Cables which include waterblocking provisions

A cable (20) includes a plurality of conductors (24) included in a core (22) enclosed in a sheath system. Voids between the conductors are filled by a mixture of a filling composition characterized by a styrene-rubber block copolymer having a styrene/rubber ratio of from 0.2 to 0.5, an ASTM Type 104A oil and polyethylene and a superabsorbent polymer material. The mixture has a viscosity in the range of about 400 cps at 88.degree. C. to 11 cps at 110.degree. C. and may be used to fill substantially voids in a cable comprising as many as 3000 pairs of insulated metallic conductors. The superabsorbent polymer is incorporated into the gel composition in a concentration of about 10 parts by weight to per 100 parts by weight of the filling mixture. A flooding material which comprises a mixture of a flooding composition and a superabsorbent polymer may be used to flood voids between layers of the sheath system.

TECHNICAL FIELD 
This invention relates to a cable which includes waterblocking provisions. 
More particularly, this invention relates to a communications cable which 
includes core filling and sheath flooding compositions of matter to 
protect conductors of the cable from water. 
BACKGROUND OF THE INVENTION 
Cable used in the telecommunications industry, such as in telephone 
systems, generally requires a waterblocking material in the cable to 
protect the cable from water entry and/or from the longitudinal travel of 
water along the cable. This is true whether the cable is buried beneath 
the ground or laid under water. It is also sometimes required in aerial 
applications. 
Attempts to waterproof cable such as buried cable began nearly 100 years 
ago and were unsuccessful in a practical sense until the introduction of 
plastic insulated cable during the 1950's. Specially sheathed cables, with 
an inner plastic jacket, aluminum and steel shield metals and an outer 
plastic jacket, have been used successfully. Pressurized cable also 
contends successfully with water problems. However, both of these 
approaches are deficient, the former leaves the cable vulnerable and the 
latter is expensive to maintain and subjects the cable to critical 
exposure in the event of failure of the pressurization system. 
Since 1970, large quantities of cable have been filled with waterproofing 
compounds. This approach followed the recognition that in plastic 
insulated cable, the localized intrusion of water into the cable sheath is 
not in itself a serious problem. Disruption or deterioration of service 
occurs when long lengths of cable become flooded. Flooding occurs because 
water that penetrates into a localized opening in the cable sheath is free 
to channel as far as gravity allows, often hundreds of feet. Not only does 
this upset the capacitance balance of the transmission lines, but it 
introduces more potential corrosion sites in proportion to the length of 
wire that is wetted. Corrosion typically occurs slowly, but the useful 
life of water soaked wires is obviously shorter than that of dry wires. 
A solution that has been widely adopted is to fill the voids in the cable 
with a water insoluble filling material that simply plugs the cable to 
channeling water. However, though the physical function of the cable 
filling material is straightforward, the choice of the material is not. 
Among the many considerations that are important for materials used in 
this application are the hydrophobic nature of the material, stability on 
aging, low temperature properties, flow characteristics at elevated 
temperatures, processing characteristics, handling characteristics, 
dielectric properties, toxicity and cost. 
Materials that satisfy most of these criteria, and which have been used 
widely in this application, are described in U.S. Pat. Nos. 3,607,487 and 
3,717,716 issued Sep. 21, 1971 and Feb. 20, 1973, respectively. These 
materials are essentially a petroleum jelly mixed with a polymer, usually 
polyethylene, to impart consistency and prevent flowing at warm 
temperatures. 
Similar hydrophobic filling materials have been proposed for filling splice 
closures. For example, U.S. Pat. No. 3,879,575 issued Apr. 22, 1975 
describes a mixture of a low viscosity oil, gelled by a 
styrene-isoprenestyrene copolymer, again with a polyethylene wax added to 
impart consistency and reduce slump. 
More recently, an improvement over the petroleum jelly-polyethylene wax 
cable filling material has been disclosed in U.S. Pat. No. 4,259,540 
issued Mar. 31, 1981 in the name of R. A. Sabia. This patent discloses a 
material which overcomes the objectionable handling characteristics of the 
petroleum jelly-polyethylene cable filling material. For example, because 
installation and maintenance of cables often requires the cable to be 
spliced, such splicing generally requires the isolation and removal of 
filling material from individual wires or optical fibers in the splice 
region where the cables are filled with the petroleum jelly material. 
