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Publication numberUS3735025 A
Publication typeGrant
Publication dateMay 22, 1973
Filing dateJul 30, 1971
Priority dateJul 30, 1971
Publication numberUS 3735025 A, US 3735025A, US-A-3735025, US3735025 A, US3735025A
InventorsLing T, Solomon M, Wade R
Original AssigneeAnaconda Wire & Cable Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Semiconducting composition and cable jacketed therewith
US 3735025 A
Abstract
Electrical cables are jacketed with a novel thermoplastic semiconducting composition comprising chlorinated polyethylene, ethylene ethyl acrylate and carbon black.
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Description  (OCR text may contain errors)

ilnited States Patent Ling et a1.

[4 1 May 22, 1973 SEMICONDUCTING COMPOSITION AND CABLE JACKETED THEREWITH Inventors: Ting H. Ling, Marion; Robert M. Wade, Wabash; Marwick H. Solomon, Muncie, all of Ind.

Assignee: Anaconda Wire and Cable Company,

New York, NY.

Filed: July 30, 1971 Appl. No.: 167,741

US. Cl...l74/l20 SC, 174/102 SC, 174/105 SC,

Int. Cl. ..H0lb 5/16, HOlb 9/02 Field of Search 174/ 120 SC, 102 SC, 174/105 SC, 110 PM, 106 SC, 102 C, 120 R, 115, 113 R [56] References Cited UNITED STATES PATENTS 3,684,821 8/1972 Miyauchi et a1. ..174/120 SC 3,155,631 11/1964 Zapp ..174/120 SC 3,571,613 3/1971 Plate etal l74/115 X 3,260,694 7/1966 Wang .174/1 10 PM 2,953,541 9/1960 Pecha et al. 174/11O PM FOREIGN PATENTS OR APPLICATIONS 1,150,690 4/1969 Great Britain 1 74/ 102 SC Primary Examiner-Bernard A. Gilheany Assistant ExaminerA. T. Grimley Attorney-Victor F. Volk [5 7] ABSTRACT Electrical cables are jacketed with a novel thermoplastic semiconducting composition comprising chlorinated polyethylene, ethylene ethyl acrylate and carbon black.

6 Claims, 1 Drawing Figure CHLORINATED POLYETHYLENE, ETHYLENE ETHYL ACRYLATE,0nd SEMICONDUCTING CARBON BLACK PATENTEL M22 1575' ETHYLENE, HYL ACRYLATE,cmd ING CARBONZBLACK RINATED POLY LENE ET C E SEMICONDUCT SEMICONDUCTING COMPOSITION AND CABLE JACKETED THEREWITH BACKGROUND OF THE INVENTION Polymeric compositions that will conduct electricity have utility for a number of purposes, varying from the discharge of frictionally induced electrostatic charges on plastic surfaces where such charges cause an accumulation of dust, to the transmission of useful currents by the conductors of ignition cables. The conductivity of polymeric compositions does not equal that of metals since the composition resitivities usually vary from about 1 to 10,000 ohm-centimeters. For this reason such compositions are usually referred to as semiconducting as they shall be in this application. A recent commercial interest in electric cables with semiconducting jackets, particularly for direct burial, has been stimulated by the development of cables of a type described in US. Pat. No. 3,474,189. These cables have drain wires embedded in a semiconducting outer jacket that provides both electrical shielding and mechanical protection. Modern cables for burial service employ vulcanized compositions such as vulcanized polyethylene for insulation. This means that they have higher temperature ratings than thermoplastic-insulated cables. Fully to utilize the higher thermal ratings of vulcanized insulation the jackets of the cables should be equally highly rated and, what is even more exacting as a requirement for this modern type of cable, the electrical conductivity of the cable jackets should remain high through the whole service temperature range. Attempts have been made to meet these requirements with vulcanized semiconducting jackets. But vulcanized compounds, when used for jacket stocks, have the serious disadvantage that they bond firmly to the surface of the insulation and cannot be readily stripped clean at splices and terminations. Further requirements for jacket compositions for buried cables, which presently known materials do not fully meet, include extrudability at high manufacturing speeds. This has particular significance for the embedded drain wire cables since the jackets can then be applied in tandem with the insulation extrusion without slowing down the former. The composition must, in addition, retain its properties in water and other commonly encountered solvents, and resist burning. Significantly, since cables are buried with a view to service for many years the jacket composition must age exceptionally well, i.e. retain its good characteristics after thousands of cycles of heating and cooling and years of burial. No compositions are presently known fully to satisfy all the enumerated requirements for cable jacketing.

