Carbon filled irradiation cross-linked polymeric insulation for electric cable

• US 4,384,944 A
• Filed: 09/03/1981
• Issued: 05/24/1983
• Est. Priority Date: 09/18/1980
• Status: Expired due to Fees

• Current Assignee: Pirelli Cable Corporation (Prysmian SPA)
• Original Assignee: Pirelli Cable Corporation (Prysmian SPA)
• Inventors: Silver, David A., Lukac, Rudolf G., Rubinstein, Solomon
• Primary Examiner(s): Bleutge, John C.
• Assistant Examiner(s): Koeckert, A. H.
• Application Number:
  US06/299,038
• Time in Patent Office: 628 Days
• Field of Search: 204/159.2, 204/159.13
• US Class Current: 524/496
• CPC Class Codes: H01B 3/004 with conductive additives or conductive layers
• CPC Class Codes: H01B 3/44 vinyl resins; acrylic resins silicones H01B3/46
• CPC Class Codes: H01B 3/46 silicones
• CPC Class Codes: H01B 9/027 composed of semi-conducting layers
• CPC Class Codes: Y10S 174/27 including a semiconductive layer
• CPC Class Codes: Y10S 174/30 having insulation with a particular dimension or geometry
• CPC Class Codes: Y10T 428/2947 Synthetic resin or polymer in plural coatings, each of different type
• CPC Class Codes: Y10T 428/296 Rubber, cellulosic or silicic material in coating
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

Insulation for an electric power cable, and a power cable including such insulation, the insulation having an improved dielectric strength and being irradiation cross-linked polymeric material having mixed therewith carbon black having a particle size in the range from about 200 to about 500 millimicrons, the carbon black content being about 10% to about 40% of the weight of the mixture of carbon black and the polymeric material. Also, the cable insulation may be layers of different density polyethylene, at least one of the layers being the described mixture of polyethylene and carbon black.

Claims

1. An electrical insulator comprising a radiation cross-linked, polymeric material with carbon black distributed therein, the amount and particle size of the carbon black which is present in the polymeric material being such that the volume resistivity of said insulator is at least 1×

10¹⁰ ohm-cm., the carbon black having a particle size in the range from about 200 to about 500 millimicrons and being present in the polymeric material in an amount of about 10% to about 40% of the total weight of the polymeric material and the carbon black having a particle size in said range, said insulator being distinguished from other insulators comprising said radiation cross-linked, polymeric material with carbon black therein in particle sizes and amounts different from particle sizes in said range and in said amount not only by having a resistivity of at least 1×

10¹⁰ ohm-cm. but also having a greater dielectric strength and a reduction in at least one of the number and of the size of electron trees therein as compared to such other insulators having lesser amounts of said carbon black.

2. An electrical insulator as set forth in claim 1 wherein said volume resistivity of said insulator is at least 1×

10¹⁵ ohm-cm. and said carbon black having a particle size in said range is present in an amount from 20-30%.

3. An electrical insulator as set forth in claim 2 wherein substantially all the carbon black which is present in said polymeric material has a particle size in the range from 200-500 millimicrons.

4. An electrical insulator as set forth in claim 1, 2 or 3 wherein said polymeric material is selected from the group consisting of polyethylene, polyvinyl chloride, silicone rubber, styrene butadiene rubber, ethylene copolymers, ethylene terpolymers, and mixtures thereof.