Radiation curable resin composition

Abstract

The present invention relates to a coated optical fiber comprising a glass optical fiber with a single protective coating or a combination of an inner and an outer primary coating applied thereon and optionally with a colored coating subsequently applied thereon wherein the inner primary coating or at least a portion of the single coating is prepared from a radiation curable composition which when cured as a capillary film with a 10OW medium pressure mercury lamp has a percentage reacted acrylate unsaturation of at least about 54% after exposure to a dose of about 4.4 mJ/cm 2 or wherein the outer primary coating is prepared from a radiation curable composition which when cured as a capillary film with a 10OW medium pressure mercury lamp has a percentage reacted acrylate unsaturation of at least about 56% after exposure to a dose of about 4.4 mJ/cm 2 . The invention further relates to a radiation curable composition having a high cure speed.

1 . Coated optical fiber comprising a glass optical fiber with a single protective coating or a combination of an inner and an outer primary coating applied thereon and optionally with a colored coating subsequently applied thereon wherein the inner primary coating or at least a portion of the single coating is prepared from a radiation curable composition which when cured as a capillary film with a 100W medium pressure mercury lamp has a percentage reacted acrylate unsaturation of at least about 54% after exposure to a dose of about 4.4 mJ/cm 2  or wherein the outer primary coating is prepared from a radiation curable composition which when cured as a capillary film with a 100W medium pressure mercury lamp has a percentage reacted acrylate unsaturation of at least about 56% after exposure to a dose of about 4.4 mJ/cm 2 .  
     
     
         2 . Coated optical fiber according to  claim 1  wherein at least one of the inner primary coating or single coating is prepared from a radiation curable composition which when cured as a capillary film with a 100W medium pressure mercury lamp has a percentage reacted acrylate unsaturation of at least about 56% after exposure to a dose of about 4.4 mJ/cm 2 .  
     
     
         3 . Coated optical fiber according to any one of claims  1  or  2  wherein at least one of the coating compositions achieves a percentage reacted acrylate unsaturation of at least about 60% after exposure to a dose of about 4.4 mJ/cm 2 .  
     
     
         4 . Coated optical fiber according to  claim 3  wherein at least one of the coating compositions achieves a percentage reacted acrylate unsaturation of at least about 66% after exposure to a dose of about 4.4 mJ/cm 2 .  
     
     
         5 . Coated optical fiber according to any one of claims  1 - 4  wherein the inner primary coating composition or at least a portion of the single coating composition achieves a percentage reacted acrylate unsaturation of at least about 26% after exposure to a dose of about 2.9 MJ/cm 2  or wherein the outer primary coating composition achieves a percentage reacted acrylate unsaturation of at least about 49% after exposure to a dose of about 2.9 mJ/cm 2 .  
     
     
         6 . Coated optical fiber according to any one of  claims 1  to  5  wherein the inner primary coating composition or at least a portion of the single coating composition achieves a percentage reacted acrylate unsaturation of at least about 30% or wherein the outer primary coating composition achieves a percentage reacted acrylate unsaturation of at least about 52% after exposure to a dose of about 2.9 mJ/cm 2 .  
     
     
         7 . Coated optical fiber according to  claim 6  wherein the inner primary coating composition or at least a portion of the single coating composition achieves a percentage reacted acrylate unsaturation of at least about 40% or wherein the outer primary coating composition achieves a percentage reacted acrylate unsaturation of at least about 54% after exposure to a dose of about 2.9 MJ/cm 2 .  
     
     
         8 . Coated optical fiber according to any one of claims  1 - 7  wherein the composition comprises at least two photoinitiators.  
     
     
         9 . Coated optical fiber according to  claim 8  wherein the photoinitiators are free radical type photoinitiators.  
     
     
         10 . Coated optical fiber according to any one of claims  1 - 9  wherein the cured inner primary coating, when prepared from a composition that is applied as a 500 microns thick layer on a glass plate and cured at 1.0 J/cm 2  under 0.2 m 3 /min of N 2 and when having an outer primary coating subsequently applied and cured thereon, shows a color change ΔE of less than about 30 after aging for 8 weeks under low intensity fluorescent light.  
     
     
         11 . Coated optical fiber according to  claim 10  wherein the cured inner primary coating shows a color change ΔE of less than about 20 after aging for 8 weeks under low intensity fluorescent light.  
     
     
         12 . Coated optical fiber according to any one of claims  1 - 9  wherein the outer primary coating, when prepared from a composition that is applied as a 500 microns thick layer on a glass plate and cured at 1.0 J/cm 2  under 0.2 m 3 /min of N 2  shows a color change ΔE of less than about 20 after aging for 8 weeks under low intensity fluorescent light.  
     
     
         13 . Coated optical fiber according to  claim 12  wherein the outer primary coating shows a color change ΔE of less than about 75 after aging for 8 weeks at a temperature of about 125° C.  
     
     
         14 . Coated optical fiber according to any one of claims  1 - 4  wherein the cured outer primary coating shows a color change ΔE of less than about 10 after aging for 8 weeks under low intensity fluorescent light.  
     
