Coated optical fiber

Abstract

In a coated optical fiber comprising a quartz glass fiber, a primary coating, and a secondary coating, the secondary coating is formed by curing a resin composition comprising (A) 20-90 wt % of polyurethane (meth)acrylate oligomer having a Mn of up to 20,000 and (B) 80-10 wt % of a mono-ethylenically unsaturated compound containing at least one N-vinyl compound, whose homopolymer has a Tg of at least 50° C., with electron beams accelerated at a low voltage of 50-125 kV. The coated optical fiber has a minimized transmission loss.

1 . A coated optical fiber comprising a quartz glass fiber, a primary coating thereon, and a secondary coating on the primary coating, wherein 
 said secondary coating is formed by curing a resin composition comprising (A) 20 to 90% by weight of a polyurethane (meth)acrylate oligomer having a number average molecular weight of up to 20,000 and (B) 80 to 10% by weight of a mono-ethylenically unsaturated compound containing at least one N-vinyl compound, whose homopolymer has a glass transition temperature of at least 50° C., with electron beams accelerated at 50 to 125 kV.    
     
     
         2 . The coated optical fiber of  claim 1  wherein said N-vinyl compound is N-vinylpyrrolidone, N-vinylcaprolactam or N-vinylformamide.