CA1100752A - Insulated electrical conductors - Google Patents

Abstract

10,995 INSULATED ELECTRICAL CONDUCTORS

ABSTRACT

Vulcanizable semi-conducting compositions that can be used to provide strippable insulation shielding compositions for electrical conductors, and articles of manufacture wherein the crosslinked product of said vulcanizable compositions are directly bonded to a crosslinked polyolefin substrate.

S P E C I F I C A T I O N

1.

Description

1100752 10,995 BACKGROUND OF THE INVENTION

This lnvention relates to vulcanizable semi-conductive compositions which provide strip-pable semi-conductive insulation shielding compositions for insulated electrical conductors.
The construction of insulated electrical conductors, i.e., wires and cable, designed for medium to high voltage applications is well known in the art and commonly comprises a core conductor which comprises one or more strands or a conducting metal or alloy such as copper or aluminum, a layer of semi-conductive conductor shielding, a layer of insulation, such as cross-linked polyethylene, and a layer of semi-conductive insulation shielding overlying said insulation. A plurality of neutral wires which are usually made of copper or aluminum may be embedded in or wrapped around the layer of semi-conducting insulation shielding, if desired, in the form of a concentric ring around the insulated cable.
The insulation layer and its overlying semi-conductive shielding layer can be formed in the art by what is known as a two pass operation or single pass triple extrusion. The two pass operation is one in which the insulation is first extruded and crosslinked prior to extrusion and crosslinking of the semi-conductive ~nsulation shielding layer. In the single pass triple e~trusion operation (sometimes called a tandem

2.

~ V75Z 1~,995 extrusion when referring only to the insulation layer and its semi-conductive shielding layer) the semi-conductive conductor shielding layer, the insulation layer, and the overlying semi-conductive insulation shielding layer are extruded in sequence and cured (crosslinked) simultaneously in a single operation to minimize manufacturing steps. For obvious reasons the single pass triple extrusion method is preferred by manufacturers. However, the simultaneous ~uring of the insulation layer and its overlying semi-conductive shielding layer of the triple extrusion method results in apparent mixing a~ the interface and formation of crosslinking bonds across the inter~ace which in general makes the shielding layer more fully bonded in most cases to the insulation than it might be if i~ were made as a result of a two pass operation.
The formation of these crosslinking bonds between the insulation and shielding makes ~0 subse~uent separation of the two layers (insulation and semi-conductive shielding) such as occurs in making splices or terminal connections, very difficult and time consuming. Such a strong bond also makes the semi-conductive layer prone to leave carbon residue on the insulation even when it is finally peeled off. Accordingly, a strippable semi-conductive shielding which can be easily and cleanly stripped from the insulation of an insulated conductor that has been made by a single pass triple extrusion operation is therefore very desirable in this art.

