Patent ID: 11952453
Assignee: COVESTRO (NETHERLANDS) B.V.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  G | IPC C  G

Claim 0:
1. 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. %.