Water-Blocking Optical Fiber Coating via Swellable Polymer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing optical fiber coatings fail to effectively prevent water penetration into fiber bundles and tubes, leading to fiber degradation and signal loss, especially under stress and extreme conditions, and current water-blocking methods like gels or powders complicate handling and processing.

Innovation Solution

A radiation-curable, water-absorbing and swellable coating composition based on polyacrylic acid, neutralized with an inorganic base, and mixed with a multifunctional monomer and photosensitive initiator, which can be applied uniformly on optical fibers to form a strong, expandable barrier against water penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional coatings (UV-cured urethane acrylate or polyimide) are applied to protect optical fibres, then mechanical protection and microbending attenuation reduction are improved, but water penetration prevention capability deteriorates

Engineering Contradiction:
Improvemechanical protectionVSAvoidwater penetration
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies a composite coating structure consisting of a conventional protective coating layer (UV-cured urethane acrylate or polyimide) combined with a water-blocking polymer layer (polyacrylic acid neutralized with inorganic base). This composite structure provides both mechanical protection from the conventional coating and water penetration prevention from the polymer layer, resolving the contradiction between mechanical strength and water resistance.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If gels or powders are used as water-blocking materials in fiber bundles, then water penetration is prevented, but handling and processing complexity increases

Engineering Contradiction:
Improvewater penetration preventionVSAvoidhandling and processing
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent merges the water-blocking function with the protective coating by applying the water-blocking polymer layer directly onto the optical fiber surface as part of the coating process. This integration eliminates the need for separate gel or powder water-blocking materials, simplifying handling and processing while maintaining effective water penetration prevention.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the water-blocking function from separate bulk materials (gels or powders) and transforms it into a thin film coating applied directly on the fiber. This extraction allows the water-blocking capability to be incorporated into the coating structure itself, eliminating the need for additional bulky water-blocking materials and simplifying cable construction.

Inventive Principle:
Principle #2Taking out (Extraction)

3Object-affected harmful factors

If bulky water-blocking materials are used in fiber bundles, then water penetration is blocked, but cable volume and weight increase

Engineering Contradiction:
Improvewater penetration blockingVSAvoidcable volume
Core Design Contradiction:
Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent uses a thin film polymer coating (polyacrylic acid layer) applied directly on the optical fiber surface to block water penetration. This thin film approach replaces bulky water-blocking materials with a conformal coating that provides effective water protection while maintaining compact cable dimensions and reducing overall cable volume.

Inventive Principle:
Principle #30Flexible shells and thin films

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 coating composition effectively blocks water penetration, even under pressure, and maintains absorption capacity over time, reducing fiber degradation and signal loss, while allowing for easy handling and efficient production without the need for bulky water-blocking materials.

Implementation Method 1

an optical fibre coating composition that provides water blockage due to its swelling behaviour

Methodology Applied
Scientific EffectSwelling:

Implementation Method 2

A radiation-curable, water-absorbing and swellable coating composition based on polyacrylic acid, neutralized with an inorganic base, and mixed with a multifunctional monomer and photosensitive initiator

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS11099320B2Method for coating an optical fibre and an optical fibre comprising the same
Publication Date: 2021.08.24 ARTOFIL COATINGS BV

AI summary

A method for applying a water-absorbing polymer coating onto an optical fibre having a core, a cladding and at least a primary coating includes coating the optical fibre with an organic solvent-free radiation curable coating composition and initiating polymerization. The polymerization may be initiated with UV light. The coated optical fibre may be combined in a tubular or flat sheath, e.g., as a multi-fibre cable or ribbon. The coated optical fibre may be a coloured coated optical fibre.