Otherwise, an oily interface may form between the wire and the 
polyurethane material subsequently used to encapsulate the splice. This 
oily interface which can serve as a path for water entry into the splice 
can result in service-affecting trouble. Moreover, removing just 
sufficient material to effect the splice is time consuming and the task is 
generally undesirable. Further, handling at low temperatures is 
significantly more difficult, necessitating on occasion use of a torch to 
preheat the cable or the use of solvents to soften the encapsulated core. 
The improved material described in U.S. Pat. No. 4,259,540 overcomes the 
aforementioned objections to the cable filled with the petroleum 
jelly-polyethylene material. The improved material according to the patent 
is a mixture of a naphthenic or paraffinic oil having specific 
characteristics, a styrene-ethylene butylene-styrene (S-EB-S) triblock 
copolymer having a styrene-rubber ratio of from about 0.2 to 0.5 and 
polyethylene having a softening point of 110.degree. C. to 130.degree. C. 
See also U.S. Pat. No. 4,176,240 which issued on Nov. 27, 1979 in the name 
of R. A. Sabia. 
It should be noted that the term styrene-rubber ratio, when used herein, 
refers to the weight ratio of the styrene block to the rubber block in the 
copolymer. Further, whenever the term S-EB-S is employed, it refers to a 
triblock copolymer whereas the term S-EB refers to a diblock copolymer. 
Whereas the cable filling material of U.S. Pat. No. 4,259,540 has proved to 
be excellent in blocking the flow of water in a cable, it alone may not be 
completely suitable in meeting newly established standards for 
waterblocking. These standards set forth that there shall be no flow of 
water through an eight-foot length of cable when the length of cable is 
subjected to a twelve (12) foot head of water for twenty-four hours. 
The patent literature also describes cables including water swellable 
polymers such as polyvinyl alcohol, polyacrylamides, or cellulose 
derivatives, which are applied to bundle wrappings or contained in 
moisture barriers which are spaced along the length of the cable outside 
of the conductor bundles and between portions of a sheath system. The area 
outside the core and the between portions of the sheath system is referred 
to as the flooding zone. 
Such cables are, however, characterized by certain disadvantages and 
limitations. In the case of those which include one of the above-described 
water swellable polymers, the polymer is generally supplied in powdered or 
granular form. If not distributed throughout the cable core, effective 
water absorbence is not assured throughout that zone. The powder may be 
included in a tape laminate which extends longitudinally along the cable. 
Using lower concentrations of the powder in the filling material 
compromises the water blockage capabilities of the filling material. 
Further, certain swelling agents such as polyvinyl alcohols and 
polyacrylamides do not swell quickly enough in cold water to effect proper 
water blockage when a cable core is only partially filled whereas filling 
the core completely with such agents is prohibitively expensive and causes 
problems with swelling in the confined space when contacted by water. 
More recently, in PCT/US 90/01863 having an international publication 
number WO 90/12406 is disclosed a gel composition which can be used as 
both a filling and or an encapsulating compound. The composition is 
comprised of a fluid, a thickener for mixing with the fluid to form a gel 
matrix, and a water absorbent polymer having anionic groups attached to 
the polymeric backbone which is generally supplied in the form of a fine 
powder. This powdered hydrocarbon polymer is mixed with the dielectric gel 
matrix. In many cases, the dielectric gel matrix is hydrophobic and the 
addition of a supplementary hydrophilic substance is beneficial. 
The gel composition itself provides an initial barrier to the entry of 
water into the confined space in which the gel is located. If water does 
enter the space, whether the space is the inside of a fiber optic cable, a 
housing or splice, or the filling or flooding zone of a telecommunications 
cable, the water absorbent polymer in the gel is activated and the water 
is absorbed. Once the water is contacted by the polymer in the gel, a 
highly viscous semi-solid material forms that, depending on the viscosity 
of the gel composition, is incapable of fluid movement. 
The gel composition of the above-identified PCT document therefore plays 
several roles in protecting the contents or components of a confined space 
such as a housing or cable from water damage. First, if there is invasive 
moisture, the gel composition repels the water. Additionally, in the 
presence of water, the water absorbent polymer of the gel is activated to 
absorb the water, preventing its further migration. 
In the PCT disclosure, it is generally preferred that the viscosity range 
of the gel is from about 2 centistokes at 100.degree. C. to about 90,000 
centistokes at 40.degree. C. The viscosity of the composition in the PCT 
document must be relatively high judging from the inclusion of thickeners. 
