Water-soluble water-blocking element
The present invention provides optical-fiber communication cables with an improved water-blocking element that reduces or eliminates microbending caused by water-swellable particulate powders. In one embodiment, such water-swellable powders may be employed in conjunction with a smooth water-soluble carrier tape. In another embodiment, such water-swellable powders may embedded within a water-soluble binder. The water-blocking element is deployed within optical-fiber buffer tubes to water-block the buffer tubes and to minimize microbending that can occur when water-swellable particulate powders press against optical fibers.
1. An optical-fiber cable, comprising:
a plurality of optical fibers;
a buffer tube enclosing said plurality of optical fibers, said buffer tube possessing a filling coefficient of at least about 0.20;
a water-blocking element positioned between said plurality of optical fibers and said buffer tube, said water-blocking element comprising (i) a water-soluble, first carrier tape and (ii) water-swellable particulate powder bonded to said first carrier tape, wherein said water-blocking element at least partially surrounds said plurality of optical fibers, and wherein said first carrier tape is positioned adjacent to said plurality of optical fibers and said water-swellable powder is positioned opposite said plurality of optical fibers; and
a polymeric cable jacket surrounding said buffer tube;
wherein the optical-fiber cable complies with the GR-20-CORE temperature cycling requirement.
2. An optical-fiber cable according to claim 1 , wherein said buffer tube possesses a filling coefficient of at least about 0.50; and
the optical-fiber cable complies with the GR-20-CORE temperature cycling requirement.
3. An optical-fiber cable according to claim 1 , wherein the optical-fiber cable complies with the GR-20-CORE water-penetration requirement.
4. An optical-fiber cable according to claim 1 , comprising a second carrier tape, said water-swellable particulate powder being disposed between said first carrier tape and said second carrier tape.
5. An optical-fiber cable according to claim 4 , wherein said second carrier tape is water-soluble.
6. An optical-fiber cable according to claim 1 , wherein said first carrier tape comprises methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, latex powder, cellulose ether, and/or polyvinyl alcohol.
7. An optical-fiber cable according to claim 1 , wherein said first carrier tape comprises a strength-enhancing fibrous material.
8. An optical-fiber cable according to claim 1 , wherein said first carrier tape is substantially incompressible.
9. An optical-fiber cable according to claim 1 , wherein said first carrier tape possesses a density of at least about 0.25 g/cm 3 .
10. An optical-fiber cable according to claim 1 , wherein said first carrier tape possesses a density of at least about 0.90 g/cm 3 .
11. An optical-fiber cable according to claim 1 , wherein said first carrier tape is a non-foamed carrier tape.
12. An optical-fiber cable according to claim 1 , wherein said first carrier tape comprises a plurality of perforations.
13. An optical-fiber cable, comprising:
an optical fiber;
a buffer tube enclosing said optical fiber;
a water-blocking element positioned between said optical fiber and said buffer tube, said water-blocking element comprising (i) a water-soluble, first carrier tape possessing a density of at least about 0.25 g/cm 3 , (ii) a water-soluble, second carrier tape possessing a density of at least about 0.25 g/cm 3 , and (iii) a water-swellable particulate powder disposed between said first carrier tape and said second carrier tape and bonded to said first carrier tape and/or said second carrier tape, wherein said water-blocking element at least partially surrounds said optical fiber, and wherein said first carrier tape is positioned adjacent to said optical fiber and said water-swellable powder is positioned opposite said optical fiber; and
a polymeric cable jacket surrounding said buffer tube.
14. An optical-fiber cable according to claim 13 , wherein:
said buffer tube encloses a plurality of optical fibers, said buffer tube possessing a filling coefficient of at least about 0.20; and
the optical-fiber cable complies with the GR-20-CORE temperature cycling requirement.
15. An optical-fiber cable according to claim 13 , wherein said buffer tube possesses a filling coefficient of at least about 0.50; and
the optical-fiber cable complies with the GR-20-CORE temperature cycling requirement.
16. An optical-fiber cable according to claim 13 , wherein the optical-fiber cable complies with the GR-20-CORE water-penetration requirement.
17. An optical-fiber cable according to claim 13 , wherein said first carrier tape comprises methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, latex powder, cellulose ether, and/or polyvinyl alcohol.
18. An optical-fiber cable according to claim 13 , wherein said first carrier tape comprises a strength-enhancing fibrous material.
19. An optical-fiber cable according to claim 13 , wherein said first carrier tape is substantially incompressible.