U.S. patent application number 16/549414 was filed with the patent office on 2019-12-12 for sap coating layer for cable component and related systems and methods.
The applicant listed for this patent is Corning Optical Communications LLC. Invention is credited to Dana Craig Bookbinder, Waldemar Stocklein.
Application Number | 20190377148 16/549414 |
Document ID | / |
Family ID | 57007439 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190377148 |
Kind Code |
A1 |
Bookbinder; Dana Craig ; et
al. |
December 12, 2019 |
SAP COATING LAYER FOR CABLE COMPONENT AND RELATED SYSTEMS AND
METHODS
Abstract
A process and system for making a water resistant cable
component and water resistant cable components are provided. The
water resistant cable includes a cable body including an inner
surface defining a channel within the cable body and an elongate
cable component located within the channel of the cable body. The
cable also includes a contiguous layer of crosslinked super
absorbent polymer surrounding the elongate cable component. The
layer of crosslinked super absorbent polymer is formed by applying
a liquid layer including a carrier material and an uncrosslinked
super absorbent polymer pre-polymer material onto an outer surface
of a component of the cable and then by crosslinking the super
absorbent polymer pre-polymer while on the cable component to form
a layer of crosslinked super absorbent polymer surrounding the
cable component.
Inventors: |
Bookbinder; Dana Craig;
(Corning, NY) ; Stocklein; Waldemar; (Coburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corning Optical Communications LLC |
Charlotte |
NC |
US |
|
|
Family ID: |
57007439 |
Appl. No.: |
16/549414 |
Filed: |
August 23, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15709844 |
Sep 20, 2017 |
10422973 |
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16549414 |
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PCT/US16/20188 |
Mar 1, 2016 |
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15709844 |
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62139929 |
Mar 30, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4435 20130101;
G02B 6/4494 20130101; G02B 6/443 20130101 |
International
Class: |
G02B 6/44 20060101
G02B006/44 |
Claims
1. An optical cable comprising: a cable body including an inner
surface defining a channel within the cable body; and a plurality
of tubes located in the channel of the cable body, wherein each of
the plurality of tubes includes an outer surface, an inner surface
and a channel defined by the inner surface of the tube; and a
plurality of optical fibers located within the channel of each
tube, wherein each optical fiber comprises: an optical core;
cladding of a different refractive index than the optical core
surrounding the core; a polymer coating layer surrounding the
cladding; and a contiguous layer of crosslinked super absorbent
polymer surrounding the polymer coating layer, wherein the
contiguous layer of crosslinked super absorbent polymer is
contiguous both circumferentially around the optical fiber and
axially along the optical fiber for at least a length of 1 cm.
2. The optical cable of claim 1 wherein the contiguous layer of
crosslinked super absorbent polymer has a maximum thickness less
than 200 micrometers.
3. The optical cable of claim 1 wherein the contiguous layer of
crosslinked super absorbent polymer has a maximum thickness less
than 60 micrometers.
4. The optical cable of claim 1 wherein the contiguous layer of
crosslinked super absorbent polymer has a maximum thickness less
than 60 micrometers and an average thickness, T1.sub.ave, in
micrometers of 1.ltoreq.T1.sub.ave.ltoreq.50.
5. The optical cable of claim 1 wherein the mass, m1, of the
crosslinked super absorbent polymer in the contiguous layer of each
optical fiber in milligrams per meter length of the optical fiber
is 1.ltoreq.m1.ltoreq.200.
6. The optical cable of claim 1 wherein the mass, m1, of the
crosslinked super absorbent polymer in the contiguous layer of each
optical fiber in milligrams per meter length of the optical fiber
is 1.ltoreq.m1.ltoreq.60.
7. The article of claim 1 wherein the channel of each tube has an
inner diameter, BID, and a cross-sectional area, BID1.sub.XC,
wherein a total cross-sectional area of the crosslinked super
absorbent polymer inside each tube is a1.sub.total, and wherein
0.2%.ltoreq.100% (a1.sub.total/BID1.sub.XC).ltoreq.10%.
8. The optical cable of claim 1 wherein the polymer coating of the
optical fiber includes a colored section, wherein the contiguous
layer of crosslinked super absorbent polymer is translucent such
that the colored section is visible through the contiguous layer of
crosslinked super absorbent polymer.
9. The optical cable of claim 8 wherein the transmittance of the
contiguous layer of crosslinked super absorbent polymer at least
one wavelength between 400-700 nm is between 0.2 and 1.
10. The optical cable of claim 1 wherein each of the plurality of
tubes includes at least six optical fibers, wherein the inner
diameter of the tube is between 0.7 and 3 millimeters.
11. An optical fiber cable component comprising: an optical fiber
including an optical core and a cladding layer of a different
refractive index than the optical core surrounding the core; an
outer polymer layer located outside of and surrounding the optical
fiber; and a contiguous layer of crosslinked super absorbent
polymer surrounding the outer polymer layer, wherein the contiguous
layer of crosslinked super absorbent polymer is contiguous
circumferentially around the optical fiber and contiguous axially
along the optical fiber for at least a length of 1 cm.