Also, such relatively high viscosity should be evident from the manner of 
use to fill cables. The gel composition of the foregoing PCT document 
apparently is used to fill cables in the 20 conductor pair range. Cables 
today may include 3000 or more conductor pairs. Of course, a plurality of 
20 pair units each could be filled and then the units assembled in a very 
large conductor pair size cable. However, this technique does not result 
in all the interstices, particularly those between the units, being 
filled. 
What is needed and what seemingly is not available is a large conductor 
pair size cable which includes a waterblocking material which fills the 
interstices in the core and a flooding material which floods between 
layers of a sheath system of the cable to preserve the electrical 
characteristics of the cable under new waterblocking requirements. More 
particularly, the sought-after cable should include waterblocking 
compositions which not only are suitable for filling and flooding but 
which also may be applied in a manufacturing line on which the cable is 
made. 
SUMMARY OF THE INVENTION 
The foregoing problems of the prior art have been overcome by the cable of 
this invention. A cable includes a core comprising a plurality of 
insulated metallic conductor pairs having a plurality of longitudinally 
extending transmission media and a waterblocking material. Advantageously, 
the waterblocking material is disposed in interstices among the 
transmission media. The waterblocking material is a mixture comprising a 
filling composition and a superabsorbent polymer. The filling composition 
includes a styrene-rubber block copolymer, a compatible oil and 
polyethylene in proportions to provide a cable filling composition. The 
superabsorbent polymer is included in an amount no greater than about 10 
parts by weight per 100 parts by weight of the waterblocking mixture. 
Desirably, the viscosity of the mixture is such that a cable core 
comprising as many as 3000 metallic conductor pairs may be filled on a 
manufacturing line with said waterblocking material, said cable being 
characterized by a dissipation factor of 10.sup.-4 microradian and a 
dielectric constant less than about 2.3.

DETAILED DESCRIPTION 
Referring now to FIGS. 1 and 2, there is shown a cable, which is designated 
generally by the numeral 20, and which includes a core 22 having a 
plurality of insulated metallic conductor pairs 24--24. The conductors may 
be grouped together in units and the units assembled together into the 
core 22. Binders 25--25 are used to bind together the conductors. The core 
22 is disposed within a plastic material 26 which is wrapped thereabout 
and which commonly is referred to as the core wrap. Typically, the core 
wrap is made of a plastic material such as polyethylene terephthalate. 
The core 22 is filled with a mixture 30 which includes a filling 
composition of matter which typically is referred to as a filling material 
or filling composition. The mixture comprises a filling composition 
referred to as FLEXGEL filling composition and a superabsorbent polymer in 
powder form. FLEXGEL filling compositions are described in U.S. Pat. No. 
4,176,240 which has been previously mentioned and which is incorporated by 
reference hereinto. 
About the core 22 is disposed a sheath system 40. The sheath system may 
include a corrugated metallic layer 42 and a plastic jacket 44. A flooding 
material 46 may be disposed between layers of the sheath system such as 
between the core wrap 26 and the metallic layer 42 and/or between the 
metallic layer and the jacket 44. 
The FLEXGEL filling composition comprises an extender oil type 104B per 
ASTM D 2226 such as Sunpar LW 120 marketed by the Sun Refining and 
Marketing Company. The oil extender is included in the amount of 88.5 to 
89.5 parts by weight. Also included is a styrene-rubber block copolymer in 
the amount of 5.4 to 5.6 parts by weight. A suitable rubber is a triblock 
designated Kraton G 1652 marketed by the Shell Chemical Company. The 
filling composition includes about 4.9 to 5.1 parts by weight of 
polyethylene. A suitable polyethylene is one designated AC-9 or AC-9A as 
marketed by the Allied Signal Company. A compatibilizer in the amount of 
0.4 to 0.6 part by weight and an antioxidant in the amount of 1 part by 
weight are included. A suitable compatibilizer is Kronitex 100 marketed by 
the FMC Corporation whereas a suitable antioxidant is Irganox 1035 
marketed by the Ciba-Geigy corporation. One preferred composition includes 
89.0 parts by weight of the extender oil, 5.5 parts by weight of rubber, 5 
parts by weight of polyethylene, 0.5 part by weight of the compatibilizer 
and 1 part by weight of Irganox 1035 stabilizer. 
