Radiation-curable fiber optic materials having reduced moisture content

Abstract

A method of making radiation-curable, fiber optic materials having extended shelf-life and reduced water content which when suitably cured provide reliable and consistent adhesion characteristics to optical glass fibers.

What is claimed is:  
     
         1 . A radiation-curable resin coating composition having extended shelf-life and being adapted for use in forming a radiation-cured coating on an optical glass fiber for signal transmission, which when suitably cured provides reliable and consistent resistance to delamination from the optical glass fiber, said uncured coating composition comprising: 
 a radiation-curable oligomer or monomer, and    a silane coupling agent containing at least one functionally-effective group capable of bonding to said glass fiber and which is susceptible to hydrolysis under normal shelf storage conditions for said coating composition;    said coating composition having a controlled stoichiometric water content less than the stoichiometric amount of said functional groups present in said coupling agent.    
     
     
         2 . The radiation-curable resin coating composition according to  claim 1 , wherein said coupling agent contains a silane group.  
     
     
         3 . The radiation-curable resin coating composition according to  claim 1 , wherein said functional group is an alkoxy group.  
     
     
         4 . The radiation-curable resin coating composition according to  claim 2 , wherein said coupling agent is a mercapto-silane coupling agent having a functional alkoxy group.  
     
     
         5 . The radiation-curable resin coating composition according to  claim 4 , wherein the amount of water in said composition is less than about 0.08 wt. %.  
     
     
         6 . In processes for the formulation or production of radiation-curable coating composition adapted for use in forming inner primary coatings on optical glass fibers for signal transmission and including a coupling agent, 
 said coupling agent containing at least one functionally-effective group capable of bonding to said glass fiber and which is susceptible to hydrolysis under normal shelf storage conditions for said coating composition,    the improvement for providing an extended shelf-life for said coating composition, which when suitably cured provides reliable and consistent resistance to delamination from the optical glass fiber, consisting essentially of the steps of:    maintaining the total water content of the components used to formulate said coating composition such that the water content present in said coating composition is an amount less than the stoichiometric amount of water required to react via hydrolysis with the amount of said functional groups present in said coating composition.    
     
     
         7 . A process according to  claim 6 , wherein said step-of maintaining the water content further consists essentially of maintaining the water content of each of the components used to formulate said coating composition such that the water content of the coating composition is in an amount less than the stoichiometric amount of water required to react via hydrolysis with the amount of said functional groups present in said coating composition.  
     
     
         8 . A process according to  claim 6 , wherein said coupling agent is a mercapto-functional silane coupling agent having at least one functional alkoxy group and said step of maintaining the water content further consists essentially of maintaining the water content of the components used to formulate said coating composition such that the ratio of the total molar water content of said coating composition to the hydrolysis number of said coupling agent is less than one.  
     
     
         9 . A process for extending the shelf-life of radiation-curable resin coating compositions adapted for use in forming inner primary coatings on optical glass fibers for signal transmission and containing a coupling agent, which when suitably cured provides reliable and consistent resistance to delamination from the optical glass fiber, 
 said coupling agent having a functionally-effective group which bonds with said glass fiber and which is susceptible to hydrolysis under normal shelf storage conditions for said coating composition,    consisting essentially of the steps of:    establishing the water content for each component utilized for the preparation of the coating composition such that the ratio of total molar water content of the final coating composition to the total molar content of said functional groups is less than one.    
     
     
         10 . A process for extending the shelf-life of radiation-curable resin coating compositions adapted for use in forming inner primary coatings on optical glass fibers for signal transmission and containing a coupling agent, which when suitably cured provides reliable and consistent resistance to delamination from the optical glass fiber, 
 said coupling agent having a functionally-effective group which bonds with said glass fiber and which is susceptible to hydrolysis under normal shelf storage conditions for said coating composition,    consisting essentially of the steps of:    formulating the coating composition from components having sufficiently low respective water contents such that after formulation the ratio of total molar water content of the formulated coating composition to the total molar content of said functional groups is less than one.    
     
     
         11 . A radiation-curable fiber optic material composition comprising the following pre-mixture ingredients: 
 about 10 wt. % to about 90 wt. % of at least one radiation-curable oligomer comprising at least one urethane and ether repeat units;    about 10 wt. % to about 90 wt. % of at least one monomer diluent;    about 0.5 wt. % to about 10 wt. % of at least one optional photoinitiator;    about 0.3 wt. % to about 0.5 wt. % of at least one adhesion promoter;    wherein the water content of said composition is less than 0.08 wt. %.    
     
     
         12 . The radiation-curable resin composition of  claim 11 , wherein said adhesion promoter is a hydrolyzable silane compound.  
     
     
         13 . The radiation-curable resin coating composition according to  claim 11 , wherein said adhesion promoter contains a mercapto group.  
     
     
         14 . The radiation-curable resin coating composition according to  claim 11 , wherein said adhesion promoter comprises a plurality of alkoxy groups.  
     
     
         15 . A composition according to  claim 11 , wherein said moisture content is less than 0.06 wt. %.  
     
     
         16 . A composition according to  claim 11 , wherein said water content is less than 0.06 wt. %.  
     
     
         17 . A composition according to  claim 11 , wherein said adhesion promoter is gamma-mercaptopropyltrimethoxysilane, said oligomer is a urethane acrylate oligomer, and said fiber optic material is an inner primary coating.  
     
     
         18 . A coated optical fiber comprising a glass fiber, a radiation-cured inner primary coating, and a radiation-cured outer primary coating, wherein said inner and outer primary coatings, before radiation-cure, were formulated to have moisture content of less than 0.08 wt. %.  
     
     
         19 . An optical fiber cable comprising a plurality of coated fiber according to  claim 18 .  
     
     
         20 . An optical fiber cable according to  claim 19 , wherein said cable comprises a radiation-cured ribbon matrix material, wherein said matrix material, before radiation-cure, was formulated to have a moisture content of less than 0.08 wt. %.