CA1107628A - Cable shieldig tape and cable - Google Patents

Abstract

ABRIDGEMENT
The present invention resides in an improved corrosion resistant cable shielding tape comprising a metal strip having a deformation resistant layer of polymeric resinous material tightly bonded to at least one side thereof, the deformation resistant layer having a deformation temperature of at least about 132°C. The shielding tape must meet both the adhesion and deformation resistance requirements simultaneously to provide satisfactory corrosion protection to the shielding tapes by restricting the path of corrosive attack to the exposed metal edges.

Description

2~

This invention relates to new and useful improvements for electrical cables adapted for use in supplying electrical power and communications and, more particularly, to an improved corrosion resistant cable shielding tape forming a part of such cables.
More speci~ically, the present invention relates to cable shielding tapes comprising a relatively thin metal strip with one or more layers of polymeric resinous material adhered to at least one side thereof~
In the art of designing and construating electrical cables, especially telecommunication cables such as telephone cables, it is known to assemble in-sulated conductors in a core and surround it by shield and jacket components. A well known telephone cable design of such construction is referred to in the art as an "Alpeth" cable. This type of cable is more fully described in the F. W. Horn et al paper l'Bell System Cable Sheaths Problems and Designs" in A. I. E. E.
Proceedings 1951, Volume 70~ The shielding tape of the "Alpeth" cable is formed of a layer of bare aluminum having a thickness of abou~ 8 mils which is usually corrugated transversely prior to being wrapped about the cable c~re. The corrugations impart greater flexi-bility to the cable and permit bending of the cable without wrinkling or ruptuxing of the shielding tape.
The term "shield, screen, or shielding tape"
as used herein means a relatively thin layer of any metal, bare or coated, which can provide mechanical protection and electrostatic and electromagnetic screening for the conductors in the core of electrical power and communication cables~

17,942-F

.,s~

When telephone cables are installed under-ground by being buried directly in soil, the outer jacket of such cables, which is ormed of a polymeric resinous material such as polyethylene, may be subjected to damage due to the rigors of installation; rocks;
rodents; lightning; frost; or dig-ins. The underlying shielding tape can thus be exposed to sub-surface water or brine and the attendant potential for corrosion.
Where ~he outer jacket of such cables is formed from a polymeric resinous material, the jacket is not well adhered to the shielding tape of bare metal.
The outer plastic jacket is known to slip over the shielding tape and to fold up into shoulders as the cables are pulled through ducts or placed into trenches.
The shielding tape is also known to kink, curl or twist during installion causing fatigue in the tape and, in extreme cases, rupture of the tape ~ecause of mechanical bending stresses exerted thereon.
In order to improve the corrosion resistance of a shielding tape of bare metal, a special adhesive poly-ethylene f ilm may be applied to cover one or both sides of the metallic strip as taught in U.S. Patent Nos~

3,233,036 and 3,795,540. Such shielding tapes are widely used in the manufacture of electrical power and communi-cations cables. The adhesive polyethylene used for this film contains reactive carboxyl groups which have the ability to develop firm adhesion to the metallic strip and also to the overlying polyethylene jacket. The metal component of such shielding tapes provide electro-static screening and mechanical strength to the cable;

17,942-F -2-~L~, ru~/lra~

the polymeric resinous material coating, e.g., ethylene acrylic acid (EAA) copolymer coating, provides bondability, sealability and corrosion protection to the metal component.
A metallic strip, such as aluminum, which is protected by the adhesive polyethylene film normally has higher resistance to corrosion.
When a polyethylene jacket is extruded over the metallic strip coated with the adhesive polyethylene film, the heat from the semi-molten polyethylene jacket bonds the film coated metal strip to the jacket, forming a unitized component which combines the strength of the metal strip with the elongation and fatigue resistance of the polyethylene jacket component. Such cable construc-tion is referred to in the art as a "Bonded Jacket"
cable design. If the heat imparted to the jacket-foxming polye~hylene is sufficiently high, the shielding tape would become hot enough so that the overlapped portions of the shielding tape bond together at the seam, thereby forming a sealed tube or pipe around the core of the cable. The "Bonded Jacket" cable with a sealed seam has improved re~istance to moisture penetration into the cable coxe. This cable construction also has been shown to have greater mechanical strength necessary to withstand repeated bending of the cable, i.e. kinking and fatigue failures of the shielding tape, resulting from bending stresses during installations. Further, the stresses induced by the temperature cycles under service conditions are reduced.
The plastic coating protects the metal to some degree from coxrosion by limiting the area over which 17~942-F -3-such corrosion can occur or by preventing contact between the metal and the water or brine. The coating should be tightly bonded to the metal to resist significant delamination therefrom during exposure to the cor~osive water and the mechanical forces exerted by the formation of voluminous metal corrosion products, thereby restricting the path of corrosive attack to the exposed metal edges of the shielding tape.
Recently, examination of several commercial cables utilizing poly-meric resinous material coated shielding tapes representative of the prior art has revealed, however, that the coatings on such tapes are damaged during cable manufacture exposing numerous corrodible bare spots on the surfaces of the metal strip. More specifically, when a polyethylene jacket is extruded over a plastic coated shielding tape, the h0at from the molten polyethylene jacket softens or melts the polymeric resinous material coating making it difficult or impossible to obtain a bond to the jacket and a sealed seam.
While the coating is in such softened or molten state, it is penetrated or abraded by the smooth, corrugated or embossed core wraps, by the seams of the tape, by the binder tapes, and/or by the weight of the core itself, thereby exposing numerous corrodible bare spots on the surfaces of the metal strip. As a result, the corrosion rate at the damaged spots is accelerated due to an unfavorable ratio of the anodic and cathodic areas of bare and coated metal. Furthermore, corrosion propagates between damaged spots and prematurely destroys the longitudinal continui*y of the shielding tape which, in turn, can render the ~, - ~1-, 2~

cable inoperative. Since telephone cables are expected to have a long service life, corrosion of shiélding tapes which can lead' to premature cable failures is indeed a serious technical and financial problem for the wire and cable industry. The problem of coating damage has not been recognized until the present invention because of the industry's preoccupation with other major problems.
One of such problems was the need to develop thermal barrier materials to protect the cable core from heat damage.
Another problem was associated with the introduction of fully-filled telephone cable designs wherein the cable core is filled with a grease-like compound to prevent ingress and migration of water.
The corrodible bare spots may occur on either side o~ the shielding tape but the problem is-parti-cularly critical with the use,of corrugated metal1i~
strips where it'has been observed that the penetration and/ox abrasLon damage exposing the bare metal is con-centrated on the raised corrugated surfaces of the shielding tape disposed toward,the core. A corrosive attac~ on this type of circumferentially concentrated damaged area of the corrugated metal strip will quickly destroy the longitudinal electrical function of the shielding tape. In order to maintain the prior art criterion of restricting corrosion to the shielding tape edges, it is now recognized that penetration and/or abrasion resistance of the plastic coatings is required, in addition to delamination resistance, to insure that corrosion is generally confinec~ to the edges of the shielding tape instead of being e~tended over the entire ,, surface theLeof'.
', ~ 2-F _5_ . .
,~

Although there is no known prior ~rt directly concerned with overcoming the above identified problems, the following prior patents speciically referred to hereinbelo~ and in Table II illustrate the closest kno~;n S prior art in the plasti~ coated shielding tape technology.
U.S. Patent No. 3,586,756 and U.S. Patent No.
3,950,605 (Example 3 and 6 - Table II) disclose shielding tapes comprising a metal strip having an adhesive polymer coating adhered to at least one side of the metal strip.
However, these prior patents do not provide for a de-ormation resistant layer of a polymeric resinous material composition having a deformation temperature of at least 130C as hereinafter described in this specification.
The coating on such tapes will be deformed during cable manufacture exposing numerous corrodible bare spots on the surfaces of the metal strip.
U.S. Patent No. 3,507,978 (Example 4 ~ Table II) teaches a shielding tape comprising a metal foil having layers of a copolymer such as ethylene/acrylic acid che~i-cally bonded to both sides of t~e metal foil and an additional layer of high density polyethylene bonded to one of the copolymer layers~ However, there is no teaching or suggestion in U.S. Patent No~ 3,507,~78 of the damage problem overcome by the present invention 2S and examination of commercial cables incorporating such a shielding tape also illustrates that penetration and/or abrasion of the hi~h density polyethylene la~er occurs at current cable manufacturing and service use conditions.