12. The optical fiber cable component of claim 11 wherein the
contiguous layer of crosslinked super absorbent polymer has a
maximum thickness less than 60 micrometers and an average thickness
in micrometers, T1.sub.ave, of 1.ltoreq.T1.sub.ave.ltoreq.50.
13. The optical fiber cable component of claim 11 wherein outer
polymer layer is at least one of a buffer tube, a ribbon body, and
an optical fiber coating layer surrounding and in contact with the
cladding layer.
14. A water resistant cable comprising: a cable body including an
inner surface defining a channel within the cable body; an elongate
cable component located within the channel of the cable body; and a
contiguous layer of crosslinked super absorbent polymer surrounding
the elongate cable component; wherein the contiguous layer of
crosslinked super absorbent polymer is contiguous circumferentially
around the elongate cable component and contiguous axially along
the length of the elongate cable component for at least a length of
1 cm.
15. The water resistant cable of claim 14 wherein the contiguous
layer of crosslinked super absorbent polymer has a maximum
thickness less than 60 micrometers and an average thickness in
micrometers, T1.sub.ave, of 1.ltoreq.T1.sub.ave.ltoreq.50.
16. The water resistant cable of claim 14 wherein the elongate
cable component is at least one of an optical fiber, a buffer tube
and an optical fiber ribbon.
17. The water resistant cable of claim 14 wherein the elongate
cable component is an electrical conductor.
Description
PRIORITY APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 15/709,844, filed Sep. 20, 2017, which is a continuation
of International Application No. PCT/US16/20188, filed Mar. 1,
2016, which claims the benefit of priority to U.S. Application Ser.
No. 62/139,929, filed Mar. 30, 2015, the contents of which are
relied upon and incorporated herein by reference in their
entirety.
BACKGROUND
[0002] The disclosure relates generally to cables and more
particularly to cables, such as optical communication cables, that
include a crosslinked layer, film or coating of a super absorbent
polymer material surrounding one or more cable components. Cables,
including optical communication cables, have seen increased use in
a wide variety of electronics and telecommunications fields.
Optical communication cables contain or surround one or more
optical fibers, and other non-optical cables typically including a
conducting element (e.g., a copper wire) that acts as a
transmission element. The cable provides structure and protection
for the optical fibers wires within the cable.
SUMMARY
[0003] One embodiment of the disclosure relates to a method of
manufacturing an optical fiber component. The method includes
applying a liquid layer including a carrier material and an
uncrosslinked super absorbent polymer pre-polymer material onto an
outer surface of an optical fiber cable component. The method
includes crosslinking the super absorbent polymer pre-polymer while
on the optical fiber cable component to form a layer of crosslinked
super absorbent polymer surrounding the optical fiber cable
component. The method includes forming a polymer structure around
the optical fiber component following formation of the layer of
crosslinked super absorbent polymer.
[0004] An additional embodiment of the disclosure relates to an
optical cable. The optical cable includes a cable body including an
inner surface defining a channel within the cable body. The cable
includes a plurality of tubes located in the channel of the cable
body, wherein each of the plurality of tubes includes an outer
surface, an inner surface and a channel defined by the inner
surface of the tube. The cable includes a plurality of optical
fibers located within the channel of each tube. Each optical fiber
includes an optical core, cladding of a different refractive index
than the optical core surrounding the core and a polymer coating
layer surrounding the cladding. Each optical fiber also includes a
contiguous layer of crosslinked super absorbent polymer surrounding
the polymer coating layer. The contiguous layer of crosslinked
super absorbent polymer is contiguous both circumferentially around
the optical fiber and axially along the optical fiber for at least
a length of 1 cm.
[0005] An additional embodiment of the disclosure relates to an
optical fiber cable component. The optical fiber cable component
includes an optical fiber having an optical core and a cladding
layer of a different refractive index than the optical core
surrounding the core. The optical fiber cable component includes an
outer polymer layer located outside of and surrounding the optical
fiber. The optical fiber cable component includes a contiguous
layer of crosslinked super absorbent polymer surrounding the outer
polymer layer. The contiguous layer of crosslinked super absorbent
polymer is contiguous circumferentially around the optical fiber
and contiguous axially along the optical fiber for at least a
length of 1 cm.
[0006] An additional embodiment of the disclosure relates to a
water resistant cable. The cable includes a cable body including an
inner surface defining a channel within the cable body. The cable
includes an elongate cable component located within the channel of
the cable body. The cable includes a contiguous layer of
crosslinked super absorbent polymer surrounding the elongate cable
component. The contiguous layer of crosslinked super absorbent
polymer is contiguous circumferentially around the elongate cable
component and contiguous axially along the length of the elongate
cable component for at least a length of 1 cm.
[0007] Additional features and advantages will be set forth in the
detailed description which follows, and in part will be readily
apparent to those skilled in the art from the description or
recognized by practicing the embodiments as described in the
written description and claims hereof, as well as the appended
drawings.
