U.S. patent application number 09/791375 was filed with the patent office on 2001-09-06 for fiber optic cable having a component with an absorptive polymer coating and a method of making the cable.
Invention is credited to Field, Larry W., Patel, Naren I..
Application Number | 20010019649 09/791375 |
Document ID | / |
Family ID | 22216286 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010019649 |
Kind Code |
A1 |
Field, Larry W. ; et
al. |
September 6, 2001 |
Fiber optic cable having a component with an absorptive polymer
coating and a method of making the cable
Abstract
A fiber optic cable (10) having at least one optical fiber (22)
and a component disposed within the cable (10) between a core (20)
and a jacket section (30) of the cable, and a method of making the
cable. The component includes a substrate (34) with a water
blocking formulation (50) thereon, the water blocking formulation
(50) comprising a radiation curable resin (52) and a water
absorptive substance (54) at least partially embedded or compounded
in the radiation curable resin (52). The radiation curable resin
(52) includes an initiator for rapid processing speeds. The water
blocking formulation (50) may include a non-compatible material for
reducing friction and/or enhancing physical properties. Water
blocking formulation (50) is advantageously adaptable to
application on various exemplary cable components (40, 75, 87, 94,
96, 98, 104).
Inventors: |
Field, Larry W.; (Hickory,
NC) ; Patel, Naren I.; (Hickory, NC) |
Correspondence
Address: |
CORNING CABLE SYSTEMS LLC
P O BOX 489
HICKORY
NC
28603
US
|
Family ID: |
22216286 |
Appl. No.: |
09/791375 |
Filed: |
February 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09791375 |
Feb 23, 2001 |
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09089201 |
Jun 2, 1998 |
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6195486 |
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Current U.S.
Class: |
385/100 ;
385/105; 385/127; 385/134 |
Current CPC
Class: |
G02B 6/4433 20130101;
G02B 6/4486 20130101; G02B 6/4494 20130101; G02B 6/4411 20130101;
G02B 6/4495 20130101; G02B 6/4409 20130101 |
Class at
Publication: |
385/100 ;
385/105; 385/127; 385/134 |
International
Class: |
G02B 006/44; G02B
006/02; G02B 006/22; G02B 006/00 |
Claims
What is claimed is:
1. A method of making a fiber optic cable with at least one optical
fiber, comprising the steps of: (a) coating a substrate with a
radiation curable resin; (b) creating a water blocking formulation
by depositing a water absorptive substance on the radiation curable
resin so that the water absorptive substance becomes at least
partially embedded in the radiation curable resin; (c) irradiating
the water blocking formulation with a radiation-emitting radiation
source; (d) curing the water blocking formulation with the
radiation-emitting radiation source; and (e) incorporating the
substrate and the water blocking formulation in said fiber optic
cable.
2. The method of claim 1, wherein the water blocking formulation is
applied to the substrate as a mixture of particulates.
3. A method of making a fiber optic cable with at least one optical
fiber, comprising the steps of: (a) creating a water blocking
formulation comprising a radiation curable resin and a water
absorptive substance compounded in the radiation curable resin; (b)
coating a substrate with said water blocking formulation so that
the water absorptive substance is at least partially embedded in
the resin; (c) irradiating the water blocking formulation with a
radiation-emitting radiation source; (d) curing the water blocking
formulation with the radiation-emitting radiation source; and (e)
incorporating the substrate and water blocking formulation in said
fiber optic cable.
4. The method of claim 3, wherein the water blocking formulation is
applied to the substrate as a mixture of particulates.
5. A fiber optic cable, comprising: at least one optical fiber; a
cable jacket; a cable component associated with said cable jacket,
said cable component including a water blocking formulation
disposed on a substrate, said water blocking formulation comprising
a radiation curable resin and an absorptive substance at least
partially embedded therein.
6. The fiber optic cable of claim 5, wherein said radiation curable
resin includes a photoinitiator that is photoactive in wavelengths
at or below the visible wavelength range.
7. The fiber optic cable of claim 5, wherein said radiation curable
resin includes a photoinitiator that is photoactive in wavelengths
at or below the UV wavelength range.
8. The fiber optic cable of claim 5, wherein said radiation curable
resin includes a photoinitiator that is photoactive in wavelengths
in the vacuum UV wavelength range.
