ELECTRIC CABLE HAVING IMPROVED RESISTANCE TO MOISTURE

• US 3,590,141 A
• Filed: 02/17/1969
• Issued: 06/29/1971
• Est. Priority Date: 02/17/1969
• Status: Expired due to Term

• Current Assignee: Raymond C. Mildner
• Original Assignee: Raymond C. Mildner
• Inventors: Mildner, Raymond C.
• Application Number:
  US04/799,674
• Time in Patent Office: 862 Days
• US Class Current: 174/105.00R
• CPC Class Codes: H01B 11/1869 Construction of the layers on the outer side of the outer conductor
• CPC Class Codes: H01B 7/288 using hygroscopic material or material swelling in the presence of liquid

Abstract

An electric cable having a cylindrical protective metal shield formed by overlapping the edges of a metal strip to form a longitudinal seam and an outer plastic jacket is rendered resistant to moisture by means of a sheath in the form of a layer of a hygroscopic material such as paper or a blend of a polymer and a siccative drying agent and a metal shield surrounding the layer of hygroscopic material and having the edges thereof in overlapping relationship to form a longitudinal seam bonded together by means of an adhesive polymer. The sheath is disposed within the cable between the protective metal shield and the outer plastic jacket such that the layer of hygroscopic material is in contact with the protective metal shield and the metal shield of the sheath is in contact with the outer plastic jacket.

Claims

1. In a cable comprising at least one conductor for transmitting electric signals, insulating means surrounding said conductor, a protective metal shield surrounding said insulating means and characterized by having a longitudinal seam formed by overlapping the edges of a metal strip used to form said protective metal shield, and an outer jacket of plastic material, the improvement comprising a sheath comprising, in combination:

A. a layer of hygroscopic material disposed around said protective metal shield interiorally of said outer jacket to serve as a sink for absorbing moisture, and B. a metal shield surrounding said layer of hygroscopic material and disposed between said layer of hygroscopic material and said outer jacket, said metal shield having the edges thereof in overlapping relationship to form a longitudinal seam bonded together by means of an adhesive polymer.

2. A cable according to claim 1 wherein said layer of hygroscopic material is fashioned of a material selected from the group consisting of paper, cloth, blends of polymer material and calcium chloride, blends of polymer material and sodium sulfate and blends of polymer material and sodium chloride.

3. A cable according to claim 1 wherein said metal shield surrounding said layer of hygroscopic material is fashioned of a metal selected from the group consisting of aluminum, copper, bronze, steel, and composites of two or more of the foregoing metals.

4. A cable according to claim 1 wherein said metal shield disposed between said layer of hygroscopic material and said outer jacket is adhesively bonded to said outer jacket by means of an adhesive comprising a polymer of an olefin and an ethylenically unsaturated carboxylic acid.

5. A cable according to claim 1 wherein said conductor is a single conductor of copper disposed substantially in the center of said cable, said insulating means comprises a plurality of disc-shaped spacers transversely positioned on said conductor and longitudinally spaced thereon, and said protective metal shield comprises a conductor fashioned of a material selected from the group consisting of copper and aluminum.

6. A cable according to claim 1 which includes a layer of plastic material disposed between said protective metal shield and said layer of hygroscopic material.

7. A cable according to claim 6 wherein an adhesive comprising a copolymer of an olefin and an ethylenically unsaturated carboxylic acid is disposed as a layer over substantially the entire areas of contact a. between said protective metal shield and said layer of plastic material which is disposed between said protective metal shield and said layer of hygroscopic material, and b. also between said metal shield, which is disposed between said layer of hygroscopic material and said outer jacket, and said outer jacket.

8. A cable according to claim 1 wherein said conductor is a single conductor of copper disposed substantially in the center of said cable, said insulating means comprises a foamed polyolefin, and said protective metal shield comprises a conductor fashioned of a material selected from the group consisting of copper and aluminum.