[0008] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary, and are intended to provide an overview or framework to
understand the nature and character of the claims.
[0009] The accompanying drawings are included to provide a further
understanding and are incorporated in and constitute a part of this
specification. The drawings illustrate one or more embodiment(s),
and together with the description serve to explain principles and
operation of the various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of an optical fiber cable
according to an exemplary embodiment.
[0011] FIG. 2 is a cross-sectional view of the buffer tube of FIG.
1 according to an exemplary embodiment.
[0012] FIG. 3 is a cross-sectional view of an optical fiber of the
cable of FIG. 1 according to an exemplary embodiment.
[0013] FIG. 4 is a schematic view showing a system and process for
forming an SAP coated cable component according to an exemplary
embodiment.
[0014] FIG. 5 is a schematic view showing a system and process for
forming an SAP coated cable component according to another
exemplary embodiment.
[0015] FIG. 6 is a perspective view of an optical fiber cable
according to another exemplary embodiment.
DETAILED DESCRIPTION
[0016] Referring generally to the figures, various embodiments of a
cable (e.g., a fiber optic cable, an optical fiber cable, a
communication cable, an electrical conductor cable, etc.) are
shown. In general, in the various cable embodiments disclosed
herein, one or more cable component is coated or surrounded by a
crosslinked super absorbent polymer (SAP) material. In various
embodiments, the super absorbent polymer material forms a
contiguous, continuous and relatively thin layer or film of super
absorbent polymer material that surrounds one or more component of
the cable. In various embodiments, the SAP coated cable components
may be elongate cable components such as optical fibers, optical
fiber buffer tubes, optical fiber ribbons, and/or electrical
conductor wires.
[0017] In general, the systems, processes and related cable
components relate to cable components that include the water
blocking/absorbing functionality of the SAP material. However, in
contrast to cable arrangements that utilize SAP powders or
particles, the SAP coated components discussed herein may provide
for even distribution of SAP along the length of the cable
component, and this even distribution may result in a reduction or
elimination of particle-based bend attenuation that may be
experienced by optical fibers within a cable utilizing SAP
particles for water blocking. In addition, because the SAP coating
layer discussed herein surrounds the cable components, the SAP
material of the presented disclosure tends to remain substantially
fixed relative to the coated cable component even as the cable is
wound, unwound and deployed in the installation environment.
[0018] In addition, in various embodiments, the SAP coating layer
provides a relatively thin but consistent thickness of SAP material
distributed along the length of the coated cable component. It is
believed that the thin, evenly distributed SAP coating disclosed
herein allows the cable component to hold enough SAP material to
provide satisfactory water blocking capabilities while at the same
time allowing for a the cable component to have a smaller overall
cross-sectional area as compared to cables that use a particulate
SAP water blocking material.
[0019] The present disclosure also relates to a system and method
for forming an SAP coated cable component. In various embodiments,
a cable component is provided, and an application device applies a
liquid material including an uncrosslinked SAP pre-polymer material
on the outer surface of the cable component. Following application,
the SAP pre-polymer material is crosslinked or cured while on the
outer surface of the cable component forming a relatively thin and
continuous SAP layer or film around the cable component. In this
manner the present disclosure provides a system and process for
forming an SAP coated cable component in a continuous process
suitable for integration with cable formation systems. For example,
in various embodiments, the continuous SAP layer is formed around
one or more optical fiber, and then following SAP layer formation,
a buffer tube is extruded around the one or more SAP coated fibers.
In other embodiments, the continuous SAP layer may be formed on the
outer surface of a wide range of cable components including optical
fiber buffer tubes, optical fiber ribbons, armor layers, strength
members, electrical conductors, etc.
[0020] In various non-limiting embodiments the SAP comprises
polyacrylate and polyacrylamide polymers and copolymers;
polyacrylic acid; polyacrylic acid ammonium and/or alkali salts
where the alkali comprises salts Li, Na or K; maleic anhydride
(acid) copolymers and their ammonium and/or alkali salts where the
alkali comprises salts Li, Na or K; carboxymethylcellulose and its
ammonium and/or alkali salts where the alkali comprises salts Li,
Na or K; polyvinyl alcohol polymers and copolymers and polyethylene
oxide polymers and copolymers.
[0021] Referring to FIG. 1, a cable, shown as cable 10, is shown
according to an exemplary embodiment. Cable 10 includes a cable
body, shown as cable jacket 12, having an inner surface 14 that
defines a channel, shown as central bore 16. In various
embodiments, cable 10 may include one or more optical fiber cable
component located within bore 16. In various embodiments, the
optical fiber component may include a plurality of optical
transmission elements, shown as optical fibers 18, located within
bore 16. Optical fibers 18 can include a wide variety of optical
fibers including multi-mode fibers, single mode fibers, bend
insensitive fibers, multi-core optical fibers, etc. Generally,
cable 10 provides structure and protection to optical fibers 18
during and after installation (e.g., protection during handling,
protection from elements, protection from vermin, etc.).
