Water-Blocked Optical Cable and Process for the Production Thereof

• US 20080267569A1
• Filed: 11/05/2004
• Published: 10/30/2008
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Prysmian Cavi E Sistemi Italia Srl (Prysmian SPA)
• Original Assignee: Prysmian Cavi E Sistemi Italia Srl (Prysmian SPA)
• Inventors: Maritano, Mauro, Pizzorno, Massimo, Ginocchio, Alessandro, Consonni, Enrico, Presa, paolo Arturo
• Granted Patent: US 7,860,361 B2
• Time in Patent Office: Days
• US Class Current: 385/109
• CPC Class Codes: G02B 6/441 built up from sub-bundles G02B6/4429, G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence

Abstract

An optical cable for communication includes at least one retaining element blocked with respect to the water propagation as well as a process for manufacturing such an optical cable. The optical cable includes, in addition to the retaining element, at least two transmission elements housed within the retaining element and a water swellable yarn housed within the retaining element. The water swellable yarn is selected according to the following equation:

$\begin{array}{cc}\frac{V_w}{V_{\mathrm{TF}}}=\frac{k}{V_t}+R& \left(1\right)\end{array}$

• • in which V_W is the volume of the water swellable yarn after swelling upon contact with water; V_TF is the total free volume in the retaining element; k is a constant ≧180; R is a constant ≧1.4; and V_t is the free volume per each transmission element. Advantageously, the optical cable is water-blocked and the water swellable yarn does not induce microbending effects on the transmission elements.

Claims

1-20. -20. (canceled)

21. An optical cable for communication comprising:

a retaining element;

at least two transmission elements housed within said retaining element; and

a water swellable yarn housed within said retaining element, wherein the water swellable yarn is selected according to the following equation;

22. The optical cable according to claim 21, wherein the retaining element has a thickness of 0.3 to 0.8 mm.

23. The optical cable according to claim 21, wherein the retaining element has a thickness equal to or less than 0.2 mm.

24. The optical cable according to claim 23, wherein the retaining element has a clearance equal to or greater than 1%.

25. The optical cable according to claim 21, wherein the retaining element has an inner diameter of 1 mm to 1.2 mm.

26. The optical cable according to claim 21, wherein the transmission elements are optical fibers.

27. The optical cable according to claim 21, wherein there are 4-12 transmission elements.

28. The optical cable according to claim 21, wherein the transmission elements are SZ stranded.

29. The optical cable according to claim 21, wherein the water swellable yarn has a swelling time equal to or less than 2 minutes.

30. An optical cable according to claim 21, wherein the water swellable yarn is selected from polyacrylate filaments or fibers, optionally associated with polyester filaments or threads, and aromatic polyamide filaments or threads coated with a super-absorbent polymer.

39. The process according to claim 21, wherein the transmission elements are optical fibers.

31. A process for manufacturing an optical cable comprising a retaining element housing at least two transmission elements and a water swellable yarn, said process comprising the steps of:

associating the transmission elements and the water swellable yarn together to form a bundle; and

extruding the retaining element around said bundle,

wherein the step of associating the transmission elements and the water swellable yarn together comprises the step of applying a powdery anti-friction agent over the transmission elements.

32. The process according to claim 31, wherein the step of associating the transmission elements and the water swellable yarn together comprises the step of stranding the transmission elements and the water swellable yarn.

33. The process according to claim 32, wherein the stranding step is effected after the step of applying a powdery anti-friction agent.

34. The process according to claim 31, wherein the step of applying a powdery anti-friction agent comprises the step of advancing together the transmission elements through a powdery anti-friction agent applicator.

35. The process according to claim 31, wherein the step of applying a powdery anti-friction agent over the transmission elements comprises the step of shielding the water swellable yarn from powdery anti-friction agent application.

36. The process according to claim 32, wherein the stranding step is an SZ stranding step.

37. The process according to claim 31, wherein the powdery anti-friction agent is talc.

38. The process according to claim 31, wherein the powdery anti-friction agent has an average grain size diameter D₅₀δ

5 μ

m.

40. The process according to claim 31, comprising the step of eliminating a surplus of powdery anti-friction agent from the surfaces of at least one of transmission elements and water swellable yarn.