An optical fiber coating die assembly is provided. The optical fiber coating die assembly includes a housing defining a guide chamber having an inlet for receiving optical fiber and an outlet, a guide die located at the outlet of the guide chamber, and a sizing die. The optical fiber coating die assembly also includes a coating applicator disposed between the guide die and the sizing die, and a tube operatively coupled to the inlet of the guide chamber and axially aligned with the chamber to receive the optical fiber fed into the guide chamber and provide a barrier to air flow.

An optical fiber coating die assembly is provided. The optical fiber coating die assembly includes a housing defining a guide chamber having an inlet for receiving optical fiber and an outlet, a guide die located at the outlet of the guide chamber, and a sizing die. The optical fiber coating die assembly also includes a coating applicator disposed between the guide die and the sizing die, and a tube operatively coupled to the inlet of the guide chamber and axially aligned with the chamber to receive the optical fiber fed into the guide chamber and provide a barrier to air flow.

An optical fiber manufacturing method includes a first process of passing a glass fiber through a fiber path. The fiber path is formed through a cooling tube that is housed in a first casing. The method also includes a second process of leading the glass fiber into a second casing before leading into the first casing. The first process includes supplying a first dry gas, having a dew point lower than the temperature of the cooling tube, into a first dry space formed between the first casing and the cooling tube. The second process includes supplying a second dry gas into a second dry space formed inside the second casing so as to cause air pressure in the second dry space to be higher than air pressure in an external space. The dew point of the second dry gas is lower than the dew point in the external space.

The optical fiber manufacturing method includes: a drawing step of drawing a glass fiber from an optical fiber base material with a melted tip; a passing step of passing the glass fiber through a fiber passage formed in a die; and a resin coating step of forming a resin layer on the outer periphery of the glass fiber by supplying a resin to the fiber passage through a flow path communicating with the fiber passage formed in the die. In the resin coating step, a temperature of the resin is controlled so that a supply pressure of the resin to the fiber passage becomes a value in a predetermined range.

The optical fiber manufacturing method includes: a drawing step of drawing a glass fiber from an optical fiber base material with a melted tip; a passing step of passing the glass fiber through a fiber passage formed in a die; and a resin coating step of forming a resin layer on the outer periphery of the glass fiber by supplying a resin to the fiber passage through a flow path communicating with the fiber passage formed in the die. In the resin coating step, a temperature of the resin is controlled so that a supply pressure of the resin to the fiber passage becomes a value in a predetermined range.

A resin composition comprises a base resin containing a urethane (meth)acrylate oligomer, a monomer and a photopolymerization initiator, and a hydrophobized spherical inorganic oxide, wherein the inorganic oxide is dispersed in the resin composition and a content of the inorganic oxide is 1 to 60% by mass based on a total amount of the resin composition.

A resin composition comprises a base resin containing a urethane (meth)acrylate oligomer, a monomer and a photopolymerization initiator, and a hydrophobized spherical inorganic oxide, wherein the inorganic oxide is dispersed in the resin composition and a content of the inorganic oxide is 1 to 60% by mass based on a total amount of the resin composition.

A method for producing an optical fiber coated with a UV-curable resin material around a glass fiber includes: a step of applying the UV-curable resin material to the periphery of the glass fiber; a step of passing the glass fiber coated with the UV-curable resin material through an interior of a cylindrical body (illustrated with a quartz tube) capable of transmitting UV light; a step of irradiating UV light from outside the cylindrical body by using a light source (illustrated with a UV bulb) to cure the glass fiber and form a coating; and a step of controlling (illustrated with a power controller) a power input to the light source so that a cure extent of the coating is constant based on the illuminance of the UV light from the light source and the illuminance of the UV light transmitted through the cylindrical body.

A method for producing an optical fiber coated with a UV-curable resin material around a glass fiber includes: a step of applying the UV-curable resin material to the periphery of the glass fiber; a step of passing the glass fiber coated with the UV-curable resin material through an interior of a cylindrical body (illustrated with a quartz tube) capable of transmitting UV light; a step of irradiating UV light from outside the cylindrical body by using a light source (illustrated with a UV bulb) to cure the glass fiber and form a coating; and a step of controlling (illustrated with a power controller) a power input to the light source so that a cure extent of the coating is constant based on the illuminance of the UV light from the light source and the illuminance of the UV light transmitted through the cylindrical body.

An optical fiber includes a glass fiber and a coating resin layer surrounding the outer periphery of the glass fiber. The coating resin layer has a primary resin layer that surrounds the outer periphery of the glass fiber, and a secondary resin layer that surrounds the outer periphery of the primary resin layer. The primary resin layer has a thickness of 7.5 μm or more and 17.5 μm or less. The primary resin layer has a Young's modulus of 0.10 MPa or greater and 0.50 MPa or less at 23° C. The secondary resin layer has a thickness of 5.0 μm or more and 17.5 μm or less. The secondary resin layer has an outer diameter of 165 μm or more and 175 μm or less. The secondary resin layer has a Young's modulus of 1200 MPa or greater and 2800 MPa or less at 23° C.