Radiation curable compositions for coating optical fiber and the coatings produced therefrom

A radiation curable composition for coating an optical fiber comprising:

• a reactive oligomer comprising at least one polymerizable group and a backbone comprising a compound derived from a polypropylene glycol;
• a reactive diluent monomer;
• a photoinitiator;
• and
• optionally, one or more additives;
• wherein, relative to the weight of the entire composition, the reactive oligomer is present in an amount of at least 70 wt. %;
• wherein the radiation curable composition possesses a liquid glass transition temperature (Tg, rheo), a first viscosity at 25° Celsius (C) (η25), a second viscosity at 55° (η55), and a third viscosity at 85° C. (η85);
• wherein the first viscosity of the radiation curable composition is from 0.1 to 20 Pascal seconds (Pa·s) at a shear rate of 10 s−1;
• wherein
• the Tg, rheo of the radiation curable composition is from −120 to −82° C., wherein Tg, rheo is determined by fitting equation (8) to experimental viscosity versus temperature data for the radiation curable composition:
• η
• ⁡
• (
• T
• )
• /
• η
• 2
• ⁢
• 5
• =
• 1
• ⁢
• 0
• ⁢
• (
• -
• 562.5
• /
• (
• 62.5
• -
• T
• g
• ,
• rheo
• )
• *
• (
• T
• -
• 25
• )
• 37.5
• +
• T
• -
• T
• g
• ,
• rheo
• )
• ,
• (
• 8
• )
• where η(T) is the viscosity of the composition at temperature, T (in ° C.);
• and
• wherein the polypropylene glycol is present by weight, relative to the total weight of the reactive oligomer, from 80 wt. % to 96 wt. %.