Note: Descriptions are shown in the official language in which they were submitted.
~3~2
BACKGROUND OF THE INVENTION
a) The Invention
The invention relates to a sealed cable article and
method for sealing the area between two or more cables and
between the cables and an enclosure at a location where the
cables exit from the enclosure. The invention also relates
to a sealed cable end article and method for sealing the
exposed end of a cable.
b) Backqround Information
At various places in an electrical distribution system,
an electrical cable is divided into two or more components,
for example, where a branch-off cable is connected to a main
cable or where a cable containing three or more cores, is
separated into the individual cores. Where one or more
cables or cores are divided from the main cable, the cable
insulation generally has been removed to permit the jointing
of a branch-off cable or breakout of the cable cores. The
area where the insulation has been removed must then be
reinsulated. In the case of shielded or armored power
cable3, the shielding and armoring is also removsd and
must be re-established. This is generally accompli~hed
by installing an enclosure around that region of the
cables. The term "breakout" is used in this application
to refer to either two or more cabLes or two or more cores
where they separate from a main cable or cables.
Enclosures suitable for this use can be, for example,
resin filled joint cases, polymeric sleeve~ or the like.
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~,:273~7~:
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The location where the individual cables exit from an
enclosure, the area between the cables and between the
cables or cores and enclosure must be ssaled to prevent
ingress of moisture. A number of methods have been used
to seal breakouts with varying success. A heat shrinkable
polymeric boot may be positioned on the breakout using
mastic or adhesive to hold the boot in place. Heat
shrinkable boots however are costly to manufacture because
of their shape and usually require access to the cable
conductor ends to slip the boot into the proper position
over the breakout area. Adhesives and mastics have been
put in the area between the breakout cable core and the
main cable (crotch area) to seal but these are difficult
to pack into the crotch area without leaving voids resulting
in a poor seal and may require heat to cause them to flow
and fill the crotch area. The application of heat can
damage the conductor covering or the conductor. Tapes
of dimensionally stable polymeric material with an
adhesive or mastic have been used to wrap the cable
breakout area but tend to leak if not properly overlapped.
Shaped articles have been used as sealing elements in
a variety of methods. In US 4,438,2g4 a sealing element
of a thermoplastic or plastic material for a cable entrance
socket is disclosed. The sealing element seals the area
between the ~heaths of cables using ~traight sided or
concave articles which surround only a portion of the cable
and conductor~ in the crotch area. No gels are disclosed
and the thermoplastic or plastic materials described are
substnatially non-tacky and rigid.
30~
In Great Britain Patent No. 2,057,202, a polymeric
article is described comprising a cylindrical member with a
plurality of channels for enclosing a plurality of cables.
The articles may seal by being made heat recoverable or may
be sealed with an adhesive or mastic. They are described as
non-tacky useful to seal, protect and ins~late cables. In
US Patent No. 4,298,415 a branch off seal is disclo.sed
comprising a heat recoverable sleeve and one or more clips
attached to the sleeve opening to form the sleeve into a
desir~d number of cable conduits.
SUMMARY OF THE INVENTIO
In one method aspect, the invention relates to a method
of sealing an area between two or more cables and between
the cables and an enclosure at a location where the cables
exit from the enclosure, which method comprises
a) providing a shaped article of polymeric gel said
polymeric gel having
i) a cone penetration value of about 30 to about
~00 ~ 10-lmm),
ii) an elongation of from about 25~ to about 850~;
b) po31tioning the shaped article such that it surround.s
each of the cables7 and
c) positioning the enclosure such that it surrounds the
shaped article.
--4--
In a preferred embodiment the polymeric gel has a
number of holes extending therethrough corresponding to the
number of cables to be positioned through the holes.
In another method aspect the invention relates to a
method of sealing the end of one or more cables comprising
a) providing one or more shaped articles of polymeric
gel corresponding to the number of cable ends to be
sealed, said polymeric gel having
i) a cone penetration value of about 30 to about
400 ~10-1 mm),
ii) an elongation oE from about 25% to about 850%;
b) positioning the shaped article at the end of the
cable such that the expo~ed areas of the cable end are
sealed;
c) positioning an enclosure such that it ~urrounds the
shaped article and adjacent re,gion of the cable.
Optionally, the shaped article may have a hole a portion
of the way therethrough for positioning the cable end.
