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US-12617708-B2 - Method for manufacturing optical fiber

US12617708B2US 12617708 B2US12617708 B2US 12617708B2US-12617708-B2

Abstract

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.

Inventors

  • Yudai Watanabe
  • Kazuyuki Sohma
  • Tatsuya Konishi

Assignees

  • SUMITOMO ELECTRIC INDUSTRIES, LTD.

Dates

Publication Date
20260505
Application Date
20240220
Priority Date
20230224

Claims (10)

  1. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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.

Description

TECHNICAL FIELD The present disclosure relates to a method for manufacturing an optical fiber. This application claims priority based on Japanese Patent Application No. 2023-027508 filed on Feb. 24, 2023, the entire contents of which are incorporated herein by reference. BACKGROUND Japanese Unexamined Patent Application No. 2017-65949 discloses a method for manufacturing an optical fiber. This method for manufacturing an optical fiber includes applying an ultraviolet curable resin to an optical fiber bare wire to obtain an optical fiber, and then irradiating the optical fiber with ultraviolet light using a semiconductor luminescent element. An ultraviolet LED is used as the semiconductor luminescent element. SUMMARY A method for manufacturing an optical fiber according to an aspect of the present disclosure is 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 6.0⁢0×1⁢0-5≤N*⁢φ *⁢t≤2.8⁢8×1⁢0-1 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 [m] 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*lν*k)*exp(-N*φ*Lv*kD)+C⁢0*(1-exp(-φ*lk+LkDv))*(1-(1+N*lv*4⁢kR*C⁢0*(1-exp(-φ*lk+LkDv)))-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. It should be noted that the ratio of normalized output φ is a set value that takes a value of from 0 to 1 (0≤φ≤1). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a drawing illustrating a cross-section perpendicular to an axial direction of an optical fiber according to an embodiment. FIG. 2 is a graph illustrating the relationship between actual measurement values and predicted values of a reaction rate of a photoinitiator. DETAILED DESCRIPTION Problems to be Solved by the Present Disclosure Insufficient ultraviolet irradiation in a forming step of a primary resin layer when manufacturing an optical fiber may cause the primary resin layer to undergo post-cure by subsequent steps. This may increase the Young's modulus of the primary resin layer and increase the micro-bending loss of the optical fiber. However, excessive ultraviolet irradiation in the forming step of the primary resin layer may cause the primary resin layer to adhere to the glass fiber due to overcuring and reduce coating removability. The coating of an optical fiber may be removed for tests in construction sites, etc., so that it is necessary to ensure removability. It is an object of the present disclosure to provide a method for manufacturing an optical fiber that is capable of suppressing micro-bending loss and ensuring coating removability. Advantageous Effects of the Present Disclosure The present disclosure is capable of providing a method for manufacturing an optical fiber that is capable of suppressing micro-bending loss and ensuring coating removability. Description of Embodiments of the Present Disclosure Embodiments of the present disclosure will first be listed and described. (1) A method for manufacturing an optical fiber according to an aspect of the present disclosure is 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.×1⁢0-5≤N*⁢φ *⁢t≤2.88×1⁢0-1 wherein a concentration C [mass %] of the photoinitiator in the forming of the primary resin layer is in acc