11~()752 lo,995 It has now been discovered that such types of easily strippable semi-conducting insulation shielding compositions can be prepared from the w lcanizable semi-conductive insulation shielding compositions of this invention which contain both an ethylene copolymer and butadiene-acrylonitrile copolymer as des-cribed more fully below, the cured insulation shieldings of which have been found to be more easily strippable from the cured insulation than that of corresponding cured insulation shieldings obtained from vulcanizable ethylene copolymer compositions free of butadiene-acrylonitrile copolymer, when both the insulation and insulation shielding layers are cured simultaneously in one operation.
p Thus, it is an object of this invention to provide a vulcanizable semi-conductive insulation shielding composition which is particularly useful for providing a strippable shielding for insulated electrical ~onductors, e.g., wires and cables, that contain, as the primary insulationJ a crosslinked ; polyolefin. Another object of this invention is to provide an article of manufacture comprising the crosslinked product of said w lcanizable semi-conductive insulation shielding composition of this invention bonded directly to a crosslinked polyolefin substrate.
Yet another object of this invention is to provide an article of manufacture as defined above wherein said crosslinked polyethylene is th~ primary insulation of an insu~ated electrical conductor, thus providing insulated electrical conductors, e.g., wires and cables, comprising, as the primary insulation, )7S2 lo, 995 a crosslinked polyolefin, and as the material for said insulation an easily strip?able crosslinked semi-conductive shielding composition. Other objects and advantages of this invention will become readily apparent from the follow-ing description and appended claims.
More specifically, the instant invention may be described as a strippable vulcanizable semi-conductive in-~ulation shielding composition consisting essentially of (A) an ethylene copolymer selected from the group consisting of an ethylene-alkyl acrylate copolymer containing from about 27 to 45 weight percent of alkyl acrylate based on the total weight of said copolymer, said alkyl acrylate being selected from the group consisting of the Cl to C8 alkyl esters of acrylic acid and methacrylic acid, and an ethylene-vinyl acetate copolymer containing from about 27 to 45 weight percent of vinyl acetate based on the total weight of said copolymer, (B) a butadiene-acrylo-nitrile copolymer containing from about 10 to about 50 percent by weight of acrylonitrile based on the total weight of said copolymer, (C) conductive carbon black, and (D) as the only crosslinking agent in said composition OC , bis-(tertiary-butylperoxy) diisopropylbenzene wherein the weight ratio of (A) to (B) in said composition is 1:9 to 9:1, wherein the weight ratio of (C) to the sum weight of (A) + (B) in said composition is O,l to 1.5 and wherein (D~
is present in an amount of from about 0.2 to about 5 percent by weight based on the total weight of the composition.

~101)7SZ lo, 995 DESCRIPIION OF THE PREFERRED EM:BODIMENIS

The vulcan~zable ethylene-alkyl acrylate copolymers and/or their methods of preparation which can be employed in this invention are well known in the art. Illustrative ethylene-alkyl acryla~e copolymers include the copolymers of ethylene and the Cl to C8 alkyl esters of acrylic acid or methacryl~ acid $~ch as methyl acrylate, ethyl acrylate, methyl methacrylate, butyl methyl acrylate, 2-ethyl hexyl acrylate and the like, the preferred copolymer being an ethylene-ethyl acrylate copolymer. The ethylene-alkyl acrylate copolymer employed herein should contain 27 to 45 weight percent - of alkyl acrylate based on the to~al weight of said copolymer. `-The vulcanizableethylene-vinyl acetate copolymer and/or their method of preparation, which can be employed in this invention are well known in the art.

The ethylene-vinyl acetate copolymer employed herein should contain from 27 to 45 weight percent of vinyl acetate based on the ~otal weight of said copolymer.

Of course, it is understood that while it is generally preferred to employ only one type of ethylene copolymer in a given composition the vulcanizable compositions of this invention also include and encompass the use of mixtures of two or more differen~
ethylen~lkyl acrylate copolymers, mi~tures of two or more ethylene-vinyl acetate copolymers having different weight percents of vinyl acetate, as well as mixtures of ethylene-alkyl acrylate and ethylene-vinyl acetate copolymers. Moreover, of the two types of ethylene lo, 995 ll~V75~:

copolymers, ethylene-vinyl acetate is preferred.
The w lcanizable butadiene-acrylonitrile co-polymers and/or methods for their preparation are well known in the art. Such copolymers are also commonly referred to in the art as nitrile rubber or simply NBR. The butadiene-acrylonitrile copolymers employab-le in this invention can contain from about 10 to about 50 weight percent of acrylonitrile based on the total weight of the copolymer. Of course, if desired, mixture of such copolymers having different weight percents of acrylonitrile can also be employed.
The employment of conductive carbon black in semi~conductive insulation shielding compositions is well known in the art and any conductive carbon black in any suitable form can be employed in this invention including channel blacks or acetylene blacks, providing they are electrically conductive.
As pointPd out above the weight ratio of (A) ethylene co~olymer to (B) butadiene-acrylonitrile copolymer in the vulcanizable semi-conductive insulation shielding compositions of this invention is 13 9 to 9:1, while the weight ratio of conductive carbon black (C) to the sum ~ight of ethylene copolymer plus butadiene-acrylonitrile copolymer (A+B) in said compositions is 0.1 to 1.5. Thus, for example, based on 100 parts by weight of the sum of ethylene copolymer (A) plus butadiene-acrylonitrile copolymer (B), the weight ratioo ethylene copolymer (A) to butadiene-acrylonitrile copolymer (B) to conductive carbon black (C) ranges from about 10 to about 90 parts by weight of ethylene 1100752 lo, 995 copolymer (A) to about 90 to about 10 parts by weight of butadiene-acrylonitrîle copolymer (B) to about 10 to about 150 parts by weight of conductive carbon black (C). More preferably the weight ratio of conductive carbon black (C) to the sum weight of ethylene copolymer plus butadiene-acrylonitrile copoly-mer (A+B) in said ~ompositions is 0.5 to 1; i.e., about 50 to about 100 parts by weight of conductive carbon black (C~ to the sum of e~hylene copolymer plus butadiene-acrylonitrile copolymer (A+B).
The only crosslinking agent employed in the semi-conductive compositions of this invention is e~
c~' bis(tertiary-butylperoxy)diisopropylbenzene. Said crosslinking agent employed herein is desirable for its slow decomposition rate. For instance, it has a slower decomposition rate and is less scorchy (less susceptible to premature crosslinking) than di-C~-cumyl peroxide. Moreover since steam tube vulcanizable (the common method employed in single pass triple extrusion cable production) heats the cable from the outside in, it is desirable that the outside contain a ~lower cure system so ~hat the crosslinked density of the product is about the same throughout and such is more lîkely to be obtained with ~ ,o~' bis-(tertiary-butylperoxy) diisopropylbenze that with di-O~-cumyl per~xide. In addition, less ~,sA~
bis-(tertiary-butylperoxy)diisopropylbenzene cross-linking agent than di-o~-cumyl peroxid~ should be needed for an equivalent curing operation. While the preferred amount of crosslinking agent employed herein may vary depending upon the particular l~OU75Z lo, 995 copolymers employed and other such obvious conditions, in general, it is considered that said amount of crosslinking agent will normally fall within the range of about 0.2 to 5, preferably about 0.6 to 2, weight percent based on the total weight of the vulcanizable semi-conductive composition.
Whether or not a particular w lcanizable composition will furnish a crosslinked polyolefin insulated electrical conductor with an easily strippable semi-conductive insulation shielding, said conductor being manufactured via ~ single pass triple extrusion operation, may be generally determined by measuring the adhesion between a simultaneously cured laminate of crosslinked polyolefin and the crosslinked product of the vulcanizable semi-conductive composition according to AsTM-D903. While the actual adhesion levels of such layers on a conductor may be slightly higher than that obtained for the corresponding laminate, the above test serves as a use ul guideline for predetermining such results.
Thus, in order to be considered an easily strippable insulation shielding composition the simultaneously cured laminate adhesion level of the crosslinked product of the semi-conductive composltion for the crosslinked polyolefin should not be more than 15 pounds pPr half inch strip when measured according to said test method.
Of course, it is to be also understood that the vulcanizable semi-conductive insulation shielding compositions of this invention, if desired, can contain other conventional additives in the conventional used quantities commonly employed in semi-conductive composi-tions. Exampl~s of such additives include e.g., age 1 1~ 0 75 Z 10,995 resistors, processing aids, stabilizers, antioxidants, crosslinking boosters and retarders, pigments, fillers, lubricants, ultraviolet stabilizers, antiblock agents and the like. The total amount of such additives which are commonly used normally amounts to no more than about 0.05 to 3 percent by weight based on t'nz total weight of the insulation shielding composition. For instance, it is generally preferred to employ about 0~2 to about 1 percent by weight based on the to~al weight of the insulation shielding composition of an antioxidan~ such as polymerized l? 2-dihydro-2, 2,4-trimethylquinoline.
As pointed out above, another aspect of this invention may be described as an article of manufacture comprising the crosslinked product of the vulcanizable semi-conductive shielding composition of this invention defined above bonded directly to a crosslinked polyole-fin substrate. Said article of manufacture may take any shape or form de~ired, e.g., it could be a laminated plaque or sheet, which is obviously useful in determining whether or not said crosslinked product would be useful as an easily strippable insulation shielding for an electrical conductor as explained above.
More preferably, the crosslinked polyolefin of said article of manufacture of this invention is the primary insulation of an insulated ~lectrical conductor, the crosslinked product of said vulcanizable composition being the external semi-conductive shielding for said insulation. Accordingly, the preferred article of manufacture of this invention may be more specifically described as an insulated electrical conductor, e ~., electrical wire, electrical cable, etc., containing 10 .