SUMMARY We have invented a composition which is thermoplastic and so will not bond to cable insulation but is servicable at elevated temperatures, retains its electrical conductivity under adverse conditions, as shall be shown, and can be extruded at high speed. Our composition comprises a homogenous blend of -90 or, more preferably 50-80, or particularly 60-75 parts by weight of a chlorinated polyolefin such, preferably, as polyethylene; the difference to make up 100 parts by weight of ethylene ethyl acrylate; and 30-75 or, more preferably 40-60, or particularly 45-55 parts by weight of semiconducting carbon black.

We have invented an electric cable comprising a conductor, a layer of polymeric insulation such, preferably as vulcanized polyethylene, surrounding the conductor, and a semiconducting thermoplastic polymeric jacket directly surrounding the insulation. The jacket comprises 50-80 or, preferably, 65-75 parts by weight of chlorinated polyethylene, the difference to make 100 parts by weight of ethylene ethyl acrylate, and 40-60 or, preferably, 45-55 parts by weight of semiconducting carbon black.

DESCRIPTION OF THE DRAWING The FIGURE shows a pictorial lengthwise view of a cable of our invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In the FIGURE a cable suitable for underground power service is indicated generally by the numeral 10. In the cable 10 a conductor 1 1, which may be stranded, is covered in known manner by a layer 12 of semiconducting strand shielding composition. The conductor, including the layer 12 is insulated with a surrounding layer 13 of vulcanized polyethylene. Our invention has particular utility where the insulation 13 is vulcanized because the cable can then make most advantage of the high-temperature properties of the jacket, to be described. Other vulcanized compositions, such as ethylene propylene copolymers or diene terpolymers can also be employed within the scope of our invention, and, of course, certain advantages will still accrue where the insulation is thermoplastic, such as therrnoplastic polyolefin, although, generally, the temperature rating will then be lower.

Over the insulation layer 13 there is directly extruded a thermoplastic semiconducting jacket 14 into which drain wires have been embedded during the extrusion operation. Since the jacket 14 is in direct surface contact with the insulation 13 it would bond to the insulation if both were vulcanized. An advantage of our cable resides in the fact that the thermoplastic jacket can always be cleanly stripped, even from a vulcanized layer of insulation.

EXAMPLE Parts by weight chlorinated polyethylene ethyl ethylene acrylate 30 semiconducting carbon black 50 The chlorinated polyethylene of the EXAMPLE was obtained from Dow Chemical Company under the designation 2243.28, with a chlorine content of 25 percent, crystallinity of 28 percent and specific gravity of 1.08. Although we prefer to use chlorinated polyethylene with chlorine contents of 20-30 percent our invention includes chlorine contents of 15-70 percent.

The ethylene ethyl acrylate of the EXAMPLE was supplied by the Union Carbide Plastics Company under the designation DPD-6169 having an ASTM D638 stiffness of 5000 psi, an ASTM D1505 density of 0.93 grams per cc and an ASTM D1238 melt index of 6.0 grams/10 minutes. The term ethylene ethyl acrylate, as used in this application applies to copolymers of ethylene and ethyl acrylate, which are commercially available with combined ethyl acrylate contents of about 3-25 percent by weight.

The semiconducting carbon black of the EXAMPLE was supplied by Godfrey L. Cabot, Inc. under the designation Vulcan XC-72. semiconducting carbon blacks suitable for the practice of our invention are, however, commercially available from a number of sources known to persons skilled in plastic compounding arts.

The lead phthalate and stearate serve as stabilizers and the epoxy as an extrusion lubricant. For the additional flame retarder of the EXAMPLE antimony oxide can be used or Dechlorane furnished by the Hooker Electrochemical Company, and a suitable antioxidant is polymerized 1,2-dihydro-2,2,4-trimethylquinoline. Other suitable antioxidants, of which a number are well known to plastic compounders can also be used within the scope of our invention. Other suitable compounding agents are known that can be employed within the scope of our invention which is not limited except as hereinafter specifically claimed.

