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

• US 6,658,185 B2
• Filed: 02/22/2002
• Issued: 12/02/2003
• Est. Priority Date: 08/23/1999
• Status: Expired due to Term

• 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
• Primary Examiner(s): Nasri, Javaid H.
• Application Number:
  US10/079,602
• Publication Number:
  US 20030049002A1
• Time in Patent Office: 648 Days
• Field of Search: 385/100, 385/109, 428/383, 428/379, 428/401
• 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 fiber cable, comprising a buffer tube comprising at least one optical fiber housed therein, said buffer tube being made from a polyolefin material wherein said polyolefin material forming said buffer tube has a density of at least 0.940 g/ml or higher, measured according to ASTM standard D792, on the material which has been cooled in water at 15°

C. after being heated up to its melting temperature, and a melt flow index at 190°

C. and 2.16 kg lower than about 3 g/lomin, 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 mm.

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 buffer tube is in contact with a waterblocking filling composition.

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

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

7. Optical fiber cable according to claim 6, wherein said waterblocking filling composition comprises a polyolefin base oil.

8. Optical fiber cable according to claim 7, wherein said polyolefin base oil is an internal polyolefin.

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

10. Optical fiber cable according to claim 9 wherein said polyolefin material shows a solubility in n-heptane at 85°

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

11. Optical fiber cable according to claim 9 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.