In another aspect the invention relates to a cable
sealing kit which comprise~
(a) one or more ~haped articles of a polymeric gel
having one or more holes at least a portion of the way
therethrough, the polymeric gel having
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--5--
i) a cone penetration value of about 30 to about400 (lo-l mm),
ii) an elongation of ~rom about 25~ to about 850~,
and
(b) an enclosure for surrounding the shaped article.
The shaped article may have the hole a portion of the
way therethrough for sealing end~ of cables or al]. the way
therethrough for positioning a cable therein.
In its article aspect the invention relates to an `
article comprising
(a) two or more cahle~;
(b) a shaped article of a polymeric gel, the polymeric
gel having
i) a cone penetration value of about 30 to about
~0 0 ( 10 ~1 ~
ii) an elongation of from about 25~ to about 850%,
and
(c) a enclo~ure surrounding the shaped article,
~d) the shaped article po~itioned such that it encloses
the cables and seal~ the area between the cabLes and
between the cables and the enclosure.
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26775-83
Another article of the invention relates t~ an article
comprising
(a~ one or more cable ends with a portion of the cable
end exposed;
(b~ one or more shaped articles of a polymeric gel
corresponding to the number of cable ends to be sealed, the
polymeric gel having
i) a cone penetration value of about 30 to about
400 (lo~l mm)
ii) an elonyation of from about 25~ to about 850%;
(c) the shaped article positioned at ~he cable end;
(d) an enclosure that surrounds the shaped artlcle and
the adjacent region of the cable.
Optlonally the shaped artlcle may have a hole a portlon
of the way therethrough f or positionin0 the cable end.
The invention will be further described with reference
to the aecompanyiny drawings in whichl
Figure 1 shows a cable with cores which have been
separated from the cable by removal of the protec~ive sheath;
Figure 2 shows the same cable with a shaped article of a
polymeric gel wherein cables have been posi~,ioned through holes;
Flgure 3 shows the aable of Figure 2 wherein an
enclosure surrounds the shaped article of polymeric yel;
Flguras 4 and 5 show shaped articles of a polymeric, gel;
Figure 6 shows a shaped article with a hole for
positionlng a cable and therein;
Figure 7 shows a cable end with a shaped artic,le sealing
;... . ..
73~
26775-~3
the end of the cable and enclosed by the enclosure leaving el
portion of ~he gel exposed to the environment;
Figure 8 shows a cross sectlon o~ a sealed ~able end
where there is a shaped article with no hole positioned at the end
o~ the cable and surrounded by enclosure; and
Figure 9 shows another embodiment of the cable end
sealing of the invention.
DETAILED DESCRIPTIO~ OP TH~ I~V~TION
Gels are widely known in the art, for example silicone-
based gels, polyurethane-based gels or polystyrenebutadiene-
styrene, polystyrene-isoprene-styrene, and polystyrene-ethylene
butylene-styrene block copolymer based gels. Preferred gels for
use in this invention ar gelloid
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composi-tions comprising a crosslinked non-silicone polyme:r having
an olefinic unsaturated content of less than 10 mole percent and
having dispersed therein a liquid in an amount of from about 20%
to about 95% by weight based on the weight of the liquid and
polymer and from 0 to 0O3 volume fraction of a filler, said cross-
linked polymer
a) if derived from a solid, relatively high molecular
weight polymer, having a gel fraction of at least
about 50~, or
b) if derived from a liquid, relatively low molecular
weight polymer, having at least about 0.1
(preferably 0.1 to about 3) crosslinks per weight
average molecule;
said composition having a storage modulus of
(1~2.5v-~14.1v2)x dynes/cm2 wherein x is less than 5x105 at 30C
and greater than 5X102 at 90C, and v i.s the volume fraction of
the filler, with the proviso that, if the crosslinked polymer is
prepared from a solid high molecular weight polymer, the storage
modulus at 1~0C is at leas-t about 70% of the storage modulus at
70C, and a dynamic viscosi-ty of (1~2.5v~1~.1v2)y poises wherein y
is less than lx105 at 30C and greater than 5X102 at 90C and v is
the volume :Eraction of the :Eiller, said composition exhibiting
first degree blocking. These compositions are described more
fully in Canadian Application Serial No. 489,732.
The shaped article preferably has a number oE holes,
corresponding to the number of cables or cores of the breakout.