17,~42~
, i, .S

U.S. Patent No. 3,379,824 (E~ample 8 ~
Table II) teaches a shielding tape comprising a three layer structure with an aluminum foil laminated between two polypropylene layers or a polypropylene layer and a polyethylene terephthalate layer. Again, there is no teaching or suggestion of the damage problem over-come by the present invention. In addition, although these plastic layers will resist penetration and abrasion, they do not provide corrosion protection when a corro-sive environment is present in a cable since both polypropylene and polyethylene terephthalate are highly inert and can develop only a poor mechanical bond to the metal strip based on friction adhesion. Therefore, both the polypropylene and polyethylene terephthalate layers will easily delaminate under exposure to corro sive conditions and the mechanical forces exerted by metal corrosion products.
U.S. Patent No. 3,325,589 (Example 9 to 11 -Table II) discloses a plastic coated metal shielding tape comprising a metal strip having an adhesive layer immediately adjacent to the metal strip and an additional Myla ~ or polypropylene layer adhered to one side of the metal strip. Such a shielding tape was subjected to simulated conditions of cable manufacture and a laboratory corrosion test. It was found that the tape did not provide satisfactory corrosion resistance to the metal, i.e., the path of corrosive attack was not confined to the exposed metal edges. The adhesive layer was deformed from pressure exerted through the polypropylene or Myla layer thereby exposing bare aluminum spots. Corrosion ~= Registered Trademark 17,942-F ~7~

h~ 2~

was taking place on these bare spots after subjecting -the cable to a standard corrosion test with sodium hy-droxide, as hereinafter defined in this specification, due to the infiltration of the NaOH between the adhesive layer and the polypropylene (PP) or Myla ~ layers.
U.S. Patent No. 3,7g0,694 (Example 8 - Table II) discloses a polypropylene layer adhesively bonded to a metal strip. The patent does not specify the use of any particular adhesive. Since ethylene acrylic acid (EAA) copolymex is the best known metal adhesive in the industry today, the shielding tapes made according to the teachings of that patent were found to give similar results to those of U.S. Patent No. 3,325,589.
The patent teaches bonding of the jacket, a screen, and composite tapes together during extrusion of the cable jacket. Since the thermoplastic coatings on the screen and composite tapes must be above its melting point to effect bonding they were found to be damaged a priori. Thus, this prior art patent also failed to recognize the problem of coating damage on shielding tapes. U.S. Patent Nos. 3,325,589 and 3,790,694, are related to a heat resistant core wrap (thermal barrier) and a fully filled cable, respectively.
U.S. Patent No. 3,321,572 (Example 13 - Table II) and U.S. Patent No. 3,622,683 (Example 8 - Table II) disclose, inter alia, shielding tapes comprising a metal strip having a polymeric resinous material coating adhered to at least one side thereof and capable of resis-ting deformation at an elevated temperature. However, these shielding tapas were found to fail the adhesion 17,942-F -8-..~

requirement of the present invention. In these tapes, it was found that the path of corrosive attack was not confined to the exposed edges of the metal strip because of the infiltration of corrosive element between the polymex coating and the metal strip.
U.S. Patent No. 3,484,539 teaches the adhesion of a heat sealable layerr such as, for example, poly-vinyl chloride to a polymer layer capable of resisting deformation at cable~forming temperatures. However, the polymer layer of this patent, having adhered thereto a heat sealable layer, is not "tightly bonded" to the metal strip and is thus open to corrosive attack due to the infiltration of corrosion causing liquids whan the cable jacket is damagedO
None of the prior art patents hereinabove discussed show or suggest that a deformation resistant layer can be used in a shielding tape to prevent damage to the protective coating during cable manufacture, installation or service use~ Furthermore, none of the polymer coatings on the shielding tapes disclosed in the prior patents meet both the bonding or adhesion and deformation resistance requirements of the present in-vention to provide satisfactory corrosion resistance to the shielding tapes by restricting the path of corro- ;
sive atkack to the exposed metal edges.
Although the "bonded jacket" cables have im-proved resistance to moisture penetration into the cable core and have greater mechanical strength necessary to withstand repeated bending thereof, some problems have also been encountered in terminating and splicing khe 17,942-F -9-2~

cables., More specifically, it is cumbersome to separate the jacket from the shielding tape for the purpose of making electrical connections to the tape. ~hile it is possible to terminate and splice the "bonded jacket"
cables without separating the jacket from the shielding . tape, it has been shown that the quality of electrical connections is not as good as that with the jacket removed. More particularly, the electrical properties of the connections to the shielding tape are known to change less with time than the connections to the shielding tape and bonded jacket of electrical cables SUM~`5ARY AND DEFINITIONS
The present invention resides in an improved corrosion resistant cable shielding tape comprising (l) a metal strip having tightly and directly adhered to one side thereof a first ad-hesive layer composed of a copolymer of ethylene and from about 2 to a~out 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid; and (2) a first deformation resistant layer composed of a polymeric resinous material tightly adhered to said first adhesive layer, said first deforma-tion resistant layer having a deformation tempera-ture o at least about 270F.
The present invention also resides in an improved cable adapted for use in sup?lying electrical power and communications comprising a core of at least one insulated ~onductor, a shield surroundina saic core com?risina 17,942-~ -10 (1) a metal strip having tightly and directly adhered to one side thereof a first adhesive layer composed O r a copolymer of ethylene and from about 2 to about 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid; and (2) a first deformation resistant layer composed of a polymeric resinous material tightly adhered to said first adhesive layer, said first deforma-tion resistant layer having a deformation tempera-ture of at least about 270F and positioned inwardly in the direction of said core and an outer plastic jacket surroundin~ said shield, wherein the adhesive bond between said metal strip and said first adhesive layer and between said first adhesive layer and said first deformation resistant layer is at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 7~C.
In a preferred embodiment, the adhesive layer has a deformation temperature of at least about 270F after being irradiated with an effective amount o a high energy -`
ionizing radiation.
In another embodiment, a second deformation resis-tant layer and/or other layers of polymeric resinous materials is included in the shielding tape thereby providing a multilayered structure having a combination of desirable functional characteristics. For example, deformation resistant layers of pol~eric resinous material are tightly bonded to both sides of the metal strip, if desired, to provide penetration and~or abrasion resis-tance on both sides of the shielding ta~e.

17.~ -10~-In a further embodiment, adhesive layers of polymeric resinous materials having good bonding character-istics to both the metal strip and the deformation resis-tant layer or layers l7,9~'t2-F ~lOb-are used to tightly bond the deformation resistant layer to the metal strip when direct adhesion of the same is insufficient to adequately provide corrosion protection for the metal strip.
In another embodiment, heat seal layers of thermoplastic polymeric resinous material are included in the shielding tape of this invention to provide a hermetically sealable shield seam in the cable structure and to provide a good bond between the cable shielding tape and outer plastic jacket of the cable.
In a further embodiment, an adhesive/heat seal layer of thermo-plastic polymeric resinous material having both good metal bonding and heat seal characteristics is tightly bonded directly to one side or to opposite sides of the metal strip.
The combined layers of polymeric resinous materials described above have high electrical resistivity, high resistance to chemicals and moisture and exceptionally good bonding to the metal strip thereby being able to withstand the rigors of manufacturing processes as well as penetra-tion and/or abrasion when in use without delamination in a corrosive environ- .-~
ment.
The shielding tape of this invention must meet both the adhesion or bonding and deformation resistance requirements to provide satisfactory corrosion protection to the shielding tape by restricting the path of corrosive attack to the exposed metal edges of the metal strip.
Lamina~ed tapes of the present invention are readily fabricated utilizing well known laminating or extrusion or coextrusion techniques such as those described in United States patent 3,679,513 issued July 25, 1972 to Addinall et al, United States patent 3,402,086 issued September 17, 1968 to Smith et al, and United States patent 3,557,265 issued January 19, 1971 to Chisholm et al. When the laminating technique is used, the resinous polymeric material is first converted into either a blown or a flat film utili~ing a well known extrusion process. The resulting ~ilm is bonded to ,~, -11-the metal strip by heat and pressure. Sometimes it is advantageous and/or necessary to employ an adhesive inbetween the film and the substrate to achieve a better adhesion therebetween.
The present invention-is not limited by either thc process used to prepare the films from the resinous polymeric materials or the technique used to fabricate the laminated tapes therefrom. However, as it is well known in the art, the manner in which these films are prepared can induce some differences in properties thereof. For example, the deformation resistance of these films is, among other things, related to the degree of molecular orientation imparted thereto: a film of a given polymeric com-position having a relatively high degree of molecular orientation will characteristically have a relatively high deformation resistance and vice versa. For example, as it is seen in Examples 1 and 15 of Table 1 below, a polymeric composition comprising 50 percent by weight of polypropylene and 50 percent by weight of ethylene/acrylic acid copolymer has a deformation temperature of 164C when the composition is converted into a film using a blown film process (Example 15) and 1~4C when a flat film process ~Example 1) is employed. However, an additional degree of molecular orientation can be imparted to blown or cast films by well known stretching techniques, e.g.
that described in United Stat~s patent 3,055,048 issued September 25, 1962 to H. P. Koppehele. These films can advantageously be stretched simultane-ously in the machine and transverse directions.
When the laminated tapes of the present invention are prepared by utilizing the well known extrusion coating technique, a molten polymeric resinous material is forced through a slot in a flat die and is applied directly onto the metal strip. The coating thus prepared is known to have about the same degree of molecular orientation as the corresponding flat film of the same polymeric composition.
When the laminated structures of the present invention comprise a plurality of polymeric layers such as, for example, adhesive layer -lla-~76.~

deformation resistant layer and heat seal layer, it is most advantageous to employ well known coextrusion techniques in preparing the blown or flat films or in carrying out the e~trusion coating step.
The nccessary bond strength between the metal strip and an adjacent layer of polymeric resinous material is obtained by the well known post heat-ing step such as the one described in United States patent No. 3,~02,086.
Typically, the laminate is heated in an oven to a temperature of from 80 to ~50C
The present invention also provides a cable sh.ielding tape to which an outer jacket is firmly bonded and wherein the jacket is easily removed to -llb-2~

facilitate the splicing and grounding procedures and yet provides corrosion protection in all areas of such shielding tape by allowing removal of the jacket in such a manner that a tightly bonded adhesive layer remains on the metal com-ponent of the tape after stripping of the jacket.
More specifically, such a shielding tape has a bond between a metal strip and an adhesive layer tightly bonded thereto which bond is stronger than the interlayer bond of other tightly bonded layers of polymeric resinous material. By judicious selection of the types and propor-tions of polymer composition for the deformation resistant layer, the bond of the deformation resistant layer to the adjacent layers of polymeric resinous material is made weaker than that of the adhesive layer to the metal strip. The interlayer bond must be capable of withstanding delamination under conditions of normal use but which will separate prior to delamination of the adhesive layer from the metal strip.
More specifically, as herein defined, "metal strip" means a relatively thin layer of any metal whi~h has good' electrical or mechanical properties useful in electrical power and communications cablesO
As herein defined, the term "tightly bonded" means restricting the path of corrosive attack -to the exposed metal edges of the shielding tape by chemically and/or mechan-ically bonding the deformation resistant layer to the metal strip, either directly or indirectly with an adhesive layer, or by bonding an adhesive/hea~ seal layer directly to the meta~ strip, to prevent significant delamination of the defor-mation resistant and adhesive/heat seal layers from the metal strip under exposure to corrosive conditions and the resulting mechanical forces exerted by the metal corrosion products.

