The present invention is directed to a radiation curable primary coating
composition and an optical fiber with said coating. The primary coating
preferably results in excellent mechanical and physical properties, and
when coated on optical fibers in a reduction in micro-bending transmission
losses over optical fibers with conventional coatings. In one embodiment
of this invention, it relates to a coated optical fiber comprising an
optical fiber and a radiation cured primary coating wherein the radiation
cured primary coating on the optical fiber comprises an oligomer and
wherein the oligomer is formed from a reaction comprising a polyol having
"m" hydroxyl functional groups, wherein "n" hydroxyl groups of said polyol
are terminated in forming the oligomer and "m" is greater than "n".