It is important that the material have a proper viscosity. The filling 
process is carried out at elevated temperature. From the standpoint of the 
processing equipment and the effectiveness of the filling process, it is 
more desirable to lower the viscosity of filling material than to raise 
the temperature. The operating temperature is limited to the vicinity of 
110.degree. C. by the material commonly used to insulate the conductors. 
Therefore further variation is obtained by choice of the composition. A 
suitable range is 400 cps at 88.degree. C. to 11 cps at 110.degree. C. The 
second criterion is the slump characteristics after two hours exposure to 
three temperatures, 50.degree., 60.degree. and 70.degree. C. This measures 
the retention of the filling material in an acceptably rigid state at 
elevated service temperatures. Mechanical properties of the filling 
composition indicated were found to be adequate in nearly every case. The 
mechanical characteristics of the materials can be summarized in a 
subjective manner that is perhaps more meaningful. The prior art petroleum 
jelly material is a grease-like substance whereas the materials described 
here have a consistency resembling a soft gum eraser. 
An important physical property of the material is its handleability. This 
property was evaluated subjectively and was one basis for choosing the 
styrene ethylene-butylene-styrene block copolymer. Another is flow at 
elevated temperatures and is the basis for choosing composition limits. 
The superabsorbent powder which is mixed with the FLEXGEL filling 
composition may be an ARIDALL.TM. 1125-J superabsorbent polymer, as 
marketed by the Chemdal Corporation. The mixture of the filling 
composition and superabsorbent polymer is such that the superabsorbent 
polymer is included in the amount of up to about 10 parts by weight per 
100 parts by weight of the mixture. 
ARIDALL polymers are crosslinked acrylics in a class of products commonly 
referred to as superabsorbents. This classification also includes 
starch-graft polymers, crosslinked glycolate and cellulose ethers. Of 
these types, the crosslinked acrylics are rapidly becoming the most 
popular of the superabsorbents. ARIDALL polymers combine the advantages of 
high absorbent capacity and suitable gel stiffness, making them ideal 
absorbent media for a wide range of personal care and medical disposables. 
Like all acrylic-based superabsorbents, ARIDALL polymers derive absorbency 
from carboxylate groups located on the spine of the polymer. When an 
aqueous medium contacts the polymer, the carboxylate groups solvate 
rapidly and develop mutually repulsive negative charges. This causes the 
polymer to uncoil and absorb the medium to many times its weight. 
Crosslinking prevents solution of the polymer. The medium quickly becomes 
oriented on the polymer's surface by virtue of hydrogen bonding. The 
resulting gel has a remarkable ability to hold water even under pressure. 
ARIDALL polymers hold fluids by a physio-chemical mechanism. 
The foregoing superabsorbent polymer material has an absorption capacity of 
35 g/g saline, a moisture content of 6.+-.2%, 600 ppm max. residual 
acrylate monomer, a pH (0.1% solids) of 7.+-.0.3 and a particle size 
distribution of 100-1000 micron. 
Another suitable superabsorbent polymer is one marketed by Absorbent 
Technologies, Inc., and designated Aqua Keep J-550 superabsorbent polymer. 
The latter has a capacity (0.9% saline) of 65 ml/g, a retention (0.5 psi) 
of 43 ml/g, a pH of 7.5 and a residual monomer of 75 ppm and a particle 
size distribution of 32 to 200 mesh with 3.7% passing the 200 mesh. 
Another FLEXGEL filling material which is suitable is one comprising 77.5 
to 78.5 parts by weight of an extender oil Type 104B per ASTM D 2226. A 
suitable extender oil is the previously mentioned SUN LW 120. Included 
also are 3.9 to 4.1 parts by weight of KRATON G-1726 styrene-rubber 
diblock copolymer and 0.9 to 1.1 parts by weight of KRATON G1652 
styrene-rubber triblock copolymer, both of which are available from the 
Shell Chemical Company. A polyethylene in an amount of 6.9 to 7.1 parts by 
weight, a polybutene in amount of 9.8 to 10.2 and 1 part by weight of 
antioxidant also are included. The polybutene may be one designated H-300 
and marketed by the Amoco Chemical Company. The polyethylene preferably is 
the previously mentioned AC-9 or AC-9A whereas the antioxidant is Irganox 
1035. See previously mentioned U.S. Pat. No. 4,259,540 which is 
incorporated by reference hereinto. 