[0022] In the embodiment shown in FIG. 1, cable 10 includes a
plurality of different optical fiber cable components within
central bore 16. As shown in FIG. 1, optical fiber cable elements
include buffer tubes 20 and central strength member 22. Each buffer
tube 20 surrounds and contains one or more optical fibers 18.
Buffer tubes 20 are arranged around central strength member 22 that
is formed from a material such as glass-reinforced plastic or metal
(e.g., steel). In various embodiments, optical fibers 18, buffer
tubes 20 and central strength member 22 are elongate cable
components that extend the length of cable 10 between opposing ends
of cable 10. In various embodiments, cable 10 can include a variety
of optic fiber cable components including filler rods, helically
wound binders, electrical conducting elements, etc.
[0023] In the embodiment shown, buffer tubes 20 are shown in a
helical stranding pattern, such as an SZ stranding pattern, around
central strength member 22. In some embodiments, one or more
intermediate layer, shown as layer 24, surrounds buffer tubes 20.
In some embodiments, layer 24 may be a thin-film, extruded sheath
that holds buffer tubes 20 in position around strength member 22.
In various embodiments, cable 10 may include a reinforcement sheet
or layer, such as a corrugated armor layer, between layer 24 and
jacket 12, and in such embodiments, the armor layer generally
provides an additional layer of protection to optical fibers 18
within cable 10, and may provide resistance against damage (e.g.,
damage caused by contact or compression during installation, damage
from the elements, damage from rodents, etc.). In some embodiments,
designed for indoor applications, cable 10 may include a variety of
fire resistant components, such as fire resistant materials
embedded in jacket 12 and/or fire resistant intumescent particles
located within channel 16.
[0024] Referring to FIG. 2, a buffer tube 20 and optical fibers 18
are shown according to an exemplary embodiment. Buffer tube 20
includes an outer surface 30 that defines the exterior surface of
the buffer tube and an inner surface 32 that defines a channel,
shown as central bore 34. Optical fibers 18 are located within
central bore 34. In various embodiments, optical fibers 18 may be
loosely packed within buffer tube 20 (e.g., a "loose buffer"), and
in such embodiments, cable 10 is a loose tube cable. In general,
buffer tubes 20 are formed from a polymer material, such as
polyethylene, polypropylene, etc., and as discussed in more detail
below may be extruded around optical fibers 18.
[0025] As noted above, in various embodiments, one or more cable
component may be coated or covered within a continuous crosslinked
or layer of SAP polymer material. In various embodiments, any of
the cable components of cable 10 may be coated with an SAP coating
as discussed herein. In general, the SAP materials discussed herein
are polymeric materials that swell and absorb water. In this manner
the SAP coatings discussed herein limit water propagation within
cable 10 by swelling and absorbing water. Thus, the SAP coating
layers discussed herein are different from many other polymer
layers and materials typically found in cable constructions (e.g.,
acrylate polymer layers surrounding optical fiber cores, ribbon
bodies, buffer tubes, cable jackets, etc.). As will be noticed in
FIG. 1, in various embodiments, cable 10 does not include separate
SAP yarns or SAP tapes as a result of the inclusion of the SAP
coating layers formed on other cable components. In this manner, in
various embodiments, the SAP coating layers discussed herein may
allow for the construction of more compact optical fiber cables
with smaller cross-sectional areas because of the elimination of
separate water blocking structures, such as water blocking tapes
and yarns.
[0026] Referring to FIG. 2 and FIG. 3, in one embodiment, optical
fibers 18 are coated or surrounded with a layer 40 of crosslinked
SAP material. In various embodiments, SAP layer 40 is a continuous
layer that surrounds optical fibers 18 in the circumferential
direction and also extends in a continuous, contiguous and unbroken
layer along a substantial length of optical fiber 18. In various
embodiments, SAP layer 40 extends in a contiguous layer both
circumferentially around and axially along optical fibers 18 to
form an uninterrupted cylindrical film layer that extends least 1
cm in the axial direction of fiber 18 and more specifically for at
least 10 cm in the axial direction of fiber 18. Thus, in contrast
to prior cable arrangements that utilized SAP powders, layer 40
provides SAP material distributed continuously along at least
portions of the length of fibers 18. In one embodiment, SAP layer
40 is in contact with the outermost surface of fiber 18 without
being chemically bonded or adhered via an adhesive to the outer
fiber surface. In such embodiments, SAP layer 40 is maintained
around fiber 18 primarily by friction at the interface between the
outer fiber surface and the inner surface of layer 40 and the
inherent axial and circumferential structural integrity of the
bonds between SAP molecules within layer 40. As used herein, the
area, mass and volume of SAP refer to the super absorbent polymer
itself and does not include the solvent (e.g., water).