9. The fiber optic cable of claim 5, wherein said radiation curable
resin includes an initiator that is active in wavelengths within
the Infrared wavelength range.
10. The fiber optic cable of claim 5, wherein said absorptive
substance is compounded in said radiation curable resin.
11. The fiber optic cable of claim 5, wherein said substrate is a
tape disposed at least partially along said jacket section.
12. The fiber optic cable of claim 5, wherein said substrate is a
slotted core surface adjacent said jacket section.
13. The fiber optic cable of claim 5, wherein said substrate is
conductor insulation adjacent said jacket section.
14. The fiber optic cable of claim 5, wherein said substrate is a
core tube.
15. The fiber optic cable of claim 5, wherein said substrate is the
seam of a tape, said water blocking formulation comprising a seam
guard over said seam.
16. The fiber optic cable of claim 5, wherein said substrate is a
strength member.
17. The fiber optic cable of claim 5, wherein said substrate is a
strengthening rod.
18. The fiber optic cable of claim 5, wherein said substrate is a
rip cord.
19. The fiber optic cable of claim 5, wherein said substrate is a
cable core.
20. A fiber optic cable, comprising: a cable core including at
least one optical fiber; a cable component associated with said
cable core, said cable component having a water blocking
formulation disposed on a substrate, said water blocking
formulation comprising a radiation curable resin and an absorptive
substance therein.
21. The fiber optic cable of claim 20, wherein said radiation
curable resin includes a photoinitiator that is photoactive in
wavelengths at or below the visible wavelength range.
22. The fiber optic cable of claim 20, wherein said radiation
curable resin includes a photoinitiator that is photoactive in
wavelengths at or below the UV wavelength range.
23. The fiber optic cable of claim 20, wherein said radiation
curable resin includes a photoinitiator that is photoactive in
wavelengths in the vacuum WV wavelength range.
24. The fiber optic cable of claim 20, wherein said radiation
curable resin includes an initiator that is active in response to
being irradiated with radiation wavelengths within the infrared
wavelength range.
25. The fiber optic cable of claim 20, wherein said absorptive
substance is compounded in said radiation curable resin.
26. The fiber optic cable of claim 20, wherein said absorptive
substance is at least partially embedded in said radiation curable
resin.
27. The fiber optic cable of claim 20, wherein said substrate is a
tape at least partially surrounding said core.
28. The fiber optic cable of claim 20, wherein said substrate is a
slotted core.
29. The fiber optic cable of claim 20, wherein said substrate is
conductor insulation adjacent said core.
30. The fiber optic cable of claim 20, wherein said substrate is a
core tube.
31. The fiber optic cable of claim 20, wherein said substrate is
the seam of a tape, said water blocking formulation comprising a
seam guard over said seam.
32. A fiber optic cable, comprising: at least one optical fiber; a
component disposed within said cable between a core and a jacket
section of said cable, said component including a substrate with a
composite water blocking formulation disposed thereon, said
composite water blocking formulation comprising a radiation curable
resin, a water absorptive substance at least partially embedded in
the radiation curable resin, and a non-compatible material
dispersed in said radiation curable resin.
33. The fiber optic cable of claim 32, wherein said non-compatible
material is a lubricant for reducing friction.
34. The fiber optic cable of claim 33, wherein said lubricant is a
liquid lubricant.
35. The fiber optic cable of claim 33, wherein said lubricant is a
dry lubricant.
36. The fiber optic cable of claim 32, wherein said non-compatible
material is selected from the group consisting of solid fillers,
powders, fibers, particulates, and glass/polymeric
micro-spheres.
37. The fiber optic cable of claim 33, wherein the lubricant
functions as a release agent for reducing friction.
Description
[0001] The present invention is a Continuation of pending Ser. No.
09/089,201 filed Jun. 2, 1998.
[0002] The present invention relates to fiber optic cables and,
more particularly, to water blocking features of fiber optic
cables.
[0003] Fiber optic cables include optical fibers which transmit
information in cable television, computer, and telephone systems. A
fiber optic cable may be installed in an environment where the
cable is exposed to water. The migration of water in a fiber optic
cable may occur where the cable jacket has been breached and water
enters the cable. The migration of water in a cable may cause the
flooding of a cable passageway or enclosure, and/or it may
negatively affect the performance of the optical fibers.
