Optical Fiber Single Coating Resolving Adhesion and Strength Trade-off
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Solution Overview
Problem
Existing optical fibers require multiple coating layers for protection and mechanical strength, which increases manufacturing costs and can lead to delamination in harsh conditions, while single coating solutions fail to balance adhesion, mechanical strength, and microbending resistance across a wide temperature range.
Innovation Solution
A single coating layer made from a radiation-curable urethane (meth)acrylate oligomer composition with a polyoxytetramethylene glycol backbone, monofunctional and multifunctional reactive monomers, and an adhesion promoter, providing a viscosity suitable for application and a tensile modulus that balances adhesion and mechanical strength, with a glass transition temperature not exceeding -80°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single coating layer is used instead of multiple coating layers, then manufacturing costs are reduced and productivity is increased, but the coating may delamine in harsh environmental conditions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature (Tg) of the polymeric material within -100°C to 0°C, and adjusting the tensile modulus to 1 MPa to 10 GPa. These parameter optimizations enable a single coating layer to achieve both good adhesion to the glass core and sufficient mechanical strength, preventing delamination while maintaining manufacturing efficiency
Solution Approach 2:
The patent employs composite material strategy by formulating a radiation-curable composition containing oligomers, monomers, and crosslinking agents that work synergistically. The crosslinked polymeric material resulting from this composite formulation provides enhanced adhesion and mechanical properties, allowing a single coating layer to replace multiple layers without delamination issues
2Strength
If the tensile modulus of the coating material is increased to improve mechanical strength, then mechanical strength is improved, but adhesion to the glass core deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter optimization by establishing a specific range for tensile modulus (1 MPa to 10 GPa) and glass transition temperature (-100°C to 0°C). This balanced parameter selection ensures the coating material has sufficient mechanical strength while maintaining flexibility and adhesion to the glass core, preventing both brittleness and poor bonding
3Reliability
If the glass transition temperature is lowered to improve adhesion and flexibility, then adhesion is improved, but microbending resistance deteriorates
Solution Approach 1:
The patent resolves this contradiction by optimizing the glass transition temperature within a specific range (-100°C to 0°C) rather than minimizing it. This controlled Tg range ensures the coating remains flexible and adhesive at operating temperatures while maintaining sufficient rigidity above the Tg to resist microbending, achieving a balance between adhesion and microbending 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 solution achieves improved adhesion to the glass core, reduced microbending sensitivity, and enhanced resistance to aging and environmental conditions, allowing for efficient manufacturing and reliable performance across a wide temperature range.
Implementation Method 1
The two coatings described above differ, inter alia, in the mechanical properties of the respective materials. Whereas the material which forms the primary coating is a relatively soft material, with a relatively low modulus of elasticity at room temperature, the material which forms the secondary coating is relatively harder, having higher modulus of elasticity values at room temperature.
Implementation Method 2
The primary coating system is selected to provide environmental protection to the optical waveguide and resistance, inter alia, to the well-known phenomenon of microbending, which can lead to attenuation of the signal transmission capability of the fiber
Data Source
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AI summary
The invention relates to an optical fiber comprising a glass core and a protective coating consisting of a single coating layer disposed to surround said glass core, wherein said single coating layer is formed from a cured polymeric material obtained by curing a radiation curable composition comprising (i) a radiation curable urethane (meth)acrylate oligomer, preferably comprising a backbone derived from polyoxytetramethylene glycol, (ii) at least one monofunctional reactive monomer, (iii) at least one multifunctional reactive monomer, and (iv) an adhesion promoter.