[0027] Referring to FIG. 3, a detailed cross-sectional view of an
SAP coated optical fiber 18 is shown according to an exemplary
embodiment. In various embodiments, each optical fiber 18 has an
optical core 42 surrounded by a cladding layer 44 that may be
formed from one or more layers of cladding material. Cladding layer
44 has a different refractive index than optical core 42 and helps
guide light down optical core 42 of the optical fibers by total
internal reflection. In addition, each optical fiber 18 includes at
least one polymer fiber coating layer 46 surrounding cladding layer
44. In various embodiments, fiber coating layer 46 may be a UV
curable polymer material such as an acrylate or urethane acrylate
material. In various embodiments, each optical fiber 18 has a fiber
diameter, shown as FD. In various embodiments, FD of optical fiber
18 is between 75 micrometers and 350 micrometers, specifically
between 100 micrometers and 300 micrometers. In various
embodiments, FD is about 250 micrometers (e.g., 250 micrometers
plus or minus 10 micrometer). In other various embodiments, FD is
about 200 micrometers (e.g., 200 micrometers plus or minus 10
micrometer).
[0028] In the embodiment shown SAP layer 40 has a thickness shown
as T1. In various embodiments, T1 graphically represents a maximum
thickness of SAP layer 40 (also referred to herein as T1.sub.max),
and in some embodiments, T1 graphically represents an average
thickness of SAP layer 40 along the length of the fiber (also
referred to herein as T1.sub.ave). In various embodiments,
T1.sub.max and/or T1.sub.ave is less than the average diameter of
the typical SAP particles used in optical cables. In various
embodiments, T1.sub.max and/or T1.sub.ave is less than 200
micrometers. In various embodiments, T1.sub.max and/or T1.sub.ave
is less than 60 micrometers and more specifically is less than or
equal to 50 micrometers. In addition, because SAP layer 40 is
substantially contiguous, in some embodiments layer 40 has a
minimum thickness greater than or equal to 1 micrometer.
[0029] In some embodiments, in addition to having a relatively low
maximum thickness, SAP layer 40 also has a relatively even or
consistent thickness in the circumferential direction and/or in the
axial direction, as compared to cables that use SAP particles for
water blocking. For example, in some such embodiments, T1.sub.ave
is greater than or equal to 1 micrometer and less than or equal to
200 micrometers. In other embodiments, T1.sub.ave is greater than
or equal to 1 micrometer and less than or equal to 50 micrometers
(i.e., 1 micrometers.ltoreq.T1.sub.ave.ltoreq.50 micrometers). In
another exemplary embodiment, T1.sub.ave is greater than or equal
to 1 micrometer and less than or equal to 30 micrometers (i.e., 1
micrometers.ltoreq.T1.sub.ave.ltoreq.30 micrometers). In various
embodiments, the average thickness of layer 40 is relatively small
as compared to the size of optical fiber 18. In various
embodiments, the average thickness of SAP layer 40, T1.sub.ave, is
between 0.2% and 30% of FD, and in other embodiments, T1.sub.ave is
between 1% and 20% of FD.
[0030] Referring back to FIG. 2, in various embodiments, inner
surface 32 of buffer tube 20 defines a buffer tube inner diameter,
shown as BID. In various embodiments, because of the relatively
thin and even distribution of SAP layer 40 along fibers 18, both
BID and total outer buffer tube diameter may be less than the
corresponding dimensions of a buffer tube in which particulate SAP
material is located within buffer tube channel 34 along with
optical fibers 18. In various embodiments, BID is between 0.7
millimeters and 3 millimeters.
[0031] In various embodiments in which buffer tube 20 contains
optical fiber ribbons instead of or in addition optical fibers 18,
BID is between 1 millimeters and 7 millimeters. Each tube
surrounding the optical fibers or optical fiber ribbons the has an
inner diameter, BID, thus having an inner cross-sectional area,
BID1.sub.XC, and the total cross-sectional area of the crosslinked
super absorbent polymer inside the tube (that is all of the SAP
coated on all of the fibers or fiber components inside the tube) is
a1.sub.total. In various embodiments, the cross-sectional area
percent of the SAP inside the tube relative to the tube inner
diameter cross-sectional area is 0.01%.ltoreq.100%
(a1.sub.total/BID1.sub.XC).ltoreq.10% and, in various other
embodiments, is 0.2%.ltoreq.100%
(a1.sub.total/BID1.sub.XC).ltoreq.10%. It should be noted that
a1.sub.total is the cross-sectional area of the crosslinked super
absorbent polymer inside the buffer tube prior to the swelling that
occurs in the presence of water.
[0032] In some buffer tube designs that utilize SAP particles
within the buffer tube, optical attenuation of optical fibers can
occur because of microbending experienced by the optical fiber at
the point of contact between the optical fiber and the relatively
large and discreet SAP particles. However it is believed that, in
various embodiments discussed herein, the even distribution of SAP
provided by layer 40 decreases/eliminates the microbending common
with SAP particle water blocking arrangements, and correspondingly,
decreases or reduces the optical attenuation associated with
microbending in the presence of SAP particles. Further, in various
embodiments, the SAP layer 40 on the outer surface of fiber 18 acts
to limit sticking, friction or adhesion between the SAP coated
optical fiber and adjacent cable components. In such embodiments,
the SAP layer 40 results in the coated optical fiber having a lower
pull-out force (i.e., the force required to withdraw one of the
optical fibers out of its buffer tube) as compared to a buffer tube
filled with optical fibers without SAP layer 40.