When forming the gel into such a shaped article the holes are
:
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Eormed preEerably slightly smaller than the size oE the cabLe that
is to be lnserted therein. The gels used in the invention will
stretch to accommodate the increased size cable and the tension
created provides a be-tter seal. The number oE holes should cor-
respond to the number oE cables to pass -therethrough. The holes
may be s-tretched by placing tubes, mandrels or other articles in
the holes to keep them in an expanded condition prior to placing
the shaped article around the cables. The tubes may then be re-
moved when the shaped article is in place. There is preferably a
slit extending from the edge of each hole -to the outer edge of the
article so that the shaped article may be placed around the cables
without access to the free end of the cable. A hole may also be
larger or the same size as the cableO
When the shaped article is to be used to seal a cable
end, if a hole is used, the hole should not pass all the way
through the shaped article. The shaped article need not have any
hole. Rather, it must be at least slightly larger than the cable
end and substantia]ly conform thereto. (see Figure 8). The
shaped article will provide the environmen-
~ 0 ~
_g_
tal seal necessary and be held in place by an enclosureused.
The polymeric gel is selected such that it has a cone
penetration value as measured by ASTM D-937-77, of ~rom
about 30 to about 400 (10~1 mm) and preferably from about 50
to about 350 (10~1 mm). FurtherJ said gel is selected such
that it has an elongation, as measured by ASTM D-412~ of
from about 25% to about 850~ and more preferably from about
100~ to 750%. The gels may further be selected for their
insulative, stress grading, or conductive as well as their
sealing properties. Generally, it is preferable that the
gel should have a dielectric constant (permittivity) of les~
than 6 at 50 Hz for insulating gels and greater than 6 for
stress grading gels (as measured by ASTM D-150). Where the
gel is used a~ insulation as well as sealing, the gels pre-
ferably have a volume re~istivity of at least 101 ohm-cm
(as measured by ~STM D-257). For stress grading applica-
tions, the gels preferably have a specific impedance of
107-101 ohm-cm at 50 Hz (ASTM D-150), and for conductive
applications, the gels preferably have a volume re~istivity
of less than 107 ohm-~m- The gel~ possess sufficient tack
to seal and adhere to the breakout or cable end. Further
the properties of the gel allow cable movement without
breaking the seal formed, due to the gels ability to deform
and return substantially to its original shape while main-
taining the tack necessary to seal.
~ s mentioned above, the preferred gels for use in this
invention are gelloid compositions comprising a cross-
linked, non-silicone polymer having dispersed therein from
73~7~
--10--
about 20% to about 95~ by weight of a liquid and having cer-
tain specified properties.
These compositions are preferably prepared by subjecting
a non-silicone liquid polymer containing from about 20% to
about 95~ by weight of a liquid to a crosslinking means such
as a chemical means or irradiation means. The polymer
starting material is a cro~slinkable liquid polymeric
material, preferably a non-silicone liquid rubber, with low
or no unsaturation prior to crosslinking. The liquid poly-
meric material preferably has a molecular weight of less
than about 90,000, preferably less than about 50,000, and a
Mooney viscosity of ML 1+4 at 100C of less than 10. Mooney
viscosity is measured by ASTM D-1646. Said polymers are
primarily liquids at these molecular weights and viscosi-
ties. The liquid polymer preferably has a molecular weight
less than about 7.5 times the polymer's critical molecular
weight (see e.g. Mechanical prop of Polymers, Nielsen 1962
for a discussion of critical molecular weight). rhe poly-
mers can be a hydrocarbon backbone polymer or a polymer con-
taining carbon as well as other atom~, e.g. oxygen,
nitrogen, etc. in the backbone with the exception of sili-
cone. The polymers are limited to those which have low or
no unsaturation prior to crosslinking. In general, the
amount of unsaturation will be less than about 10% mole,
preferably less than about 7 mole percent and preferably
less than 4 mole percent. If the unsaturation i9 too high
the resulting product tends to be thermally unstable.
Preferred liquid polymeric material~ include liquid
butyl rubber, epichlorohydrin rubber, ethylene-propylene-
.: .., :
.,
: ,
~; ...