17,9~2-F -12-"Adhesive layer", as herein defined, means a layer of polymeric resinous materials having good bonding characteristics with the metal strip and defor-mation resistant layer and the plastic jacket of the electrical cable.
"Heat seal layer", as herein defined, means a layer of thermoplastic polymeric resinous materials having a sealing temperature of 121C or lower and, pre-ferably, 110C or lower which will easily seal to itself, or other polymeric resinous materials such as, for example, those materials forming the outer plastic jacket of a cable.
"Adhesive/heat seal layer", as herein de-fined, means a layer of thermoplastic polymeric resinous materials having both good metal bonding and heat seal ~haracteristics for the adhesive and heat ~eal layers which will tightly adhere to the metal strip.
"Deformation resistant layer", 25 herein de-fined, means a layer of polymeric resinous mat~rials that substantially resist penetration and/or abrasion at deformation temperatures of at least about 130C
and pressures normally associated ~ith cable manufacture, installation and/or service use.
Improved cables adapted for use in supplying electrical power or communications can be constructed with the improved corrosion resistant cable shielding tape described above~ Such cables comprise a core of at least one insulated conductor, a shield of the im-proved corrosion resistant cable shielding tape surrounding the core, and an outer plastic jac~et surroundin~ the ... .
~ F -13-tape. The deformation resistant layer of the shielding tape may be positioned in the direction of the core, in the direction of the outer jacket or in both direc-tions to overcome penetration and/or abrasion damage during manufacture and/or during service of the cable.
The invention is further understood by refer-ence to the accompanying drawings in which like characters of reference designate corresponding materials and parts throughout the several views thereof, in which:
Figure 1 is a partial cross-sectional view of a plastic coated metal shielding tape constructed according to the principles o the present invention;
Figures 2-9 are partial cross-sectional views illustrating modified plastic coated metal shielding tapes constructed according to the principles of the present invention;
Figure 10 is a cross-sectional view of a typical power cable with three insulated conductors, a plastic coated metal shield and an outer plastic jacket; and Figure 11 is a cut-away perspective view of an end of a communications cable with multi-pair in-sulated conductors in the core, plastic coated metal shield and plastic outer jacket.
DETAILED DESCRIPTION OF THE PREEERRED EMBODIMENTS
_ _ Referring now to the drawings, Figure 1 illus-trates an improved corrosion resistant cable shielding tape 10 comprising a metal strip 12 having a deformation resistant layer 1~ formed of a polymeric resinous material such as a blend of 50 weiyht percent poly-17,94Z-F -14-7~

propylene and 50 weight percent ethylene/acrylic acid copolymer tightly bonded to one side thereof. In order to provide corrosion protection for the metal strip 12, shielding tape 10 should be used in cable constructions having a plastic outer jacket formed of an adhesive composition which will tightly bond to the metal strip 12 on the side opposite to that of layer 14.
Figure 2 illustrates a modified cable shielding tape 20 having a deformation resistant layer 24 like layer 14 of Figure 1 tightly bonded to metal strip 12.
Layer 25 which is tight]y bonded to the opposite side of strip 12 may be a deformation resistant layer like layer 24 or may be an adhesive/heat seal layer formed of an ethylene/acrylic acid copolymer.
Figure 3 illustrates another modified cable shielding tape 30. The metal strip 12 may have a de-formation resistant layer 34 like layer 14 of Figure 1 tightly bonded to one side thereof and a heat seal layer 36 formed of low density polyethylene adhered to layer 34O Alternatively, layer 36 may be a deformation resistant layer formed o a material such as nylon which will not tightly bond directly to the metal strip 12 with sufficient adhesion to provide corrosion protection and layer 3~ may be an adhesive layer formed of a material such as an ethylene/acrylic acid copolymer. ~ike shielding tape lO of Figure 1, shielding tape 30 should be used in cable constructions which have a plastic outer jacket formed o~ an adhesive composition to insura corrosion protection for the metal strip 12.

17,942-F -15-~ ~ 7~2~

Figure 4 illustrates still another modified cable shielding tape 40. There are four possible struc-tures of shielding tape ~0 useful in accor~ance with this invention. Layer 45 may ~e a deformation resistan~
layer like layer 14 of Figure 1 for two of the possible structures or an adhesive/heat seal layer like layer 25 of Figure 2 for the other two structures. Layer 44 may also be a deformation resistant layer like layer 14 of Figure 1 when it will tightly bond directly to the metal strip 12 or it may be an adhesi~e layer formed of an ethylene/acrylic acid copolymer which in turn is used to tightly bond a deformation resistant layer 46 like layex 36 of Figure 3 that will not tightly bond directly to the metal strip 12. When layer 44 is a deformation resistant layer tightly bonded to the metal strip 12, layer 46 is beneficially a heat seal layer like layer 36 of Figure 3.
Figure 5 illus~rates still another modified cable shielding tape 50. There are three possible structures of tape 50 useful in accordance with this invention. First, two deformation resistant layers 56 and 57 like layer 36 of Figure 3 which t~ill not kightly bond directly to the metal strip 12 may be tiyhtly bonded to the strip 12 with adhesive layers 54 and 55 like layer 34 of Figure 3. Second, the remaining two possible structures may have a deformation resistant layer 55 like layer 14 of Figure 1 tightly bonded to the metal strip l2 a~d a heat seal layer 57 like layer 36 of Figure 3 bon~ed to layer 55. On the opposite side of the metal strip 12 there may be a deformation 17,992-F
, resistant layer 54 like layer 14 of Figure 1 tightly bonded directly to the strip 12 and a heat seal layer 56 like layer 36 of Fiyure 3 bonded to layer 54 or, in the alternative, there may be a deformation resistant layer 56 like layer 36 o Figure 3 which will not tiyhtly bond directly to the metal strip 12 that is tightly bonded to ~he strip 12 with an adhesive layer 54 like layer 34 of Figure 3.
Figure 6 illustrates a further modified cable shielding tape 60. A deformation resistant layer 66 like layer 36 of Figure 3 which will not tightly bond directly to the metal strip 12 is tightly bonded to the strip 12 with an adhesive layer 64 like layer 34 of Figure 3. A heat seal layer 68 formed of an ethylene/-acrylic copolymer is bonded to layer 66. Like shielding tapes 10 and 30, shielding tape 60 should ba used in cable constructions which have a plastic outer ~acket formed of an adhesive composition ~o insure corrosion protection for the metal strip 12.
Figure 7 illustrates a still further modified cable shielding tape 70. The adhesive layer 74, defor-mation resistant layer 76 and heat seal layer 78 are the sam~ as the corresponding layers 64, 66 and 68 found in Figure 6. Layer 75 may be a deformation resistant layer like layer 14 of Figure 1 or, in the alternative, an adhesive/heat seal layer like layer 25 of Figure 2 tightly bonded directly to the metal strip 12.
Figure 8 illustrates a still further modified cable shielding tape 80. The adhesive layer 84, defor-mation resistant layer 86 and the heat seal layer 88 17,942 F -17-are the same as the corresponding layers 64, 66 and 68 found in Figure 6. On the opposite side of the metal strip 12 there may be a deformation resistant layer 85 like layer 14 of Figure 1 tightly bonded directly to the strip 12 and a heat seal layer 87 like layer 36 of Figure 3 bonded to layer 85 or, in the alternative, there may be a deformation resistant layer 87 like layer 36 of Figure 3 which will not tightly bond directly to the metal strip 12 that is tightly bonded to the strip 12 with an adhesive layer 85 like layer 34 of Figure 3.
Figure 9 illustrates a final modified cable shielding tape 90. The adhesive layers 94 and 95, deformation resistant layers 96 and 97, and the heat seal layers 98 and 99 are the same as the corresponding layers 64, 66 and 68 found in Figure 6.
Referring now to Figures 10 and 11, a typical three-conductor power cable 100 and multi-pair conductor communications cable 110 are illustrated. The power cable 100 has low resistance metal conductors 101, which can be solid or stranded, usually of copper or aluminum, which are each insulated, usually with an extruded plastic cover 102 of, for example, polyvinyl chloride~
polyethylene or rubber. Space fillers 103 of, for example, natural fibers or foamed plastic are used to provide a substantially circular core assembly which is enclosed in a shielding tape 104 formed from any one of the shielding tape structures illustrated in Figures 1-9. The shielding tape 104 is preferably a longitudinally folded tube with an overlapping seam that may be hermati-17,942~F -18-cally sealed by heat sealing the plastic coating of the shielding tape together in the overlapping seam during cable manufacture. An outer plastic jacket 105, usually extruded polyeth~lene containing stabilizers and carbon black, is beneficially bonded to the shielding tape 104. The communications cable 110 includes an inner core of many pairs of insulated conductors 111 (e.g. plastic coated copper wires) bundled in a plastic core wrap 112 of, for example, polypropylene or poly-ethylene terephthalate which is securely bound with a binder tape 113. The bundle is enclosed in a shielding tape 114 formed from any one of the shielding tape structures illustrated in Figures 1-9. Like the shielding tape 104 of power cable 100, shielding tape 114 is preferably a longitudinally folded tube with a hermetically sealed overlapping seam. An outer plastic jacket 115 preferably of polye~hylene is extruded over the shielding tape 114 and is advantageously bonded to the same.
The metal strip which is used in accordance with this invention may have a thickness from 0 2 to 25 mils and, more preferably, from 2 to 15 mils. The metal strip may be formed, for example, from al~ninum, aluminum alloys, alloy-clad aluminum, surface modified copper, bronze, steel, tin free steel, tin plate steel, aluminized steel~ stainless steel, surface modified copper-clad stainless steel, terneplate steel, gal-vanized steel, chrome or chrome treated steel, lead, magnesium or tin. These metals may also be surface treated or have thereon surface conversion coatings.