[0033] As shown in FIG. 3, SAP layer 40 surrounds and is coupled to
the outer surface of fiber coating layer 46. In this arrangement,
an inner surface of SAP layer 40 is in contact with and adhered to
the outer surface of fiber coating layer 46 with sufficient bonding
strength that SAP layer 40 stays in place relative to fiber 18
during various processing, assembly and storage steps that fiber 18
experiences. Further, SAP layer 40 includes sufficient SAP material
to provide for satisfactory water blocking performance. In various
embodiments, SAP layer 40 comprises a mass, m1, of the crosslinked
super absorbent polymer in milligrams per meter length of the
optical fiber cable component that is 1.ltoreq.m1.ltoreq.200. In
various other embodiments, the mass, m1, of the crosslinked super
absorbent polymer in milligrams per meter length of the optical
fiber cable component is 1.ltoreq.m1.ltoreq.60. In one embodiment,
the mass, m1, of the SAP refers to the mass of SAP on each fiber
(or other optical cable component) inside the buffer tube, and, in
various embodiments, there can be more than one fiber inside the
buffer tube (e.g., 2 to 24 fibers) including a ribbon which can
have 2 to 24 fibers. It should be understood that the mass, m1, is
the mass of the crosslinked superabsorbent polymer itself and does
not include the mass of either the solvent or of absorbed water
that may be present in a particular sample.
[0034] In various embodiments, optical fiber 18 may include a
colored outer portion. For example, outer polymer layer 46 may be
formed from a colored material or may include colored indicia along
its outer surface. In such embodiments, layer 40 is formed from a
transparent or translucent SAP material such that the colored
portion of optical fiber 18 is visible through layer 40. In various
embodiments, layer 40 has a transmittance through the contiguous
layer of crosslinked super absorbent polymer at least one
wavelength between 400-700 nm that is between 0.2 and 1.
[0035] Referring back to FIG. 2, in one embodiment, buffer tube 20
is also coated or surrounded with a layer 48 of crosslinked SAP
material. While FIG. 2 shows both optical fibers 18 and buffer tube
20 including SAP layers, in some embodiments, optical fibers 18
include SAP layer 40 and buffer tube 20 does not, and in another
embodiment, buffer tube 20 includes SAP layer 48 and optical fibers
18 do not. In various embodiments, layer 48 is substantially the
same as layer 40 discussed above except that layer 48 is in contact
with and adhered to outer surface 30 of buffer tube 20. In
accordance with yet other aspects of the present disclosure, not
all fibers 18 and/or buffer tubes 20 have to be coated to provide
the water blocking properties desired. For example, in a buffer
tube 20 housing twelve optical fibers 18, water blocking may be
provided by coating as few as two or three of the fibers 18.
[0036] In FIG. 4 a system and process for preparing an SAP coated
cable component is shown according to an exemplary embodiment. In
particular, FIG. 4 shows a system 100 configured for forming an SAP
coating on one or more optical fiber (such as optical fiber 18
discussed above) and then forming a buffer tube around the coated
fiber. A cable component, shown in FIG. 4 as an optical fiber 18 is
provided into system 100 from a supply or storage area, shown as a
spool 102. Following unwinding of optical fiber 18 from spool 102,
optical fiber 18 is passed into SAP coating system 104.
[0037] In the embodiment shown, SAP coating system 104 includes
applicator 106, a heater 108 and curing station 110. In general,
applicator 106 is configured to deposit a liquid material 112 that
includes uncrosslinked SAP pre-polymer material onto the outer
surface of fiber 18 as fiber 18 moves through applicator 106. The
liquid material 112 includes a carrier material or solvent in which
the SAP pre-polymer material is suspended or dissolved. In a
specific exemplary embodiment, liquid material 112 is an aqueous
solution of SAP pre-polymer material and the carrier material is
water. In various embodiments, applicator 106 may be a variety of
application systems suitable for application of the SAP pre-polymer
liquid, including roll coaters, spray coaters, bath coaters, dip
coaters, printing systems, ink-jet printing systems, sponge
applicators, etc., such that liquid material 112 coats the entire
circumference of fiber 18. In various embodiments, applicator 106
can apply a continuous layer of liquid 112 to form a substantial
continuous SAP layer axially along fiber 18. In another embodiment,
applicator 106 can apply intermittent bands of liquid 112 to form
bands of SAP material interrupted by uncoated sections of
fiber.
[0038] In an exemplary embodiment, after liquid SAP material 112
has been applied to fiber 18, coated fiber 18 passes through heater
108. Heater 108 causes the carrier material (e.g., water) of liquid
material 112 to evaporate leaving a coating of dried SAP
pre-polymer material 114 surrounding fiber 18. Because liquid
material 112 coated the entire circumference of fiber 18, dried SAP
pre-polymer material 114 also coats and surrounds the entire outer
surface of fiber 18.
