Fiber coatings with low pullout force
An optical fiber includes an outer diameter less than 220 μm, a glass fiber that includes a glass core and a glass cladding, a primary coating, and a secondary coating. The glass cladding surrounds and is in direct contact with the glass core. The primary coating surrounds and is in direct contact with the glass fiber. The primary coating can have a Young's modulus less than 0.5 MPa and a thickness less than 30.0 μm. The secondary coating surrounds and is in direct contact with the primary coating. The secondary coating can have a thickness less than 27.5 m. A pullout force of the optical fiber can be less than a predetermined threshold when in an as-drawn state. The pullout force may increase by less than a factor of 2.0 upon aging the primary and secondary coatings on the glass fiber for at least 60 days.
1. An optical fiber, comprising:
an outer diameter of less than 220 μm;
a glass core defining a centerline through a center thereof;
a glass cladding surrounding and in direct contact with the glass core, the glass core and the glass cladding defining a glass fiber, an outer circumference of the glass fiber having a radius from the centerline given by R f in centimeters;
a primary coating surrounding and in direct contact with the glass cladding, an outer circumference of the primary coating having a radius from the centerline given by R p in centimeters, the primary coating having a thickness less than 30 μm and a Young's modulus less than 0.5 MPa;
a secondary coating surrounding and in direct contact with the primary coating, an outer diameter of the secondary coating having a radius from the centerline given by R s in centimeters, the secondary coating having a thickness less than 27.5 μm; and
a pullout force that is less than a critical pullout force (P crit ) that is given by the equation:
P
crit
=
462
·
R
f
[
(
1
+
v
p
)
ln
(
R
p
/
R
f
)
E
p
(
1
E
f
R
f
2
+
1
E
s
(
R
s
2
-
R
p
2
)
]
1
/
2
,
where E f is a Young's modulus of the glass fiber in dynes/cm 2 , E p is the Young's modulus of the primary coating in dynes/cm 2 , E s is a Young's modulus of the secondary coating in dynes/cm 2 , and v p is a Poisson ratio of the primary coating.
2. The optical fiber of claim 1 , wherein the Young's modulus of the primary coating is less than 0.3 MPa.
3. The optical fiber of claim 1 , wherein the pullout force is less than 0.90 lb f /cm.
4. The optical fiber of claim 1 , wherein the pullout force increases by less than a factor of 1.6 upon aging the optical fiber for at least 60 days.
5. The optical fiber of claim 1 , wherein a tear strength of the primary coating is greater than 30 J/m 2 .
6. The optical fiber of claim 1 , wherein a tensile toughness of the primary coating is greater than 500 kJ/m 3 .
7. The optical fiber of claim 1 , wherein the outer diameter of the optical fiber is less than 200 μm.
8. The optical fiber of claim 1 , wherein the thickness of the primary coating is less than 20 μm.
9. The optical fiber of claim 1 , wherein the secondary coating has a thickness of less than 20 μm.
10. The optical fiber of claim 1 , wherein the primary coating thickness and the secondary coating thickness are each less than 20 μm.
11. The optical fiber of claim 1 , wherein a ratio of the thickness of the primary coating to the thickness of the secondary coating is between 0.7 and 1.25.
12. The optical fiber of claim 1 , wherein the pullout force is less than 0.66 lb f /cm and the outer diameter is less than 180 μm.
13. The optical fiber of claim 1 , wherein a puncture resistance of the secondary coating has a normalized puncture load greater than 4.4×10 −4 g/μm 2 .
14. An optical fiber ribbon comprising a plurality of the optical fiber of claim 1 .
15. The optical fiber of claim 1 , wherein the primary coating comprises a polyol compound, the polyol compound having an unsaturation of less than 0.1 meq/g.
16. The optical fiber of claim 1 , wherein the primary coating comprises a mercapto-functional silane compound.