3Q~
diene monomer rubber (EPDM), hydrogenated polyisoprene,hydrogenated polybutadiene, hydrogenated styrene-butadiene
rubber (SBR), hydrogenated poly~hloroprene, ~unctionalized
polyisobutylene (i.e. polyisobutylene with reactive groups
added that are capable of crosslinking such as hydroxy,
amine or carboxy groups), chlorinated polyethylene, liquid
fluorinated polymers (e.g. Viton~from DuPont), hydrogenated
nitrile rubber and other hydrogenated liquid polymers.
Further, one can combine the various polymers to form com-
positions of desired properties.
The liquid dispersed in the crosslinkad polymer in
accordance with this invention can be any liquid which is
capable of being dispersed in the polymer in an amount from
about 20% to about 95%, and which does not react during
cros~linking of the polymer. The liquid may be a plasti-
cizer, compatibilizer, tackifier, or the like. Suitable
liquids include, for example, paraffinic oils, naphthenate
oils, aromatic oils, liquid polybutenes, alkyl ~or aryl)
phthalates, vegetable oils, mineral oils, trimellitates,
esters of polyethylene glycol~, alkyl (or aryl) phosphates,
methyl e~ter of hydrogenated wood rosin, liquid rosin oils,
pine tar, polyterpenes, non-reacting liquid rubbers, the
starting li~uid polymer which remains uncrosslinked or at
least crosslinked less than .1 crosslink per weight average
molecule, and the like.
Crosslinking may be by any conventional crosslinking
means, preferably W means, irradiation means or by chemical
means. Radiation crosslinking can be accomplished by
)I' fra~ r~4
lZi3~
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electron beam, or the like treatment. Suitable crosslinking
promoters can be incorporated to encourage radiation
crosslinking such as triallylcyanuate and triallyliso-
cyanuate. Suitable chemical crosslinking agents can be cho-
sen based on the individual polymer or polymers used. For
example, a phenolic re~in or p-quinone dioxime can be used
to cure butyl rubber, peroxide can be used to cure EPDM or
diisocyanate dimer acid can be used to cure epichlorohydrin
rubber.
Optionally, plasticizers may be added to help obtain a
gelloid with the desired cone penetration values. Such
plasticizers preferably would include all liquids which are
capable of raducing the viscosity of the base rubber, have
low or no unsaturation as described above and are compatible
with the base rubber.
~ filler may be added to t~e composition, if desired.
Generally, the amount o~ filler added is from 0 to 0.3
volume fraction. Preferably, the filler is in an amount
from .l to 0.2 volume fraction. The term "filler" is used
herein to include all solid additive~ including particulate
matter or fibrous matter present in the composition. These
fillers include pigments, fillers known for conductive,
~both electrical and thermal) stress grading and insulative
purposes e.g. carbon black, barium titnate, zinc oxide, iron
oxide, silicone carbide, metals and the like, reinforcing
agent3, thermal stabilizers, fungicides, biocides, flame
retardants, for example, aluminum trihydrate, and the halo-
genated flame retardants, leak indicators ~i.e. chemicals
.~ ,
~2~3~72
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which react upon exposure to certain chemicals~, corrosion
inhibitors, ultraviolet light stabilizers, processing aids,
impact modifiers and the like.
The compositions are formed preferably by mixing a
liquid non-silicone polymer with any desired fillers in an
amount of from O to 0.3 volume fraction, any crosslinking
agents or the like and the liquid and subjecting the mixture
to a crosslinking means. The composition will generally
take the shape of the container during crosslinking but can
be reshaped e.g. by cutting as desired.
The term cable is used in this application to refer to
one or more electrical conductors surrounded by electrical
insulation. In the case of a breakout, two or more cores,
i.e. conductor and insulation, are divided from a main
cable which contains those cores surrounded by a common
insulation layer, optionally with shielding and/or armoring.
The sealing method of this invention, is applied to
sealing between the individual cores and the individual
cores and enclosure. The term cable in the general
clescription and claims is to be understood to cover the
individual cores of a breakout or the main cable or the
like. In the case of a branch-off one or more cables
are jointed to a main cable. The sealing method of this
invention i~ applie~ to ~ealing between the two or more
branch-off cable~ and and the main cable mentioned above.
The term breakout is used herein to apply to such branch-
offs as well as breakouts.
-14-
The enclosure may be any material suitable for
enclosing a cable breakout or cable end. One ~skilled in
the art would be able to select an appropriate enclosure.
