to the conductor 4. The wire 2 additionally has an outer skin layer 12 arranged around the dielectric layer 10. The dielectric layer 10 here has been manufactured from a foamed uncrosslinked thermoplastic olefin-based polymer.

[0049] In the working example shown here, the inner skin layer 8 has a thickness D1 of about 60 m, the dielectric layer 10 has a thickness D2 of about 1.35 mm, and the outer skin layer 12 has a thickness D3 of about 90 m. Thus, the thickness D2 of the dielectric layer makes up about 90% of a total thickness of the wire sheath 6.

[0050] FIG. 2 shows a cable 14 in the form of a coaxial cable. The cable 14 has a wire 2 according to FIG. 1, surrounded by an outer conductor 16. The inner conductor 4 and the outer conductor 16 thus form two concentric conductors of the coaxial cable, between which is arranged the dielectric layer 10 as dielectric having a particular thickness D2. Arranged around the outer conductor 16 is an outer shell 18. The outer conductor 16 additionally forms a shielding layer 20.

[0051] FIG. 3 shows a variant of the cable 14, which takes the form here of a symmetrical data cable, having two wires 2 each of the form according to FIG. 1. The two wires 2 are collectively surrounded by a shielding layer 20 surrounded in turn by an outer shell 18.

[0052] Table 1 below shows results from comparative tests of respective suitability for soldering compared to conventional cables from very poor () to very good (++). Used here as a comparison, i.e. a reference, is a conventional wire 2 having only a conductor 4 of copper with a foamed dielectric layer 10 applied thereto as wire sheath 6.

TABLE-US-00001 TABLE 1 Outer Inner Inner Dielectric skin Outer Outer Suitability for No. conductor skin layer layer layer conductor shell soldering Ref. Cu PE-LD or PP-X/EPP 1 Cu PE-LD PE-Xb + 2 Cu PE-Xb PE-LD PE-Xb ++ 3 Cu PE-Xb PE-LD PE-Xb D shield PVC Inner conductor ++ Outer conductor ++ 4 Cu PE-Xb PP-X/EPP PE-Xb D shield PVC Inner conductor ++ Shielding layer ++

[0053] In test series 1, a wire 2 having an inner conductor 4 composed of copper, without an inner skin layer 8, of a dielectric layer 10 composed of foamed uncrosslinked polyethylene, PE-LD for short, and of an outer skin layer 12 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, without an outer conductor 16 or shielding layer 20 and without outer shell 18, was tested. This wire 2 already exhibits good soldering characteristics (+) in the case of soldering of the inner conductor 4 compared to wires according to the prior art.

[0054] In test series 2, a wire as shown in FIG. 1 was tested. The wire 2 consists of an inner conductor 4 composed of copper, of an inner skin layer 8 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, of a dielectric layer 10 composed of foamed uncrosslinked polyethylene, PE-LD for short, and of an outer skin layer 12 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, and has no outer conductor 16, no shielding layer 20 and no outer shell 18. Because of the inner skin layer 8, this wire 2 shows much better soldering characteristics (++) on soldering of the inner conductor 4 compared to test series 1.

[0055] In test series 3, a cable 14 in the form of a coaxial cable, as shown in FIG. 2, was tested. The coaxial cable consists of a wire 2 having an inner conductor 4 composed of copper, of an inner skin layer 8 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, of a dielectric layer 10 composed of foamed uncrosslinked polyethylene, PE-LD for short, of an outer skin layer 12 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, of an outer conductor 16, which is a D shield here, and of an outer shell 18 composed of PVC. Because of the inner skin layer 8, both the inner conductor 4 and the outer conductor 16 and hence the cable 14 have much better soldering characteristics (++) overall.

[0056] In test series 4, a data cable 14 in the form of a symmetric, i.e. paired, data cable, as shown in FIG. 3, was tested. The data cable consists of two mutually stranded wires 2 each having an inner conductor 4 composed of copper, of an inner skin layer 8 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, of a dielectric layer 10 composed of foamed uncrosslinked polyethylene, PE-LD for short, an outer skin layer 12 composed of unfoamed silane-crosslinked polyethylene, PE-Xb for short, and of a shielding layer 20 which surrounds the two wires 2 and is a D shield here, and of an outer shell 18 composed of PVC that surrounds the shielding layer 20. Because of the inner skin layer 8, the wires 2 and the shielding layer 20 and hence the cable 14 show a distinct improvement in soldering characteristics (++) overall.

[0057] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:

TABLE-US-00002 2 wire 4 inner conductor 6 wire sheath 8 inner skin layer 10 dielectric layer 12 outer skin layer 14 cable 16 outer conductor 18 outer shell 20 shielding layer D1, D2, D3 thickness