Optical Fiber Primary Coatings for Low Pullout and Clean Stripping
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Solution Overview
Problem
Existing primary coatings for optical fibers face challenges in achieving low Young's modulus, low pullout force, and good cohesion, leading to difficulties in clean stripping and resistance to defect formation during fiber handling and splicing operations.
Innovation Solution
A curable coating composition forming a primary coating with low Young's modulus, low pullout force, and strong cohesion, using a combination of polyether urethane diacrylate and di-adduct compounds, which can be stripped cleanly from glass fibers while resisting defect formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the Young's modulus of the primary coating is reduced to minimize bending losses, then the coating becomes softer and more effective at dissipating stresses, but the cohesion of the primary coating deteriorates and it becomes more susceptible to damage and defect formation
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating material, specifically using oligomeric materials formed from isocyanate, hydroxy acrylate compound and polyol to achieve a Young's modulus between 0.1-10 MPa while maintaining adequate cohesion and resistance to defect formation
Solution Approach 2:
The patent employs a composite oligomeric material system combining multiple components (isocyanate, hydroxy acrylate, polyol) to achieve the desired balance between softness for stress dissipation and cohesion for defect resistance, creating a material with properties that cannot be achieved by single-component systems
2Strength
If the adhesion of the primary coating to the glass fiber is increased to prevent damage during handling, then the coating becomes more securely attached, but it becomes difficult to achieve a clean strip during splicing operations
Solution Approach 1:
The patent optimizes the pullout force parameter (adhesion strength) to a specific range that allows the coating to remain attached during handling but be removable during splicing, achieving clean stripping without excessive residue while maintaining adequate adhesion for protection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition enables stable adhesion and consistent performance over time, allowing for clean stripping with minimal residue and high resistance to defect formation, suitable for individual fibers or fiber ribbons.
Implementation Method 1
The present disclosure provides primary coatings formed as cured products of curable compositions
Data Source
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AI summary
Fiber coatings with low Young's modulus, low fiber pullout force for fibers in the as-drawn state, and small time-dependent increases in pullout force as the fiber ages. The fiber coatings are cured products of coating compositions that include an oligomer formed from an isocyanate, a hydroxy acrylate compound and a polyol. The oligomer includes a polyether urethane acrylate and a di-adduct compound. The reaction mixture used to form the oligomer includes a molar ratio of isocyanate:hydroxy acrylate:polyol of n:m:p, where when p is 2, n is in the range from 3.0 to 5.0 and m is in the range from 1.50n-3 to 2.50n-5. Control of the n:m:p ratio leads to compositions that, when cured, provide coatings and cured products having low Young's modulus, low pullout force on glass, and weak variations with time as the fiber ages.