For example, dimensionally stable, preferably polymeric,
t~pes, shells and the like can be applied. Polymeric
materials include polyethylene, polypropylene, polyvinyl-
chloride, polyvinylidene fluoride, polyamides, polyesters,
Eluorinated polymers, ethylene-propylene rubbers, EPDM and
polystyrene-bukadiene-styrene (SBS), poly3tyreneisoprene-
styrene (SIS) and polystyrene-ethylenebutylene-styrene
(SEBS) block copolymers. Dimensionally recoverable poly-
meric articles are especially preferred for enclosures.
The dimensionally recoverable polymeric article
is preferably oE the heat recoverable type, preferably a
polyolefen ~uch as polyethylene. Other polymers such as
polyvinyl chloride and polymeric blends can also be used.
Particularly preferred is cross-linked polyethylene.
The term "recoverable article" is used herein to mean
an article the dimensional configuration of which may be
made substantially to change when subjected to some treat-
ment. Heat-recoverable articles, which recover when heated,
are particularly preEerred in the practice of this inven-
tion. Usually these articles recover, towards an original
shape from which they have previously been deformed but the
term "recoverable~, as used herein, al90 includes an article
which adopts a new configuration, even iE it has not been
previously deformed.
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In their most common form~ such articles comprise a
heat-shrinkable ~leeve made from a polymeric material exhi-
biting the property of elastic or plastic memory as
described, for example, in U.S. Patents 2,027,962, 3,086,242
and 3,597,372. As is made clear in, for example, U.S.
Patent 2,027,962, the original dimensionaily heat-stable
form may be a transient form in a continuous process in
which, for example, an extruded tube is expanded, while hot,
to a dimensionally heat-unstable form but, in other applica-
tions, a preformed dimensionally heat-stable article is
deformed to a dimensionally heat-unstable form in a separate
stage.
In the production of heat recoverable articles, the
polymeric material may be cross-linked at any stage in the
production of the article that will enhance the de~ired
dimensional recoverability. One manner of producing a heat-
recoverable article comprises shaping the polymeric material
into the desired heat-stable form, subsequently cross-
linking the polymeric material, heating the article to a
temperature above the crystalline melting point or, for
amorphous materials the softening point, a~ the case may be,
of the polymer, deforming the article and cooling the
article while in the deformed state so that the deformed
~tate of the article is retained~ In use, since the
deformed state oE the article is heat-unstable, applicati.on
of heat will cau~e the article to assume lts original heat-
stable shape.
In other article~, as de~cribed, for example, in
British Patent 1,440,524, an ela~tomeric member such as an
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inner tubular member is held in a stretched state by a
second member, such as an outer tubular member, which, upon
heating weakens and thus allows the elastomeric member to
recover.
Articles which are dimensionally recoverable without
the application of heat are de~cribed in U.S. Patents Nos.
4,070,746, 4,179,320 and 4,338,970. Such articles comprise
an elastomeric member held in a stretched state by a
retaining member. The elastomeric member is retained in the
stretched state until released from the retaining member by
application of solvent or by mechanically breaking or
removing the retaining member. Typically, such articles
comprise an elastomeric tube held in a stretched state by an
outer tubular member to which it i9 adhered. Polymeric
sleeve which recover without application of heat can be used
in the practice of this invention.
Optionally, the enclosure may have an inner layer of
adhesive to aid in bonding the enclosure to the shaped
article and any overlap of the enclosure onto the cable or
cable insulation. The adhesive inner layer can be any
sealant typically used to bond an enclosure to a cable.
Such sealants typically comprise mastics or hot melt adhesi-
ves .
Particularly preEerred for an adhesive inner layer are
hot malt adhesive~ containing ethylene copolymers, for
example copolymer~ o~ ethylene with vinyl acetate, malaic
anbydric acrylic acid, methacrylic acid or an alkyl acrylate
3~
-17-
5uch as ethyl acrylate. Mastics can also be used, for
example, low molecular weight polyisobutylene based ma~tic
compositions.
The enclosure, the shaped article and/or the adhesive
inner layer can contain various additives as desired.
Additives include, for example, stabilizers, reinforcing or
non-rein~orcing fillers, pigments, carbon black, plastici-
zers, surfactents, processing aids, corrosion inhibitors con-
ductive fillers, fungicides, biocides, leak indicators and
the like where appropriate.
