Silane-Functional Oligomers for Controlled Optical Fiber Coating Adhesion
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Solution Overview
Problem
Existing adhesion promoters for optical fiber coatings, particularly those containing silane groups, face synthesis challenges such as fast and uncontrolled reactions with isocyanate groups, or slow reactions requiring undesirable tin catalysts, leading to regulatory and environmental issues.
Innovation Solution
Development of ethylenically unsaturated oligomers with specific structural moieties that allow for efficient synthesis and improved adhesion performance, using moieties like —Y—Si(X)3, —O—Si(X)3, and —S—Si(X)3, which are inert to isocyanate groups at low temperatures, and can be synthesized using environmentally friendly catalysts like bismuth neodecanoate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amino-functional silane is used as adhesion promoter, then adhesion performance is improved, but reaction with isocyanate is extremely fast and difficult to control
Solution Approach 1:
The patent introduces an intermediary compound (isocyanate-functional silane) that mediates between the amino-functional silane and the polyisocyanate. The isocyanate-functional silane first reacts with polyisocyanate to form a controlled intermediate structure, which then reacts with amino-functional silane to provide adhesion. This two-step intermediary approach controls the reaction rate and prevents the extremely fast uncontrolled reaction that would occur between amino-functional silane and polyisocyanate directly.
2Reliability
If thiol-functional silane is used as adhesion promoter, then adhesion performance is improved, but reaction with isocyanate is sluggish and requires tin catalysts
Solution Approach 1:
The patent uses isocyanate-functional silane as an intermediary that reacts with polyisocyanate first, creating an activated intermediate that then reacts with thiol-functional silane. This intermediary mechanism activates the otherwise sluggish thiol-isocyanate reaction, eliminating the need for tin catalysts while maintaining acceptable reaction rates and productivity.
Solution Approach 2:
The patent changes the reaction parameters by introducing the isocyanate-functional silane intermediary, which alters the reaction pathway and kinetics. This parameter change enables the thiol-functional silane to react effectively with the coating system without requiring tin catalysts, thus improving environmental compatibility while maintaining productivity.
3Productivity
If tin catalysts are used to accelerate thiol-functional silane reaction, then reaction rate is improved, but regulatory and environmental issues arise
Solution Approach 1:
The isocyanate-functional silane acts as an environmentally friendly intermediary that eliminates the need for toxic tin catalysts. By mediating the reaction between thiol-functional silane and polyisocyanate, it achieves acceptable reaction rates without introducing harmful substances, thus resolving the environmental conflict.
Solution Approach 2:
The patent converts the naturally sluggish reaction between thiol-functional silane and isocyanate (which would require harmful catalysts) into a beneficial two-step process using isocyanate-functional silane intermediary. This approach maintains sufficient reaction rate while eliminating toxic catalysts, turning a potential harm into an environmental benefit.
4Reliability
If reactive urethane oligomer with silane groups is used, then adhesion to glass fiber is improved, but synthesis becomes complex and requires multiple reactants
Solution Approach 1:
The patent merges the adhesion promoter function and the oligomer backbone into a single integrated molecule. The reactive urethane oligomer is synthesized with silane groups directly incorporated into its structure, eliminating the need for separate adhesion promoter additives and simplifying the overall formulation and synthesis process while maintaining adhesion performance.
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 new oligomers provide enhanced adhesion in optical fiber coatings, facilitating efficient synthesis and reducing environmental impact while maintaining high adhesion performance.
Implementation Method 1
radiation curable optical fiber coatings are the cured product of a composition containing a mixture of one or more components possessing one or more ethylenically unsaturated bonds which, under the influence of irradiation, undergo crosslinking by free-radical polymerization
Implementation Method 2
the reactive urethane oligomer may itself contain hydrolysable silane groups
Implementation Method 3
the adhesion promoter provides a link between the polymer primary coating and the surface of the optical glass fiber
Data Source
AI summary
Oligomers that contain an ethylenically unsaturated group, a silane group, and an aspartate group and/or hydantoin group are described. Also disclosed are methods for producing and using such compounds, such as their use in coating compositions, such as coating compositions suitable for application to optical glass fiber substrates.