Still another filling composition employs a styrene-rubber diblock 
copolymer to replace all or part of the styrene-rubber-styrene triblock 
copolymer and is disclosed in U.S. Pat. No. 4,870,117 which issued on Sep. 
26, 1989 in the names of A. C. Levy and C. F. Tu and which is incorporated 
by reference hereinto. The composition includes about 80 to 87 parts by 
weight of an extender oil, type 104B per ASTM D 2226. A suitable extender 
oil is one available from the Sun Refining and Marketing Company under the 
designation Sunpar LW110. Two styrene-rubber block copolymer constituents 
are included, one being Kraton G1726 in the amount of 0.4 to 0.6 part by 
weight and the other being Kraton G 1652 in the amount of 4.9 to 5.1 parts 
by weight both marketed by the Shell Chemical Company. Also included are 
6.9 to 7.1 parts by weight of AC-9 or AC-9A polyethyelene as marketed by 
the Allied-Signal Company and 6.9 to 7.1 parts by weight of H-300 
polybutene marketed by the Amoco Chemical Company. An antioxidant in the 
amount of 1 part by weight is included, it preferably being Irganox 1035 
marketed by Ciba-Geigy Corporation. 
The prior art triblock rubber molecule is capped on both ends by styrene. 
The material has a higher pseudo-crosslink density than the styrene-rubber 
diblock copolymer used in the filling composition wherein the rubber has a 
styrene cap on one end only. The crosslinks are physical in nature because 
they are not present in the melt and result from separate styrene and 
rubber block domains which form due to the inherent incompatibility of the 
two types of blocks. Inasmuch as the styrene blocks are rigid below their 
glass transition temperature, T.sub.g, of approximately 90.degree. C., 
they act as physical crosslinks below the styrene T.sub.g where the 
styrene block is on both ends of the molecule (triblock). This lower 
physical crosslink density causes the oil, which is incorporated in the 
composition, to be more effectively gelled. Accordingly, syneresis 
(separation) and cell filling of foamed insulation are significantly 
reduced or eliminated. 
Further, one may select a styrene-rubber diblock copolymer which is 
approximately half the molecular weight of the prior 
styrene-rubber-styrene copolymer, but having approximately the same 
styrene block to rubber block ratio. A lower viscosity material makes it 
possible to add polybutene oil and polyethylene wax to the filling 
composition to aid in preventing insulation cell filling and in improving 
high temperature flow characteristics. Such a lower viscosity material can 
be obtained by using a low viscosity processing oil but not without 
incurring a significant penalty with respect to parameters such as flash 
point and volatility. If sufficient styrene-rubber copolymer is used, no 
polybutene oil addition is necessary. However, because the copolymer is 
generally more costly than the polybutene oil, from an economic 
standpoint, it is desirable to use a combination of the two material to 
prevent cell filling of foamed insulation. However, for spliced 
encapsulant compatibility and the processability of the filling compounds 
considerations, it is desirable to minimize the polybutene oil level. 
Hence, depending upon the consideration which is most important to the 
user, the formulation can be adjusted in various ways. It is apparent that 
the substitution of the styrene-rubber diblock copolymer for all or part 
of the styrene-rubber-styrene triblock copolymer of the prior art is 
extremely desirable. Even low levels of the styrene-rubber diblock 
copolymer (about 1%) are found to be particularly useful in formulations 
which require flame-retardant properties where syneresis can be a problem. 
Although the use of a diblock copolymer reduces the viscosity, it tends to 
result in a somewhat greasy material which may not be acceptable to some 
customers. The increased viscosity is brought on by the triblock copolymer 
which is used to impart gelness to the filling material. It has been found 
that a less greasy, reduced viscosity composition can be achieved by 
reducing the diblock copolymer content and including a lower viscosity 
oil. 
The handleability of the filling compound can be changed by varying the 
ratio of the diblock copolymer to the triblock copolymer. The higher the 
diblock copolymer content, the more greasy is the filling compound. On the 
other hand, a high triblock copolymer content results in a highly gelled 
filling material. In a preferred embodiment, the ratio by weight percent 
of the diblock copolymer to the triblock copolymer should be in the range 
of from about 0.05 to 5. 
The viscosity measurement indicates the processability of the material. 