     
         15 . Radiation curable composition comprising 
 (A) an oligomer,    (B) a reactive diluent, and    (C) a photoinitiator package of at least two free radical photoinitiators having an overall absorption spectrum in methanol which is the sum of the absorption spectra of each individual photoinitiator wherein said overall absorption spectrum has a minimum value of a molar extinction coefficient E in a range between 280 nm (λ 1 ) and 320 nm (λ 2 ) of at least about 525 lmol −1 cm −1  or wherein said overall absorption spectrum has an average value of ε in a range between 280 nm (Xi) and 320 nm (λ 2 ) of at least about 980 lmol −1 cm 1 .    
     
     
         16 . Radiation curable composition according to  claim 15  wherein the overall absorption spectrum in methanol of the photoinitiators (Ci) in the range between 280 nm (λ 1 ) and 320 nm (λ 2 ) has a minimum value of E of at least about 600 lmol −1 cm −1  or an average value of ε of at least about 1200 lmol −1 cm −1 .  
     
     
         17 . Radiation curable composition according to any one of claims  15 - 16  wherein the overall absorption spectrum of the photoinitiator package shows a peak or shoulder in the range between 280 and 320 nm.  
     
     
         18 . Radiation curable composition comprising 
 (A) an oligomer,    (B) a reactive diluent, and    (C) at least three free radical photoinitiators wherein 
 (i) at least one of the photoinitiators has an absorption spectrum in acetonitrile having a difference between two absorption maxima λ max(1ij) =(λ max ) 1j −(λ max ) 1i  in the range between 240 and 360 nm of at least about 15 nm, and wherein  
 (ii) considering at least two of the photoinitiators (1 and 2), the difference between the absorption maximum (λ max ) 1  of the absorption spectrum in acetonitrile of photoinitiator 1 and the absorption maximum (λ max ) 2  of the absorption spectrum in acetonitrile of photoinitiator 2 Δλ max(12) =(λ max ) 2 −(λ max ) 1  in the range between 280 and 320 nm is at least about 5 nm.  
   
     
     
         19 . Radiation curable composition according to any one of claims  15 - 18  wherein at least one of the photoinitiators contains a phosphorous, sulfur or nitrogen atom.  
     
     
         20 . Radiation curable composition according to any one of claims  15 - 19  wherein the photoinitiator package comprises at least a combination of a photoinitiator containing a phosphorous atom and a photoinitiator containing a sulfur atom.  
     
     
         21 . Radiation curable coating composition for optical glass fiber comprising (A) an oligomer, (B) a reactive diluent, and (C) at least four different photoinitiators (C1), (C2), (C3), and (C4).  
     
     
         22 . Radiation curable coating composition according to any one of claims  15 - 21  wherein the total amount of compound (C) is between about 0.10 and about 20.0 wt. % relative to the total amount of the coating composition.  
     
     
         23 . Radiation curable coating composition according to any one of claims  21 - 22  wherein the compounds (C1), (C2), (C3) and (C4) are each individually present in an amount between about 0.03 and about 10.0 wt. % relative to the total amount of the coating composition.  
     
     
         24 . Radiation curable coating composition according to  claim 23  wherein each compound (Ci) is present in an amount between about 0.05 wt. % and about 4.0 wt. %.  
     
     
         25 . Radiation curable coating composition according to any one of claims  15 - 24  wherein the compounds (Ci) are free radical photoinitiators.  
     
     
         26 . Radiation curable coating composition according to  claim 25  wherein at least two of the compounds (Ci) are homolytic free radical photoinitiators.  
     
     
         27 . Radiation curable coating composition according to  claim 25  wherein at least two of the compounds (Ci) are α-cleavage homolytic free radical photoinitiators.  
     
     
         28 . Radiation curable coating composition according to  claim 27  wherein (C) comprises at least a combination of a photoinitiator containing a phosphorous atom and a photoinitiator containing a sulfur atom.  
     
     
         29 . Radiation curable coating composition according to  claim 28  wherein at least one of the compounds (Ci) is oligomeric.  
     
     
         30 . Radiation curable coating composition according to any one of claims  15 - 29  wherein compound (C) comprises five different α-cleavage homolytic free radical photoinitiators (C1) to (C5) each individually present in an amount between 0.05 and 4.0 wt. % relative to the total amount of the coating composition.  
     
     
         31 . Radiation curable coating composition according to  claim 30  wherein each photoinitiator (Ci) is present in an amount between 0.1 and 2.5 wt. % relative to the total amount of the coating composition.  
     
     
         32 . Radiation curable coating composition according to any one of claims  15 - 31  wherein (A) is a urethane (meth)acrylate oligomer.  
     
     
         33 . Radiation-curable coating composition according to any one of claims  15 - 32  wherein the coating when cured is an inner primary coating.  
     
     
         34 . Radiation-curable coating composition according to any one of claims  15 - 32  wherein the coating when cured is an outer primary coating.  
     
     
         35 . Radiation-curable coating composition according to any one of claims  15 - 32  wherein the coating when cured is matrix or bundling material.  
     
     
         36 . Radiation-curable coating composition according to any one of claims  33 - 35  wherein the composition is colored.  
     
     
         37 . Cured coating derived from a composition according to any one of claims  15 - 36  wherein the composition is cured with a lamp having at least 6% of its emission in the range between 280 and 320 nm.  
     
     
         38 . Method of increasing the cure speed of a radiation curable composition by combining three or more free radical photoinitiators each individually present in an amount between 0.3 and 1.5 wt. % relative to the total amount of the coating composition.