17,9~2-F -19-The deformation resistant layer which is used in accordance with this invention may have a thickness from 0.1 to 15 mils and, more preferably, from OOS to 2.0 mils. Beneficially, the deformation resistant layer may be formed from any polymeric resinous material which will provide a layer deformation temperature of at least about 132~C such as, for example, polypropylene, carboxyl modified polypropylene, polyamides, polyethylene terephthalate, fluoropolymers, 1-4 di-methyl pentene polymers, ethylene/propylene copolymers, stereo regular polystyrene, flexible thermoset polymeric resinous materials, Saran~, or irradiated carboxyl modified olefin polymers. These polymeric resinous materials may be blended with, for example, low or high density polyethylene, ethylene/ethyl acrylate copolymers, ethy-lene/vinyl acetate copolymers, carboxyl modified ethylene polymers, ethylene/acrylic acid copolymers, ionic olefin polymers, or chIorinated polyethylene, provided the layer deformation temperature is at least about 132~C.
Flexible thermoset polymeric resinous materials such as, ~or example, polyurethanes mav also be used provided the 132C deformation temperature i5 achie~ed.
The adhesive layer may have a thickness from 0.1 to 10 mils, preferably from 0.3 -to 2.5 mils. Such layer may be formed from any thermoplastic polymeric resinous material which will tightly bond the de~ormation resistant layer to the metal strip. Copol~mers of ethy-lene and ethylenically unsaturated carboxylic acids readily form a strong adhesive bond with aluminum and are preferred in achieving beneficial results of the 17,~2-F -20-present invention. The adhesive polymer which is bene-ficially used in accordance with this invention is a normally solid thermoplastic polymer of ethylene modified by monomers having reactive carboxylic acid groups, particularly a copolymer of a major proportion of ethy-lene and a minor proportion, typically from 1 to 30, preferably ~rom 2 to 20, percent by weight, of an ethy-lenically unsaturated carboxylic acid. Specific examples of such suitable ethylenically unsaturated carboxylic acids (whieh term includes mono- and polybasic acids, acid anhydrides, and partial esters of polybasic acids) are acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, maleic anhydride, monomethyl maleate, monoethyl maleate, monomethyl fumarate, monoethyl fumarate, tripropylene glycol monomethyl ether acid maleate, or ethylene glycol monophenyl ether acid maleate. The carboxylie acid monomer is preferably selected from ~ ethylenieally unsaturated mono- and polycarboxylic acids and acid anhydrides having from 3 to 8 earbon atoms per molecule and partial esters of such polycarboxylic acid wherein the acid moiety has at least one carboxylic acid group and the alcohol moiety has from 1 to 20 carbon atoms. The copolymer may consist essentially of ethylene and one or more of such ethylenically unsaturated acid comonomers or can also contain small amounts of other monomers copoly merizable with ethylene. Thus, the copolymer can contain other copolymerizable monomers including an ester of acrylic acid. The comonomers can be combined in the copolymer in any way, e.g., as random copolymers, 17~942-F -21-2~

as block or sequential copol~ners, or as graft copoly-mers. Materials of these kinds and methods of making them are readily kno~ln in the aL-t.
Beneficially, thc heat seal layer may have a thickness from 0.1 mils to 10 mils and, preferably, from 0.3 mils to l mil. The heat seal layer may be formed from, for example, low or high density poly-ethylene, ethylene/ethyl acrylate copolymers, ethylene/
vinyl acetate copolymers, carboxyl modified ethylene polymers, or blends of the above.
The adhesive/heat seal layer may have a thickness from 0.1 mils to 10 mils and, more preferably, from 1 mil to 3 mils. The adhesive/heat seal layer may be formed from, for example, carboxyl modified olefin polymers, ionic olefin polymers, blends of carboxyl modified oiefin polymers or biends of ion7c. olefin polymers.
Deformation resistance of a layer of polymeric resinous material is normally tested by means of a penetrometer. However, kno-~n penetrometers are designed for coatings (comprising one or more layers of synthetic resinous material) 60 to 125 mils (1.52 to 3.17 mm) thic~
and data therefrom do not apply to the coating thic}cnesses on cable shielding tapes or ter.lperatures and pressures associated with the cable manufacture or use. There-fore, a special penetrometer test was developed to evaluate the ability of relatively thin coatings, i.~., coatings having a thicklless of 10 mils (0.254 N~l) OL-less, on plastic clad metals to resist deformation at elevated temperatures. The sl~ecial penetromcter consists of a metal blocX weig]lin~ l.G~ ~;g onto whicl '.

~ 17,g~l2-F -22-... .

~76j~Z 3 a circular ring has been machined. The ring has an outside diameter of 38.1 mm an~ a thickness of 25 mils, The cutting edge of the rin~ in contact with the coated shielding tape sample is rounded to a 0.79 ~m radius which applies a pressure to the sample of 35 pounds per square inch (24.6 gm/mm ). The testing procedure consists of placing the sample of shielding tape on a base such as a metal plate and then positioning the special penetrometer on the sample with the ring in contact with the coating thereon. An electrical circuit, open because of the coating, is connected between the penetrometer and the metal strip of the sample. Thereafter, the entire assembly is placed in a circulating air oven preheated to 218C which increases the temperature of the shielding tape being tested at a rate of approximately 1~C per minute. ~hen Lhe ring peneLrates the coating the electrical circuit is completed and the temperature of the coating, determined by a thermocouple or other ' means, is recorded. This temperature is the deformation temperature, for the coating be,ing tested~ It has been found that the conditions of this test correlate well with the temperatures and pressures associated with cable manufacturing and/or service use. It has been found that the deformation resistant l~yer should have a deformation temperature of at least ab~ut 130C
and prefexably at least about 138C and above to resist the temperatures and pressures normally asso-ciated ~ith cable manu~acturing and/or service use.
The degree of adhesion between plastic layers, and between a plastic layer and the metal strip of a shielding tape o~ this inventi,on, which wi]l sa`tisy the ,~,, 17,9~2~~ -23-1~7~

requirement for "tightly bonded" thereof, should represent a value of at least about 1 kg/2.54 cm of tape width, prefera~ly at least about 2 kg/2.~4 cm, after i~ersion of a tape sample in deionized water maintained a~ a temperature for a period of time of 7 days. The degree of adhesion is determined by preparing a 6 inch wide by 6 inch long by 60 mil (15.24 cm x 15.24 cm x 3.175 mm) thick molding of a plastic jacketing material using a procedure similar to that described in the U.S.D.A.*
Rural Electrification Administration (REA) specificatio~
PE-200. A sheet of shielding tape of the same dimen-~ions (~ in. x 6 in.) was placed over the molding.
A strip of polyester film of 1 mil (0.254 mm~ thickness was placed between the shielding tape and the molding of the jacketing material to prevent bonding to one end of the jacketing material to form a "tab'; for use in a tensile strength testing machine. The shielding tape was bonded to the molding using a compression molding press and a molding temperature of 190C. The molding pressure was 300 pounds per square inch (0.2 };g/mm2). The heating cycle was as follows:
3 minutes to reach temperature Wit}l no pressure; ~
minutes under pressure; and 5 minutes to cool to room temperature. After the shielding tape/jacketing material laminate was prepared one inch (2.54 cm) wide samples for bonding tests were cut on a sample cutter. The samples were placed on a tellsile testing machine and tested for bGnd strengt]l as ~ollows: the unbonded portion of the shieldin~ tape was folded bac~ ~800r;
the sample was inserted inLo the tensile testin~ machine *UIlited States ~epartr,;ent of ~g~ic~lture '.

1~,942-1 -2q-with the shielding tape in the upper jaw and the molding of jacketing material in the lower jaw; a rigid metal plate was placed behind the molding to maintain the peeling angle at 180C; and the shielding tape was then separated from the rigid molding of the jacketing material at a crosshead speed of 5 inches per minute.
The required force to separate the shielding tape from the molding was recorded as a measure of adhesive strength~ The separation can occur at the metal strip/
plastic layer interface, or plastic layer/plastic layer interface or plastic layer/jacketing material interface.
Several shielding tapes of plastic coated aluminum were prepared and were tested for corrosion resistance thereof. More specifically, test samples of the shielding tapes having an area of 5.08 cm x 5.08 cm were first subject to a simulated jacketing test, as described hereinafter, and were then immersed in one (1) normal sodium hy-droxide (1~ NaOH) solution for 24 hours~ Bare aluminum spots on the surfaces of the shielding tapes, which had been exposed by damage to the plastic coatings thereon during the simulated jacketing test, were thereby corro-ded. The number of corroded spots, which were easily identifiable in the test sample of shielding tape, were counted and recorded as a corrosion damage index thereof.
An index of 0 indicates that no corrosion spots are present while a given number indicates the number of corrosion spots which can be counted on the sample.
Shielding tapes having poorly bonded plastic coatings 3~ thereon resulted in total dissipation of the metal o~ten accompanied by delamination of the coatings.

