Optical fiber cable with components having improved compatibility with waterblocking filling compositions

• US 20030049002A1
• Filed: 02/22/2002
• Published: 03/13/2003
• Est. Priority Date: 08/23/1999
• Status: Active Grant

• Current Assignee: Prysmian Cavi E Sistemi Italia Srl (Prysmian SPA)
• Original Assignee: Pirelli Cavi e Sistemi S.P.A. (Prysmian SPA)
• Inventors: Campana, Antonio, Maritano, Mauro, Zaopo, Antonio, Bosisio, Claudio
• Granted Patent: US 6,658,185 B2
• Time in Patent Office: Days
• US Class Current: 385/109
• CPC Class Codes: G02B 6/4407 with internal fluted support member G02B6/4429, G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/4409 for ribbons
• CPC Class Codes: G02B 6/443 Protective covering
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/4486 Protective covering
• CPC Class Codes: G02B 6/4489 of central supporting members of lobe structure

Abstract

An optical fiber cable having improved compatibility with a waterblocking filling composition is provided. In particular, the optical fiber cable has a cable component, wherein an optical fiber can be housed, such as a buffer tube or a slotted core, made of a polyolefinic material having high compatibility with a waterblocking filler disposed therein. The cable component is manufactured by employing a suitable polyolefinic material, polyethylene in particular, having a density in the finished component of at least 0.940 g/ml, preferably of about 0.942 g/ml or higher, up to about, e.g., 0.975. The material preferably has a melt flow index (MFI) at 190° C. and 2.16 kg lower than about 3 and a shear sensitivity of the same, a shear sensitivity higher than about 40.

Claims

1. Optical cable comprising a cable component made from a polyolefin material wherein said polyolefin material forming said component has a density of at least 0.940 g/ml or higher and a melt flow index at 190°

C. and 2.16 kg lower than about 3 g/10 min, the ratio between the melt flow index at 190°

C. and 21.6 kg and the melt flow index at 190°

C. and 2.16 kg of said polyolefin material being higher than about 40.

2. Optical fiber cable according to claim 1 wherein said melt flow index is lower than about 2 g/10 min.

3. Optical fiber cable according to claim 1 wherein said ratio is higher than about 70.

4. Optical fiber cable according to claim 1 wherein said cable component is in contact with a waterblocking filling composition.

5. Optical fiber cable according to claim 1 wherein said cable component is made from polyethylene.

6. Optical fiber cable according to claim 1 wherein said cable component is a buffer tube comprising at least one optical fiber housed therein.

7. Optical fiber cable according to claim 1 wherein said cable component is a slotted core comprising at least one groove extending longitudinally along the outer surface of said core and at least one optical fibre housed within said groove.

8. Optical cable according to claim 1 wherein said at least one fiber is immersed into a waterblocking filling composition in contact with said cable component.

9. Optical cable according to claims 8 wherein said waterblocking filling composition comprises a polyolefin base oil.

10. Optical cable according to claim 9 wherein said polyolefin base oil is an internal polyolefin.

11. Optical fiber cable according to claim 1 wherein the polyolefin material forming said cable component has a density of 0.950 g/ml or higher when subjected to a natural cooling from its molten state.

12. Optical fiber cable according to claim 11 wherein said polyolefin material shows a solubility in n-heptane at 85°

C. after 24 hours of less than about 2%.

13. Optical fiber cable according to claim 11 wherein said polyolefin material shows a weight increase of less than 10%, preferably of less than about 8% when contacted at 85°

C. with a polyolefinic oil having a kinematic viscosity of about 30 cSt at 40°

C., a viscosity index of about 128 and a weight average molecular weight in the range from approximately 400 Dalton to approximately 600 Dalton.