Coated optical fibers

Abstract

The present invention provides a coated optical fiber having a primary coating and a secondary coating, wherein the primary coating has good attenuation loss resistance and is obtained by curing a composition having high cure speed.

What is claimed is:  
     
         1 . A coated optical fiber comprising: 
 (i) an optical fiber;    (ii) a primary coating; and    (iii) a secondary coating;    wherein 
 (a) said coated optical fiber has an attenuation increase of less than 0.650 dB/km at 1550 nm;  
 (b) said primary coating is obtained by curing a primary coating composition, said composition having a cure dose to attain 95% of the maximum attainable modulus of less than 0.65 J/cm 2 ; and  
 (c) said primary coating has a Tg of less than −35° C.  
   
     
     
         2 . The coated optical fiber of  claim 1 , wherein said primary coating has an in-situ modulus is less than 0.56 MPa.  
     
     
         3 . The coated optical fiber of  claim 1 , wherein said primary coating has an in-situ modulus is less than 0.54 MPa.  
     
     
         4 . The coated optical fiber of  claim 1 , wherein said primary coating has an in-situ modulus is less than 0.52 MPa.  
     
     
         5 . The coated optical fiber of  claim 1 , wherein said attenuation increase is less than 0.500 dB/km.  
     
     
         6 . The coated optical fiber of  claim 1 , wherein said primary coating composition comprises an ethylenically unsaturated oligomer.  
     
     
         7 . The coated optical fiber of  claim 6 , wherein said oligomer is prepared by reacting the following components: 
 (1) one or more polyisocyanates;    (2) one or more polyols; and    (3) one or more hydroxyfunctional (meth)acrylates.    
     
     
         8 . The coated optical fiber of  claim 7 , wherein said one or more polyols includes polypropylene glycol.  
     
     
         9 . The coated optical fiber of  claim 7 , wherein said one or more polyols consists essentially of polypropylene glycol.  
     
     
         10 . The coated optical fiber of  claim 7 , wherein said one or more polyols includes a polyester polyol.  
     
     
         11 . The coated optical fiber of  claim 7 , wherein said one or more polyols each have a molecular weight of at least 3,000 g/mol.  
     
     
         12 . The coated optical fiber of  claim 7 , wherein said one or more hydroxyfunctional (meth)acrylates includes hydroxyethyl acrylate.  
     
     
         13 . The coated optical fiber of  claim 1 , wherein said primary coating composition comprises one or more monomers.  
     
     
         14 . The coated optical fiber of  claim 13 , wherein said one or more monomers includes an alkoxylated acrylate monomer.  
     
     
         15 . The coated optical fiber of  claim 13 , wherein said one or more monomers includes an alkoxylated aliphatic polyacrylate monomer.  
     
     
         16 . The coated optical fiber of  claim 1 , wherein said cure dose is below 0.55 J/cm 2 .  
     
     
         17 . The coated optical fiber of  claim 1 , wherein said primary coating has a Tg below −45° C.  
     
     
         18 . The coated optical fiber of  claim 1 , wherein said an optical fiber is an optical glass fiber.