A resin composition for secondary coating of an optical fiber is a resin composition comprising: a photopolymerizable compound comprising a urethane (meth)acrylate having a number average molecular weight of 10000 or more and 40000 or less; and a photopolymerization initiator, the content of the urethane (meth)acrylate is 0.05 parts by mass or more and 15 parts by mass or less based on the total amount of the resin composition of 100 parts by mass, and the urethane (meth)acrylate is a reaction product of a polyol having a number average molecular weight of 1800 or more and 4500 or less, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

A resin composition for secondary coating of an optical fiber is a resin composition comprising: a photopolymerizable compound comprising a urethane (meth)acrylate having a number average molecular weight of 10000 or more and 40000 or less; and a photopolymerization initiator, the content of the urethane (meth)acrylate is 0.05 parts by mass or more and 15 parts by mass or less based on the total amount of the resin composition of 100 parts by mass, and the urethane (meth)acrylate is a reaction product of a polyol having a number average molecular weight of 1800 or more and 4500 or less, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

This resin composition for secondary coating of an optical fiber contains: at least one type of polyoxyalkylene monoalkyl ether compound selected from the group consisting of a polyoxyalkylene monoalkyl ether having a number average molecular weight of 2500-10,000 and a derivative of said polyoxyalkylene monoalkyl ether; a photopolymerizable compound; and a photopolymerization initiator.

This resin composition for secondary coating of an optical fiber contains: at least one type of polyoxyalkylene monoalkyl ether compound selected from the group consisting of a polyoxyalkylene monoalkyl ether having a number average molecular weight of 2500-10,000 and a derivative of said polyoxyalkylene monoalkyl ether; a photopolymerizable compound; and a photopolymerization initiator.

The present invention is a method for manufacturing an optical fiber which includes a resin coating step in which a resin is supplied to a resin coating section via piping, and a glass fiber is passed through the resin coating section such that the resin is coated on the outer circumference of the glass fiber. In the resin coating step, the temperature of the resin inside the piping is measured, and a heating unit provided on the outer circumference of at least some of the piping is controlled such that the temperature of the resin inside the piping reaches a set target temperature; and a viscometer is disposed in between the resin coating section and the piping on which the heating unit is provided, and the set value of the target temperature is adjusted such that the viscosity of the resin measured by the viscometer reaches a target viscosity.

The present invention is a method for manufacturing an optical fiber which includes a resin coating step in which a resin is supplied to a resin coating section via piping, and a glass fiber is passed through the resin coating section such that the resin is coated on the outer circumference of the glass fiber. In the resin coating step, the temperature of the resin inside the piping is measured, and a heating unit provided on the outer circumference of at least some of the piping is controlled such that the temperature of the resin inside the piping reaches a set target temperature; and a viscometer is disposed in between the resin coating section and the piping on which the heating unit is provided, and the set value of the target temperature is adjusted such that the viscosity of the resin measured by the viscometer reaches a target viscosity.

An optical fiber comprises a glass fiber comprising a core and a cladding, and a coating resin layer, wherein the coating resin layer has a primary resin layer being in contact with the glass fiber and coating the glass fiber, and a secondary resin layer coating the primary resin layer, and the primary resin layer and the secondary resin layer are resin layers containing inorganic oxide particles.

An optical fiber comprises a glass fiber comprising a core and a cladding, and a coating resin layer, wherein the coating resin layer has a primary resin layer being in contact with the glass fiber and coating the glass fiber, and a secondary resin layer coating the primary resin layer, and the primary resin layer and the secondary resin layer are resin layers containing inorganic oxide particles.

The present disclosure provides coating compositions and cured products formed from the coating compositions. The cured products can be formed at high cure speeds from the coating compositions and feature low Young's modulus, high tear strength, and/or high tensile toughness. The cured products can be used as primary coatings for optical fibers. The primary coatings provide good microbending performance and are resistant to defect formation during fiber coating processing and handling operations. The coating compositions include an oligomer, an alkoxylated monofunctional acrylate monomer, and preferably, an N-vinyl amide compound.

The present disclosure provides coating compositions and cured products formed from the coating compositions. The cured products can be formed at high cure speeds from the coating compositions and feature low Young's modulus, high tear strength, and/or high tensile toughness. The cured products can be used as primary coatings for optical fibers. The primary coatings provide good microbending performance and are resistant to defect formation during fiber coating processing and handling operations. The coating compositions include an oligomer, an alkoxylated monofunctional acrylate monomer, and preferably, an N-vinyl amide compound.