Optical fiber coating composition and method of preparing a cured coating composition

Abstract

A curing composition comprising (1) a fluorine-containing curing monomer containing a fluorinated alkyl group having not less than 6 carbon atoms, (2) a fluorine-containing curing monomer containing a fluorinated alkyl group having not more than 5 carbon atoms, and (3) a polyfunctional curing monomer, the weight ratio of said fluorine-containing curing monomer (1) to said fluorine-containing curing monomer (2) ranging from 75/25 to 99/1. The composition is coated on an optical fiber base and cured by active energy rays to provide a core/clad optical fiber excellent in transparency, mechanical strength, environmental resistance, and optical characteristics.

1. A curable coating composition comprising:
 1) a first monomer represented by formula (A) 
   RfOCOC(R)═CH 2   (A)  
 
  wherein Rf represents a linear or branched fluorinated alkyl group having not less that  than 6 carbon atoms, a hydroxyl substituted fluorinated alkyl having not less that  than 6 carbon atoms, a fluorinated sulfonamide having not less that  than 6 carbon atoms, or a fluorinated amide having not less that  than 6 carbon atoms, and R represents H.  , F, or C 1-10  fluorinated alkyl;  
 2) a second monomer represented by formula (B) 
   Rf′OCOC(R′)═CH 2   (B) 
 
  wherein Rf′ represents a linear or branched C 1-5  fluorinated alkyl and R′ represents —H, —F, or —CH 3 ; and  
 3) at least one polyfunctional methacrylic curable monomer, wherein the weight ratio of the first monomer to the second monomer is from 75:25 to 99:1.  
 
     
     
       2. A curable coating composition as defined in  claim 1 , wherein the first monomer is a member of the group consisting of C 8 F 17 CH 2 CH 2 OCOC(R)═CH 2  and C 6 F 13 CH 2 CH 2 OCOC(R)═CH 2  and R represents H, F, or C 1-10  fluorinated alkyl. 
     
     
       3. A curable coating composition as defined in  claim 1 , wherein Rf′ is at least one of a branched C 1-5  fluorinated alkyl or a linear C 1-5  fluorinated alkyl, each having a fluorohydrocarbon end group. 
     
     
       4. A curable coating composition as defined in  claim 1 , wherein the second monomer is a member of the group consisting of H(CF 2 CF 2 ) 2 CH 2 OCOC(R′)═CH 2  and (CF 3 ) 2 CHOCOC(R′)═CH 2 . 
     
     
       5. A curable coating composition as defined in  claim 1 , wherein the polyfunctional curable monomer is present in an amount of 1 to 50% by weight compared to the total weight of the curable composition. 
     
     
       6. A curable composition as claimed in  claim 1 , wherein said polyfunctional curing monomer (3) is (CH 2 ═C(R)COOCH 2 ) 3 CC 2 H 5 , wherein R represents a hydrogen atom, a methyl group, or a fluorine atom. 
     
     
       7. A curable composition as claimed in  claim 1 , wherein said polyfunctional curing monomer (3) is trimethylolpropane triacrylate. 
     
     
       8. A curable composition as claimed in  claim 1 , wherein said composition contains a thiol-containing compound. 
     
     
       9. A curable composition as claimed in  claim 8 , wherein said thiol-containing compound is γ-mercaptopropyltrimethoxysilane. 
     
     
       10. A process for preparing a transparent cured coating on a substrate, comprising the steps of:
 (A) applying on a substrate a coating of a curable resin composition comprising: 
   1 ) a first monomer represented by formula (A) 
   RfOCOC(R)═CH 2   (A)    
  wherein Rf represents a linear or branched fluorinated alkyl group having not less than  6  carbon atoms, a hydroxyl substituted fluorinated alkyl having not less than  6  carbon atoms, a fluorinated sulfonamide having not less than  6  carbon atoms, or a fluorinated amide having not less than  6  carbon atoms, and R represents H, F, or C 1-10  fluorinated alkyl;  
   2 ) a second monomer represented by formula (B) 
   Rf′OCOC(R′)═CH 2   (B)    
  wherein Rf′ represents a linear or branched C 1-5  fluorinated alkyl and R′ represents —H, —F, or —CH 3 ; and  
   3 ) at least one polyfunctional methacrylic curable monomer, wherein the weight ratio of the first monomer to the second monomer is from  75 : 25  to  99 : 1 ; and  
   (B) curing the coating by applying active energy radiation, heat, or a combination of active energy radiation and heat.   
     
     
       11. A process as in  claim 10 , wherein the first monomer is a member selected from the group consisting of C 8 F 17 CH 2 CH 2 OCOC(R)═CH 2  and C 6F   13 CH 2 CH 2 OCOC(R)═CH 2  and R represents H, F, or C 1-10  fluorinated alkyl. 
     
     
       12. A process as in  claim 10 , wherein Rf′ is at least one member selected from the group consisting of a branched C 1-5  fluorinated alkyl and a linear C 1-5  fluorinated alkyl, each having a fluorohydrocarbon group. 
     
     
       13. A process as in  claim 10 , wherein the second monomer is one member selected from the group consisting of H(CF 2 CF 2 ) 2 CH 2 OCOC(R′)═CH 2  and (CF 3 ) 2 CHOCOC(R′)═CH 2.   
     
     
       14. A process as in  claim 10 , wherein the polyfunctional curable monomer is present in an amount of  1  to  50 % by weight compared to the total weight of the curable composition. 
     
     
       15. A process as in  claim 10 , wherein said polyfunctional curing monomer ( 3 ) is (CH 2 ═C(R)COOCH 2 ) 3  CC 2 H 5 , wherein R represents a hydrogen atom, a methyl group, or a fluorine atom. 
     
     
       16. A process as in  claim 10 , wherein said polyfunctional curing monomer ( 3 ) is trimethylolpropane triacrylate. 
     
     
       17. A process as in  claim 10 , wherein said composition contains a thiol-containing compound. 
     
     
       18. A process as in  claim 17 , wherein said thiol- containing compound is γ-mercaptopropyltrimethoxysilane.