Abstract: A single-core cord of reinforced optical fiber comprising an optical fiber element including an optical fiber and a primary coating formed of silicone rubber and covering the optical fiber, and a secondary coating covering the optical fiber element. The secondary coating has a three-layer structure which comprises a reinforcing inner layer formed of longitudinally arranged reinforcing fibers and cured non-styrene binder comprising an unsaturated polyester resin containing a non-styrene monomer as a cross-linking agent, a reinforcing outer layer formed of fiber-reinforced cured styrene resin and a surface layer formed of thermoplastic resin, the reinforcing outer layer and the surface layer being intimately bonded together with an anchoring effect therebetween.

Abstract: A method of continuous molding a rod-like product includes forming an uncured rod-like molding by passing reinforcing fibers impregnated with uncured thermosetting resin through a squeezing die having a predetermined shape. Molten thermoplastic fluororesin is extruded in a ring shape to enclose the rod-like molding. A sheathing layer of the thermoplastic resin is formed by causing the thermoplastic resin to come into contact with the outer periphery of the uncured rod-like molding and by cooling and solidifying the thermoplastic resin. The uncured rod-like molding and the sheathing layer are introduced into a heated tank thereby hardening the thermosetting resin. The sheathing layer is stripped from the molding to form a rod-like product having a surface of fiber reinforced thermosetting resin.

Abstract: A reinforced optical fiber includes a reinforcing inner layer interposed between a buffer layer of silicon rubber and a FRP layer made of styrene resin and fibers. The reinforcing inner layer is formed by binding filaments attached longitudinally onto the buffer layer with a non-styrene resin. The additional reinforcing inner layer improves crushing resistance and also keeps low an increase of transmission loss. The reinforcing inner layer directly covering the buffer layer is formed by the steps of longitudinally attaching dry filaments to the buffer layer and then impregnating the filaments with a curable resin.