Optical Fiber Primary Coating with Internal Urethane Linkages
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Solution Overview
Problem
Current primary coatings for optical fibers face challenges in minimizing microbending losses while maintaining mechanical integrity, as they are prone to stress-induced defects and have limited cohesive strength due to their low Young's modulus, which can lead to defects during manufacturing and handling processes.
Innovation Solution
Development of a curable coating composition incorporating oligomers with internal urethane linkages, formed by reacting a polyol with a diisocyanate compound and capping with a curable functional group, providing a primary coating with desirable mechanical properties such as low Young's modulus and high tear strength to reduce microbending losses and resist stress-induced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a primary coating with low Young's modulus is used to buffer stresses, then microbending losses are reduced, but the coating becomes prone to stress-induced defects and has limited cohesive strength
Solution Approach 1:
The patent employs composite material design by combining multiple components in the curable coating composition: oligomers with internal urethane linkages, monomers with curable functional groups, and crosslinking agents. This composite approach creates a coating with optimized mechanical properties that simultaneously provides stress buffering and defect resistance. The synergistic interaction between different material components allows the coating to achieve both low Young's modulus for microbending protection and high cohesive strength for defect prevention.
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical structure of the oligomers to include internal urethane linkages, which fundamentally alter the mechanical properties of the coating. The urethane linkage introduces specific molecular flexibility and bonding characteristics that enable the coating to maintain low Young's modulus while improving cohesive strength and stress distribution. This chemical parameter change transforms the coating's stress-response behavior to simultaneously address both microbending protection and defect resistance.
2Stress or pressure
If the primary coating is made softer to dissipate stresses, then bending stresses are attenuated, but the coating strength and mechanical integrity decrease
Solution Approach 1:
The patent applies local quality principle by creating regions of different mechanical properties within the coating structure. The oligomers with internal urethane linkages provide localized stress dissipation zones with lower modulus, while the crosslinked network structure provides localized strength zones with higher cohesive energy. This spatial differentiation of material properties allows the coating to simultaneously achieve effective stress attenuation and maintained mechanical integrity throughout its structure.
Solution Approach 2:
The patent implements beforehand cushioning by designing the coating composition to inherently contain stress-absorbing urethane linkage structures that are pre-configured to dissipate bending stresses before they can cause damage. The curable functional groups and crosslinking agents are incorporated in advance to create a resilient network that proactively buffers stresses during fiber bending, preventing stress concentration that would lead to defects while maintaining overall coating strength.
3Strength
If a curable coating composition is used to enhance mechanical properties, then tear strength and cohesive strength improve, but the complexity of the coating formulation increases
Solution Approach 1:
The patent applies universality principle by designing oligomers with internal urethane linkages that serve multiple functions simultaneously: they provide stress dissipation, contribute to cohesive strength, enable crosslinking reactions, and maintain mechanical integrity. The curable functional groups incorporated in the oligomers perform multiple roles including participation in crosslinking networks, providing tear resistance, and ensuring proper curing. This multi-functionality reduces the need for separate additives and simplifies the overall formulation complexity while achieving enhanced mechanical properties.
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 oligomer-based coating composition effectively minimizes microbending losses and enhances the mechanical integrity of optical fibers by offering a balance of low Young's modulus and high tear strength, reducing defects during manufacturing and handling, and maintaining excellent low-temperature microbending performance.
Implementation Method 1
The primary coating is a relatively soft material and is designed to buffer or dissipate stresses that result from forces applied to the outer surface of the secondary coating. Dissipation of stresses within the primary coating can attenuate the stress and minimize the stress that reaches the glass waveguide.
Implementation Method 2
An oligomer according to embodiments disclosed herein may be made by reacting a polyol with a diisocyanate compound to form a pre-oligomer compound having one or more internal urethane linkages and terminal OH groups. The terminal OH groups are then capped to create the oligomer. The oligomers may be incorporated into a curable coating composition that is cured to form a urethane-acrylate coating.
Data Source
AI summary
Curable compositions that include an oligomer with one or more internal urethane linkages and OH groups capped by an Acrylate-End-Capping (AEC) compound. The curable compositions may be made by reacting a polyol with a diisocyanate compound to form a pre-oligomer compound having one or more internal urethane linkages and terminal OH groups. The curable coating compositions may be cured to form a coating for an optical fiber, for example, a primary coating for an optical fiber.