Patent ID: 7067564

Claim:
A coated optical fiber comprising a glass optical fiber, a primary coating applied thereon, a secondary coating having a volumetric thermal expansion coefficient α 23 of at least about 3.15×10 −4 K −1 , and optionally an ink composition subsequently applied thereon, wherein said primary coating is obtained by curing a primary coating composition comprising: (a) 20–98% by wt, relative to the total weight of components (a) through (d), of at least one oligomer having a number average molecular weight of about 1000 or higher; (b) 0–80% by wt, relative to the total weight of components (a) through (d), of one or more reactive diluents; (c) 0.1–20% by wt, relative to the total weight of components (a) through (d), of one or more photoinitiators for initiation of a radical polymerization reaction; wherein the primary coating has a storage modulus at 23° C. (E′ 23 ), has an equilibrium modulus of 1.2 MPa or less, and a cavitation strength at which a tenth cavitation appears (σ 10 cav ) of at least about 1.0 MPa as measured at a deformation rate of 0.20% min −1 , said cavitation strength being at least about 1.4 times said storage modulus at 23° C.