Interstices between a jacket section and the core of the cable
present potential water migration paths.
[0004] To block the flow of water in the interstices, known fiber
optic cables may include a flooding compound, and/or a more
craft-friendly, dry water absorbent substance. A typical water
absorbent substance includes a polymer chain with reaction sites
that react with water, thereby transforming the water absorbent
substance into an expanded mass of viscous gel. The viscous gel
acts as a physical barrier to the migration of water.
[0005] U.S. Pat. No. 5,179,611 discloses a slotted rod type fiber
optic cable that includes a water absorptive tape disposed between
a jacket section and the slotted rod. The tape is a non-woven
fabric, a paper or other sheet-like material, which is topically
coated or impregnated with a combination of a thermoplastic
elastomer binding agent and a water absorptive resin combined with
a water soluble resin. Application of the water absorptive tape to
the slotted rod requires manufacturing equipment that is expensive
to purchase and to maintain. Additionally, the water absorptive
tape is a cable component that adds to the cost, size, and weight
of the cable. Further, a craftsman will be obliged to perform the
time consuming task of cutting and removing tape binders and the
water absorptive tape in order to gain access to optical fibers in
the cable.
[0006] A patent assigned to the assignee hereof discloses a fiber
optic cable which eliminates the necessity for a water absorptive
tape. U.S. Pat. No. 5,188,883 discloses an armor tape having an
ethylene copolymer coating to which a layer of a swellable water
blocking material is bonded. In a first method of making the armor
tape, the layers are bonded together by heating the ethylene
copolymer to soften it and then pressing the metal and water
blocking tape layers together. In an alternative method of making
the armor tape, the swellable material is applied directly to and
is bonded with the coated metal tape layer. This alternative method
is accomplished by heating and thereby softening the ethylene
copolymer, and then depositing particles of the water swellable
material directly on the softened copolymer by way of gravity
acting on the particles as they are dispensed from a hopper. The
water swellable tape of the first method may be expensive, and the
application of the tapes to a cable core requires expensive
manufacturing equipment. The manufacturing steps associated with
wrapping the tape about the core contributes to the cost of
production of the cable, and the use of a heater to soften the
ethylene copolymer may likewise slow production speeds and increase
costs.
OBJECTS OF THE INVENTION
[0007] In view of the foregoing, it is an object of the present
invention to provide a fiber optic cable that includes a at least
one optical fiber, a cable jacket, and a cable component associated
with the cable jacket, the cable component including a water
blocking formulation disposed on a substrate, the water blocking
formulation comprising a radiation curable resin and an absorptive
substance at least partially embedded therein.
[0008] It is another object of the present invention to provide a
fiber optic cable that includes a cable core including at least one
optical fiber, a cable component associated with the cable core and
at least partially surrounding the cable core, the cable component
having a water blocking formulation disposed on a substrate, the
water blocking formulation comprising a radiation curable resin and
an absorptive substance therein.
[0009] It is an object of the present invention to provide a fiber
optic cable that includes a least one optical fiber, a component
disposed within the cable between a core and a jacket section of
the cable, the component including a substrate with a composite
water blocking formulation disposed thereon, the composite water
blocking formulation comprising a radiation curable resin, an
absorptive substance at least partially embedded in the radiation
curable resin, and a non-compatible material dispersed in the
radiation curable resin.
[0010] It is a further object of the present invention to provide a
method of making a fiber optic cable with at least one optical
fiber, the method having the steps of coating a substrate with a
radiation curable resin, creating a water blocking formulation by
depositing an absorptive substance on the resin so that the
absorptive substance becomes at least partially embedded in the
resin, irradiating the water blocking formulation with a radiation
source that emits radiation in the infrared wavelength region or
with radiation having shorter wavelengths, curing the water
blocking formulation with the radiation-emitting radiation source,
and incorporating the substrate and the water blocking formulation
in the fiber optic cable.
[0011] It is an object of the present invention to provide a method
of making a fiber optic cable including the steps of creating a
water blocking formulation comprising a radiation curable resin and
an absorptive substance compounded in the radiation curable resin,
coating a substrate with the water blocking formulation so that the
absorptive substance is at least partially embedded in the resin,
irradiating the water blocking formulation with a radiation source
that emits radiation in the infrared wavelength region or with
radiation having shorter wavelengths, curing the water blocking
formulation with the radiation-emitting radiation source, and
incorporating the substrate and water blocking formulation in the
fiber optic cable.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0012] FIG. 1 is an isometric view of a fiber optic cable according
to the present invention.