[0039] Following drying, fiber 18 coated with dried SAP pre-polymer
material 114 passes through curing station 110. In general, curing
station 110 causes the SAP pre-polymer to crosslink with each other
to form an SAP material layer, such as SAP layer 40 discussed
above, surrounding fiber 18. Curing station 110 may be any curing
system suitable for causing crosslinking of the SAP pre-polymer
material present on fiber 18. In various embodiments, curing
station 110 may generate UV radiation or heat to crosslink the SAP
pre-polymer material.
[0040] In general, following formation of the SAP layer on the
cable component, an exterior polymer layer or polymer tube is
formed around the SAP coated cable component. In the embodiment of
FIG. 4, following formation of layer 40, SAP coated fiber 18 passes
through an extrusion device, shown as buffer tube extruder 116.
Buffer tube extruder 116 extrudes a fiber optic buffer tube, such
as buffer tube 20, around optical fiber 18. Following buffer tube
extrusion, the formed buffer tube 20 surrounding one or more SAP
coated optical fibers 18 is stored in storage device, such as
take-up spool 118. It should be understood that, for clarity and
explanation, FIG. 4 shows a single optical fiber 18 coated with SAP
material and surrounded by buffer tube 20. However, in various
embodiments, system 100 may be scaled such that multiple optical
fibers (e.g., 2, 4, 6, 12, 24, etc.) are coated with SAP material
via SAP coating system 104, and that the multiple coated fibers are
passed through buffer tube extruder 116 such that multiple SAP
coated optical fibers are located within a single buffer tube
20.
[0041] Further, as shown in FIG. 4, system 100 and SAP coating
system 104 in particular provides a continuous system in which
optical fibers are coated with SAP materials in line with buffer
tube extrusion, and then the buffer tube is stored prior to cable
formation. Thus, such a system provides a flexible manufacturing
system that allows for manufacture of buffer tubes and cables not
limited by the length of SAP tapes and SAP yarns common in many
cable manufacturing systems. In addition, the in-line and
continuous process of system 100 may allow for the use of less
overall SAP material within a buffer tube or cable due to the
higher level of control provided by coating system 104 as compared
to the typical SAP yarns and tapes. In another embodiment, cable
jacket formation is performed in line with SAP layer formation and
buffer tube extrusion. In another embodiment, optical fibers may be
precoated with SAP layer 40 and stored prior to processing for
buffer tube formation.
[0042] It should be understood that while FIG. 4 describes a system
that coats optical fibers prior to and continuous with buffer tube
extrusion, SAP coating system 104 can be used to apply SAP coating
to essentially any other cable component, including optical fiber
cable components, such as buffer tubes, strength members, armor
layers, etc., as well as metal conductor wires in non-optical
cables. An embodiment of one such system is shown in FIG. 5.
[0043] Specifically, FIG. 5 is a schematic view of a process and a
system that applies an SAP layer onto a buffer tube prior to cable
jacket extrusion. As will be understood, after formation of buffer
tubes 20 around fibers 18, buffer tubes 20 may be stored on reels
120. In various embodiments, buffer tubes 20 are extruded around
fibers 18, and then are cooled prior to winding onto reels 120.
Once cooled, buffer tubes 20 are wound onto reels 120 and may be
stored prior to cable formation. In addition, one or more filler
tube or rod may be stored on a reel similar to reels 120, and a
central strength member 22 may be stored on reel 122.
[0044] To produce a cable, such as cable 10, buffer tubes 20 are
unwound from reels 120 and are advanced through SAP coating systems
104. SAP coating systems 104 form an SAP coating layer, such as
layer 48, around each buffer tube 20, in the same manner discussed
above regarding FIG. 4.
[0045] Following formation of the SAP layer, SAP coated buffer
tubes 20 move into stranding station 124. Stranding station 124
couples buffer tubes 20 together along with any filler tubes and
central strength element 22. In one embodiment, buffer tubes 20 and
any filler tubes are coupled around strength element 22 in a
pattern 126, such as a helical pattern or in a reversing helical
pattern, such as an SZ stranding pattern. Similar to the system
described in FIG. 4, after buffer tubes 20 are coated with SAP by
SAP coating systems 104, a polymer tube, e.g., a cable jacket, is
formed around the SAP coated buffer tubes. In the embodiment shown
in FIG. 5, following stranding, the components of cable 10 are
passed into one or more additional stations 128 to extrude a jacket
12 around coated buffer tubes 20 and any other interior cable
components. Following jacket extrusion, cable 10 may then be stored
on a reel 130.
[0046] Referring to FIG. 6, a cable 140 is shown according to an
exemplary embodiment. Cable 140 includes a stack 142 of a plurality
of optical fiber components, shown as fiber optic ribbons 144,
located within a buffer tube that is located within the channel of
cable body 12. As will be generally understood, optical fiber
ribbons 144 typically include a plurality of optical fibers
arranged in an array (e.g., a linear array) that is surrounded by a
polymer ribbon body. In various embodiments, each fiber optic
ribbon 144 includes an SAP coating layer, similar to layers 40 and
48 discussed above, that coats the outer surface of the polymer
body of each ribbon 144.
