Optical Fiber Coating with Hydrophobic Silica for Void Suppression
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Solution Overview
Problem
The generation of voids in optical fibers is exacerbated by the large difference in curing shrinkage rates between the primary and secondary resin layers, leading to stress and defects, particularly at low temperatures.
Innovation Solution
Incorporating hydrophobic silicon dioxide particles in the secondary resin layer, with a specific content range and particle size, and combining it with a primary resin layer of defined Young's modulus to reduce curing shrinkage and suppress void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary resin layer is formed using conventional resin compositions, then the coating provides basic protection, but large curing shrinkage rates cause void generation and stress concentration
Solution Approach 1:
The patent changes the chemical composition parameters of the resin by incorporating silane-modified polymers with specific functional groups and controlling the ratio of polyfunctional monomers to oligomers. This parameter optimization reduces curing shrinkage from conventional high levels to 5-15%, preventing void formation while maintaining coating integrity
Solution Approach 2:
The patent creates a composite resin system combining silane-modified polymers, polyfunctional monomers, and oligomers. This composite formulation synergistically reduces curing shrinkage while providing both flexibility and strength, resolving the contradiction between protection reliability and material loss during curing
2Stability of the object's composition
If the difference in effective linear expansion coefficient between primary and secondary resin layers is reduced, then peeling is prevented, but stress management at low temperatures remains challenging
Solution Approach 1:
The patent applies different resin formulations to different layers: the primary resin layer uses one composition while the secondary resin layer uses the optimized silane-modified composition. This local differentiation allows each layer to have tailored properties that collectively manage both peeling resistance and low-temperature stress
Solution Approach 2:
By modifying the chemical composition parameters of the secondary resin layer (incorporating silane groups and controlling monomer/oligomer ratios), the patent adjusts the effective linear expansion coefficient to better match the primary layer, reducing peeling while the crosslinked structure maintains low-temperature stress resistance
3Adaptability or versatility
If the Young's modulus of the primary resin layer is controlled within 0.04-1.0 MPa, then flexibility is improved, but coating strength may be compromised
Solution Approach 1:
The patent divides the coating into two functional segments: the primary resin layer provides flexibility with low Young's modulus (0.04-1.0 MPa), while the secondary resin layer provides strength with higher modulus. This segmentation allows each layer to specialize, resolving the contradiction between flexibility and strength
Solution Approach 2:
The secondary resin layer uses a composite formulation with silane-modified polymers and polyfunctional monomers that creates a crosslinked network structure. This composite material provides the necessary strength to compensate for the flexibility-focused primary layer, maintaining overall coating integrity
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 effectively reduces curing shrinkage and suppresses void generation, enhancing the toughness and integrity of the optical fiber coating, while maintaining appropriate strength and flexibility.
Implementation Method 1
a silane crosslinked structure formed by a silane crosslinking reaction of a silane-modified polymer
Implementation Method 2
the resin composition for the secondary resin layer comprises a silane-modified polymer, a polyfunctional monomer, an oligomer, and a photopolymerization initiator
Data Source
Figure 1
AI summary
An optical fiber comprises a glass fiber comprising a core and a cladding, a primary resin layer being in contact with the glass fiber and covering the glass fiber, and a secondary resin layer covering the primary resin layer, wherein the Young's modulus of the primary resin layer is 0.04 MPa or more and 1.0 MPa or less at 23°C ± 2°C, the secondary resin layer consists of a cured product of a resin composition comprising a base resin containing a urethane (meth)acrylate oligomer, a monomer, and a photopolymerization initiator and hydrophobic inorganic oxide particles, and the content of the inorganic oxide particles is 1% by mass or more and 60% by mass or less based on the total amount of the resin composition.