Cables are filled by injecting the filling material into the voids between 
the wire pairs. Typically, in copper wire cable, this is done after 
forming cores consisting of a number of units of wires. Therefore, it is 
important that the material have a proper viscosity. The filling process 
involves elevated temperature. From the standpoint of the processing 
equipment and the effectiveness of the filling process, it is more 
desirable to lower the viscosity of the filling material than to raise the 
temperature. The operating temperature is limited to the vicinity of 
110.degree. C. by the insulation commonly used. Therefore, further 
variation is obtained by choice of the composition. A maximum of 60 
centipoise at 110.degree. C. has been imposed on the composition for 
acceptable processing. 
It has been found that cables which include 3000 insulated metallic 
conductor pairs and which have been filled and flooded with the 
hereinbefore described mixture have successfully passed the BELLCORE 
12-foot waterhead test. The test has been passed for a cable which has 
been filled on the jacketing line with the powder added in a supply 
chamber adjacent to the line in which the filling material is held at an 
elevated temperature. 
In addition to filling compounds used to block water entry into cable 
cores, flooding compounds are used to provide a seal against water entry 
into sheath interfaces and to prevent slipping of the outer, plastic cable 
jacket during placing operations. One of the superabsorbent polymers 
listed elsewhere in this Detailed Description can be added to the flooding 
compound, in the same concentration range as for filling compound, to 
produce swelling in the presence of water. Waterblocking in the sheath 
interfaces is thereby enhanced without detriment to the tacticity required 
for the prevention of jacket slipping. 
A superabsorbent polymer also may be mixed with a flooding composition of 
matter which is an atactic polypropylene or polybutylene, the latter being 
preferred and available from the Amoco Chemical Company. Herein as in the 
filling mixture, the superabsorbent powder is included in the amount of as 
much as 10% by weight of the mixture. 
The filling mixture comes into intimate contact with the insulating 
material of the conductors comprising a cable core. It is important, 
therefore, that the filling mixture not degrade the electrical or 
mechanical characteristics of the insulating material. Tests have shown 
that FLEXGEL compounds containing superabsorbent polymers, listed 
elsewhere in this Detailed Description, do not cause degradation of those 
properties. Specifically, tests have shown that the oxidative stability of 
certain insulating materials remains high following exposure to FLEXGEL 
filling compounds including superabsorbent polymer at 70.degree. C. for 28 
days (the aging criterion in use in the U.S. cable manufacturing 
industry). Also, the electrical characteristics of cable of this invention 
are very acceptable. The dielectric constant is less than about 2.3 and 
the dissipation factor is less than 10.sup.-4 microradian. 
Going now to FIG. 3, there is shown in schematic form a manufacturing line 
designated generally by the numeral 50 in which a core comprising 
conductor pairs which have been grouped together into units after which 
the units have been assembled together into a cable core is provided with 
a sheath system comprising a jacket. Of course, as mentioned hereinbefore, 
the cable sheath system includes elements in addition to the jacket. 
The core 22 is moved from a core truck 52 through a filling chamber 54. In 
the filling chamber 54, a mixture of a FLEXGEL filling composition and a 
superabsorbent powder provided from a supply tank 56 at an elevated 
temperature of about 100.degree. C. is flowed under pressure to engage the 
core. The viscosity of the mixture and its temperature are such that the 
mixture fills substantially the interstices of the core. 
The filled core is moved out of the filling chamber and is enclosed with a 
tape 58 of plastic material such as polyethylene terephthalate plastic 
material which is wrapped about the filled core. Over the core wrap may be 
disposed a shielding system which may comprise one or more corrugated 
metallic layers. For example, an inner layer may comprise corrugated 
aluminum tape 61 and an outer layer may comprise corrugated steel tape 63. 
Over the metallic layers, an extruder 65 applies an outer plastic jacket. 
In some cables, an inner jacket also may be used. The plastic jacketed 
cable is moved through a cooling trough 67 by a capstan 69 and is then 
taken up on a reel 71. 
Between the foregoing described layers of the sheath system is disposed a 
flooding material described earlier herein which enhances the 
waterblocking capabilities of the cable. The flooding material is applied 
selectively by apparatus 73 between portions of the sheath system. 
It is to be understood that the above-described arrangements are simply 
illustrative of the invention. Other arrangements may be devised by those 
skilled in the art which will embody the principles of the invention and 
fall within the spirit and scope thereof.