Method of manufacturing an optical fiber having coatings of distinct kinds
A method of coating an optical fiber constituted by a doped silica core ( 1 ) and by silica cladding ( 2 ) consists in surrounding the doped silica core ( 1 ) and the silica cladding ( 2 ) in coating constituted by a first coating portion ( 3 ) of photocurable resin and a second coating portion ( 4 ) made by extruding a thermoplastic polymer.
1. A method of coating an optical fiber constituted by a doped silica core and silica cladding, in which said core and said cladding are surrounded by a coating constituted by a first coating portion of photocurable resin and a second coating portion made by extruding a thermoplastic polymer, said thermoplastic polymer having mixed therein an additive constituted by a thermotrophic liquid crystal polymer.
2. A method according to claim 1 , in which said thermoplastic polymer is selected from the group comprising at least polyethylene and polyamide.
3. A method according to claim 2 , in which said thermoplastic polymer is polyamide 12.
4. A method according to claim 1 , in which said thermotrophic liquid crystal polymer is selected from the group comprising at least polyesters, and in particular completely aromatic polyesters, and aromatic copolyesters.
5. A method according to claim 1 , in which said additive and said thermoplastic polymer are previously mixed hot in selected proportions in order to constitute an alloy.
6. A method according to claim 5 , in which the concentration of said additive by weight is not greater than about 10% of the weight of the alloy.
7. A method according to claim 6 , in which said concentration of additive, by weight, lies in the range about 2% to about 10% of the weight of the alloy.
8. A method according to claim 7 , in which said alloy is cooled down and then granulated.
9. A method according to claim 8 , in which said granules are dried prior to being extruded.
10. A method according to claim 1 , in which said second portion of the coating is extruded using an extruder having a tubing die.
11. A method according to claim 1 , in which said photocurable resin is acrylic based.
12. An optical fiber constituted by a doped silica core and silica cladding in which said core and said cladding are surrounded by a coating constituted by a first coating portion of photocurable resin and a second coating portion of thermoplastic polymer containing an additive constituted by a thermotropic liquid crystal polymer.