Optical fiber and optical fiber ribbon
An optical fiber comprises a glass fiber including a core and a cladding surrounding the core, a non-strippable resin layer that adheres to and covers a surface of the glass fiber, and a buffer layer that covers the non-strippable resin layer, when pullout force measurement in which a length of 10 mm of each of the glass fiber and the non-strippable resin layer is pulled out at a tensile speed of 5 mm/min from the buffer layer is performed, a pullout force at 23° C. is 1.0 kg or less and a pullout force at 95° C. is 0.50 kg or less.
1. An optical fiber comprising:
a glass fiber including a core and a cladding surrounding the core;
a non-strippable resin layer that adheres to and covers a surface of the glass fiber;
a buffer layer that covers the non-strippable resin layer, wherein when pullout force measurement in which a length of 10 mm of each of the glass fiber and the non-strippable resin layer is pulled out at a tensile speed of 5 mm/min from the buffer layer is performed, a pullout force at 23° C. is 1.0 kg or less and a pullout force at 95° C. is 0.50 kg or less,
wherein the buffer layer includes a primary layer and a secondary layer, and
the primary layer being comprised of a cured ultraviolet curing resin composition containing an oligomer, a monomer and a photoinitiator, and the ultraviolet curing resin composition containing 30% by mass or more of a one-end-capped oligomer, based on an amount of the entire oligomer,
the one-end-capped oligomer being a compound in which only one terminal of the oligomer is a reactive terminal one-end-capped oligomer.
2. The optical fiber according to claim 1 , wherein the pullout force at 23° C. is 0.70 kg or less and the pullout force at 95° C. is 0.30 kg or less.
3. The optical fiber according to claim 1 , wherein the ultraviolet curing resin composition contains 60% by mass or more of the one-end-capped oligomer, based on the amount of the entire oligomer.
4. The optical fiber according to claim 1 , wherein a Young's modulus of the non-strippable resin layer is 600 MPa or more at 23° C.
5. The optical fiber according to claim 1 , wherein a Young's modulus of the primary layer is 0.5 MPa or more at 23° C.
6. The optical fiber according to claim 1 , wherein a Young's modulus of the primary layer is 0.3 MPa or less at 23° C.
7. The optical fiber according to claim 1 , wherein the glass fiber is a multimode fiber having a trench portion disposed between the core and the cladding,
a diameter of the core is 40 to 60 μm, an outer diameter of the cladding is 90 to 110 μm and an outer diameter of the non-strippable resin layer is 122 to 128 μm, and
a relative refractive index difference Δcore of the core is 0.7% or more, a relative refractive index difference Δtrench of the trench is −0.2% or less and a width of the trench is 1 μm or more.
8. The optical fiber according to claim 7 , wherein the Δtrench is −0.4% or less.
9. An optical fiber ribbon in which a plurality of the optical fibers according to claim 1 are arranged laterally in a row and each of the optical fibers is covered with a ribbon material.