17,9~2-F -25-~L~7~2~ `

The simulated jacketing test was designed to simulate temperature and pressure conditions normally encoulltered inside a cable, during and following .hn jacketing operation, in order to study the effects thereof on cable components. The test is particularly well suited to study the effect of the temperature and pressure conditions on the plastic coating or plastic coated shielding tapes. In order to conduct this test, a cylindrical section of a cable having a length of about 5~0 cm is converted into a rectangular configuration having planar surfaces. The test is carried out using the follo~ing procedure: A sample of molded jacketing material of about 5.08 cm x 5.08 cm and weighing 13 grams and having a thickness of 100 mil (2.54 mm) was heated in an oven to a temperature of 218C; the jacketing material was removed froltl the oven after 6 to 7 rninutes and within a period of S seconds a sample of corrugated shielding tape (5.08 cm x 5.08 cm) was placed on the jacketing material; a corrugated core wrap of polyester film, a section of a cable core having a generally rec-tangular configuration and weighing 218 gramsr and a 2000 gram weight were then successively stacked on top of the shielding tape; and finally, the entire assembly was placed on a large aluminum bloc]c (weighing 95S
grarns) ~o cool while the temperature of the core wrap/-shield int~rface was recorded through a thermocouple placed tllerebetween. Thc al~ninum block provides a heat sink and thereby simulates the cooling bath located downstream of the extruder head.

17,9~2-~ -2G~

~7~

The temperature-time relationships fo~ the shield obtained with this test correlate to those obtained with cables containing a large number of con-ductor pairs during extrusion of the jacket.l Heat sealability was determined on film samples of the coatings by means of a special seal test. Two samples of film 50.8 mm wide are placed in contact with each other in a heat sealer apparatus such as a Sentinel Brand, Model 24AS, or equivalent. The temperature of the sealer bar is increased in 5C increments from 88C to a temperature sufficient to seal the films together. The temperature at which the films seal to each other is recorded as the minimum seal temperature.
The dwell time in seconds for the sealer bar i5 equal to 26.25 times the film thickness in mm. The air pressure on the sealer bar is set to 28 g/mm2 The effect of "fillers" for the cable core was tested with samples of plastic coated shielding tapes in which coatings on both sides thereof were exposed to petro-latum filling compounds (Witco 5B) and floodant (Witco 4) at 115.5C for two seconds. A percent swell was calculat~d based on the amount of filler picked up by the coating as follows after the surface thereof is wiped clean of any filler compound: The original weight of the coating Z5 was subtracted from the weight of the coating after exposure and this difference was divided by the original weight. This number was mul~iplied by 100 to obtain percent swell. The results of this test are listed in Table IX.
lR. C. Mildner, P. C. Woodland, H. A. Walters, and G. E.
Clock, entitled, "A Novel Form of Thermal Barrier for Communication Cables," presented at the 14th International Wire and Cable Symposium, Atlantic City, New Jersey, 1965.

17,942 F -27-~76~

In a "connector stability" test, coated metal samples approximately 50 mm x 150 mm were corrugated.
Then two Griplok~ connectors were attached to each longi-tudinal end of the samples. The initial resistance in milli-ohms was measured across the connectors using a Kelvin Bridge. The samples were then given 50 temperature cycles from -40C to +60C, with each cycle being of an 8 hours duration, and the resistance was measured again. The results of these tests are listed in Table X.
In a jacket bond strength and bend performance test, a bonded jacket gas pipe was fabricated on a cable jacketing line using lengths of corrugated laminates. The laminates were oriented such that the multilayer coated side contacted the extruded jacket. Samples of the pipe were then collected for determination of jacket bond strength and bend perfoxmance. The results of these tests are listed in Table XII.
The following additional test methods were used:
1. Physical properties of the coating were determined by ASTM D-638.
2. Elmendorf Tear was determined by ASTM
D-1922.
3. Melt Index was determined by ~STM D-1238.
Representative examples of the presen~ inven-tion along with deformation ternperatures and corrosion index test results, are shown in Table I. The examples were formed by extruding the plastic layers, each of about one mil thickness, and then laminating them to a hot metal strip having a temperature of about 190C.

17,942~F -28-~7~2~

Bonded jac~et cables incorporating these examples were fabricated on commercial cable manufac-turin~ lines under norr~al proccssinc; conditions.
The penetrometer test for defor~a~tion resis-tance was used to obtain the deormation temperature.
Examples 8-11 in Table I show the use of three component blends as the deformation resistant layerO
Example 12 establishes the use of a four com-ponent blend as the deformation resistant layer~
Example 13 establishes the lower limit for deformation temperature of a blend of polyethylene with polypropylene of about 130C.
Example 14 illustrates the use of an adhesive - jacket to substantiate the utility of single side coated metals according to Figures 1, 3 and 6.
Ex~mple 15 ilIust~a''es an embod~ment in ~7hich polypropylene is used as a deformation resistant layer.
An EAA-PP blend is used as a second adhesive layer ~o bond the deformation resistant layer to a first adhesive layer of EAA. A second DAA-PP blend layer and a heat seal layer o~ EAA can ~e successively applied to the PP layer to obtain low temperature sealability.
~xamples 16~18 are comparative examples and were prepared according to the procedure of this invention.
However, the composition of the blend in the deformation resistant layex was selected where it was not sufficient to provide a deformation temperature of at least 130C.
Example 19 illustrates a particular blend in the deformation resistant layer which falls within the desir-able range of deformation temperature and corrosion incle~.

17,9~2-~ -29-~7~2~

Example 20 illustrates a functional ex~ple with copper. Since copper degrades an EA~ coating in the presence of moisturc, a copper stabilizer, OABH
(oxalic acid bis (benzylidene hydrazide)), has been added to the EAA.
Example 21 illustrates a functional example with ionomer (Surlyn~ 1652, 11% ~LA) as the metal adhesive layer Example 22 illustrates a functional example with an EAA-polyethylene blend as the metal adhesive layer.
Examples 23-25 illustrate functional examples with crosslinked coatings which were unusual in that they maintained their bondability, sealability, and corrosion protection qualities after irradiation.
Examples 26-27 illustrate functional exarl~les with Saran as the heat deformation resistant layer.
These structures are not illustrated in the drawings.
Like Example 15, a second adhesive layer consisting of a blend or a suitab]e pol~ner is used to tightly bond a heat deformation layer to metal. The basic structures would be: 15etal/Adhesive layer/Second Adhesive layer/Deformation layer; Metal/Aahesive layer/Second Adhesive layer/Defor-mation Resistant layer/Heat Sealable layer (EVA); or Metal/Adhesive layer/Second Adhesive layer (blend)/Defor-ma~ion layer/Second ~dhesive layer (blend)/Sealable layer.
A comparative analysis of Tables I and II
demonstrates the damaye that occurs to the plastic coated s~lielding tape of the prior art as measured ~y - 30 the nur,lher o corrosion spots counted on a 25 cm2 '.

~ 17,9~2-~ -30 ~,,a,,J7$~

sample. It also demonstrates the need for a deformation resistant layer having a deformation temperature of at least about 130C and tight bonding to prcvent the occurance of ~are spots on the surface o~ the tal~e and the attendant potential for corrosion thereon.
Examples 9-11 in Table II illustrate that dama~e to lower melting point coatings on rnetal can occur through a deformation resistant layer. Without tight adherence between a deformation layer and a metal adhesive layer, or with bonds between the two that are water sensitive, corrosion can occur at the defects in the adhesive coating on the r,letal.
Example 12 illustrates the non-functionality of this patent construction for corrosion protection.
Example 13 illustrates the need for tight adherence of coatings to metal.
Table III and IV illustrate the initial bond strengths and bond strengths after aging for 7 days in 70C deionized water. Two sets of numbers are given in Table III because multilayer coatings may not necessarily fail at the irterface of the metal and an immediately adjacent plastic layer during bond strength tests. If the metal bond exceeds the bond of the various plastic layers to each other r then bond failure occurs at the weakest inter~ace thereof. (The example numhers re~er to those in Table I ancl Tahle II where the detailed shielding tape constructions are shown.) The mir.umum - bond strength is 1.0 );~/2.5~ cm rec3ardless of whetller the bond strcncJth refexs to a me~al/pol~eric layer 3~ ' bond or to a polymeric layer/pol~neric lay~r bond.

17,~2~F -31~

For -the former, corrosion rcsistance and mechanical performance will be deficient below the minimum bond strength. For the latter, the ability to withstand handling without delamination will also be impaired below this minimum bond strength.
From Table III, it can also be seen that the judicious selection of the types and proportions of pol~mer compositions will provide a bond between the metal strip and adhesive layer which is stronger than the interlayer bond of the other layers of polymeric resinous materials while still providing a minimum bond strength of 1.0 kg/2.54 cm between the polymeric coating/polymeric coating bond.
Table V and VI show that the multilayer coatings have improved ultimate tensile strength, elongation, and tear strength when compared to coatings of the presently known art. The example numbers refer only to the improved coating structure shown in Table I
and not to the coated metal structure~
Tablec VII and VIII show actual cable data wherein the cables are made using several shielding tapes described in Tables I and II. The same example numbers are used.
Table IX shows that the improved coatings of this invention have increased resistance to adverse effects of filling and flooding compounds. The attribute is also of benefit in e~tending the service life of filled cables.