[0013] FIG. 2 is a partial cross sectional view of a portion of the
fiber optic cable of FIG. 1.
[0014] FIG. 3 is a cross sectional view of a portion of a tape
coated with a water blocking material according to the present
invention.
[0015] FIG. 4 is a schematic view of a manufacturing line according
to the present invention.
[0016] FIG. 5 is a cross sectional view of a fiber optic cable
according to the present invention.
[0017] FIG. 6 is a cross sectional view of a fiber optic cable
according to the present invention.
[0018] FIG. 7 is an isometric view of a fiber optic cable according
to the present invention.
[0019] FIG. 8 is a partial cross section of a fiber optic cable
according to the present invention.
[0020] FIG. 9 is a partial cross section of a fiber optic cable
according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Referring to FIGS. 1-3, an exemplary fiber optic cable 10
according to a first embodiment of the present invention will be
described. Fiber optic cable 10 includes a cable core 20, a jacket
section 30, and may include a seam guard 40 as disclosed in U.S.
Ser. No. 09/001,679, which is incorporated by reference herein. In
a preferred embodiment of the present invention, jacket section 30
includes a cable component comprising a substrate, the substrate
being a layer of tape 34 having a water blocking formulation 50
thereon. Water blocking formulation 50 preferably comprises a
cross-linkable resin, for example, a radiation-curable resin,
combined with a superabsorbent substance. In an embodiment of the
present invention the radiation-curable resin comprises a
light-curable resin.
[0022] As is best shown in FIG. 1, cable core 20 may include a
dielectric central member 21 surrounded by a first set of buffer
tubes 23. Buffer tubes 23 are, in turn, surrounded by a
water-blocking tape 24, and each tube 23 includes respective
optical fibers 22 therein. Optical fibers 22 may be embedded in a
conventional water-blocking gel or grease. Cable core 20 may
include a second set of buffer tubes 26 with respective optical
fibers 25 therein which may be disposed in a water-blocking
material.
[0023] Jacket section 30 includes a cable jacket 36, and a
substrate in the form of a tape 34. Tape 34 may be of a sheet or a
non-woven fabric type, and may be formed of a metallic material,
e.g. steel, or a non-metallic material, e.g. plastic. Tape 34 is
wrapped around core 20 whereby water blocking formulation 50 is
effective to block the longitudinal migration of water in cable 10.
In an embodiment of the present invention, tape 34 is a metallic
tape that is mechanically robust enough to withstand attack by
rodents and to resist the migration of moisture into the cable
core. Tape 34 may include a seam 35 of the overlap type which is
formed by a non-offset tape layer 39 and an offset tape layer 39
(FIG. 2). In a preferred embodiment, offset tape layer 38 is
located radially outside of non-offset tape layer 39 with water
blocking formulation 50 disposed therebetween whereby water
blocking formulation 50 provides water blocking protection to seam
35. For additional sealing of seam 35, a seam guard 40 having a
substrate in the form of a strip of polymeric tape is placed over
seam 35 and against portions of tape layers 38, 39. The polymeric
tape of seam guard 40 may include water blocking formulation 50
thereon. Cable jacket 36 surrounds both tape 34 and seam guard 40
and may be formed of, for example, a polyethylene or a PVC
material.
[0024] Alternatively, the invention may be practiced in the form of
a fiber optic cable 10' (FIG. 8) whereby water blocking formulation
50 defines a seam guard without a polymeric tape. As further
described below, water blocking formulation 50 may be a composite
of non-compatible materials, e.g., a composite of a light curable
resin and a liquid or a solid lubricant that is not compatible with
the resin. The lubricant functions as a release agent that is
effective, upon cable bending or twisting, to reduce the
coefficient of friction between jacket 36 and tape 34, thereby
de-coupling jacket 36 from tape 34 and inhibiting jacket
zippering.
[0025] As is best shown in FIG. 3, water blocking formulation 50,
is a combination of a light curable resin 52 and a water absorptive
substance 54 that is bonded to a substrate, for example, tape 34.