Resistivity tests of the composition of the EXAMPLE were conducted over a period of five weeks in accordance with the following schedule: specimens were aged in a 90C oven from 4:30 PM to 8:30 AM each weekday and over the Friday to Monday weekend. From 8:30 AM to 11:30 AM each weekday they were aged in a 130C oven. From 11:30 AM to 4:30 PM they were permitted to cool at room temperature. Resistivity measurements were made each weekday at 8:05 AM while the samples were in the 90C oven, at 1 1:05 AM while they were in the 130C oven and at 4 PM at room temperature.

Values of the resistivities obtained are shown in TABLE 1.

TABLE I Resistivity, Ohm-Cm Week Day 90C 130C Room Temp. 1st Mon 935 2630 190 Fri. 840 2040 158 2nd Mon 740 2130 171 Fri. 757 1750 167 3rd Mon 610 1670 149 Fri. 650 1320 147 4th Mon 528 1350 148 Fri. 612 1680 153 5th Mon 510 1380 151 Fri. 493 1390 152 The data of Table I evidence an unexpected improvement in conductivity of our composition with aging, over a wide range of temperatures.

Specimens of cable jacketed with our composition made in accordance with the EXAMPLE and specimens jacketed with semiconducting polyethylene were tested for resistivity of the jacket at different temperatures by holding the specimens in an air oven for two hours at each temperature. The results are shown in Table 11.

TABLE ll Ohm-Cm Temp. C Polyethylene Example 25 162 235 50 4,610 671 75 29,700 900 100 5,980,000 1,820 130 8,710 5,030 I50 3,500 2,520

The resistivity of the composition of the EXAMPLE is seen not to rise excessively upon hot water immersion by the data of Table III. Measurements were made at room temperature.

TABLE I11 Weeks water Resistivity immersion at 90C Ohm-Cm 0 185 1 2750 2 4710 4 6710 After 4 weeks immersion in different solutions and solvents the resistivity of the composition of the EX- AMPLE did not rise unduly, as shown in Table IV.

TABLE IV Solution or Solvent Resistivity Ohm-Cm 30% sulfuric acid 951 10% nitric acid 967 10% hydrochloric acid 603 5% acetic acid 765 10% sodium hydroxide 884 gasoline 525 acetone 253 ethylene dichloride 318 heptene 547 ASTM No. 2 oil 766 transformer oil 622 The resistance to heat deformation of the composition of the EXAMPLE is shown in Table V to be superior at elevated temperatures to that of semiconducting polyethylene or of polyvinyl chloride jacket stock.

TABLE V Heat Deformation C C12lC 150C semiconducting polyethylene 0 2.63 polyvinyl chloride 2.84 4.75 13.64 61.30 Example 2.80 4.88 5.58 53.30

We have invented a new and useful cable and composition of which the foregoing description has been exemplary rather than definitive and for which we desire an award of Letters Patent as defined in the following claims.

We claim:

1. An electric cable comprising a conductor, a layer of polymeric insulation surrounding said conductor, and a semiconducting thermoplastic polymeric jacket directly surrounding said insulation; said jacket comprising: 50-80 parts by weight of chlorinated polyethylene, the difference to make 100 parts by weight of ethylene ethyl acrylate, and 40-60 parts by weight of semiconducting carbon black.

2. The cable of claim 1 wherein said jacket comprises 65-75 parts by weight of chlorinated polyethylene and 45-55 parts by weight of said carbon black.