17,~42-F -32-Table X shows that the connector stability to coated mctal is improved with the improved coati~g since the increase in resistance over the initial value is smaller.
Table XI shows that the electrical brea~do~,m strength and resistance to permeation ls improved with the new coating. The electrical strength of the new coating may be used to advantage in filled cable designs by elimination o, the standard electrical barrier which is wrapped about the core. The reduced rates of permeation may serve to improve corrosion resistance.
The bond strength figures of Table XII re-flect the levels of interlayer bond of the multilayer samples. These bond values are approximately 1/2 that of the prior art example 5 of Table II~ However, the interlayer failure provides a means ~or controlling the level of bond between the polymer layers of the shielding tape and the jacket, i.e. a bond strong enough to provide g~od mechanical properties while allowing easy stripping of the jacket for splicing. Moreover, at least the adhesive layer of the multilayer coating remains intact on the metal strip to provide continued corrosion protectionO

~7,~4~
5 ~ ~

1~76~B

The bend performance values are sur~rising since the multilayer samples, at half the bond strength, exhibited bend performance equivalent to the control sample. These rcsults tend to suggest that bend per-formance requires a moderately high jacket bond strength but perhaps even more important is the ability to relieve stresses. The multilayer film provides a means of stress relief via the lower interlayer adhesion.

17,'~12-F -3~1-~$q~

roJ x ~n ~
o~ o o o o o o o o o o s~ ~
S-l H

o O `
,~ a) ~) ~ ~ ~ o d' S~
O ~1 A
~H O
E~

Z
O
~H
Z
P~
~ ~ ~ ~ ~ ~ C~
æ
H ~ _ _ ~
. _ ~ d~Do~ o\O
H
~ ~ ~ W
E~ , P~ C --oP
P~ P~ ~ W ~1 o ~
H O ~ ~Lr~ ~ D O D
.,.1 o o o ~4 ~ _ ~ m 1~7 1~:1 ~ IJ-~ ~D 1~ ~~1 o~O I I I
~ :1 O I I I d~ ¢l--m o ~ P m ~ Q 1 0~1n 0~ 5 dO o~ dP ~ O ~ O o~ ~ dP
O O O o o --_~ ~ ~p, _ `_ _ _ _ _ _ _ ~ ~
I ~ ~ E~
^ U~
Ç~

O

~1 a X ~

17 ~ 942-F ~35~

~q~ .

~ro~ x O ~ O O O O O ~ ~D L/~
~ ~ ~ a~
h 1-l O
O' rJ a ~ 5~
e ~
o h ,1 ,1 ~ ~ ,1 ,1 a Q E~
E~
~ '' ' ~ ' .
~4 _ .
.-~ t) . ,.
'- z; . ~P p,~., ' ''. _ O

O ~ O~
E~ ~ ~ ~ p~ ~ o P~ p~ o o ,î
. . ~ ~
1~ I W
~0 U ~ X
F; I h dP ~ o'~O ,~ o\O o~O o~O o~O o~
C) G~ C~ O ~; O O O O O
~:1 ~1 ~ ~ ~' ~ ~ ~ ~ ~
_ ~

' "
'~ ~ W ~ ~ W ' ~ ~ ~
~1 ~ ~ ~ ~ ~1 ~ ~1 ~_ ~ -- o'~--~ o~
~¢ ~ O 11~
~ ~ ~ ~ ~W W ~ ~ ' G.) p~ ~; ~ ~'C *

F~ ~

17,9~ 36-rl X
o~ o o o o o o o o h ~
h H
U
o O `
h ~ ~ c~~r ~ o o o o h d ~1~1 ~I t`l ~ ~ ,~
O ~1 A A A A
a) E~

.~ ~
O ~ .
U o'~D
Ln U?
æ ~ ~ .,, o ~ ~ ~
H ~ ^ ~ ~I JJ
E~ a u~
Z
Z o ~ ~ h ~
H ~ ~ tJ~ o U~ ~
H O ~::1 ~1 a) 1¢ ~ t~ o ~ ~ Pl -- O O ~ ~ .¢ Q
E~ ~ ~ ~ ~~
O ,_1 ~ ~ ~rl E~ ~) h ¢ ~ ~ ~ D\D ~ ,C a~
5_1 o~D ~ a) 0 1~ 0 H ~ I¢ o ~ ~) h Lnal r-l aJ
u~ ~ td ~ h I h a~
I O ~1 rl H .¢
~J O ~ 11~ O E~
a: c~ ~ 3 ~ 0 ~ 1 0 ~::
E I h ~I d i¢ ~
1~1 ~I Q O
u~
~ ~ ~a _ ,- _ _ -- o ~ ~:
a~ x ~ ~ ~ ~1 ~ O
O d h O ~ ; ~ O O r~
O
~ H I ~ r~ W
~î
h ~ t~
'~ U
h ~ a) ~ h E3 ~ dO _ _.
O O ~
d U) ~ f5~ 1~ 1~ ~ ~1 O
O o ~ ,¢ ,¢,5 ,~ u~ ~

r-l ~1 a) C~
~e ~ Q ~ ~ ~ ~ ~ ~D l~
X _~
1~1 Z

17, 942-F -37-~762~

h ~ .
o o r~P
,t o ')~C O c~ q U `¢
V rl C) 5~ ~ o~ ~
h ~ ~1 rl ~ ~O O ~ ' .~ :

æ ~ R~ 0 O
H .4.q U~ ~ ~~ 3 Z t~d. cr. 0~ ~D O u') >1 W o~ ~ R
~ O O~
h h S~ C X co X 5 ~J 0 0 ~ ~ Q)0 X ~ '`
~n :~,>1r~ ' ''I ''I 'd~ a) ~,~' ~ , ~ H
t( 0 a) H
h 0 a~ 0 ,~
H ~ o o ~
r-l ~i r~ O U) U

~ o~ $ 0 a) m o o o 3 ~ U o ~ Q
~ U U C~ O O 0 0 E~ ~ 0 0 ` ~ ~
~ rd '~ h ~ >Y~ r1 IJ S-l ~i - .r r~ ~r .~ 1 0 u ~ a , ,_~
0 0 -~ --I .
Pl o ~
0 O P~ h :~ 0 h ~ ~ ~ 0 u t~ V 0 ~ ~ ~~ ~ ~ ~ u~ a 0 a),~ Q~ Q.r~ r1 u) 0 ~
r~ r~ r~ O o ~ o r~ ~Dr: ~ 0 0 0.~1 h h1~ 1 0 0 ~ U
r~.~ P~ 0 O >1 Q, ~ ~
J ~ O O rl r~ O ~ ~ rt O .~_1 , ~ ~ $ ~ z; ~ E~ r~
~' ~~ ~ ^ ~ r~ h r-l ~ ~ p~ r-l p~ O
~$ r1; f~ PJ
P~
~ , r l Q ~

17~) 'I 7~~l 3 ~3 - r r 7~-~
x H
O I~ o O
o ~>
o a~
S~
O o O ~ O ~1 0 ~ ~D O
0 ~1 A
~H

E~

E~ o a~ r ~ o ~ ~ ~ co co co ~; w u~ o In a~
a~ ~ ~D r~ ~ In ~ ~ ~o o a~
p:; o ~u~ o ~ ~ 3 Ir) ~ ~ I` ~ ~ ~

O o~ ~ 0 1` ~ ~9 H
~ ~:~ ~ ~ ~ H ~ ~ :~ ~> ~ p *
o ~I
o ~
"
s~ ~ ~ I
~ ~ ~ _ U~
~ ~ ~ ~ ~ o _~
O
C~ ~ H ~ --h ~d ^ O
~1 -- O ~

~ O
,¢ h ~ ~1 ~ ~

P~
~ Sl ~ ~ ~p, o o a) ~I h o cn o X ~
r~ z;

17, 94 2-F _39_ x ~ ~ u~
~ ~ a~
o co ~ o ~,~
0 ~ ~ o ~ ~
O '~
S~
h ~ u~
O ~ o o 1 Q ~ d ~
C) U~ ~ IJ>1 0 O ` ~ u ,1 ~ 4~ a s~
~ ;~ o o o ~ , O
0 ~1 A A ~ rl cn a) Q ~ 1 ~>, o a ~ ~h ~1 ~ ,1 5~ o a) a~~ td U
O O ~ ~ (~1 X

O ~ O H
o ~ e s~
~ ~o ~ O ~ OU3 ~ ~1 ~1 >1 E-l ~ O H Q, ~ U

u~ ~ u~ hO m ~ 5~ rd~ Q) o ~ e H a) ~1~ ~ ~ O
~ ~ 1 0 Pl ~, e ~ o tn . ,_ ~z ~ ~
H ~1 ~(d ~1 ~rl a) a)~ --I O
H
pil ~ ~ a) u ~:1 ~ ~1~1 ~ 3 f¢ IJ a~
m ~ ~ ~ u ~: o ~ ~ z E~ ,1 ~ ~~ ~ ~ ~ ~ O
o ~ ~ ~ ~ ~ ~ V
h ~1 ~ 0 _ ~11 3 u~ ~ 0 ~11~ ~,1 Il~` ~ ~n ~ ~ ~rl,Y ~ U ~ 0 o ~ o ~ ~ a a ,~ a ~e _ ~aH :~ ~ a) 3 h O ~ ~ o ~ ~ ~
W ~ E~ ~ ~ ~I E 3 e * ,I W -- h ^ ~1 ~
~ *
D ~ h O 1 r~ U ,C -I .¢
o p~ ,~ ~ O ~
~ a ~ w o ,~ ~ ~d '~' a s~ # s~
a~
e~,~ ~ ~ ,~