Light curable resin 52 is preferably a tough, abrasion resistant
but flexible light curable resin, e.g. a urethane acrylate, that is
advantageously adaptable to mass production processes. Resin 52 is
preferably of the type which will undergo chemical cross-linking
between molecules of the resin during curing. To enhance the mass
production of formulation 50, light curable resin 52 includes a
suitable initiator additive for fast processing speeds. As
described in more detail below, preferably with the assistance of
an initiator additive, resin 52 is substantially cured by energy
radiated thereon.
[0026] Water blocking formulation 50 may be a composite. For
example, to improve mechanical characteristics and/or
processability of resin 52, water blocking formulation 50 may be a
composite of a UV curable resin mixed with a non-compatible
material. Suitable non-compatible materials comprise solid fillers,
powders or fibers, particulates, and glass/polymeric micro-spheres.
Additionally, resin 52 may be cellularized with a non-compatible
foaming agent, e.g., a chemical or a mechanical foaming agent.
Moreover, to reduce friction between water blocking formulation 50
and other cable components, resin 52 may include a non-compatible
material in the form of a lubricant, e.g., a liquid lubricant such
as a silicone or a wax which exudes to the surface, or a solid
lubricant, e.g., Teflon.
[0027] Water absorptive substance 54 may include a single species
of poly-sodium-acrylate polymer having a suitable gel strength,
swell rate, and swell capacity. Alternatively, water absorptive
substance 54 may be a mixture of two or more species of
superabsorbent substances, as disclosed in co-pending U.S. Ser. No.
09/049,417 which is incorporated by reference herein. Additionally,
water absorbent substance 54 may include an antifreeze substance
that is effective to depress the freezing point of water.
Anti-freeze substances are disclosed in U.S. Pat. No. 5,410,629,
U.S. Pat. No. 5,321,788, and U.S. Pat. No. 4,401,366, which patents
are incorporated by reference herein.
[0028] In an exemplary manufacturing line 100 according to the
present invention, tape 34 is at least partially coated with water
blocking formulation 50 (FIG. 4). Manufacturing line 100 is
preferably a continuous type process and includes a tape pay-off
105, a light curable resin application chamber 110, a water
absorbent substance coating chamber 114 preferably having a
substance recovery/recycling system (not shown), and a radiation
chamber 118. Manufacturing line 100 further includes a conventional
programmable logic controller (PLC) 130 and a length sensor 131.
PLC 130 is operative to activate/deactivate chambers 110, 118 in
response to tape length information provided by length sensor 131.
Light curable resin application chamber 110 may include a
conventional coating type nozzle 112, and water absorbent substance
coating chamber 114 may include a conventional powder coating type
nozzle 116. Light curable resin 52, in a melted state, and water
absorbent substance 54, in particulate form, are respectively
supplied to nozzles 112, 116 by conventional supply means (not
shown) under suitable pressure and temperature conditions. A
conventional fluidized bed apparatus (not shown) may be used as an
alternative to powder coating nozzle 116. Suitable substance
recovery systems are made available by the Nordson Corporation.
[0029] During the manufacturing operation (FIG. 4), tape 34 is fed
from pay-off 105, and the length of the tape is monitored by sensor
131 which inputs the length information to PLC 130. When the tape
length is substantially equal to a pre-programmed length value, PLC
130 activates nozzle 112 of light curable resin application chamber
110 whereby a bead of light curable resin 52, is applied to tape
34. Next, when the tape length information indicates the movement
of tape 34 into coating chamber 118, PLC 130 activates water
absorbent substance nozzle 116 whereby water absorptive substance
54 is propelled toward resin 52. The particles of water absorbent
substance 54 are propelled onto light curable resin 52 so that they
become at least partially embedded therein, thereby defining a
liquid state water blocking formulation 50'. Next, tape 34 with
water blocking formulation 50 is conveyed to radiation chamber 118.
Alternatively, water absorbent substance 54 may be compounded with
resin 52 and applied to tape 34 at the same time.
