Takayori Ito, Hidefumi Miyagi, Dai Fujiwara and Yoshihisa Kano
UV-curable resins are used as the coating material for optical fibers, and their physical properties change with the degree of curing, thereby influencing the transmission characteristics of the fiber. In order to maintain stable quality of the finished product it is necessary to evaluate the degree of curing of the coating resin while it is on the fiber. The authors have measured the logarithmic damping ratio for optical fibers double-coated with UV resin using a rigid-body pendulum-type viscoelasticity testing apparatus, and, from the results, have clarified the relationship between the dose of UV irradiation and the degree of curing of the coating resin on the optical fiber.
It is also necessary, as a means of improving the efficiency of manufacturing optical fibers, to develop a rapidly curable UV coating material, but since the reaction proceeds in such a short time, it has been difficult to establish an effective method of evaluating the degree of UV curing. In this work it has been possible, using a rheometer incorporating a fast oscillation mode program, to evaluate changes over time in the modulus of elasticity of UV-curable resins under irradiation.