Filled optical fiber cables

• US 4,464,013 A
• Filed: 03/29/1982
• Issued: 08/07/1984
• Est. Priority Date: 03/29/1982
• Status: Expired due to Term

• Current Assignee: Fitel USA Corporation
• Original Assignee: AT&T, Inc.
• Inventors: Sabia, Raffaele A.
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): Wise, Robert E.
• Application Number:
  US06/362,603
• Time in Patent Office: 862 Days
• Field of Search: 350/96.23, 350/96.34, 524/474, 174/23 C, 174/25 C
• US Class Current: 385/109
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: H01B 7/285 by completely or partially filling interstices in the cable

Abstract

A filling composition comprising a styrene-rubber-styrene block copolymer and an oil is used to prevent water entry into optical fiber cable. The composition provides:

(1) suitably low viscosity to allow filling the cable at elevated temperatures;

(2) low modulus to minimize microbending loss in the optical fibers; and

(3) high slump temperature to minimize flow of the material at an elevated service temperature from the end of a filled cable.

Claims

1. A cable comprising one or more optical fibers contained within a sheath leaving voids between the fibers and the sheath, and a filling material at least partially filling the voids, characterized in that

the filling material comprises a mixture of (1) 85 to 94 weight percent ASTM Type 103, 104A, or 104B, or mixtures thereof, paraffinic or napthenic oil having a minimum specific gravity of 0.855;

a minimum SUS viscosity at 210 degrees F. of 40; and

a maximum pour point ASTMD 97 of -5 degrees F.; and

a maximum of 5 percent aromatic oils;

(2) from 6 to 15 weight percent of a styrene-ethylene-butylene-styrene block copolymer having a styrene-rubber ratio of approximately 0.2 to 0.5;

with the foregoing ingredients (1) and (2) comprising at least 99 weight percent of said filling material, and further comprising up to 1 weight percent thermal oxidative stabilizer.

2. The cable of claim 1 wherein said filling material comprises approximately 93 weight percent oil, approximately 7 percent copolymer, and approximately 0.2 percent oxidative stabilizer by weight.