[0030] Radiation chamber 118 includes a radiation source 120 that
emits light in an appropriate spectrum thereby effecting a rapid
polymerization of resin 52. In other words, upon exposure to light
energy emitted by radiation source 120, light curable resin 52
undergoes a rapid transition from a liquid state to a solid or a
semi-solid state. As the transition occurs, the disposition of
water absorptive substance 54 is generally fixed in and on resin
52. Rapid polymerization is advantageously enhanced by the
initiator additive in resin 52 that is activated by complementary
light energy radiated by radiation source 120. Where the initiator
is a photoinitiator it functions by: absorbing energy radiated by
radiation source 120; photo-cleaving, i.e., fragmenting, into
reactive species; and then initiating a polymerization/hardening
reaction of the monomers and oligomers in light curable resin 52.
The result is a solid or a semi-solid network of cross-linking
between the monomers, oligomers, and other additives in resin 52.
In a preferred embodiment of the present invention, the
photoinitiator has a characteristic photoactive region, i.e., a
photoactive wavelength absorbency range, which exhibits peak
photoactivity for inducing a maximum curing speed of light curable
resin 52. In the preferred embodiment, the photoinitiator in light
curable resin 52 is matched with a radiation source 120 that emits
a high degree of energy within a range of frequencies that is
complementary to the peak photoactive region of the photoinitiator,
thereby assuring the rapid curing of light curable resin 52.
Commercially available photoinitiators that are suitable for use in
light curable resin 52 include Irgacure products marketed by
Ciba.
[0031] The photoinitiator in light curable resin 52 may have a
photoactive region in the visible light wavelength range, or it may
have a photoactive region in wavelengths which are shorter. For
example, the photoinitiator in light curable resin 52 may have a
photoactive region in the vacuum ultra-violet (VUV)(about 160-200
nm), ultra-violet (UV)(about 200-400 nm), visible light
(V-light)(about 400-700 nm) wavelength range. Light curable resin
52, having a suitable photoinitiator, is preferably cured by being
irradiated with a VUV, UV, V-light radiation source 120 that, as
noted above, complements the peak photoactive absorbency range of
the photoinitiator. In the case of an Infrared radiation curable
resin, e.g. an elastomer, a suitable free-radical initiator can be
used that is active upon being irradiated with an Infrared
radiation source emitting wavelengths in the order of about visible
light to about 1.times.10.sup.6 nm.
[0032] Suitable radiation sources may be in the form of
commercially available bulbs, for example, an H bulb having a
standard mercury spectral line, or a D bulb (mercury vapor plus
metal halide(s)). Alternatively, an excimer type bulb, for example,
a Cobalt or a Xenon-chloride bulb, may be used as well. A
conventional high intensity Infrared spectrum bulb, or an
electrical resistance heater, can be used to cure the Infrared
light curable resin. After water blocking formulation 50 is cured,
tape 34 may be reeled about a take-up reel (not shown).
Alternatively, tape 34 may be sent directly to a corrugation
machine, or a tape forming apparatus whereby the tape is wrapped
about a cable core. Tape 34 may be formed into an overlap type seam
35 (FIG. 2) using an apparatus according to U.S. Pat. No.
4,151,365, U.S. Pat. No. 4,308,662, or U.S. Pat. No. 5,410,901,
which patents are incorporated herein in their respective
entireties. Alternatively, tape 34 may be formed into a butt type
seam, for example, as taught in U.S. Pat. No. 3,785,048, which
patent is incorporated by reference herein. Where water blocking
formulation 50 defines a seam guard (FIG. 8), a bead of the
formulation may be applied directly to the overlap or butt type
joint and cured with a radiation source 120.
[0033] As an alternative to application of light curable resin 52
and water absorbent substance 54 described above, the light curable
resin 52 and water absorbent substance 54 may be applied to the
substrate in situ as a dry or a moist mixture of particulates,
e.g., with a conventional electrostatic spray nozzle. The mixture
can then be heated to the point of melting light curable resin 52
so that the resin, with the water absorbent substance therein
and/or thereon, will bond to the substrate. The mixture may then be
irradiated with a radiation source 118 to bring about the cross
linking of resin 52, preferably to the degree that surface
tackiness is avoided. Alternatively, a radiation source 118 can be
used that will simultaneously emit Infrared radiation, to heat the
resin, and shorter wavelength radiation, to photoactivate the
cross-linking process.