1~0075Z
lo, 995 as the primary insulation, crosslinked polyolefin and as the external semi-conductive shielding for said insulation, the crosslinked product obtained upon crosslinking the ~ulcanizable semi-conductive insulation shielding composition of this invention which has been already previously defined above.
Of ~ourse, it is to be understood that the term "crosslinked polyolefin" as used herein includes and encompasses compositions derived from a crosslinkable L0 polyethylene homopolymer or a crosslinkable polyethylene copolym~r such as ethylene-propylene ru~ber or ethylene-propylenediene rubber insulations for electrical conductors. Normally, the preferred cross-linked polyolefin insulation is derived from a cross-linkable polyethylene homopolymer. The use of articles of manufacture containing a crosslinked shielding directly bonded to a crosslinked polyolefin sub-strate and the manner of their preparation are so well known that no further discussion is required to enable one skilled in the art to understand how to produce and use said articles. For instance, the vulcanizable semi-conductive shielding composition can be extruded over a crosslinked polyolefin substrate and cured (crosslinked) thereon. More preferably it is extruded over an uncrosslinked polyolefin substrate and both crosslinkable layers simultaneously cured. More specifically by way of illustration the use of low density polyethylene compositions which if desired, may contain conventional additives such as fillers, age resistors, talc, clay, calcium carbonate and other processing aides, along with a conventional crosslinking 11 .

1 1~ 0 7S Z 10,995 agent is well known in the art as are conventional semi-conducting conductor shielding compositions.
The insulated electrical conductors of this invention are preferably prepared by the conventional single pass triple extrusion procedure involving simultaneously curing (crosslinking) of both the insulation and insulation shielding layer. However, if desired the conventional method of curing the insulation layer prior to contact with the vulcanizable semi-conductive in-sulation shielding composition can also be employed.
In general, it is considered desirable to prevent any premixing of the insulation composition and vulcanizable semi-conductive insulation shielding composition prior to curing said compositions since such can allow the crosslinking agents employed to assert their influen~e on adhesion between the two layers through intercrosslinking across the interface of the two layers. The other particular attributes of the articles of manufacture of this invention e.g. insulated electrical conductors may also conform to the conventional structure of such articles and are not critical for they depend for the most part merely upon the desired end use of such articles.
The following examples are illustrative of the present invention and are not to be regarded as limitative. It is to be understood that all parts, percentages and proportions referred to herein and in the appended claims are by weight unless otherwise indicated.
GLOSSARY
EVA = ethylene vinyl acetate copolymer NBR = butadiene-acrylonitrile copolymer )7S2 10,995 A series of w lcanizable semi-conductive compositions were prepared wherein the weight percent of ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer was varied. The components of each composition are listed below in Table I and each composition contained in addition to the components listed 38 weight percent of conducting carbon black and 0.4 weight percent of polymerized 1, 2-dihydro-2, 2,4-trimethyl quinoline, an antioxidant, the amounts of all the ingredients in each composition being based on the total weight of each composition.
The compositions were formed by uniformly admixing the components thereof in a Brabender Plasticorder mixer at about 135C. for about 10 minutes and about 50 grams of each composition were prepared.
In order to evaluate the strippability properties of these compositions as semi-conductive insulation shieldings, each composition was respectively used to prepare a polyethylene/semi-conductive composition laminate. ~aid laminates were prepared from laboratory test plaques, the polyethylene plaque in each instance was derived from a crosslinkable polyethylene homopolymer composition consisting of polyethylene homopolymer (98%), di-c~-cumyl peroxide (2%) and bis(2-methyl, 5-tertiary butyl, 4-hydroxy-phenyl) sulfide (0.2%), an antioxidant.
In Examples l to 6 each polyethylene/semi-conductive composition laminate was made by first molding the polyethylene plaque (measuring 8" by 8" and 75 mils thick) at 130C. for 5 minutes so as not to ~ 13.
.

