Optical fiber with reduced attenuation loss
View Patent ↗An optical fiber having an internal glass portion, a first coating layer surrounding the glass portion and a second coating layer surrounding the first coating layer. The first coating layer is formed from a cured polymeric material obtained by curing a radiation curable composition having a radiation curable oligomer having a backbone derived from polypropylene glycol and a dimer acid based polyester polyol. The cured polymeric material has: (a) a hardening temperature (Th) from −10° C. to about −20° C. and a modulus measured at the Th lower than 5.0 MPa; or (b) a hardening temperature (Th) from −20° C. to about −30° C. and a modulus measured at the Th lower than 20.0 MPa; or (c) a hardening temperature (Th) lower than about −30° C. and a modulus measured at the Th lower than 70.0 MPa.
1. An optical fiber comprising an internal glass portion, a first coating layer surrounding said glass portion and a second coating layer surrounding said first coating layer, wherein said first coating layer is formed from a cured polymeric material obtained by curing a radiation curable composition comprising a radiation curable oligomer comprising a backbone derived from polypropylene glycol and a dimer acid based polyester polyol, said cured polymeric material having:
a) a hardening temperature (Th) from −10° C. to about −20° C. and a modulus measured at said Th lower than 5.0 MPa; or
b) a hardening temperature (Th) from −20° C. to about −30° C. and a modulus measured at said Th lower than 20.0 MPa; or
c) a hardening temperature (Th) lower than about −30° C. and a modulus measured at said Th lower than 70.0 MPa.
2. The optical fiber according to claim 1 , wherein said material forming said coating layer has:
a) a hardening temperature (Th) from −10° C. to about −20° C. and a modulus measured at said Th lower than 4.0 MPa; or
b) a hardening temperature (Th) from −20° C. to about −30° C. and a modulus measured at said Th lower than 15.0 MPa; or
c) a hardening temperature (Th) lower than about −30° C. and a modulus measured at said Th lower than 50.0 MPa.
3. The optical fiber according to claim 1 , wherein said polymeric material has an equilibrium modulus lower than about 1.5 MPa.
4. The optical fiber according to claim 1 , where said polymeric material has an equilibrium modulus lower than about 1.4 MPa.
5. The optical fiber according to claim 1 , wherein said polymeric material has an equilibrium modulus lower than about 1.3 MPa.
6. The optical fiber according to claim 1 , wherein the polymeric material has a glass transition temperature not higher than about −30° C.
7. The optical fiber according to claim 1 , wherein the polymeric material has a glass transition temperature not higher than about −40° C.
8. The optical fiber according to claim 1 , wherein the polymeric material has a glass transition temperature not higher than about −50° C.