Slotted Core Halogen-Free Flame Retardant Material

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Solution Overview

Problem

Existing slotted core optical cables do not have optimized fire performance, particularly in compliance with European construction product directives, and suffer from decreased mechanical strength during bending due to inadequate flame retardancy.

Innovation Solution

A slotted core made partially from a halogen-free flame retardant material with a polymeric matrix and inorganic fillers, such as metallic hydroxides and calcium carbonate, is used to delay flame propagation and maintain mechanical strength, featuring a Limiting Oxygen Index of at least 25, and a two-process extrusion design with grooves on the outer surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional polyethylene or nylon slotted core material is used, then ease of manufacture is improved, but fire performance deteriorates (does not comply with European construction product directives)

Engineering Contradiction:
Improveease of manufactureVSAvoidfire performance
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by combining a polymeric matrix (polyethylene or polypropylene) with inorganic fillers (metallic hydroxides such as aluminium hydroxide and magnesium hydroxide, and/or extenders such as calcium carbonate and talcum) to create a halogen-free flame retardant material that maintains ease of manufacture while achieving compliance with fire safety directives

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by incorporating inorganic fillers into the polymeric matrix, specifically achieving a Limiting Oxygen Index of at least 25, which transforms the material's fire resistance properties while maintaining manufacturability

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If halogen free flame retardant material with inorganic fillers is used, then fire performance is improved, but mechanical strength during bending deteriorates

Engineering Contradiction:
Improvefire performanceVSAvoidmechanical strength
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent optimizes the material composition parameters by carefully selecting the types and proportions of inorganic fillers (metallic hydroxides and extenders) within the polymeric matrix to achieve a Limiting Oxygen Index of at least 25 while maintaining adequate mechanical strength for optical fiber protection during bending

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite structure of polymeric matrix with dispersed inorganic fillers provides both fire retardancy through the hydroxide decomposition and mechanical strength through the matrix-filler interaction, resolving the contradiction between fire performance and mechanical strength

Inventive Principle:
Principle #40Composite materials

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 provides enhanced fire resistance and maintains mechanical strength during bending, ensuring compliance with European construction product directives and minimizing combustible material in the optical cable.

Implementation Method 1

said inorganic filler comprises a flame retardant filler, such as a metallic hydroxide

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

presenting a limited combustion and of preventing a decrease in mechanical strength in the optical fibers when the optical cable is subjected to bending

Methodology Applied
Scientific EffectCombustion inhibition:

Data Source

PatentEP1956404B1Slotted core with improved fire properties for a cable use
Publication Date: 2012.05.16 NEXANS SA
  • EP1956404B1 patent drawingFigure 1

AI summary

The present invention concerns a slotted core (1,10) comprising at least one groove (2) extending along the outer surface of said core, said slotted core comprising a halogen free flame retardant material. The halogen free flame retardant material comprises generally a polymeric matrix and at least one inorganic filler, and aims at delaying the flame propagation in case of fire. The inorganic filler comprises a flame retardant filler, such as a metallic hydroxide, and/or an extender, such as calcium carbonate or talcum. The polymeric matrix is preferably made of polyethylene or polypropylene.