.

1~0~7SZ
10,995 crosslink it. Then the vulcanizable semi-conductive plaque (measuring 8" by 8" and 75 mils thick) was separately molded at 130C. for 5 minutes so as not to crosslink it. Each laminate was then made by pressing each vulcanizable semi-conductive composition plaque together with each uncrosslinked polyethylene plaque at 200C. and 700 psi ram pressure for 20 minutes during which time both laminate layers were simultaneously crosslinked.
The adhesion between the test laminates (cut to 5" by 1/2") were then determined according to ASTM
Test Method D903 which measures the peel strength between the two plaques of the laminate in terms of pounds per half-inch strip and which is employed herein as a measure of the strippability of a crosslinked semi-conductive composition insulation shielding from a crosslinked polyethylene insulation. The test results for each laminate (said results representing the average value for testing at least 5 such laminates for each vulcani~able semi-conductive composition) are given in Table I below.

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llC~(J7S;~
lo, 995 The above data demonstrates that the addition of butadiene-acrylonitrile copolymer to the semi-conductive composition substantially reduces the adhesion to crosslinked polyethylene insulation when the semi-conductive composition and polyethylene are covulcanized in a laminate form.

. _ _ Three vulcanizable compositions containing the following ingredients were prepared, amounts of all the ingredients in each composition being based on the total weight of each composition.

TABLE II

Vulcanizable Example 7 Example 8 Example 9 Composition (wt. %) (wt. %) (wt. %) NBR* 25.7 24.6 EVA** 35.3 37 61.0 Condùctive Carbon Black 38.0 38.5 38.0 Antioxidant+ 0.4 0.4 0.4 Peroxide++ 0.6 0.4 0.6 *

Same as defined in Table I for Examples 7 and 9.
However for Example 8 Butadi~ene (67%)/Acryonitrile (33%) B.F. Goodrich's H~car 1452~*x 8 was used.
**Same as defined in Table I

Polymerized 1,2-dihydro-2, 2, 4-trimethylquinoline Same as defined in Table I.
~x~
The vulcanizable composition of Example 7 was prepared on a laboratory scale in a ~anbury intensive mixer and consisted of about 3 pounds. The vulcanizable composition of Example 8 was prepared on a pilot 16.

1 10l~7 5 Z 10,995 plant scale in a Banbury intensive mixer and consisted of about 33 pounds. The w lcanizable composition of Example 9 was prepared on a commercial scale and consisted of about lOS pounds.
A polyethylene/semi-conductive composition laminate was prepared with each composition in the same manner as described in Examples 1-6. The adhesion between the test laminates was then determined according to the same testing procedure described in Examples 1-6. The adhesion test results for each laminate are listed in Table III below (said results representing the average value for testing at least 5 such laminates for each vulcanizable semi-conductive composition).
In addition, other various physical property tests were conducted on a neat crosslinked molded plaque made from each vulcanizable semi-conductive composition and the results of said tests are also listed in Table III below.

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18 .

1 ~C~ 7S Z 10,995 The above data demonstrates that the addition of butadiene-acrylonitrile copolymer to the semi-conductive formulation substantially reduced laminate adhesion. Moreover, other physical properties of the crosslinked semi-conductive composition have not been unduly adversely sacrificed as compared to the cross-linked formulation free of butadiene-acrylonitrile copolymer as measured by the Monsanto Rheometer and resistance to deformation under a load at 121C.
Moreover, the volume resistivity (conductivity) of the butadiene-acrylonitrile copolymer containing formulations are seen to be more stable at the higher temperature of 90C.

.