[0047] Various embodiments of this disclosure also relate to
methods or processes for forming SAP coated cable components as
discussed herein. In specific embodiments, the coating methods
include a method of manufacturing an optical fiber component. In
such embodiments, the method includes applying a liquid layer
including a carrier material and an uncrosslinked super absorbent
polymer pre-polymer material onto an outer surface of an optical
fiber cable component. The method includes crosslinking the super
absorbent polymer pre-polymer while on the optical fiber cable
component to form a layer of crosslinked super absorbent polymer
surrounding the optical fiber cable component, and the method
includes forming a polymer structure around the optical fiber
component following formation of the layer of crosslinked super
absorbent polymer around the optical fiber cable component. In
various embodiments, such methods form SAP coated cable components
such as optical fibers 18, buffer tubes 20, and ribbons 144 as
discussed herein. In addition, in various embodiments, such methods
may be performed utilizing SAP coating systems discussed herein,
such as coating system 104.
[0048] In various embodiments, the buffer tubes discussed herein
may be formed from a variety of extruded polymer materials
including polypropylene, polyethylene, polycarbonate material,
polybutylene terephthalate (PBT), polyamide (PA), polyoxymethylene
(POM), poly(ethene-co-tetrafluoroethene) (ETFE), or combinations of
any of the polymer materials discussed herein, etc. In various
embodiments, cable jacket 12 may be a made from a wide variety of
materials used in cable manufacturing such as medium density
polyethylene, polyvinyl chloride (PVC), polyvinylidene difluoride
(PVDF), nylon, polyester or polycarbonate and their copolymers. In
addition, the material of cable jacket 12 may include small
quantities of other materials or fillers that provide different
properties to the material of cable jacket 12. For example, the
material of cable jacket 12 may include materials that provide for
coloring, UV/light blocking (e.g., carbon black), burn resistance,
etc.
[0049] The optical fibers discussed herein may be flexible,
transparent optical fibers made of glass or plastic. The fibers may
function as a waveguide to transmit light between the two ends of
the optical fiber. Optical fibers may include a transparent core
surrounded by a transparent cladding material with a lower index of
refraction. Light may be kept in the core by total internal
reflection. Glass optical fibers may comprise silica, but some
other materials such as fluorozirconate, fluoroaluminate, and
chalcogenide glasses, as well as crystalline materials, such as
sapphire, may be used. The light may be guided down the core of the
optical fibers by an optical cladding with a lower refractive index
that traps light in the core through total internal reflection. The
cladding may be coated by a buffer and/or another coating(s) that
protects it from moisture and/or physical damage. These coatings
may be UV-cured urethane acrylate composite materials applied to
the outside of the optical fiber during the drawing process. The
coatings may protect the strands of glass fiber.
[0050] While the specific cable embodiments discussed herein and
shown in the figures relate primarily to cables and core elements
that have a substantially circular cross-sectional shape defining
substantially cylindrical internal lumens, in other embodiments,
the cables and core elements discussed herein may have any number
of cross-section shapes. For example, in various embodiments, the
cable jacket and/or buffer tubes may have a square, rectangular,
triangular or other polygonal cross-sectional shape. In such
embodiments, the passage or lumen of the cable or buffer tube may
be the same shape or different shape than the shape of the cable
jacket and/or buffer tubes. In some embodiments, the cable jacket
and/or buffer tubes may define more than one channel or passage. In
such embodiments, the multiple channels may be of the same size and
shape as each other or may each have different sizes or shapes.
[0051] In accordance with yet other embodiments of the present
disclosure, the SAP coating system and methods described herein may
be used in micromodule cables. Micromodule cables are cables
comprising one or more micromodule subunits, each micromodule
subunit comprising an extremely flexible tube surrounding one or
more optical fibers, typically twelve optical fibers. The extreme
flexibility of the tube of a micromodule subunit may derive from
using a sheath material comprising inorganic fillers such as, for
example, ethylene vinyl acetate (EVA) copolymers or linear low
density polyethylene (LLDPE). An inner diameter of the flexible
tube of the micromodule subunit may be so small that during
extrusion the fibers are partly surrounded by the sheath material.
The fibers and/or the flexible tubes of the micromodule subunits
may comprise an SAP coating in accordance with aspects of the
present disclosure, resulting in a dry, water-blocked
micromodule.
[0052] Unless otherwise expressly stated, it is in no way intended
that any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its steps
or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is in no way intended that any particular order be inferred. In
addition, as used herein the article "a" is intended to include one
or more than one component or element, and is not intended to be
construed as meaning only one.
[0053] It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the disclosed embodiments. Since modifications,
combinations, sub-combinations and variations of the disclosed
embodiments incorporating the spirit and substance of the
embodiments may occur to persons skilled in the art, the disclosed
embodiments should be construed to include everything within the
scope of the appended claims and their equivalents.
* * * * *