Coated optical fiber and curable compositions suitable for coating optical fiber

Abstract

The present invention provides materials suitable for use as secondary coatings of optical fibers. According to one embodiment of the invention, a curable composition includes an oligomer and at least one monomer, which when cured forms a cured polymeric material having a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 0.7 MPa·m 1/2 . According to another embodiment of the invention, a coated optical fiber includes an optical fiber; a primary coating encapsulating the optical fiber; and a secondary coating encapsulating the primary coating, the secondary coating having a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 0.7 MPa·m 1/2 .

1. A coated optical fiber comprising
 an optical fiber having a core and a cladding surrounding the core; 
 a primary coating surrounding the optical fiber; and 
 a secondary coating surrounding the primary, the secondary coating being formed from a cured polymeric material having a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 0.7 1.1 MPa·m 1/2 . 
 
     
     
       2. The coated optical fiber of  claim 1  wherein the cured polymeric material has an average tensile strength of at least about 48 MPa. 
     
     
       3. The coated optical fiber of  claim 1 , wherein the cured polymeric material has a ductility of at least about 314 μm. 
     
     
       4. The coated optical fiber of  claim 1  wherein the cured polymeric material is the cured product of a curable composition including
 an oligomer; and 
 at least one monomer. 
 
     
     
       5. The coated optical fiber of  claim 4  wherein the oligomer has the structure
   CAP-OOC—NH—R 1 —NH—COO-CAP
 
 
       where CAP is a capping moiety having a reactive terminus and R 1  is substantially free of urethane bonds. 
     
     
       6. The coated optical fiber of  claim 4  wherein the oligomer has an M n  of less than about 1600 Daltons. 
     
     
       7. The coated optical fiber of  claim 4  wherein the oligomer is a multifunctional oligomer having the average structure
   R M -[OOC—NH—R A —NH—COO-CAP] n  
 
 
       where R M  is a core moiety having an average functionality of n, where n is greater than 2.2, and CAP is a capping moiety having a reactive terminus. 
     
     
       8. The coated optical fiber of  claim 4  wherein the oligomer includes a crystallizable polyol-derived block in its structure. 
     
     
       9. The coated optical fiber of  claim 8  wherein the oligomer has the average structure
   CAP-OOC—NH—R 1 —NH—[COO—R X —OOC—NH—R 1 —NH] w —COO-CAP
 
 
       where w is greater than zero, CAP is a capping moiety having a reactive terminus, and
 R X  includes at least one crystallizable polyol-derived moiety. 
 
     
     
       10. The coated optical fiber of  claim 4  wherein the oligomer includes a rigid subunit in the polyol-derived portion of its structure. 
     
     
       11. The coated optical fiber of  claim 10  wherein the oligomer has the average structure
   CAP-COC—NH—R 1 —NH—[COO—R L —OOC—NH—R 1 —NH] w —COO-CAP
 
 
       where w is greater than zero, CAP is a capping moiety having a reactive terminus, and R L  includes at least one cyclic rigid moiety. 
     
     
       12. The coated optical fiber of  claim 4  wherein the oligomer is present in the curable composition used to form the secondary coating at a level of less than about 25%. 
     
     
       13. The coated optical fiber of  claim 1 , wherein the secondary coating has a substantially homogeneous morphology. 
     
     
       14. A curable composition comprising
 an oligomer; and 
 at least one monomer; 
 
       wherein the curable composition when cured forms a cured polymeric material having a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 0.7 1.1 MPa·m 1/2 . 
     
     
       15. The curable composition of  claim 14 , wherein the cured polymeric material has a ductility of at least about 314 μm. 
     
     
       16. The curable composition of  claim 14 , wherein the oligomer has the structure
   CAP-OOC—NH—R 1 —NH—COO-CAP
 
 
       where CAP is a capping moiety having a reactive terminus and R 1  is substantially free of urethane bonds. 
     
     
       17. The curable composition of  claim 14 , wherein the oligomer is a multifunctional oligomer having the average structure
   R M -[OOC—NH—R A —NH—COO-CAP] n  
 
 
       where R M  is a core moiety having an average functionality of n, where n is greater than 2.2, and CAP is a capping moiety having a reactive terminus. 
     
     
       18. The curable composition of  claim 14 , wherein the oligomer includes in its structure a crystallizable polyol-derived block or a rigid subunit in a polyol-derived portion. 
     
     
       19. An optical fiber ribbon comprising
 a plurality of optical fibers; and 
 a matrix material encapsulating the plurality of optical fibers, the matrix material being the cured reaction product of the curable composition of  claim 14 . 
 
     
     
       20. A coated optical fiber comprising:
 an optical fiber; 
 a coating system encapsulating the optical fiber; and 
 a marking ink deposited on the exterior of the coating system, the marking ink being the cured reaction product of the curable composition of  claim 14 . 
 
     
     
       21. A coated optical fiber comprising:
 an optical fiber; and 
 a polymeric coating encapsulating the optical fiber, the polymeric coating being formed from a cured polymeric material having a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 0.7 1.1 MPa·m 1/2 . 
 
     
     
       22. The coated optical fiber of claim 1, wherein the fracture toughness is at least about 1.3 MPa·m 1/2 . 
     
     
       23. The curable composition of claim 14, wherein the fracture toughness is at least about 1.3 MPa·m 1/2 . 
     
     
       24. The coated optical fiber of claim 21, wherein the fracture toughness is at least about 1.3 MPa·m 1/2 . 
     
     
       25. A method of making an optical fiber, said method comprising:
 providing a glass fiber having a core and a cladding surrounding the core;   applying a primary coating composition to the glass fiber;   polymerizing the primary coating composition to form a primary coating material;   applying a second coating composition to the optical fiber over the primary coating material; and   polymerizing the second coating composition to form a cured polymeric material, wherein the cured polymeric material has a Young's modulus of at least about 1200 MPa, and a fracture toughness of at least about 1.1 MPa·m 1/2 .