A series of w lcanizable compositions were prepared in the same manner as described in Examples 1-6. The components of each composition are listed below in Table IV and each composition contained in addition to the components lsited 38 weight percent of conducting carbon black, 0.4 weight percent of polymerized 1, 2-dihydro-2, 2, 4-trimethyl quinoline, an antioxidant and 0.6 weight percent of o~ ,~' bis(tertiary-butylperoxy) diisopropyl benzene crosslinking agent, the amounts of all the ingredients in each composition being based on the total weight of each composition.
The strippability properties of these compositions were then evaulated as semi-conducting insulation shieldings by preparing a polyethylene/semi-conductive 19;

~10()7SZ
o, 995 composition laminate with each composition in the same manner as described in Examples 1 to 5 and testing procedure described in Examples 1 to 6. The adhesion test results for each laminate are listed in said Table IV below (said results representing the average value for testing at least 5 such laminates for each vulcanizable semi conductive composition).

20.

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llOV75Z
lo, 995 The above data demonstrates that lower adhesion values were obtained using an ethylene-vinyl acetate copolymer containing a higher (33%) vinyl acetate content as compared to the data in Table I showing higher adhesion values for equal composition percentages prepared with an ethylene-vinyl acetate copolymer having only 28% vinyl acetate.

XAMPL~ 16 A vulcanizable composition containing the following ingredients was prepared on a pilot plant scale in a Banbury intensive mixer and the composition consisted of about 33 pounds, the amounts of all the ingredients being based on the total weight of the composition.
Component Wt. %
EVA~ 46.2 NBR** 15.4 Conductive Carbon Black 38.0 Antioxidant+ 0.4 Peroxide++ 0.6 *

Ethylene (67%)/Vinyl Acetate (33%) copolymer, Melt Index 20 **
Butadiene (67%)/Acrylonitri~e (33%) copolymer (B. F. Goodrich Hycar 1452-~x 8) Same as defined in Table II
+~
Same as defined in Table I
T~e~ow~
A polyethylene/semi-conductive composition laminate was prepared with the above composition in the 22.

11~()~52 lo, 995 same manner as described in Examples 1-6. The adhesion between the test laminate was then determined according to the same testing procedure described in Examples 1-6. The adhesion test results for the laminate are listed in Table V below (said results representing the average value for testing at least 5 such laminates for the vulcanizable semi-conductive composition).
In addition, other various physical property tests were conducted on a neat crosslinked molded plaque made from the w lcanizable semi-conductive composition and the results of said tests are also listed in Table V below.

TABLE V
: -Physical Properties Example 16 Laminate Adhesion Lb./0.5 in. strip 7.6 Tensile Strength, psi. 2340 Elongation, % 200 Plaque Deformation % at 121C. 5.8 % at 150C. 6.5 360F. Monsanto Rheometer, max.
torque, in. lb. 81 Low Temperature Brittleness, F50 -56 Decalin Extraction % Soluble 11 This example illustrates the preparation of an insu'ated electrical cable.
23.

lo, 9~5 A standard metal conductor was sequent~ally covered with an ordinary semi-conductive strand shielding layer (40 mils), a polyethylene insulating layer (220 mils) and a semi-conducting insulation shie~ding layer (30 mils) consisting of the vulcanizable composition of Example 16 above.
In ~reparing the cable, all three layers of strand shielding, insulation and insulation shielding were extruded sequentially and simultaneously cured by a high pressure steam tube, said process procedure being conventionally known in the art as a single pass triple extrusion.
The adhenion of the crosslinked insulation shielding to the crosslinked insulation of the insulated cable was determ~ned by longitudinally scoring a 1/2 inch wide strip along a length of the cable and measuring the force necessary to peel the insulation shielding layer from the insulation at an angle of 90 by means of an Instron tensile tester at a crosshead speed of 20 inches per minute and the adhesion found to be about 8-12 pounds per half-inch strip.

