To improve a waterproof characteristic by adhering water absorptive powders consisting of a water absorptive resin to the surface of a coating layer.
The optical fiber unit 15 is obtd. by laminating three coated optical fibers 3 and providing this laminate with a coating layer 14 consisting of a UV curing resin, etc. The water absorptive powders 16, 16,... are deposited on the entire surface of the optical fiber unit 15. In such a case, the powder formed by putting a water absorptive resin into a powder form, the powder formed by adding starch to the water absorptive resin and the powder formed by subjecting the surface of the water absorptive resin to a surface treatment with a polyglycidyl compd. are adequately used as the water absorptive powders 16. Such water absorptive powders 16 have water absorptivity and the water absorptive resin swells when the water is fed thereto and therefore, the gaps are eventually filled when the powders are used as an optical fiber cable. The subsequent water infiltration may thus be prevented.
ISHIDA KATSUYOSHI
OHASHI KEIJI
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