Method for manufacturing optical fiber
A method for manufacturing an optical fiber including a glass fiber and a primary resin layer, the method includes: applying an ultraviolet curable resin composition; and forming the primary resin layer by curing the resin composition by ultraviolet irradiation reactor(s), wherein a number N of the ultraviolet irradiation reactor(s), a ratio of normalized output φ for each of the ultraviolet irradiation reactor(s), and an irradiation time t (sec) of each of the ultraviolet irradiation reactor(s) in the forming of the primary resin layer satisfy 6.00×10 −5 ≤N*φ*t≤2.88×10 −1 , wherein a concentration C [mass %] of the photoinitiator in the forming of the primary resin layer is in accordance with formula (1): C = C 0 * exp ( - N * φ * l ν * k ) * exp ( - N * φ * L v * kD ) + C 0 * ( 1 - exp ( - φ * lk + LkD v ) ) * ( 1 - ( 1 + N * l v * 4 kR * C 0 * ( 1 - exp ( - φ * lk + LkD v ) ) ) - 1 ) ( 1 ) wherein the initiation reaction rate constant k is from 20 to 100, wherein the dark reaction rate constant kD is 0≤kD≤30, and wherein the reverse reaction rate constant kR is 0≤kR≤10.
1 . A method for manufacturing an optical fiber including a glass fiber and a primary resin layer coating an outer periphery of the glass fiber, the method comprising:
applying an ultraviolet curable resin composition to be the primary resin layer, the resin composition including a photoinitiator; and
forming the primary resin layer by curing the resin composition by ultraviolet irradiation reactor(s),
wherein a number N of the ultraviolet irradiation reactor(s), a ratio of normalized output φ for each of the ultraviolet irradiation reactor(s), and an irradiation time t (sec) of each of the ultraviolet irradiation reactor(s) in the forming of the primary resin layer satisfy
6.00×10 −5 ≤N*φ*t≤ 2.88×10 −1
wherein a concentration C [mass %] of the photoinitiator in the forming of the primary resin layer is in accordance with formula (1) represented by an initial concentration C0 [mass %] of the photoinitiator, a linear velocity v [m/s] of the glass fiber, an irradiation length l [in] for each of the ultraviolet irradiation reactor(s), a non-irradiation length L [m] between the ultraviolet irradiation reactor(s), an initiation reaction rate constant k [1/(mass %·sec)], a dark reaction rate constant kD [1/(mass %·sec)], and a reverse reaction rate constant kR [1/(mass %·sec)]:
C
=
C
0
*
exp
(
-
N
*
φ
*
l
ν
*
k
)
*
exp
(
-
N
*
φ
*
L
v
*
kD
)
+
C
0
*
(
1
-
exp
(
-
φ
*
lk
+
LkD
v
)
)
*
(
1
-
(
1
+
N
*
l
v
*
4
kR
*
C
0
*
(
1
-
exp
(
-
φ
*
lk
+
LkD
v
)
)
)
-
1
)
(
1
)
wherein the initiation reaction rate constant k is from 20 to 100,
wherein the dark reaction rate constant kD is 0≤kD≤30, and
wherein the reverse reaction rate constant kR is 0≤kR≤10.
2 . The method for manufacturing an optical fiber according to claim 1 , wherein the initiation reaction rate constant k is from 30 to 90.
3 . The method for manufacturing an optical fiber according to claim 1 , wherein the dark reaction rate constant kD is from 0 to 20.
4 . The method for manufacturing an optical fiber according to claim 1 , wherein the reverse reaction rate constant kR is from 0 to 8.
5 . The method for manufacturing an optical fiber according to claim 1 , wherein a peak wavelength of ultraviolet light emitted from the ultraviolet irradiation reactor(s) is from 350 nm to 410 nm.
6 . The method for manufacturing an optical fiber according to claim 1 , wherein the primary resin layer has a Young's modulus at 23° C. of from 0.05 MPa to 0.60 MPa.
7 . The method for manufacturing an optical fiber according to claim 1 , wherein the optical fiber is compliant with at least one of the ITU-T G.652 standard, the ITU-T G.654 standard, and the ITU-T G.657 standard.
8 . The method for manufacturing an optical fiber according to claim 1 , wherein the glass fiber has an outer diameter of 125 μm±0.5 μm.
9 . The method for manufacturing an optical fiber according to claim 1 , wherein each of the ultraviolet irradiation reactor(s) includes a plurality of ultraviolet LEDs as a light source.
10 . The method for manufacturing an optical fiber according to claim 9 , wherein the plurality of ultraviolet LEDs are disposed radially around the glass fiber.