[0034] The present invention may be practiced in the form of a
cable 70 (FIG. 5) including a core having a cable component in the
shape of a slotted rod 75 that is coated with water blocking
formulation 50. Slotted rod 75 includes a central member 74, slots
73 having optical fiber ribbons 72 therein, and outer surfaces 79.
Slotted rod 75 is associated with a jacket section 77. Slotted rod
75 is a substrate upon which water blocking formulation 50 is at
least partially disposed, i.e., outer surfaces 79 and slots 73 may
each include water blocking formulation 50 thereon whereby it
surrounds at least part of the cable core, thereby potentially
eliminating the necessity for a water blocking tape wrapped around
slotted rod 75.
[0035] In the manufacture of slotted rod 75 according to the
present invention, a slotted rod type extrusion die as disclosed in
commonly assigned U.S. Ser. No. 617,710, which is incorporated
herein by reference, may be adapted to co-extrude slotted rod 75
along with water blocking formulation 50. Water blocking
formulation 50 is then cured with a radiation source 120. A
co-extrusion process as described in commonly assigned U.S. Ser.
No. 09/049,417, incorporated by reference hereinabove, may be used
to apply water blocking formulation 50 to an extrudable substrate.
Alternatively, water blocking formulation 50 may be topically
applied on the slotted core 75 and then cured with a radiation
source 120 (FIG. 4). Slotted rod 75 may be formed of, for example,
a polypropylene copolymer, a polybutylene terephtalate,
polyethylene, or a Nylon material.
[0036] The present invention may be practiced in the form of a
composite cable 80 (FIG. 6) having a water blocking formulation 50.
Composite cable 80 is capable of both optical and
electrical/electronic signal transmission, and is generally made
according to the teachings of commonly assigned U.S. Ser. No.
09/001,680 which is incorporated by reference herein. Composite
cable 80 includes a core 82 having optical fibers 84, a strength
section 85, a conductor and water blocking section 86 having cable
components in the form of twisted pair electrical conductors 87,
and a jacket section 89 having an armor tape 88. According to the
present invention, water blocking formulation 50 is co-extruded
with a substrate, for example, the insulation material of twisted
pair conductors 87, and is then cured with a radiation source 120
in accordance with the present invention. Water blocking
formulation 50 is associated with core and jacket sections 82, 89
in that water blocking formulation 50 advantageously provides water
blocking protection to interstices S defined therebetween.
Alternatively, water blocking formulation 50 may be topically
applied on the insulation of the twisted pair conductors 87 and
then cured with a radiation source 120.
[0037] The present invention may be practiced in the form of a
fiber optic cable 90 (FIG. 7) having a core with optical fiber
ribbons 92 surrounded by a core tube 94. Strength members 96 are
adjacent to core tube 94 and respective rip cords 98 are adjacent
strength members 96 for facilitating removal of a jacket 99. Water
blocking formulation 50 is applied to substrates comprising core
tube 94, strength members 96, jacket 99, and/or rip cords 98 for
water blocking protection.
[0038] The present invention may be practiced in the form of a
fiber optic cable 100 (FIG. 9) having a loose tube type core with
buffer tubes 103 having optical fiber ribbons therein. Water
blocking formulation 50 is applied to a substrate in the form of a
strengthening rod 104 for water blocking protection in the
interstices between tubes 103 and jacket section 105. Strengthening
rod 104 may be stranded with buffer tubes 103 in a loose tube cable
manufacturing process, for example, as disclosed in U.S. Pat. No.
5,283,014, which patent is incorporated by reference herein. Fiber
optic cable 100 may include water blocking formulation 50 applied
directly to the cable core, in a process described in commonly
assigned U.S. Ser. No. 09/048,486, incorporated by reference
herein. Additionally, fiber optic cable 100 may include a tape 34
with water blocking formulation 50 as described hereinabove.
[0039] The present invention has been described with reference to
the foregoing embodiments, which embodiments are intended to be
illustrative of the present inventive concepts rather than
limiting. Persons of ordinary skill in the art will appreciate that
variations and modifications of the foregoing embodiments may be
made without departing from the scope of the appended claims. For
example, the surfaces of cable components according to the present
invention may be coated with water blocking formulation 50 as a
stripe or intermittently as described in U.S. Ser. No. 09/048,486,
incorporated by reference hereinabove. Additionally, any of the
foregoing non-metallic substrates may be formed of a foamed plastic
material.
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