LED Cured Optical Fiber Coating Composition
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Solution Overview
Problem
Current radiation curable optical fiber coating compositions are not suitable for curing with LED lamps due to slow curing rates, which makes them impractical for use at industry-standard line speeds, and there is a lack of enabling disclosure for LED curable coatings for optical fibers in existing patents.
Innovation Solution
A process for coating optical fibers using a radiation curable composition comprising urethane (meth)acrylate oligomers, reactive diluent monomers, and photoinitiators, capable of undergoing photopolymerization when irradiated with LED light, resulting in a cured coating with a Percent Reacted Acrylate Unsaturation (%RAU) of 60% or greater at the top surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional radiation curable coating compositions are used with LED lamps, then the curing process can be simplified and energy consumption reduced, but the curing rate becomes too slow for industry-standard line speeds
Solution Approach 1:
The patent modifies the chemical parameters of the coating composition by selecting photoinitiators with absorption maxima that match LED emission wavelengths (380-480nm). Specifically, it uses Type I photoinitiators like 2,4,6-trimethylbenzoyl diphenylphosphine oxide and Type II photoinitiators like 2-isopropyl thioxanthone in combination with hydrogen donors, which enables efficient curing at LED wavelengths while maintaining high curing rates suitable for production line speeds.
Solution Approach 2:
The patent employs composite photoinitiator systems combining Type I and Type II photoinitiators with hydrogen donors. This composite approach creates a synergistic effect where the photoinitiators work together to achieve complete curing at LED wavelengths, overcoming the limitation of slow curing rates while maintaining energy efficiency of LED sources.
2Productivity
If mercury lamps are used to cure radiation curable coatings, then high curing rates can be achieved, but environmental harm increases due to mercury and ozone generation
Solution Approach 1:
The patent eliminates mercury from the curing system by replacing mercury arc lamps with LED light sources. The coating composition is specifically formulated with photoinitiators that absorb LED wavelengths (380-480nm), extracting the harmful mercury element while maintaining curing effectiveness through wavelength-matched photoinitiator selection.
Solution Approach 2:
The patent substitutes the mercury lamp-based UV curing system with an LED-based optical curing system. This replacement uses solid-state LED emitters with specific wavelength outputs (380-480nm) that match the absorption characteristics of the photoinitiators in the coating, eliminating mercury vapor and ozone generation while achieving comparable or superior curing rates.
3Reliability
If mercury lamps are used for curing, then effective curing can be achieved, but heat generation negatively impacts the liquid coating by causing volatile deposition on the quartz tube surface
Solution Approach 1:
The patent replaces mercury arc lamps with LED light sources that emit in the 380-480nm wavelength range. LED curing generates minimal heat compared to mercury lamps, preventing volatile deposition on the curing surface and ensuring uniform curing of the liquid coating without thermal degradation or blocking effects.
4Use of energy by stationary object
If LED lamps are used for curing, then energy consumption is reduced and no warm-up time is required, but the curing rate is insufficient for industry-standard line speeds
Solution Approach 1:
The patent optimizes the photoinitiator selection to match LED emission parameters. By using photoinitiators with absorption maxima in the 380-480nm range (such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2-isopropyl thioxanthone), the system achieves high absorption efficiency of LED light, enabling fast curing rates that meet industry line speed requirements while maintaining LED energy efficiency advantages.
Solution Approach 2:
The patent uses composite photoinitiator systems combining Type I and Type II photoinitiators with hydrogen donors to achieve synergistic curing effects. This composite approach maximizes the utilization of LED light output in the 380-480nm range, enabling sufficiently high curing rates for production applications while preserving the low energy consumption and instant-on characteristics of LED sources.
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 process enables the production of optical fibers with a cured coating suitable for high-speed line speeds, achieving efficient curing and meeting industry standards, while also incorporating bio-based ingredients to reduce environmental impact.
Implementation Method 1
curing said uncured coating on said coated glass optical fiber by irradiating said uncured coating with a light emitting diode (LED) light, having a wavelength from 100 nm to 900 nm
Implementation Method 2
Light emitting diodes (LEDs) are semiconductor devices which use the phenomenon of electroluminescence to generate light
Data Source
AI summary
A radiation curable coating composition for an optical fiber comprising: at least one urethane (meth) acrylate oligomer, at least one reactive diluent monomer and at least one photo initiator is described and claimed. The composition is capable of undergoing photopolymerization when coated on an optical fiber and when irradiated by a light emitting diode (LED) light, having a wavelength from about 100 nm to about 900nm, to provide a cured coating on the optical fiber, with the cured coating having a top surface, and the cured coating having a Percent Reacted Acrylate UĻsaturation (%RAU) at the top surface of about 60% or greater. Also described and claimed are the process to coat an optical fiber with the LED curable coating for optical fiber and a coated optical fiber where the coating has been cured by application of LED light.