D1451 methods for formulating radiation curable supercoatings for optical fiber

Abstract

The first aspect of the instant claimed invention is a method of formulating radiation curable Supercoatings for application to an optical fiber used in a telecommunications network. A Multi-layer Film Drawdown Method useful in the Method of formulating radiation curable Supercoatings is also described and claimed. Single mode Optical fibers coated with specific radiation curable Supercoatings are also described and claimed.

1 . A method of formulating radiation curable Supercoatings for application to an optical fiber used in a telecommunications network, wherein said Supercoatings comprise at least two layers, the first layer being a primary coating that is in contact with the outer layer surface of the optical fiber and the second layer being a secondary coating in contact with the outer surface of the primary coating, wherein the cured primary coating on the optical fiber has the following properties after initial cure and after at least one month aging at 85° C. and 85% relative humidity:
 1) a % RAU of from about 84% to about 99%; 
 2) an in-situ modulus of between about 0.15 MPa and about 0.60 MPa; and 
 3) a Tube T g , of from about −25° C. to about −55° C.; 
 and wherein the cured secondary coating on the optical fiber has the following properties after initial cure and after at least one month aging at 85° C. and 85% relative humidity: 
 4) a % RAU of from about 80% to about 98%; 
 5) an in-situ modulus of between about 0.060 GPa and about 1.90 GPa; and 
 6) a Tube T g  of from about 50° C. to about 80° C.; 
 said method comprising the steps of: 
 a) determining the Maximum Acceptable Increase in Attenuation requirements for the telecommunications network where the optical fiber will be installed; 
 b) determining a Field Application Environment of the Supercoatings comprising:
 i) selecting the type of glass being used in the optical fiber; 
 ii) deciding whether the secondary coating of the Supercoatings will be applied over the primary coating of the Supercoatings wet-on-dry or wet-on-wet; 
 iii) selecting the type, number of lights and positioning of lights along a draw tower manufacturing line that are used to cure the Supercoatings on the optical fiber; and 
 iv) selecting the line speed at which the Supercoatings will be applied; 
 
 c) formulating a primary coating composition in a liquid, uncured state; 
 d) formulating a secondary coating composition in a liquid, uncured state; 
 e) using a Three-Dimensional Laced Methodology, as shown in  FIGS. 2 ,  3  and  4 , of
 i) testing the primary coating and secondary coating of the Supercoatings to determine if the Supercoatings parameters 1) through 6) are achieved; wherein
 if each and every one of the Supercoatings parameters 1) through 6) are achieved then proceed to step f); and 
 if each and every one of the Supercoatings parameters 1) through 6) have not been achieved, reformulate either or both of the primary coating or secondary coating of the Supercoatings and repeat step ii) until each and every one of the Supercoatings parameters 1) through 6) are achieved; and then 
 
 ii) verifying the integrity of the reformulation of the primary coating and the secondary coating of the Supercoatings by evaluating changes in each formulation relative to the other formulation and relative to all of the Supercoatings parameters 1) through 6); 
 
 f) using the results from step e)i) and step e)ii) to finalize the selection of Supercoatings to achieve the Maximum Acceptable Increase in Attenuation of the coated optical fiber. 
 
     
     
         2 . The Method of  claim 1 , in which the Three-Dimensional Laced Methodology includes using a Multi-Layer Film Drawdown method to evaluate composite fused Primary Coating Layer and Secondary Coating Layer of Radiation curable Supercoatings. 
     
     
         3 . A Multi-Layer Film Drawdown Method comprising the steps of:
 a) selecting a substrate for the test;   b) applying a Primary coating to the substrate using a defined thickness drawdown bar;   c) optionally curing the Primary coating;   d) applying a Secondary coating to the Primary coating using a defined thickness drawdown bar, wherein the defined thickness of the drawdown bar to apply the Secondary coating is greater than the defined thickness of the drawdown bar used to apply the primary coating;   e) applying radiation to the multi-layer film sufficient to effectuate the cure of both the Primary and Secondary into a Fused Composite film;   f) removing the film from the substrate; and   g) evaluating the functional properties of the cured film.   
     
     
         4 . A single-mode optical fiber coated with Supercoatings, wherein said Supercoatings comprise,
 Primary Coating Layer and a Secondary Coating Layer;   wherein the composition of the Primary Coating layer, prior to curing, is selected from the group consisting of the formulations of Examples 1PA2, 1PB3, 1PC1, 1PD5, 2Alpha, 2Beta   wherein the composition of the Secondary Coating layer, prior to curing, is selected from the group   consisting of the formulations of Examples 2SA4 and 2SB3 and 3SA1 and 5SA1.   
     
     
         5 . A multi-mode optical fiber coated with radiation curable coatings comprising a Primary Coating Layer and
 a Secondary Coating Layer   wherein the composition of the Primary Coating layer, prior to curing, is selected from the group   consisting of the formulation of Example 4PD5; and   wherein the composition of the Secondary Coating layer, prior to curing, is selected from the group   consisting of the formulations of Examples 2SA4 and 2SB3 and 3SA1 and 5SA1.