Micro-mechanical On-fiber Analysis of the Interface Between Outer Primary and UV-cured Ink

摘要

One important performance parameter for UV curable fiber optic inks is adhesion between the color-coding ink layer and underlying outer primary coating. The adhesion performance is difficult to quantify, especially on the fiber itself. Flat film sandwiches of ink and outer primary do not represent the actual geometry, dimensions, and cure conditions of the coatings on fiber. A current industry practice to quantify adhesion on fiber is to perform a solvent-rub test until ink delaminates. However, solvent and mechanical contributions cannot be separated and solvent diffusion plays a significant role in the interfacial failure during the rub test. Micro-mechanical properties of firm interfaces can be characterized with scratch instrumentation. This paper describes scratch investigations of ink and coating layers on optical fibers. The utility of micro-scratch and nano-scratch techniques, and of blade versus traditional tip shapes, for characterizing coatings on optical fiber, is explored. The nature and threshold for ink delamination are compared for inks differing in mechanical properties and rub test performance.