9. A cable according to claim 8 wherein an adhesive comprising a copolymer of an olefin and an ethylenically unsaturated carboxylic acid is disposed as a layer over substantially the entire area of contact between said metal shield, which is disposed between said layer of hygroscopic material and said outer jacket, and said outer jacket.

10. In a cable comprising a plurality of coaxial cables arranged in a generally parallel relationship, each of said coaxial cables comprising;

a. a first conductor for transmitting electric signals, b. insulating means surrounding said first conductor, c. a second conductor in the form of a cylinder positioned around said insulating means characterized by having a longitudinal seam formed by overlapping the edges of a metal strip used to form said second conductor, and d. an outer jacket of plastic material surrounding said second conductor; and

an outer jacket of plastic material surrounding said plurality of coaxial cables, the improvement comprising a sheath comprising, in combination;

A. a layer of hygroscopic material surrounding said plurality of coaxial cable interiorally of said outer jacket and substantially coextensive with said plurality of coaxial cables to serve as a sink for absorbing moisture; and

B. a metal shield surrounding said layer of hygroscopic material and disposed between said layer of hygroscopic material and said outer jacket, said metal shield having the edges thereof in overlapping relationship to form a longitudinal seam bonded together by means of an adhesive.

11. A cable according to claim 10 which includes a layer of plastic material disposed between said plurality of coaxial cables and said layer of hygroscopic material.

12. A cable according to claim 10 wherein an adhesive comprising a copolymer of an olefin and an ethylenically unsaturated carboxylic acid is disposed as a layer over substantially the entire areas of contact a. between said second conductor and said outer jacket in each of said coaxial cables, and b. also between said metal shield and said outer jacket.

13. A cable according to claim 10 wherein a. said insulating means surrounding said first conductor in each of said coaxial cables comprises a foamed polyolefin, b. said second conductor in each of said coaxial cables is fashioned of a metal selected from the group consisting of aluminum and copper, and c. said metal shield surrounding said layer of hygroscopic material is fashioned of a metal selected from the group consisting of aluminum, copper, bronze, steel, and composites of two or more of the foregoing metals.

14. A cable according to claim 10 wherein said layer of hygroscopic material is fashioned of a material selected from the group consisting of paper, cloth, blends of polymer material and calcium chloride, blends of polymer material and sodium sulfate, and blends of polymer material and sodium chloride.

15. In a twisted pair cable comprising a pair of conductors individually insulated with a layer of foamed polyolefin and twisted together to form a twisted pair having opposed helical valleys defined by the outer surfaces of said layers of foamed polyolefin, a layer of foamed polyolefin surrounding said twisted pair and disposed substantially throughout the helical valleys therein, a protective metal shield surrounding said layer of foamed polyolefin and characterized by having a longitudinal seam formed by overlapping the edges of a metal strip used to form said protective metal shield, and an outer jacket of plastic material, the improvement comprising a sheath comprising, in combination:

A. a layer of hygroscopic material disposed around said protective metal shield interiorally of said outer jacket and substantially coextensive with said protective metal shield to serve as a sink for absorbing moisture; and

B. a metal shield surrounding said layer of hygroscopic material and disposed between said layer of hygroscopic material and said outer jacket, said metal shield having the edges thereof in overlapping relationship to form a longitudinal seam bonded together by means of an adhesive.

16. A twisted pair cable according to claim 15 which includes a layer of plastic material disposed between said protective metal shield and said layer of hygroscopic material.

17. A twisted pair cable according to claim 15 wherein said layer of hygroscopic material is fashioned of a material selected from the group consisting of paper, cloth, blends of polymer material and calcium chloride, blends of polymer material and sodium sulfate, and blends of polymer material and sodium chloride.

18. A twisted pair cable according to claim 15 wherein an adhesive comprising a copolymer of an olefin and an ethylenically unsaturated carboxylic acid is disposed as a layer over substantially the entire areas of contact between a. said layer of foamed polyolefin surrounding said twisted pair and said protective metal shield, and b. also between said metal shield and said outer jacket.