Resin composition, optical fiber, and method for producing optical fiber
A resin composition for primary coating of an optical fiber includes a photopolymerizable compound and a photopolymerization initiator. The photopolymerizable compound includes a urethane oligomer and an N-vinyl compound represented by the formula (I) below: (where R represents an alkyl group having 1 to 5 carbon atoms).
1 . A resin composition for primary coating of an optical fiber, the resin composition comprising:
a photopolymerizable compound and a photopolymerization initiator,
wherein the photopolymerizable compound includes a urethane oligomer and an N-vinyl compound represented by the formula (I) below:
(where R represents an alkyl group having 1 to 5 carbon atoms), and
wherein the urethane oligomer contains a urethane oligomer having at least one group selected from the group consisting of a group based on monohydric alcohol and a group based on an active hydrogen-containing silane compound at at least one end of the urethane bond.
2 . The resin composition according to claim 1 , wherein the N-vinyl compound represented by the formula (I) includes an N-vinyl methyl oxazolidinone.
3 . The resin composition according to claim 1 , wherein a content of the N-vinyl compound represented by the formula (I) is 1 part by mass to 30 parts by mass based on 100 parts by mass of a total amount of the resin composition.
4 . The resin composition according to claim 1 , wherein the urethane oligomer has, at at least one end of a urethane bond, at least one photopolymerizable group selected from the group consisting of a (meth)acrylamide group and a (meth)acryloyloxy group, and
wherein the urethane oligomer having the at least one photopolymerizable group is the urethane oligomer which contains the urethane oligomer having the at least one group selected from the group consisting of the group based on monohydric alcohol and the group based on the active hydrogen-containing silane compound at the at least one end of the urethane bond.
5 . The resin composition according to claim 1 , wherein the photopolymerizable compound further includes a (meth)acrylic acid ester.
6 . The resin composition according to claim 1 , wherein the urethane oligomer has a number-average molecular weight of 5,000 to 40,000, and
wherein the urethane oligomer having the number-average molecular weight of 5,000 to 40,000 is the urethane oligomer which contains the urethane oligomer having the at least one group selected from the group consisting of the group based on monohydric alcohol and the group based on the active hydrogen-containing silane compound at the at least one end of the urethane bond.
7 . An optical fiber comprising:
a glass fiber including a core and a cladding;
a primary resin layer coating the glass fiber so as to be in contact with the glass fiber; and
a secondary resin layer coating the primary resin layer,
wherein the primary resin layer includes a cured product of the resin composition according to claim 1 .
8 . A method for producing an optical fiber, the method comprising:
applying the resin composition according to claim 1 to an outer periphery of a glass fiber including a core and a cladding; and
curing the resin composition by irradiation with ultraviolet rays after the applying.