3. The cable of claim 1 wherein said insulation is vulcanized.

4. The cable of claim 2 wherein said insulation is vulcanized.

5. The cable of claim 3 wherein said insulation comprises polyethylene.

6. The cable of claim 4 wherein said insulation comprises polyethylene.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2953541 *Jun 16, 1958Sep 20, 1960Union Carbide CorpComposition of polyethylene and a copolymer of ethylene and ethyl acrylate
US3155631 *Feb 19, 1962Nov 3, 1964Du PontSemi-conductor, containing ethylene/ethyl acrylate copolymer, petroleum wax and carbon black
US3260694 *Jan 9, 1962Jul 12, 1966Phelps Dodge Copper ProdCross-linked chlorinated polyethylene
US3571613 *May 20, 1970Mar 23, 1971Anaconda Wire & Cable CoCable system
US3684821 *Mar 30, 1971Aug 15, 1972Sumitomo Electric IndustriesHigh voltage insulated electric cable having outer semiconductive layer
GB1150690A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3951871 *May 16, 1974Apr 20, 1976Union Carbide CorporationDeformation resistant shielding composition
US4025715 *Mar 15, 1976May 24, 1977Alcan Aluminum CorporationShielded electric cable
US4091139 *Sep 17, 1975May 23, 1978Westinghouse Electric Corp.Semiconductor binding tape and an electrical member wrapped therewith
US4096346 *Jan 24, 1975Jun 20, 1978Samuel Moore And CompanyWire and cable
US4256921 *Jan 22, 1979Mar 17, 1981George BahderMoisture resistant cable
US4303457 *Jun 18, 1979Dec 1, 1981Eaton CorporationMethod of making a semi-conductive paint hose
US4361799 *Jan 8, 1982Nov 30, 1982Raychem CorporationOver-temperature sense and locate device
US4487057 *Jul 30, 1982Dec 11, 1984Raychem CorporationContinuous sense and locate device
US4584431 *Oct 11, 1984Apr 22, 1986Us Of America Secr Air ForceHigh voltage RF coaxial cable
US5170010 *Jun 24, 1991Dec 8, 1992Champlain Cable CorporationShielded wire and cable with insulation having high temperature and high conductivity
US5216204 *Aug 2, 1991Jun 1, 1993International Business Machines Corp.Static dissipative electrical cable
US5331606 *May 29, 1992Jul 19, 1994Western Atlas International, Inc.Static dissipating data cable and seismic apparatus
US5807447 *Oct 16, 1996Sep 15, 1998Hendrix Wire & Cable, Inc.Neutral conductor grounding system
US6046408 *Jun 26, 1998Apr 4, 2000Hendrix Wire & Cable, Inc.Neutral conductor grounding system
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US6482386Dec 1, 2000Nov 19, 2002Cabot CorporationCarbon blacks useful in wire and cable compounds
US6506492May 7, 1999Jan 14, 2003Pirelli Cables & Systems, LlcSemiconductive jacket for cable and cable jacketed therewith
US6514608Jul 10, 1998Feb 4, 2003Pirelli Cable CorporationSemiconductive jacket for cable and cable jacketed therewith
US6790063May 15, 2003Sep 14, 2004Homac Mfg. CompanyElectrical connector including split shield monitor point and associated methods
US6796820May 15, 2003Sep 28, 2004Homac Mfg. CompanyElectrical connector including cold shrink core and thermoplastic elastomer material and associated methods
US6811418May 15, 2003Nov 2, 2004Homac Mfg. CompanyElectrical connector with anti-flashover configuration and associated methods
US6830475May 15, 2003Dec 14, 2004Homac Mfg. CompanyElectrical connector with visual seating indicator and associated methods
US6905356May 15, 2003Jun 14, 2005Homac Mfg. CompanyElectrical connector including thermoplastic elastomer material and associated methods
US7104822May 27, 2005Sep 12, 2006Homac Mfg. CompanyElectrical connector including silicone elastomeric material and associated methods
US7104823Aug 8, 2005Sep 12, 2006Homac Mfg. CompanyEnhanced separable connector with thermoplastic member and related methods
US7351082Sep 12, 2006Apr 1, 2008Homac Mfg. CompanyElectrical connector including silicone elastomeric material and associated methods
WO2011152969A1 *May 11, 2011Dec 8, 2011Dow Global Technologies LlcStrippable insulation shield for cables
Classifications
U.S. Classification174/120.0SC, 174/110.0PM, 174/102.0SC, 174/105.0SC
International ClassificationH01B1/24, H01B9/00, H01B9/02, H01B3/00
Cooperative ClassificationH01B9/027, H01B3/004, H01B1/24
European ClassificationH01B3/00W2, H01B9/02G, H01B1/24
Legal Events
DateCodeEventDescription
Feb 25, 1985ASAssignment
Owner name: ANACONDA ACQUISITION CO., 17 SQUADRON BOULEVARD, N
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ERICSSON, INC., A CORP OF DE;REEL/FRAME:004364/0732
Effective date: 19850215
Feb 9, 1981ASAssignment
Owner name: ANACONDA-ERICSSON INC., A CORP. OF DE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ANACONDA COMPANY, THE A CORP. OF DE;REEL/FRAME:003846/0822
Effective date: 19800728
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ANACONDA COMPANY, THE A CORP. OF DE;REEL/FRAME:3846/822
Owner name: ANACONDA-ERICSSON INC., A CORP. OF,DELAWARE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ANACONDA COMPANY, THE A CORP. OF DE;REEL/FRAME:003846/0822
Owner name: ANACONDA-ERICSSON INC., A CORP. OF, DELAWARE