A seal for a cable breakout area or other group of two
or more cables is formed by positioning the shaped article
of the polymeric gel around the cables. This may be done by
positioning the free ends of the cables through the holes in
the shaped article. Another method involves providing a
slit in the shaped article between the hole and an edge of
the shaped article such that the article can be opened to
position the cables inside the holes and then reclosed. The
tack of the material is such that on reclosure a seal is
formed. The shaped article may optionally be formed by
joining two or more pieces together to form the desired
shape. An adhesive can be used to join the pieces but the
tack of the material and the compressive force of the enclo-
sure may be ~ufficient to provide an adequate seal. Where
one or more cable ends are to be sealed, a ~haped article is
placed on the cable end such that the shaped article is
positioned on the ~ur~ace of the cable end or each cable end
i~ po3itioned in a hole in the ~haped articLe, the hols
, :
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being only a portion of the way through the shaped article.
An enclosure is then placed such that it surrounds the
shaped article and overlaps a portion of the cable. The gel
is so posi~ioned that when surrounded with the enclosure it
forms a seal preventing the ingress of water and the like.
Likewise the gel is chosen such that the gel itself forms a
barrier against water and the like. As can be seen from the
drawings, the enclosure surrounds only a portion of the
shaped article, the shaped article being open to the
environment. In another embodiment, a cover, e.g. a poly-
meric or metallic article is placed over the exposed portion
of the shaped article to act as a cover to protect the
shaped article against dirt, or the like. Where there is
substantial pressure from inside the cable the cover can be
used to prevent the shaped article from being forced out of
the opening in the enclosure. It is contemplated that the
enclosure can completely cover the shaped article and that
the cover is therefore an integral part of the enclosure.
In another embodiment there iQ a multiplicity of cable ends
and a multiplicity of shaped articles corresponding to the
number of cable ends wherein there is one enclosure
surrounding all the shaped articles and ad~acent portions o~
the cables. (See Figure 9).
In the drawings, Figure l shows a cable l with 3 cores
2, 3 and 4 which have been separated from the cable by remo-
val of the prokective sheath. Figure 2 shows the same cable
l with a shaped article S of a polymeric gel wherein cables
2, 3 and 4 have been po~itioned through holes, 6, 6, and 6.
Figure 3 show~ the cable o~ Figure 2 wherein an enclosure 7
~2~3~7æ
--19--
surrounds the shaped article of polymeric gel 5 and a por-
tion of the cable lo A portion of the polymeric gel is
exposed to the environment. Figures 4 and 5 show shaped
articles 8 and 11 of a polymeric gel. The articles each
have holes 9 for positioning cables therethrough and slits
10 for positioning the shaped article around cables without
access to their free end. Figure 6 shows a shaped article
1~ with a hole 13 ~or positioning a cable end therein.
Figure 7 shows a cable end 14 with a shaped article 12
sealing the end of the cable and enclosed by the enclosure
16 leaving a portion of the gel exposed to the environment.
Figure 8 shows a cross section of a sealed cable end 21
where there is a shaped article 17 with no hole positioned
at the end of cable 19 and surrounded by enclosure 18.
Figure 9 showq another embodiment of the cable end sealing
of the invention. A multiplicity of exposed cable ends 20
have shaped articles 17 positioned over their exposed ends
and are enclosed within one enclosure 18.
The following examples are illustrative only and are
not to be construed a~ limiting the invention. One skilled
in the art would readily be able to select appropriate
cros~linking agents, crosslink promotors, gels, radiation
levels, cable breakoutq, sets of cables, cable ends, enclo-
sures, adhesive~, mastics, etc. for a particular application
without undue exper~mentation.
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DESCRIPTION OF THE PREF13RRED EMBODIMENTS
Ex _ple 1 - Chemic~lly crosslinked butyl rubber
~dielectric gel)
~he following formulation was mixed then was cured for
30 minutes at 100C to form a gel.
~iquid butyl rubber lOOg
Zinc Stearate-filler 5g
Zirex*(Zinc Resinate)-chemical crosslinking
activator and fillerlOg
Paraffinic oil - plasticizer 90g
p~Quinone Dioxime (62.5% in oil)-crosslinking agent 3.2g
Lead dioxide (50% in dibutylphthalate)-cure actuator 15g
Carbon black - colorant & U.V. light stabilizer 2g
The resulting gel had a volume resistivity of 1014
ohm-cm tASTM D-150), a permitivity @ 50 Hz of 3.0 (ASTM
D-257) a cone penetration of 112 and elongation of 350%.
