| 摘要 |
PURPOSE:To reduce the transmission loss over a long distance and to increase the strength by using aromatic polyester having about 10<-6> deg.C<-1> coefft. of linear expansion as a secondary coating material for an optical fiber. CONSTITUTION:A thermoplastic resin coating an optical fiber strand is aromatic polyester subjected to molecular orientation at >=10<2>sec<-1> shear rate, having <=400 deg.C crystal/liq. crystal transition point, and contg. at least one kind of ring selected among 1,4-,1,2,4- and 1,2,4,5-substituted benzene rings and 2,6-substituted polynuclear aromatic rings in the principal polymer chain. The thermoplastic resin forming a secondary coating layer is not restricted to a polyethylene terephthalate-p-oxybenzoic acid copolymer. The resin is required only to have <=400 deg.C crystal/liq. crystal transition point. The upper limit temp. of a general extruder is 400 deg.C.
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