US 12,235,499 B2
Flame retardant fiber optic cable with halogen free sheath for blowing applications
Michael Alexander Heinz, Berlin (DE); and Ravinder Kumar Kinnera, Bogotá (CO)
Assigned to CORNING RESEARCH & DEVELOPMENT CORPORATION, Corning, NY (US)
Filed by Corning Research & Development Corporation, Corning, NY (US)
Filed on Jul. 7, 2023, as Appl. No. 18/219,327.
Application 18/219,327 is a continuation of application No. 17/591,935, filed on Feb. 3, 2022, granted, now 11,726,283.
Application 17/591,935 is a continuation of application No. 16/919,418, filed on Jul. 2, 2020, granted, now 11,256,052, issued on Feb. 22, 2022.
Claims priority of provisional application 62/871,805, filed on Jul. 9, 2019.
Prior Publication US 2023/0350146 A1, Nov. 2, 2023
Int. Cl. G02B 6/44 (2006.01)
CPC G02B 6/4436 (2013.01) [G02B 6/4432 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical fiber cable, comprising:
a subunit having a first interior surface and a first exterior surface, wherein the first interior surface defines a central bore along a longitudinal axis of the optical fiber cable,
wherein the subunit has a first thickness between the first interior surface and the first exterior surface that is from 0.05 to 0.5 mm;
a plurality of optical fibers disposed within the central bore of the subunit;
a plurality of strengthening yarns disposed around the subunit;
a cable sheath disposed around the plurality of strengthening yarns, the cable sheath having a second interior surface and a second exterior surface, wherein the second exterior surface defines an outermost surface of the optical fiber cable; and
a bedding layer disposed between the second interior surface of the cable sheath and the plurality of strengthening yarns;
wherein the cable sheath comprises a low smoke, zero halogen (LSZH) material having a storage modulus of the LSZH material in tensile mode at −40° C. that is less than 3000 MPa and at −50° C. is less than 3500 MPa,
wherein the LSZH material has a brittleness temperature below −50° C.; and
wherein the bedding layer comprises a greater amount of a flame-retardant additive than the cable sheath.