17 ~ 942--F -40-z~

s~

a~

:~ 3 h O
~; ~ ~ .
.
~; O O
O ~ ~) ~ U ~
r~
~,~ 0 H ~ 11 H .,~
V ,1 ' 1 ~ V
~ 5~ ~, V
E~ V
d ~IE~
J
a o N aJ
h O
P~

--S~
O
O ~i H P~

17, 942-F 41-7~f~ , T~BLE III. TIIIS INVE:I~TION
~ . .. . . __ . . . __ Table I Bond Stren~th in ~c3/25. 4 mrn Example To ~l~tal 'ï'o Plastic No.Ini.t;.~ftc~r f~CJinJIniti~lAft~r ~\y_ 1 7.95 9.08 3.27 4.09 2 7.95 9.11 1.04 1.09 3* 7.95 9.08 .54 .68

4 7.90 8.99 2.60 2.59 7.95 9.09 4.63 2.95 6 2.77 2.93 2.81 2.92 7- 15.44 12.94 4.27 5.0g 8 6.45 6.04 1.05 1.00 9 6.36 6.1~ 1.34 1,36 6.36 6.68 2.36 2.13 11 6. ~5 6.59 3.13 3.0~
12 6.45 6.63 1.3~ 1.32 1~ 7.95 8.90 8.~0 ~.fl~
1~ 7.55 8.35 1.07 1.05 7.95 8~77 2.31 2.30 lÇ* 8.95 9.12 8.~8 9.54 17* 8.g5 9.17 7.45 6.13 18* 8.~0 9.13 8.72 7.13 19 8.92 9.15 ~.5~ ~.51 - 20 11.20 ~0.50 ~.26 4.28 21 7.8~ 7.90 1.43 1.45 22 8.29 g.l2 2.90 2.93 ;
23 9.64 10.05 8.~5 8.90 24 6.68 7.53 6.95 6.~3 ~.07 9.50 ~.27 ~.31 26~ . ~0 9.15 1.81 1.78 ~7~ . ~2 9.23 3. ~6 3.91 *Comparativc ,~xample~

17, ~ ~ 2 1' ~ ~ 2 ` ~ ~7~2~

TABLE IV PRIOR ART

.

8Ond Stren~th in Lb/In of Width Table II To Metal To Plastic No. Init~alAft r Agin~, InitialAfter Aging 9.48 11.40 >9.48 >11.40 2 15.80 8.21 >15.80 -> 8.21 : - - 3 12 . 0013. 50 9. 39 10. 60 4 14.78 18.26 ->14.78>18.26 ,5 17.60 19.49 >17.60>19.49 6 ~10.10 >14.59 10.10 14.59 - . 7 5.9 8.18 >5.9 > 8.1~ i .8 0 0 0 0 9 17. 50 20. 10 0. 30 0 17 . 46 19 . 23 0 . 88 0 ~,.11 I7. 43 18 . 96 ~0 0 45 0 12 1. 10 . ~ >1 . 10 > 0 13 0. 37 0 0 (PSTR side) 13 15.97 17.45>15.97 >17.45 3 ~EAA side) .
!

17, 942-F -43-s .~

! , 7~2 T~BL~ V. THIS INVENTION
Minimum Table I . 2 Elmendorf Seal Tem-EY~ampleTens~le (R~ ) Elonyation Tear perat-~re No. Direction Yiel~ Ulti~ate (Percent) (~ms) _ C
1 MD~96 2~68 580 634 1 CD. 97 2~ 16 555 672 13 2 MD.99 2~ 57 605 525 CD. 95 2 ~ 22 656 717 113 4 MD1. 32 2~ 58 685 307 11 CD1.30 2. 36 685 442 3 MD1. 70 4~65 600 166 110 CD1.80 4 ~ 56 540 150 8 MD1. 38 2~ 82 770 480 104 CD1. 32 2 ~ 58 795 576 9 MD1. 37 2~ 64 775 295 104 CD1. 36 2 ~ 58 755 499 MD1. 41 2~65 695 262 107 CD1. 35 2049 750 486 11 MD1. 32 2~ 60 760 352 CD1. 29 2~ 50 800 538 110 12 MD1. 38 2~ 84 715 - 416 110 CD1. 27 2~ 47 740 589 - TABLE VI. PRIOR ART

Table II
Examyle i~o.
1 MD1.13 lo90 300 170 110 CD1. 06 1.58 450 190 MDO 74 1~ 79 450 244 10 CD. 71 1~83 560 308 7 Tensile and Elongation: ASTM D~882 ~D - l~achine Direction .
CD - Cross ~achine Direction Elmendorf Tear: ASTM D-1922 17,9~2-F
~5~
,......... .

7~

~, ,, o o o o o o C~

~; ~ ~
HO ~1 E~~ ~ o o ~u~
Z U~
r~3 s~ 0~ O
H~rl C) 1~ ~
H
E~
U
~o U
.` h E~ Q~
E~
.
H
W ~
,~ a) ~ ~ ~ 3 ~ ~ ~ a) E~ ., U~ ~ N ~`1 ~ O
~I) G) a) ~ c) a~
a) ~ sI
O S~ O S~ O ~ ~ O
Q P~C) QIC~ ~C.) O P~C.) C,) O ~ O ~1 0 ~1 ~1 h o-,~ o ~ rl O~

.

o H Z
,~ ~ ~In u~ a~
Q ~
x r~

17, 942-F -45_ ~7~

O ~ ~9 r. ~D ~
rl ~r ~ a~ I` ~ I`
o ~.

~.~
P; ~ In O U~ ~ m o ~ U~ U~
h o oo o il~ o o~
P~ a O ~ ~
H r1 0 1~; ~1 P~

' : :
~a)`
cn co ~ , o~
~: h ~1 ~1 ~1 E~ (1:~ ,~:

H
H

I:C ~ 3 E~ N
.,1 ~ ~ ~1 U~ ~ NtN ~`1~r O ~
o h` S~ h ' h ` h OS~ O ' O ~ O '~ ~ O
U Q. ~ U
t~ Q~ ~ ~ ~
~,) ~O ~ ~ O ~~1 0 h Ih-~ O-rl U -rl ~-~1 LO-rl O~rl H
~X

17,942~ F -46-~ -Li ~ o ,-i o O r~i r-i r-l r'i r~i E~ O
_ V
m r-i U.i r-i ~i a~

~i a~ O
U 1s~
h Lt , i _~
H _ ~ o u7 U~ O
~ r~i r-i ~ O
Z ~ ,~
~ a) r-i g ~- ~ r-i O
u~ h ,s: ,1 1~ ~1 a) ~ ~
z ~ v ~¢ h ~ri ~ ~) p:; ~ 1 0 Id ~i H co ~1 ¢~ ~ ~ ~0 S~
~ . ~ r i ~ r~
H ,-i ,i ,¢ . i Q, ,-1~¦ ~¢ ~ i ~i ri (5 m _ ~; ~ ,~c ~ --~ ~i ), r-i ~i ~ ai r~ v ~ o o E~ h ~ P~ I u~ ~ ~i S-i H
P~ dP ~11 oP ,1~ p V O O
~ d~ U) dP ~

5-1 O I O Ip~ oP O ~q o\ d~
~ LO ~ ~ ~ O ~1 (~
U I I r-i I r-idP 1~
~~ ~~ O I H l~i li r-i r-l r~iU~ li I H V ~1 4-i d ~ O O
c~
dP l Li dP ~ oP I~S
o o o E~ ~ ~
~D dP U~ dP ~dP U~ ~_ G) rl X X
O o ~ o ~ a) a) O ~ r-i ~ ~i ~ r-i ~ ~ ^ ~~
~ ~ Li ,i ,`i ,-i ~ i _ _ _ _ ~ X
~ ~i r~

17, 942-F _47_ TABLE X. CONNECTOR STABILITY

Table I Resistance in Milliohms(l) Example No. Initial After Cyclizing( _ . . _ . .
2 0.6663 1.187 0.6912 1.702 18 0.7353 1.7825 5(3) 0.6750 2.727 Two connectors were attached to 50 mm by 140 mm sample of coated metal; the resistance of the assembly was measured with a Kelvin Bridge 2Resistance after 50 -40 to +60C temperature cycles, each cycle of 8 hours duration 3Example No. 5 from Table II

17,942-F ~48~

~7~

,~
o ~ o CO
o ~ CO
~ ~ U~
o h ~ O
H .,1 E-~ ~
~ ~ o ~r o ~r O ~ ~ ~ ~
P~ H ~ ( O
~ ~1 Z ~
H E~ ~ -O

H : ~
~ , O ~ ~ ~
rlr l ~1 H 1--1 ~ O O O
,, O O O ~ a) ~1~1 ~I R ~1 l h E~
bl o a) ~ ~ ~
,1 ~q ~ ~
~ I I I ~ ~
3 ,~ ~ ~ X X
O ~
;`J
O
a h æ o $
m P~

17 ~ 942-E~ -49-7 Çi; 2~

.

