Optical fiber having plastic cladding and process for preparation thereof

Claim 2

A core-cladding optical fiber having a plastic cladding, wherein the cladding component is composed of an amorphous copolymer having a single glass transition temperature of at least 125°C but lower than 140°C, said amorphous copolymer comprising (a) units derived from a fluorodioxole represented by the following formula [I]: wherein R and R′ are independently selected from the group consisting of a fluorine atom and a trifluoromethyl group, and (b) units derived from at least one monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, Rf - CF = CF₂ (in which Rf stands for a primary fluoroalkyl group having 1 to 5 carbon atoms) and Rg - OCF = CF₂ (in which Rg stands for a primary fluoroalkyl group having 1 to 5 carbon atoms or a primary fluoroalkyl group having 4 to 12 carbon atoms as a whole and an oxygen atom of an ether bond).

Claim 3

A core-cladding optical fiber according to claim 1, wherein the relationship n₁ - n₂ ≧ 0.01 is established between the refractive index n₁ of the core component and the refractive index n₂ of the cladding component.

Claim 4

A process for the preparation of a core-­cladding optical fiber having a plastic cladding, which comprises melt-spinning a transparent plastic material as the core and an amorphous copolymer as the cladding component by a core-sheath conjugate spinning process, wherein the amorphous copolymer has a single glass transition temperature of at least 125°C but lower tan 140°C, and comprises (a) units derived from a fluorodioxole represented by the following formula [I]: wherein R and R are independnetly selected from the group consisting of a fluorine atom and a trifluoromethyl group, and (b) units derived from at least one monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, Rf - CF = CF₂ (in which Rf stands for a primary fluoroalkyl group having 1 to 5 carbon atoms) or a primary fluoroalkyl group having 4 to 12 carbon atoms as a whole and an oxygen atom of an ether bond).

Claim 5

A process for the preparation of a core-­cladding optical fiber having a plastic cladding, which comprises melt-spinning a transparent plastic material as the core and an amorphous copolymer as the cladding component by a core-sheath conjugate spinning process, wherein the amorphous copolymer has a single glass transition temperature of at least 125°C but lower tan 140°C, and comprises (a) units derived from a fluorodioxole represented by the following formula [I]: wherein R and R are independnetly selected from the group consisting of a fluorine atom and a trifluoromethyl group, and (b) units derived from at least one monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, Rf - CF = CF₂ (in which Rf stands for a primary fluoroalkyl group having 1 to 5 carbon atoms) or a primary fluoroalkyl group having 4 to 12 carbon atoms as a whole and an oxygen atom of an ether bond).

Claim 6

A process according to claim 3, wherein the core component and the cladding component have a melt viscosity lower than 20,000 poise at the melt-spinning temperature, and the relationship [MFR₁] ≦ [MFR₂] ≦ 40 g/cm² is established between the melt flow rates [MFR₁] and [MFR₂] of the core component and cladding component, respectively, as measured under a load of 5 kg.

Claim 7

A process for the preparation of a core-cladding optical fiber having a plastic cladding, which comprises the steps of preparing a transparent, fibrous light conductor, and then, coating the fibrous light conductor with a melt of an amorphous copolymer or with a solution of the amorphous copolymer in a solvent followed by removal of the solvent from the coated solution; said amorphous copolymer having a single glass transition temperature of at least 125°C but lower than 140°C and comprising (a) units derived from a fluorodioxole represented by the following formula [I]: wherein R and R′ are independnetly selected from the group consisting of a fluorine atom and a trifluoromethyl group, and (b) units derived from at least one monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, Rf - CF = CF₂ (in which Rf stands for a primary fluoroalkyl group having 1 to 5 carbon atoms) and Rg - OCF = CF₂ (in which Rg stands for a primary fluoroalkyl group having 1 to 5 carbon atoms or a primary fluoroalkyl group having 4 to 12 carbon atoms as a whole and an oxygen atom of an ether bond).

Claim 8

A process for the preparation of a core-cladding optical fiber having a plastic cladding, which comprises the steps of preparing a transparent, fibrous light conductor, and then, coating the fibrous light conductor with a melt of an amorphous copolymer or with a solution of the amorphous copolymer in a solvent followed by removal of the solvent from the coated solution; said amorphous copolymer having a single glass transition temperature of at least 125°C but lower than 140°C and comprising (a) units derived from a fluorodioxole represented by the following formula [I]: wherein R and R′ are independnetly selected from the group consisting of a fluorine atom and a trifluoromethyl group, and (b) units derived from at least one monomer selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, Rf - CF = CF₂ (in which Rf stands for a primary fluoroalkyl group having 1 to 5 carbon atoms) and Rg - OCF = CF₂ (in which Rg stands for a primary fluoroalkyl group having 1 to 5 carbon atoms or a primary fluoroalkyl group having 4 to 12 carbon atoms as a whole and an oxygen atom of an ether bond).