Example 2 - Chemically crosslinked epichlorohydrin (stress
grading gel-oil resistant)
The following formulation was m.ixed and then cured for 60
minutes at 100C to form a gel.
Hydrin~lOXl ~liquid epichlorohydrin rubber) lOOg
Dimer acid diisocyanate-crosslinking agent 46g
dioctyl phthalate-plasticizer lOOg
*-h~Jc ~k
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T-12 - tin catalyst lOg
Dabco 33LV (Tertiary amines - co-cataliyst) 2g
Antioxidant 2246 ~ substituted phenol type of 0.8g
antoixidant
The resulting gel had a specific impedance at 50 Hz of
1.8 x 109; a permitivity @ 50 H2 of 7.4, a cone penatration
value of 51.
Example 3 - Stress Grading Butyl gel
Kalene*200 (liquid butyl rubber) lOOg
Kaydol~oil (mineral oil) 95g
p-quinone dioxime prespersion (62.5%) 4.8g
Lead dioxide prespersion (50%) 18g
N990 Carbon Black (Thermax~MT) 69.4g
S37 Carbon Black) (Vulcan~P) 14.7g
Crosslinked at 100C for 30 minute~ resulted in a gel
with cone penetration value of 81, a specific imp~dance of
9.5 x 108, a permitivity of 32.6.
xample 4 - Conductive Butyl Gel
Kalene 200 ~liquid Butyl rubber) lOOg
Kaydol oil (mineral oil) Plasticizer 95g
p-quimone dioxime prespersion ~62.5%) curinq aqent 4.8g
Lead dioxide prespersion ~50%) curinq activiator 18g
Retjen~carbon black (conductive carbon black) 20g
The above formulation was crosslinked at 100C for 30
~ `tra.lc ~n ,, r ~
~27~
-22-
minutes and resulted in a gel with cone penetration value of
42, volume resistivity 2.4 x 105 ohm-cm.
Example 5 - Gel Tape Formulation
Xalene 800 (liquid butyl rubber) 100
Sunpar 2280*~plasticizer) (paraffinic oil) 130
Zinc Oxice Dispersion (80%) 6.25
Statex~N660 (Carbon black) 2
Irgonox~1076 (Antioxidant) 2
S~G47 (silicone antifoaming agent)
HRJ2564 (Phenolic Resin) 12
_
253.25
Cured 50 minutes @150C
Gel content (based on liquid butyl rubber) = 78%.
Storage modulus at 30C = 1.7x104 dyne.s/cm2
Storage modulus at 90C = 7.3x103 dynes/cm2
Dynamic viscosi~y at 30C = 4.2x104 poises
Dynamic viscosity at 90C = 2.0x104 poises
Exhibits first degree blocking.
Example 6
The polymeric gels in examples 1 through 5 are formed
into a shaped article with 3 hole~ in a circular fashion
(see Fig. 5) by casting the liquid rubber and remaining
ingredients into a mold and crosslinking in said mold both
with and without slits for application with and without
access to the cable ends.
*7~1c Jr74~rk
~2~30~
-23-
A three core conductor cable, each conductor be ing
4/0 gauge is stripped of its protective sheath to a distance
of about 7 in~ exposing each oE the 3 cable core. The
shaped article of polymeric gel is placed such tnat the
cable3 pass through the holes and as close to the crotch as
possible thereafter a polymeric tube of heat recoverable
cross-linked polyethylene is shrunk down over the shaped
article exposing the area whPre the cables exit the gel tsee
Fig. 3). The sealed cable is then tested for leaks by
immersion in water and then measuring the change if any in
resistance. After 200 hours immersion in water no leaks are
observed.
Example 7
The gels examples 1 through 5 are formed into a shaped
article by casting in a mold and crosslinking therein.
Samples were made with and without a hole a portian of
the way through the shaped article ~see Fig. 6 and ~).
A single conductor cable end is placed in the hole in
the shaped article or where appropraite the ~haped article
placed at the end of the cable. A tube of heat recoverable
crosslinked polyethylene is shrunk down on the shaped
article having the end of the ~haped article exposed
(see Fig. 7). The cable end seal is tested for leaks by
immersion in water ~nd then measuring the change, i~ any,
in resi~tance between a wire immQrsed in the water and the
sealed cable. AEter 200 hours immersion in water no leaks
are observed.