~1 o co ~, I
C~
, o ,, , _ ~ a ~ ~ ~D O ~
~ ~; ~ ~
O
Y h P~
O .~ U~
O Fq - . ~ ~.
~ . , , ~ . , o--S~ r~
' ~ ~ . -, . .
1~ P. . ~ ' , .
a ~ ~: : h ~ ~ r H ~ U~
X m ~ ~ ~
W ~i ~ ~
~s ~ .. ,, K rd ~
o ~1 Z ~ m ~ ~ .~
~ ~ ~ .~ ~ - v a) .~ o E~ Q O cs) ~
Q O V S '~ O Q, o ~s . . . o a - ,~,, o ~.
, ~; . ~rl rl O
~ a ~ ~

0 ~
U~r~l Q~ ~rl - ~ 'd ~ a) ~ ~
~:~rl ~ o Q)rd u~ h O ~,5 :~ O
U~ .~ Ul ~d O ~
~1) H H ~ O
H a)- ~1 U~ ,Y ,~
a) ~ ,s S~ rl ~ r~
~rl Q r-l ~Ird ~d .Q O a) (~
~S E~ ~ U) i~; Q) E~
I ~ T5 11 Q) o l ~ o Q ,~
C~ ,~1- U) ~3 o ~ l~.,l ~rl Z ~ P~ 1~ 3 ~C
U~ ¢ ~; r~ ~ ~

~7~

From the fore~oin~ detailed description, it can be seen that the present invention pr~vides an improved corrosion resistant cable shielding tapc for use as a shield in electrical po~er and communications cables.
! SpecifiCally, the present inventiOn resides in an improved corrosion resistant cable shielding tape comprising a metal strip having a deformation resis-tant layer of polymeric resinous material tightly bonded to at least one side thereof, the deformation j resistant layer having a deformation temperature of at ; least about 130~C. The 5hielding tape must meet both ! the adhesion and deformation resistance requirements simultaneously to provide satisfactory corrosion pro-tection to the shieldin~ tapes by restricting the path of corrosive attack to ~he exposed metal edges.
The deformation resistant layer of pol~eric resinous material must therefore resist penetration and/or abrasion exposing the metal strip at the tem-peratures and pressures normally associated with cable manu~acturing and/or service use.
The present invention also provides a plastic coated cable shieldiny tape which includes layers of polymeric resincus material other than the deformation resis'ant layer thereby ~ormin~ a multilayered struc-ture having a combination of desirable ~unctional characteristics, 17,~ 51 , "~

Claims (23)

1. An improved corrosion resistant cable shielding tape comprising (1) a metal strip having tightly and directly adhered to one side thereof a first adhesive layer composed of a copolymer of ethylene and from about 2 to about 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid; and (2) a first deformation resistant layer composed of a polymeric resinous material tightly adhered to said first adhesive layer, said first deforma-tion resistant layer having a deformation tempera-ture of at least about 270°F.

2. The cable shielding tape of Claim 1 wherein an adhesive/heat seal layer of thermoplastic polymeric resinous material having both good metal bonding and heat seal characteristics is tightly adhered to the opposite side of said metal strip, the adhesive bond between said metal strip and said adhesive/heat seal layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

3. The cable shielding tape of Claim 1 wherein a second deformation resistant layer of polymeric resinous material is tightly adhered to the opposite side of said metal strip, said second deformation resistant layer having a deformation temperature of at least 270°F, and the adhesive bond between said metal strip and said second deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a tempera-ture of 70°C.

17,942-F 52

4. The cable shielding tape of Claim 3 wherein a heat seal layer of thermoplastic polymeric resinous material having good heat seal characteristics is adhered to said second deformation resistant layer on the side of said second deformation resistant layer opposite to that which said metal strip is adhered.

5. The cable shielding tape of Claim 3 wherein a second adhesive layer composed of a copolymer of ethylene and from about 2 to about 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid is disposed between and tightly and directly adhered to said metal strip and said second deformation resistant layer, the adhesive bond between said metal strip and said second adhesive layer and between said second adhesive layer and said second deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

6. The cable shielding tape of Claim 1 wherein a heat seal layer of thermoplastic polymeric resinous material having good heat seal characteristics is adhered to said first deformation resistant layer on the side of said first deformation resistant layer opposite to that which said first adhesive layer is adhered.

7. The cable shielding tape of Claim 6 wherein a second deformation resistant layer composed of polymeric resinous material is tightly adhered to the opposite side of said metal strip, said second deformation resistant layer having a deformation temperature of at least about 270°F, the adhesive bond between said metal strip and said second deformation resistant layer being at least 17,942-F 53 2,2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

8. The cable shielding tape of Claim 6 wherein an adhesive/heat seal layer of thermoplastic polymeric resinous material having both good metal bonding and heat seal characteristics is tightly adhered to the opposite side of said metal strip, the adhesive bond between said metal strip and said adhesive/heat seal layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

9. The cable shielding tape of Claim 7 wherein a heat seal layer of thermoplastic polymeric resinous material having good heat seal characteristics is adhered to said second deformation resistant layer on the side of said second deformation resistant layer opposite to that which said metal strip is adhered.

10. The cable shielding tape of Claim 5 wherein a heat seal layer of thermoplastic polymeric resinous material having good heat seal characteristics is adhered to said first deformation resistant layer on the side of said first deformation resistant layer opposite to that which said first adhesive layer is adhered.

11. The cable shielding tape of Claim 10 wherein a heat seal layer of thermoplastic polymeric resinous material having good heat seal characteristics is adhered to said second deformation resistant layer on the side of said second deformation resistant layer opposite to that which said second adhesive layer is adhered.

17,942-F 54

12. The cable shielding tape of Claim 1, 2 or 3 wherein a first glue layer of thermoplastic polymeric resinous material is disposed between and tightly and directly adhered to said first adhesive layer and said first deformation resistant layer, the adhesive bond between said first adhesive layer and said first glue layer and between said first glue layer and said first deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

13. The cable shielding tape of any one of Claims 6 to 8 wherein a first glue layer of thermoplastic polymeric resinous material is disposed between and tightly and directly adhered to said first adhesive layer and said first deformation resistant layer, the adhesive bond between said first adhesive layer and said first glue layer and between said first glue layer and said first deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

14. The cable shielding tape of any one of Claims 6 to 8 wherein a first glue layer of thermoplastic polymeric resinous material is disposed between and tightly and directly adhered to said first adhesive layer and said first deformation resistant layer, the adhesive bond between said first adhesive layer and said first glue layer and between said first glue layer and said first deformation resistant layer being at least 2.2 pounds per 17,942-F 55 inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C and wherein a second glue layer of thermoplastic polymeric resinous material is disposed between and tightly and directly adhered to said first deformation resistant layer and said heat seal layer, the adhesive bond between said first deformation resistant layer and said second glue layer and between said second glue layer and said heat seal layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

15. The cable shielding tape of Claim 1, wherein said tape has less than eight (8) corrosion damage points in an area of 25.0 cm2 following simulated jacketing and corrosion tests, conducted by the test method as herein defined in the specification.

16. The cable shielding tape of Claim 1, wherein the ultimate tensile strength in a cross machine direction (CM) of multiple layers of the polymeric resinous material including said deformation resistant layer positioned on one side of the metal strip only is at least 2.0 kg/mm2 conducted by the test method (ASTM
D-882) as herein defined in the specification.

17. The cable shielding tape of Claim 1, wherein said first adhesive layer has a deformation temperature of at least about 270°F after being irradiated with an effective amount of a high energy ionizing radiation.

18. The cable shielding tape of Claim 5, wherein said second adhesive layer has a deformation 17,942-F 56 temperature of at least about 270°F after being irradiated with an effective amount of a high energy ionizing radiation.

19. An improved cable adapted for use in supplying electrical power and communications comprising a core of at least one insulated conductor, a shield surrounding said core comprising (1) a metal strip having tightly and directly adhered to one side thereof a first adhesive layer composed of a copolymer of ethylene and from about 2 to about 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid; and (2) a first deformation resistant layer composed of a polymeric resinous material tightly adhered to said first adhesive layer, said first de-formation resistant layer having a deformation temperature of at least about 270°F and positioned inwardly in the direction of said core and an outer plastic jacket surrounding said shield, wherein the adhesive bond between said metal strip and said first adhesive layer and between said first adhesive layer and said first deformation resistant layer is at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C.

20. The improved cable of Claim 19 wherein a second deformation resistant layer of polymeric resinous material is tightly adhered to the opposite side of said metal strip, said second deformation resistant layer having a deformation temperature of at least about 17,942-F 57 270°F and positioned outwardly from said metal strip in the direction of said outer plastic jacket, the adhesive bond between said metal strip and said second deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water maintained at a temperature of 70°C

21. The improved cable of Claim 19 wherein said first adhesive layer has a deformation temperature of at least about 270°F after being irradiated with an effective amount of a high energy ionizing radiation.

22. The improved cable of Claim 19, wherein a second adhesive layer composed of a copolymer of ethylene and from about 2 to about 20 percent based on copolymer weight of an ethylenically unsaturated carboxylic acid is disposed between and tightly and directly adhered to said metal strip and said second deformation resistant layer, the adhesive bond between said metal strip and said second adhesive layer and between said second adhesive layer and said second deformation resistant layer being at least 2.2 pounds per inch of shielding tape width after aging for seven (7) days in deionized water main-tained at a temperature of 70°C.

23. The improved cable of Claim 22 wherein said second adhesive layer has a deformation temperature of at least about 270°F after being irradiated with an effective amount of a high energy ionizing radiation.

17,942-F 58