This example illustrates the preparation of an insulated electrical cable.
A standard metal conductor was sequentially covered with an ordinary semi-conducting strand shielding layer (40 mils~ a polyethylene insulating layer (220 mils) and a semi-conducting insulation shielding layer (30 mils) consist-ing of the vulcanizable composition of Example 8 above.
The cable was prepared in the same manner as described in Example 17 and the adhesion of the cross-linked insulation of the insulated cable was also determined in the same manner as described in Example 17. Said adhesion was found to be about 11-14 pounds per half inch strip.

~ 4.

11~)(J752 lo, 995 Various modifications and variations of this invention will be obvious to a worker skilled in the art and it is to be understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the appended claims.

Claims (14)

10,995 WHAT IS CLAIMED IS:

1. A vulcanizable semi-conductive insulation shielding composition consisting essentially of (A) an ethylene copolymer selected from the group consisting of (i) an ethylene-alkyl acrylate copolymer contain-ing from about 27 to 45 weight percent of alkyl acrylate based on the total weight of said copolymer, said alkyl acrylate being selected from the group consisting of the C1 to C8 alkyl esters of acrylic acid and methacrylic acid and (ii) an ethylene-vinyl acetate copolymer containing from about 27 to 45 weight percent of vinyl acetate based on the total weight of said co-polymer, (B) a butadiene-acrylonitrile copolymer containing from about 10 to about 50 percent by weight of acrylonitrile based on the total weight of said copolymer, (C) conductive carbon black, and (D) as the only crosslinking agent in said composition .alpha. ,.alpha.' bis-(tertiary-butylperoxy) diisopropylbenzene, wherein the weight ratio of (A) to (B) in said composition is 1:9 to 9:1, wherein the weight ratio of (C) to the sum weight of (A)+(B) in said composition is 0.1 to 1.5 and wherein (D) is present in an amount of from about 0.2 to about 5 percent by weight based on the total weight of the composition.

2. A vulcanizable semi-conductive composition as defined in claim 1 wherein the ethylene copolymer is an ethylene-vinyl acetate copolymer.

26.

10,995

3. A vulcanizable semi-conductive composition as defined in claim 2 wherein the weight ratio of (C) to the sum weight of (A)+(B) in said composition is 0.5 to 1.0 and wherein (D) is present in an amount of from about 0.6 to about 2 percent by weight based on the total weight of the composition.

4. A vulcanizable semi-conductive composition as defined in claim 3, wherin about 0.2 to about 1 percent by weight of an antioxidant based on the total weight of the composition is also present.

5. A vulcanizable semi-conducting composition as defined in claim 4 wherein said ethylene-vinyl acetate copolymer contains about 28 weight percent of vinyl acetate based upon the total weight of said copolymer.

6. A vulcanizable semi-conducting composition as defined in claim 4 wherein said ethylene-vinyl acetate copolymer contains about 33 weight percent of vinyl acetate based upon the total weight of said copolymer.

7. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 1, said crosslinked product being directly bonded to a crosslinked polyolefin substrate.

8. An article of manufacture as defined in claim 7 wherein said crosslinked polyolefin is crosslinked poly-ethylene having been derived from a polyethylene homopolymer.

27.

10,995

9. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 2, said crosslinked product being directly bonded to a crosslinked polyethylene substrate, said crosslinked polyethylene having been derived from a polyethylene homopolymer.

10. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 3, said crosslinked product being directly bonded to a crosslinked polyethylene substrate, said crosslinked polyethylene having been derived from a polyethylene homopolymer.

11. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 4, said crosslinked product being directly bonded to a crosslinked polyethylene substrate, said crosslinked polyethylene having been derived from a polyethylene homopolymer.

12. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 5, said crosslinked product being directly bonded to a crosslinked polyethylene substrate, said crosslinked polyethylene having been derived from a polyethylene homopolymer.

13. An article of manufacture comprising the crosslinked product of a vulcanizable semi-conductive composition as defined in claim 6, said crosslinked product being directly bonded to a crosslinked polyethylene substrate, said crosslinked polyethylene having been derived from a polyethylene homopolymer.

28.

10,995

14. An article of manufacture as defined in claim 7, wherein said crosslinked polyolefin is the primary insulation of an electrical conductor and said crosslinked product is the external semi-conductive shielding for said insulation.

29.